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MEMOIRS
OF THE
NATIONAL ACADEMY OF SCIENCES.
^oluiXLe ITI PART 1.
18 8 4.
WASHINGTON: t>
GOVERNMENT PRINTING OFFIOE.
1 885.
,A-^
^114
n
IS! E M O I R S ,
1. The Sufficiency of Tekrestriai, Kotation Fon the Deflection of Streams ; isv G. K. Gilbert.
2. On the Temperature of the Surface of the Moon ; by Prof. S. P. Langley.
3. On a Method of Precisely- Measuring the Vibratory Periods of Tuning-forks, and the Determina- tion OF the Laws of the Vibrations of Forks ; with Special Reference of these Facts and Laws to the Action of a Simple Chronoscope ; by Prof. Alfred M. Mayer.
4. The Baum6 Hydrometers ; by Prof. C. F. Chandler.
5. On Small Differences of Sensation; by Prof. C. S. Peirce and J. Jastrow.
6. Description of an Articilate of Doubtful Relationshii', fro.m the Teuiiary Beds of Florissant, Colorado; by- Dk. S. H. Scudder.
7. The Structure of the Columella Auris in the Pely'cosauria : by Prof. E. D. Cope.
8. On the Structure of the Brain;of the Sessile-eyed Crustacea. L The Brain of Asellus and the Eyeless Form Cecidot.ea; by Prof. A. S. Packard.
NATIONAL ACADEMY OF SCIENCES.
VOL. III.
FIRST MEMOIR.
THE SUFFICIENCY OF TERRESTRIAL ROTATION FOR THE DEFLECTION OF STREAMS.
THE SUFFICIENCY OF TERRESTRIAL ROTATION FOR THE DEFLECTION
OF STREAMS.
By G. K. Gilbeut.
EEAD APRIL 15, 1884.
It was long ago perceived that rivers of the northern heniisjihere flowing to the north or to the south should by the rotation of the earth be thrown severally against their east or west banks. It is even many years since it was shown by Ferrel that these tendencies are but illustrations of a more general law, that all streams in the northern hemisphere are by terrestrial rotation pressed against their right banks, and all in the southern are pressed against their left bauks, the degree of pressure being independent of the direction of flow. Yet the question of the sufBciency of the cause for the production of observable modifications in the topography of stream valleys is still an open one. A number of geologists have observed peculiarities of stream valleys which they referred to the operation of the law, while others, including myself, have looked in vain for phe- uominal evidence of its efBciency. Nevertheless it is my present purpose to maintain the sufBciency of the cause.
So far as I am aware, all those who have attempted to consider analytically the mode in which the lateral tendency arising from rotation should modify the channel or valley of a stream have reached the conclusion that no appreciable results can be produced, and for the most part their conclusions legitimately follow their premises.* My own different conclusion is based upon an essentially difierent analysis of the processes involved. In the celebrated discussion of the sub- ject in the French Academy of Science, it was computed l)y Bertrand that a river flowing in 45° north latitude with a velocity of three meters per second exerts a pressure on its right bank of 63^39 of its weight, and he regarded this pressure as too small for consideration.! It has been pointed out by Henry Eutf that the deflecting force, by comliining with gravitation, gives the stream's surface a slight inclination toward the left bank, thereby increasing the depth of water near the right bank, and consequently increasing the velocity of the current at the right. To this increment of velocity he ascribed a certain erosive efiect, but regarded it as less than that assign- able to wind-waves on the same water surface. He therefore accorded a more important influence to the prevailing winds than to the rotation of the earth.J It has been held bj' others that the combination of the deflective force with gravitation is equivalent simply to a slight modification — so i'ar as the stream is concerned — of the direction of gravitation ; and that, the flood-plain of the stream having been adjusted normal to this modified direction of gravitational attraction, no other geological effects are produced. The last was my own view until I perceived the importance of certain considerations, to which I now proceed.
The foi'm of cross-section of a stream flowing in a straight channel depends on the loading and unloading of detritus, and is essentially stable. It is evident that the form of the cross section
* 1 hare receatly become cognizant of a discussion by Baines to which this sentence does not apply. See note to the following page.
t Comptes rendus, XLIX, 1859, p. 658.
} Annalcn der Chemie u. Pharii acie, IV Siipp. I Band. Leipzig and Ileidellierg, 1865-1806.
8 MEMOIRS OF THE NATIOI^AL A(3ADEMY OF SCIENCES.
coutrols the distributioti of velocities of curreut within its area, aud that through the interactions of these velocities its parts are interdependent. Each element of its curve is so adjusted to the adjacent curreut and to the detrital load of the stream that it can neither be eroded nor receive a deposit, aud the stability of the profile depends on the fact that an element not adjusted to the contiguous current and load becomes subject either to erosion or to deposition until an adjust- ment is reached. The distribution of velocities within the cross-section is symmetric, the swiftest threads of the curreut being in the center and the slowest adjacent to the banks.
If, now, curvature be introduced in the course of the channel, centrifugal force is developed. This centrifugal force is measui'ed by the square of the velocity, and is therefore much greater for swift central threads of the current than for slow lateral threads. As pointed out by Thomson* and others, the central threads, tending more strongly toward the outer bank, displace the slower threads of that bank, and the symmetry of distribution of velocities is thus destroj'ed. In other words, the centrifugal force develojied by curvature exercises a selective influence on velocities, and transfers the locus of maximum velocity from the center of the channel toward the outer bank. The conditions of symmetry in the profile of the cross-section are thus destroyed: the outer bank is eroded; a deposit is accumulated on the inner bank. Moreover, there is no compensating tend- ency to restore an equilibrium, for the erosion of the outer bank increases the sinuosity of the channel instead of rectifying it. ,
Curvature of course thus causes a stream to shift its channel laterally, and in this manner enlai'ge its valley. It is the most important condition of lateral corrasion.
As shown by Ferrel, the deflective force due to terrestrial rotation varies directly with the velocity of the stream. Therefore, it likewise has a selective influence on the velocities within the cross-section of the channel ; and it likewise tends to produce erosion at one side and deposition at the other.t For given amounts of deflective force its selective power is not the same as that of the centrifugal force developed by curvature of course, for centrifugal force varies with the sec- ond power of the velocity, while the rotational deflective force varies only with the first power; but its selective power is of the same kind, and may be quantitatively compared. For the purpose of this comparison I will develop an equation:
Let F = deflective force, per unit of mass, due to rotfition. n = angular velocity of the earth's rotation. V = velocity of stream. A = latitude of the locality. P = radius of curvature of the stream's course. /= the centrifugal force, per unit of mass, developed by such curvature.
Then
/="^ (1)
and, from Ferrel, |
F = 2to sin A (2)
Let V, = velocity of a rapid-flowing thread of the current, and 0, = velocity of a slow-flowing thread of the current. Eepresent by F,, i^„/, and/", the corresponding deflective forces due to rotation and curvature, then
F,. -F, ^ (*', - i\) X 2 n sin A - . . (3)
and
f:-f,='-l^^l w
* Trans. Brit. Ass., 1876, Sections, p. 31.
t This proposition, which it is the prime object of the present paper to set forth aud develop, was believed, at the time it was read, to be novel, but proves to have been anticipated by more tlian six years. In October, 1877, Mr. A. C. Baines read before the Pliilosophical lustitiite of Canterbury, New Zealand, a paper "On the influence of the earth's rotation on rivers," in which he arrived, by a very ditt'erent route, at essentially the same conclusion. See Trans. N. Zeal. Inst., X, pp. 9-i-iM.
t Ferrel's equation is given on page 2'.), volume 31 (second series), Am. .Jour. Sci. Instead of the sine of the lati- tude, here substituted, it includes the cosiue oC the polar distauce, which is, of course, equivalent.
«L 'iTU'lKNCV OF TKKUKSTIAL JIUTATION lOi; THE I) K FLECTION OF STREAMS. [)
P, — F, ovidi'iitl.v expiesst's tlif st'lcctivi- jiower due to lotiitioii, and /' — ./' siinilaily f^x])resses the selective i)o\veidiie to ciirvatiue. ^^'llel^■ tlie curNanue has a couvexity to tlie liglit, tliese two influences conspire, and their vesultant is deducible by aiUlition. Where the curvature has a left- ward convexity, tlie influences arc opposed, and their resultant is dediicil)le by subtraction. [The terminology here and throughout the renuiinder of the paper is adjusted to the northern hemis- phere exclusively.]
If we represent by K the joint scle(;tive jtower on curvatures of riglithand convexity and b\ /. tlu' Joint selective i)ower (Ui curvatures of lelthand convexity, then we deduce, by simple com- binations and transformations of equations (.S) and (4),
^''^'•- + f- + - i^ii ••<iii A -
L V, + i\ — - fjii sin A
r, and r, may be the velocities of any two threads of current moving at ditferent rates, but for purposes of convenience and simpliticatiou we now assume that they are symmetrically related to the mean velocity r : and introducinj>' this relation in (5) we obtain
R r -\- 1,11 sin A . .
L r — pii sin A
This ecjnation expresses the ratio between the selective luduences tending to determine the maximum velocity toward the right and left banks respectively of a meandering stream. Since these tendencies result in erosion, their ratio is a function of the tendency of a stream to erode its right bank as compared with its tendency to erode the left.
For the purpose of quantitative illustration, the Mississippi River will be considered. In its lower course the shari)er bends have a radius of curvature, measured to the center of the channel, of about S,Ono feet. These curves, together with all other channel features, are determined by the water at its flood stage. It is therefore i)roper to consider in this connection the mean tlood velocity. That was determined by Humphreys and Abbot to be, at Columbus, Ky., 8.4 feet per .second.* The latitude of the locality is 31°. Giving these values to /j, v, and A, and substituting for 11 its numerical value, .()(l(l07i;024, we obtain from (6).
^1= 1.087.
The .selective tendency toward the right bank is tiierefore nearly 1) per cent, greater than toward the left.
With the elements of another stream it is piobablc that a very different result would be obtained ; but this single exam])le suffices to show that while the influence of rotation is small as compared to that of curvature, it is still of the same order of magnitude, and may reasonably be expected to modify the results of the more jxiwerful agent. In the present state of hydraulic science it is im- jiossible to defDue the (piantitative relation between the tendency of swift threads of current toward a bank and the consequent erosion ; but whatever that relation maybe, I conceive that rotation is competent to produce appreciable results wherever those due to curvature are great.
It will be observed that the ctticiency of rotation thus advocated is only in connection with, and as an adjunct to, lateral wear by means of curvature. There are two general cases, including a large share of all streams, to which the conclusion does not apply: (1) A stream which rapidly conades the bottom of its channel docs not notably corrade its banks : and in such case the effect of rotation should not be discoverable. [2) A stream engaged in the deiiosition of detritus, as on a delta or an alluvial fan, shifts its chan'.ud from side to side by a process entirely distinct from the one Just described. It builds up its bed until it is higher than the adjacent plain, and then trans- fers its cunent bodily to aditfeient course, dotation has its share of influence in determining the direction of this transfer; and it thereliy induces the stream to build its alluvial plain higher on the right than on the left; but, the difference of level having been established, the stream has
"Uniiipliii-.vs ;iii(l Alil'iit, Ivi'jimt in\ Mississippi River, p. .">9,^, 8. .Mis. m L'
10 MEMOIK.S UF THE NATIONAL ACADEMY OF SWENCE8.
thereafter no more teudeucy to one side tbau the other. Detlective effects of rotation are there fore not to be songht in regions of alluvial deposition.
It may be remarked also that the tendency of a stream toward one bank or the other by reason of curvature and rotation is often overjjowered by an opposite tendency due to obstructions. These include resisting members of the eroded terraue, and alluvial dams dei)osited at one bank or the other by tributaries.
A general curvature in the course of the valley through which the stream flows has the same tendency as does the curvature of a short bend, only in a less degree; and this tendency must in many instances nullify or conceal the results of rotation.
Visible examples of the work of rotation are therefore to be sought esjiecially in streams which, with courses in the main direct, are slowly deepening their valleys by the excavation of homogeneous material. The best locality of which I have knowledge is one to which attention was called by Mr. Elias Lewis, in the American Journal of Science for February, 1877, and which has recently been visited at my reiinest by Mr. L 0. Russell. The south side of Long Island is a plain of remarkable evenness, descending with gentle inclination from the morainic ridge of tiie interior to the .Vtlantic ocean. It is crossedby a great number of small streams, which have excavated shallow valleys in the homogeneous modified drift of the plain. Each of these little valleys is limited on the west or right side by a bluff from 10 to 20 feet high, while its gentle slope on the left side merges imperceptibly with the general plain. The stream in each case follows closely the bluff at the right. There seems to be no room for reasonable doubt that these peculiar features are, as believed by -Mr. Lewis, the result of terrestrial rotation. As the streams carve their val- leys deeper they are induced by rotation to excavate their right banks more than their left, gradu- ally shifting their positions to the right, and maintaining s'ream cliffs on that side only.
NATIONAL ACAnEMY OF SCIENCES.
VOT.. III.
SECOND MEMOIR.
ON THE TEMPERATIIHE OE THE SIliEACE OF THE MOON.
n
ON THK TR.MrKKATrRK OK THE SIRFACE OF THE MOON.
tKoll Kl-:)lt:AR(HE.S MADE AT THE AI.I.EtiHEAy <iHt<EKrATOItr HY K I: I.ANdl.EY. A.S.SJSTEI' BY F. W. VERY A.\D
.1. E. HEELER.
l!ni/l llrltthri- 17. 1-'>I4.
FioiH tlio earliest ages it lias been observed that tlie moon's rajs bring ns b'gbt, bnt no sensi- ble Ileal. When, in the eonrse of time, the ]>henoniena of nature bej;an to be snbjeeted to more exact scrutiny, it was seen that in view of the very obvious briglitness of the moon, the absence of heat in its rays was an anomalous circumstance, and in the last century Tschiiidiausen, La Hire, and others, with the largest burning lenses or mirrors, and the most delicate thermometers of that rime, attempted to obtain indications of heat, but without success. As apparatus improved in delicacy, it began to be noticed that (on the contrary) indications of actual cold were often obtained when the tliermonieter lay in the focus of burning minors whidi concentrated the rays of the moon on it; its concentrated heat, if any existed, being so nearly «//, as to be overbalanced by the in- creased radiation of the thermometer toward space or to the substance of the mirror itself. Other observers, like Howard,* fancied they obtained signs of heat with sensitive thermonieters, but these were doubtless due to inexperience of the precautions necessary in eliminating the ettect due to the radiations from the apparatus itself, radiatio7is which may give delusive indications of marked lunar heat or cold, according (for instance) as the screen withdrawn be itself (colder or warmer than the thermometer by some immeasurably small fraction of a degree. We can hardly overstate the i)robability of error in such a reseaich in any hands but those educated to multiplied precau- tions, such as were used by Professor Forbes, t who, employing a 'ens by which the lunar heat was concentrated about (i,000 times, still obtained no certain e\idence of heat. He was able, however, to conclude from this negative result that the warming efiect of the full moon on the surface of the earth would at any rate not exceed sooVon o^'* «lt>gi'pe Centigrade.
The lirst satisfactory evidence of actual heat was obtained by .MelIoni,| who, with a polyzonal burning lens of one meter aperture and on^^ meter focus, with the newly invented thermopile, in the clear air of Vesuvius, after due inecautions against instrumental error, was enabled to announce that indications of beat had been obtained, though the eflect was still all but immeasurably small. Prof. tMazzi vSinyth, ? uixm the Peak of Teneritfe. obtained also some apparent indi(!ations of heat, but all these measures, and a large number of others which 1 do I'ot cite, including those of such skilled observers as Tyndall II and Huggins,1] lead only to the conclusion that the moon's heat is so small that we can do little more than detect its existence, though M. Marie Davy** a little later obtains some apparent evidences of the change of heat with phase, indicating a direct eft'ect of about yjToVo-o degree for the full moon, wiiich he observes is about the one-fiftieth part of that found by Smyth. Such was the state of our ex|)erimental knowledge of the subject until the time of the observations of the present Karl of lJi>sse, which, as marking (piite a new order of accuracy in lunar heat measurements, we reserve for a subse(iuent and more detailed discussion.
' Ameiirun .loiinial (il' Scii'iice, II. |i. :!-29 (18-211).
t London Pliil. Magazine, vi, ji. IXS (1*!5).
; Coniptfs icndns, xxii, p. :AI (184()).
* Report of the Tencritie As(roDoniic:il Kxpei imeiit, aildiessed lo tlie l.ciiils Ciiiiiniissionerx of llie Ailniiiall y.
II Phil. Mag., IV Series, xxii (1861).
T Proe. Royal Society, vol. xvii (18(19).
•'Coniptes rendiis, Ixix (l."'*)!)).
14 MEMOIliS OF THE NATIONAL ACADEMY OF SCIENCES.
Tlie amount of lieat received from the moon, and tlie dependent question as to the temi>era- ture of tlie lunar surface, are subjects of greater interest to us than might at first appear. They aie even ones in which we may be said to have a material concern, for until we know the tempera- ture which an airless jdanet* would attain in the sun's rays, we can have no accurate knowledge of the extent to wh ch the atmosphere of our own planet contributes to its heat, nor of some of the most important conditions of our own existence. Those conditions are only lately becoming known, for it has hitiierto been supi)Osed that the temperature of the earth's surface was chietly due directly to the radiation which it receives from the sun. It has l)een admitted, indeed, that the air acts to some extent in increasing the heat by hinderin^the radiation from the soil, bnt the man- ner and extent of this action have scai cely been, as it now appears, even surmised. Thus Sir John Herschel, distinguished as he is as a meteorologist as well as an obseiver, transferring to the moon conceptions drawn from the supposed state of things here, states that the temperatuie of the moon's surface in the lunar day must rise to L'OOo or ;50(to Fahr., and sink nearly as far below zero during the long lunar night, and the idea that the airless snrfaceof the full moon must be intensely hot (in comi)arison witli ordinary terrestrial temperatures) has since been generally accepted, Almost the oidy dissenting voice lias been that of Air. John Ericsson, who asserts that the lunar surface must, on the contrary, be intensely cold. In the ])resent writer's opinion, the temperature supposed h\ Herschel, if it exist on the moon, will imply the presence of an atmosphei'e there : and if we can set aside the weight of traditional belief and preconceived imiucssion the snpi)osition that the surface of the moon (if absolutely airless) must be cold, even in lull sunshine, is one which, however ])ara- doxical it may a])pcar, we are led to entertain by evidence at the C(Uiimand of everybody who can ascend high in our atmosphere. As we go up a mountain, we do not find the soil growing hotter, but colder, in the sunshine; and at great elevations, where the barometer is low, and we are partly approaching the conditions which must pievail on the moon (if airless), we find the surface covered with peri)etnal snow, even under the intenser solar blaze. The direct rays, indeed, are hotter, but the radiation from the soil is so far greater than below that, on the whole, with every upward step that diminishes the protection of our atmosi)heric envelope, the surface tencis to grow colder. This is a matter of the most frequent observation. It is confirmed by the analogous experience of aeronauts, and it bears to my mind but one interpretation, that if we ascended still higher, until the air had been left altogether behind, we should find there regions of still intenser cold than any which we have experienced at the highest altitudes attainable by man. It has indeed been urged that the cold of high altitudes is largely due to the expansion of ascending air currents and to analogous causes, but our conclusions also rest on means whicli are indepeiulent of this hypothesis. In ISSl the expedition under the writer's charge to Mount Whitney, in the Sierra Nevadas, made many hundred actiiiometric observations at altitudes of from 3,000 to l.">,000 feet upon the direct solar radiation, and its power to heat a thermometei- bulb virtually renioveil from every disturbing influence, so that it was possible to estimate the result which would follow if the air between it and the sun were wholly withdrawn : the conclusion being that the tempera- ture of the surface of the earth in full per|)etual sunshine would, in the entire absence of its atmos- phere, not rise much more than 4-S^ C. over that of surrouiuling space. Mow. the "temperature of space" must be conceded to be a vague and unsatisfactory term. To gi\e a meaning to the expression we must ask what final temperature the earth's surface would attain were the sun's radiation and its own internal heat wholly cut oft', and it were warmed oidy by radiations from other heavenly bodies, visible or invisible, or by the dynamic effects of meteorites, &c. I'ouillet's conclusions are well known. The writer has reached much lower values, which he will not under- take to here state or exi>lain. l''or the present [mrpose it is sufHc-ient to say that, in his belief, the surface temiierature of our planet, so far as it is due to direct solar radiation, would jirobably be such, that every licpiid we know, and perhaps every gas, would exist only as a solid, though beneath the vertical rays of the sun.
It is hence almost wholly to our atnir»pliere and its capacity (by selective absoiiition) of stor- ing the solar heat that, in the writer's view, we owe the high temperatuie which makes our exist-
" CVrtaiii ili.S(ie]>iiiicifs lietweeii oliseiviilimis on tcnesli.Tl :iinl lunar radiiitiiin snggest to ns, liowever, tin- )iossi- bility of the fxistencf of a iiiinnte Innar atirjosplieie, too small lor ift'ognition liy tin- t<-lesro])f.
TKMI'KKATl ItK OK THE SUIM-'ACE OK THE MOON. 15
cuvc (iti tlic (Mrtli's surfaco possible I'lit sticli coiiclii.sioiis arc, it must 1)h adrnittiMl, in (',()iitia(li(;- tioii not only to tlie statement alieail.v ((noted fiom Sir -loiin Heiscliel, lint also to what lias been regarded as direct exiierimeiital evidence as to the high temperature of the Innar surface obtained by the Karl of Rosse (that is, if we admit the moon to be absolutely airless, as Sir John Uerschel assumes it; for it is not only possible, but even probab'e, that a gaseous enveloite to the moon, too small to make its presence known to oidinary astiononiical observation, would greatly raise the temjieiature of its surface, and the not impossible existence of sn(!h an envelope mnst be here borne in mind).
liOrd Kosse's oltservations, in which, as we have already leiiiarked, anything like ((uantitative measurement of the lunar heat has for the first time been attained, we shall jiioceed to examine in some detail.
AHSTUACI UF IJH!I> ROSSICS VAfKUS US IHE UADIATIOS ill' HEAT FliOM IIIE MOOS', HITH COM-
MESTS liV rilK I'KESESr II HI TEH.
[l'ri)f<T(liiij;N IJiiyal .Society, XVi, \>. 4:i(_i (IStJU).]
'I'lic olijcct of tlic oliseivalioiis ili.scMsscd in tlii> iiapef i.s the ileteniiiiiatioii of wliat inopoi tions the lunar railia- lioii loMtains of —
1. Heat loiiiing from the interior of the moon, whieh will uot varv with the phase.
','. Me.it which falls from the snn on the inoon'.s Mirface and is at ouce retlected ref^nlarly and irregularly.
:i. Heat whieh, fallinj; Iroin the sun on the moon's surface, is ahsculieil, rai.ses the tempirature of the surface, and is afterward radiated as heat of low refranjiibility.
The apparatus emidoyed was a :5-foot rcHecting telescope, with two small coiideiisiug mirrors and thermopiles. (A tahle of observations made at diltereiit phases of the moou is then given in the original paper.)
Assuming that the moon is a smooth sphere * without specular rcHection, we may compute, from theory, the form of a curve, represeutiug the amount of heat received from the moou as a function of her phase. This curve approxi- mates to a sinuous form, having a greater curvature at the maximum or at lull moon than at the minimum. The ob- servations given in the table fall tolerably well on this curve, and therefore the increase and diuiinutiou of heat with the varying phase of the moon follow the snuw law as that of light. Tlie heat classilied under head (1) can have no existence in this case.
We may seek to deterniinc the relative proportions of (2) and (:{) present in the lunar radiation by experiments with thin plate-glass.
About 80 per cent, of the solar radiation probably pa.sses through glass, from direct observations it was fouiul that only 8 per cent, of the moon's rays was transmitted by the piece used in the experiment.
From this resitlt, and the generally accepted value of the ratio of sunlight to moonlight, we may deduce the ratio of solar to lunar heat radiation. T« do this Lord Kosse assuniest that all luminous rays are transmitted by glass and all obscure rai/s iire Hojiped.
We have then (according to him)
Percentage of luminous rays in lunar radiation 8 per cent. Percentage of luminous rays in solar radiation 80 per cent. KatioJ of solar to lunar luminous rays = 800. 000 : 1. liatio of total solar to total Innar radiation = 80,000 : 1.
The correctness of the value obtained for this ratio is confirmed liy other considerations: in the lirst place, by direct measurement. §
The sun's rays were reduced by jia.ssing through a small aperture, and the deviation of the galvanometer con- nected with that previously found for full moon, by using the ileviation produceil by a vessel of hot water as a term of comparison. The ratio thus found was 89,81!) : 1.
We may also dud a value of this ratio fnun theoretical eonsidcration.s. To do this he makes the Ibllowiug assump- tions the basis of calculation :
• ZoUner has shown that the lunar surface retleets nearly like a Hat ilisk, but the observations of Lord Kosse, "•iveu in the table, are subject to so great uncertainty, that they would fall eiiually well upon Ziillner's curve.
tThis assumption is so far from the facts now known as to make the determination of the heat ratio depending u)ion it of little value, for it is now ascertained that in the solar-heat siiectrum fiumed by a glass prism nearly two- thirds of the energy is represented by invisible rays.
: Lord Ko:<SK assumes the largest known determination (800,000 to 1) as the most probable. There are, however, from eight to ten determinations by observers of repute, and all of theiu smaller: and if we take the mean of these, we have, as elsewhere shown, the approximate ratio 4tlO,000 to 1. The agreement of the value 800,000 with the values obtained by the other methods given, on account of the falsity of the fundamental assumption of the latter, can ouly be regarded as a coincidence.
v\ To the fj-zif/imeKfa? determinations of tin' solar and lunar-heat intio \yx. make no obji'ction, and they are probably as reliable :is any others.
l(j MEMOIRS OF THE NATIONAL ACADEMY OK SCIENCES.
1. The unaiitity of beat leaving tlie moon at auv instant may witlumt mncli cnor be eousiileieil the same as that i'alliug ou it at that iustaut.
2. The absorptive power oi'onr atmosphere is the same tor Innai- ami solar heat.
3. As was assumed in a previous formnla, the moou is a smooth sphere, not capable ot'retleetiiig heal regularly. Deducing a t'ormnla for the amount of the moon's ditfuse heat received by the earth and substitutiug in it the
necessary values of the <iuautitles entering, we tind that the amount is yin'ijjir of that received from the sun : a result which agrees well with the previon.s values.
The value of the galvanometer deflections was obtained by comparison with a vessel of hot water, which sub- tended the same angle at the thermopile as the large mirror. It was then found (the radia ing power of the moon being supposed equal to that of the lampblack surface and the earth's atmosphere not to iutluencc the result) that a deviation of Oil for full moon (about the average ettect) appears to indicate an alteration of t<'mperatnre through hiW' Kahr. In deducing this result' allowance has been made for the imperfect absorption of the sun's rays by the lunar surface.
These observations must be regarded as merely preliminary, and the results may be sniiject to revision wlien more accurate measurements are obtained.
[Proceedings Koyal Society. XIX. page y. (Itf/d)].
In the preciding paper it was shown that a large. iiortion of the total lunar radiation cimsists of rays of low re- IVangibility emitted by the heated surface of the moon, which in the time of a complete revolution pa.sses through a range of probably more than ,)00" Fabr. of temperature.
The ratio of the intensity of solar heat to lunar beat, as deduced from the observations, agreed well witli values gi\en by independent determinations.
Since the last communication, more accurate measurements have been made, with results substantially the same as those reached in Irtti'.l.
The glass used was found to transmit 87 |ier cent, of the sun's rays. \'i per cent, of the radiation from the moon, and 1.6 per cent, of that from a body at l;iO^ Fabr.
Assumiugt then that 92 per cent, of the luminous lays in either moonlight or sunlight is transmitted V>y glass, and l.Gjier leiil. of the obscure rai/s traiixmHted. and tailing 82,60(1 (found by direct experiment) for the heat ratio of solar to lunar rays, the resulting value of the light-ratio is 676:!d0: 1. which agreeing well with the accepted value, show 8 that the heat ratio 82600 : 1 is very nearly correct.
In these experiments the quautity measured by the tberumpile was the ditlereuce between the radiation from the circle of sky containing the moon's disk and that from a circle of sky of equal diameter not containing the moon's disk : no information in reference to the absolute temperature of either the moon or the sky results from them. 'I'be aiiparent temperature of the sky was found by coniiiarisous with the radiation from blackened vessels of hot watei at different temperatures to be from 17 to '.i'i- Fabr. If the temperature of space be really as low as has been suji- jiosed, this result .seems to indicate considerable opacity of our atniospbere for heat-rays of low refrangibility.
'I'he observations made to determine tin! dependence of the beating power of the moon, on her allitude, and the law of extinction of her rays in our atmosphere, are not veiy .satisfactory on account of changes in the sky, which jireseiit greiit obstacles to measurements of this character.
The curve deduced in the first paiier is given together w ith the later observations. As far as can be juilged from so few and imperfect experiments, the maximum of heat seems to be a little after full umon.
[Proceedings Koyal Society, XXI. p. 241, (187:t).]
In this )paper is given the result of recent and more careful observations made for the purpose ot determining the- depen<lence of the moon's heating power upou her altitude, the curve obtained being uearly but not <inite the same a* that found by Professor Seidel for the light of Ibe stars, and showing a greater extinction of light than heat. Hy employing the table thus deduced, and introducing a correction for etiect of change of distance of the sun, a move accurate phase curve was deduced, indicating a more rapid increase of the radiant heat on approaching full moon than was giveu by the formula previously employed, but still not so much as Professor ZiiUner gives for the moon's light. At 79'^ zeuith distance, the etiect of atmospheric absorption is about one-tenth of the whole amount. Lord Rosse oliserves that Ibis difference may be due to the fact that Seidel's light observations were made on the stars, not on the moon, and that it hence does not necessarily imply a different law for the extinction of light from that tor beat.
From a series of simultaneous measurements of the moon's beat and light at intervals during the |)artial eclipse of November 14, 1872, it was f^/uud that the heat and light diminish nearly, if not quite proportionally, the miiiiujiim for both occurring at or very near the middle of the tclipse, when they were reduceil to about half what they w ere before and after contact with the penumbra.
The probable error of a single set of 10 galvanometer readings at this time is given as about I'J per cent., or about 8.7 per cent, for the jnobable error of a night's observation: but Lord Kos.se concludes that so large constant errors were probably present, tbat any inerea.se in the number of sets was almost powerless to obtaiu a nuire reliable result.
* It will be seen by reference to a subsequent paper that this result is considered to be erroneous. What is meant by an allowance for imperfect absorption by the lunar surface is n<it <leai,
tThe assumidions we have italicizeii iit'f^ little mater tlie ti'nt|i than those ot the previous papn and the result entitled to little more weight.
TEMPEKATUKE OF THE SURFACE OP THE MOON. 17
INatnro, XVI, \i. 43S (1877). Lofter by Lord Rosso, ropl.viii^ to M. Railliiid, who aitiibntcs the reddish tiiifie of the totally oilipsed moon to selt'-liiniiiiosity due to the high teiiiperatiirc^ acciuired iiikUu' the snu's rays, and cites olisi'i'valions of Lord Rosse in support of his views.]
M. Rnillard is mistaken in supposing- that Lord Rosse estimated the temperature of the lunar .surface at 500° Fahr. This was the range of temperature which a lanip-blaclicned vessel must have in order to exhiliit etfecis similar to those of the moon in its dill'erent phases, deduced from early ob.servatious. More accurate ob.servutions (descrilied in previous papers) show that this range is much more nearly 100'^ C, a large error having crept into the previous work. The observations made during the total Innar eclipse show that the diminution of heat ke|)l pace with that of light. Probably not nu)re than 5 per cent, of the heat, a squired since new moon is retained till the midiUe of a total eclipse, although it lias beeu shown that this heat has been absorbed by the lunar surface and reradiated. We must therefore fall back upon the usual cxplauatiou for the reddish oolor of the moon's surface during a total eclipse.
Urania I (IHHl).
On comparing the heat curves between new and full moon with that between full and new moon there appeared no conclusive evidence that the lunar surface required liuie to acquire the temperature dno to the radiation falling on it. Accordingly, observations were made at the eclip.ses of November 1-1, 1872, and August 23, 1879, but the result of these was to show that the decline and subsequent increase of the heat took place as rapidly as that of the light.
[Nature, XXX, p. 589 (October 16, lS-'4). Description of observations made during the total luuar eclipse of October 4, l884^by Otto Bocddicker, at the Earl of Rosse's observatory.]
The apparatus used was the same as that already described. Clouds prevented observations until 30 minutes before the beginning of the total phase, when the sky became exceptionally clear.
Two hundred and eleven readings of the galvanometer were taken, the time of exposure being 1 minute for each. (A curve representing these observations is given.) No observations were made during the total phase on account of the difficulty of judgiug wheu the image fell on the thermopile, but near the beginning and end of totality the effect was masked by the irregularities of the galvanometer, and was smaller than the probable error of observation. The minimum of heat seems to be later than that of light. As the moon emerged from the earth's shadow, so slowly did the reailings of the galvanometer increase again that, about twenty minntes after the total phase was over, the almost entire absence of any effect led the observer to think that the small condensing mirrors must be covered with dew, which however was not the case. *
PRELIMINARY OBSERVATIONS AT ALLEGHENY.
OBSERVATIONS ON LUNAR HEAT.
The first irieii.sares of liinar heat at Allegheny were made ou the evening of November 12, ]8S0,t more with a view to testing the sensitiveness of the then recently invented bolometer than for the sake of the measures themselves. The lunar rays were concentrated upon the face of the bolometer by means of the 13-inch equatorial of the observatory and a smaller convex lens near its focus, and an average deflection of 42 divisions of the galvanometer scale was obtained. The exposures were made by directing the tel< scope upon the moon after the galvanometer needle had come to rest, while the telescope was pointed at the neighboring sky.
On June 21, 1SS3, the bolometer and its adjuncts having been much improved in the interval, measurements of the luuar heat were resumed with apparatus better adapted to the purpose. The thick glass lenses, used in the previous experiments, absorb and reflect a large proportion of the already snfliciently minute amount of heat at disposal, and the rays absorbed are those whose presence or absence chiefly affects the conclusions to be drawn from the results of the observa- tions. In the new experiments, therefore, the dioptric system for condensing the lunar rays was rejtlaced by two silvered-glass mirrors, the absorption of silver for every iieat ray of thes])ectriim having beeu determined by previous exijeriments here. This absorption, as is well known, afi'ects chiefly the blue and violet rays, in which but a small proportion of the total energy resides. Our own observations show this absorpti(m (by silver) to be very small and tiearly constant throughout the infra red. The sensitiveness of the bolometer, and its accuracy, enable us, as will be seen, to
*Althovigh over one fourth of the moon's surface must have emerged from shadow at this time, it must be remem- bered that it was still covered by the earth's penumbra, so that the small heating etl'ect is less surprising. If the moon parts with its ac(|nircd beat so soon as these eclipse observations seem to indicate, it is difficult to see how the maximum of heat could occur at an ajipreciable time after full moon. It is in any case hard to admit that this beat from the lunar surface, which the moon has been absorbing during many days of continuous sunshine, is parted with at once, the whole earthward surface of the planet cooling almost instantaueou.sly. t American Journal of Science, CXXI (March, 1881). S. Mis. 69 3
18 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
obtain with a comparatively small mirrer, concentrating umch less heat than that dealt with by the 3-tbot reflector of Parsoustown, much more consistent indications.
Tiie lunar rays, reflected from the IL'-inch silvered mirror of a large siderostat, pass horizon tally through an 8-inch circular ajierture in the north wall of the observatory dark chamber, and fall upon a 10-iuch concave silvered glass mirror of abont .'?() inches focus, mounted on a very solid tripod stand.* The bolometer, in a case specially designed for this work, is mounted on a sliding carriage directed toward the center of the mirror, so that it can be adjusted to such a distance as to bring the working face of the instrument into the plane of the lunar image. The bolometer case referred to has a series of circular dia]ihragms of various ajtertures so disposed as to protect the bolometer itself both from air currents and extraneous radiations, while just admitting the cone of rays from the concave mirror.
This mirror is inclined slightly to the incident rays, so that the bolometer can be placed a little to one side of the Inrgi- ajierture in the wall and not obstruct them. The hniar image can theu be adjusted by means of the uiillcd headed screws, by which the mirror is secured to the vertical plate, so as to fall truly on tliM bolometer strips before observation, and afterward in actual observation be cariied on or off by a motion of the sideiostat niirror outside, or by the nuxni's own motion in the heavens. In either case no screen is interposed, and no alteration in the relation of the radiat. ing objects around takes place in reference to the bolometer, which experiences no changes, except those which come from its alternate exposure to the moon and the neighlioring sky.
The lunar iuuige is about O.liO inch in diameter, and when properly directed is received by the workiugfaceof the bolometer, which it very nearly covers; hence it will be seen that (neglect- ing the absoriition of the mirror, which is very small lor invisible heat rays), remembering that only eight inches of the mirror's diameter is utilized, the intensity of the lunar heat was increased from 780 to 1,050 times, according as the distance of the moon from the earth varied. On a clear night with a full moon, and the galvanometer in its condition of then greatest sensitiveness, a deflection of 300 millimeter divisions of its scale could be obtained (in 1883), but toward the close of 1884, with still further improvements in the apjiaratus, this limit was much exceeded.
The "exposures" in later and adopted measures were only made, as we have said, by moviur the image of the moon on and off the strijts of the bolometer, by slightly inclining the siderostav mirror, thus simply replacing the image of the lunar surface by one of the adjacent sky. This was readily efl'ected by means of a pulley on the azimuth screw of the siderostat from which a cord led into the building.
This method, we repeat, leaves the radiation from the apparatus itself unchanged by the introduction of the lunar heat, and avoids the disturbing inliuences which come from the interpo- sition and withdrawal of a screen. Other methods, however, were tried in these earlier experi- ments, such as that of displacing the image by turning one of the screws of the concave mirror mount. This method, though sometimes yielding identical results, was found to be liable to errors, as V as also that of the use of a screen, and in a still greater degree. It is not always easy to point out the exact nature of the error introduced in these delicate determinations, but we will give some of these preliminary observations to show the nature of the discrepancies presumably due to such methods of exposure, t
The character of the lunar energy, as compared to the solar, was first investigated as in Lord Rosse's experiments, by detej mining the relative transmissibility of the lunar and solar rays, as a whole, by certain pieces of glass, which were interposed in the path of the rays immediately in front of the bolometer case. Four pieces of glass were used for this ])nrpose. The first was a disk 4.2 millimeters thick, of the same glass as the i)rism made by Adam Ililger, of London, used in a previous determination of wave-lengths in the infra red of the solar spectrum ; the second was
* See Plate 1, wliere M is the concave mirror; B, the bolometer; C, the cable connectiag it with the galvauom- eter; G, the place at which llic glass is iuterposed.
tTlie appaiMtus aliovc ilcscribed, as ciiiployctl in 1883 and tlie snninicr of 1884, is snbstanlially the same as tliat used in the later Inuar heat iiicasiircs, the chict iinprovcnieiits, since it was conijih ted, lia\ ing been made in the gal- vanometer and other electrical ad jnncts of the bolcnu-ter. For a description of this instrument the reader is referred to earlier papers by the writer in the Trocecdiugs of the American Academy of Arts and Sciences, xvi, 1881, and the American Journal of Science for March, 1881, and to details given later ou in the present memoir.
TEMPKIJATLTEE OF TDK SURFACE OF TOE MOON. l9
a pii't-e of plnte glass ("A") 0.9 niilliiiieters tliick, ajiparOntly of Eiiglisli make; tlie tliird ("B") a piece of Ameiicaii plate glass, sliglitl.v greoiiisli in hue, C.(! inillinieteis tbick, and tlie fourtli a large pane of American window glass of good (piality.
On July n, 1883, October -1, 18S4, and November 20, 1884, the diathermancy of these specimens of glass was determined for solar rays. The values obtained were :
Tor cent.
For tlie Hilger glass 86
For Glass A S(i
For Glass B 77
For the large pane 70
the zenith distance of the sun being about .50°, or in the last case over 00°.
We have not as yet reduced these observations taken at somewhat different altitudes of the sun and moon to one common altitude, because it is sntliciently obvious from a comparison of the above figures without such a reduction with those indicating the absorption of the lunar heat by the same siiecimens of glass, that these absori)tions are strikingly different in the two cases, and far more so than any difference in the altitudes of the bodies under consideration can account for. "We will iiass, then, to our ]ireliminary obser\ations on this unequal absoriition before introducing small corrections which would be sn])erfluous at this stage of the inquiry.
Preliminary measurements were made in pursuance of this system on the night of June 21, 1883, when all atmospheric conditions appeared to be favorable. A screen was, however, employed ou this night to cut off the lunar rays, and the exposures made by withdrawing it (a method not capable of giving exact results).
If the glass be interposed while the lunar rays are falling ou the bolometer, radiations from or to its substance will in general be confused with the effect to be studied, and further the radiations of low refrangiljility from surrounding objects, such as those from the substance of the condensing mirror, will be cut off by it. It is always a cundition of good observation, tlien, that the glass be placed in front of the bolometer and the instrument allowed to register its separate effect before the lunar rays are allowed to fall upon it; and this method has always been used.
It was Ibund from the series of observations that the i)ercentage of the total lunar heat trans- mitted by glass A was 70 per cent, and from a second series 54 percent., giving a mean for glass A of 02 per cent.
For the ])ercentage transmitted by glass 1> were obtained the values GO i)er ceut.,.4Gper cent., and 58 per cent., giving a mean of 55 per cent.
The discrepancies in these preliminary results were partly due to the above mentioned erroneous method of exposure by withdrawal of a screen, but also to the difficulty of telling when the luiuir image was exactly coincident with the bolometer face, since, when this was not the case, part of the heat was wasted and the deflection obtained too small, and the eye could not be safely brought into a position where the strijis could be seen, since then the radiation from the ob- server's face gave a large detlection. This difficulty was subsequently overcome by placing a large sheet of glass behind the mirror, through which the observer could regard the bolometer strips without producing any disturbance of the galvanometer, the radiations from his face being com- pletely intercepted by the glass. The conclusion, apparently resulting from the preliminary ex- periments where a screen was used, is that the specimens of glass appeared to transmit the greater part of the moon's rays; but that the ai)parent transmission of the glass should be greater w hen ex posure is made by the withdrawal of a screen may be inferred from the following considerations. The screen is in general warmer than the external air, and if withdrawn while the bolometer was directed to the sky near the moon, a negative detlection of the galvanometer would be produced. When the screen is withdrawn while the bolometer is directed upon the moon, the heating effect of the latter is partly counteracted by the cooling effect of the sky or air between us and the moon, and the detiectiou obtained is smaller than that which would have been produced if the bolometer had been continuously exposed to the radiation irom the sky. When, however, the glass is inter- posed, it forms a barrier to the interchange between outside objects of low temperature and the bolometer, and nearly the same detlection is obtained whether a screen is used or not. By the use
20 MEMOIRS OF THE NATIONAL ACADEMY OF SCIEXCES.
of a screen, therefore, the aj^parent transmission of lunar heat by glass is larger than it otherwise would be. *
These and other preliminary observations, then, are not used in the final results, but it has been thought worth while to refer to them to indicate some of the subtle causes of error which beset the commencement of such a research.
SUBSEQUENT OBSERVATIONS ON THE TRANSMISSIBILITY OF GLASS FOR LUNAR RATS.
In October, 1884, these observations were again taken up and the transmissibility of the same pieces of glass redetermined.
The method of procedure was as follows : The apparatus being in adjustment and the galvano- meter needle in a position of equilibrium, the lunar image was thrown on the bolometer by turning one of the concave-mirror screws, and the deflection of the galvanometer noted. Then the lunar image was thrown oft' the bolometer, and the new position of equilibrium noted, to which the gal- vanometer needle returned. This was generally slightly different from the original position. From these readings was obtained the effect of the uninterrupted lunar beam. A piece of glass was then interposed immediately in front of the bolometer case, and alter the galvanometer needle had taken a\t a new jiosition of equilibrium, caused by the alteration of conuitions in regard to its thermal exchanges with the glass itself and with outside objects, the same operation was re- peated, and the effect of the lunar ray obtained after it had suffered reflection at the surfaces and absorption in the substance of the glass. The following resnl's, which are the means of repeated observations, were obtained bj' the writer under favorable conditions, except that exposures were made by touching the adjusting screw of the concave mirror, instead of tliat of the siderostat mirror. The image of the moon is thus replaced by that of the neighboring sky, but since the concave mirror is within the building, an alteration of the thermal conditions may be produced by an increased reflection of heat from the walls of the ai)artment in the mirror.
* To put this into syniljolical form, let C = the amonnt of heat received from the walls of the bolouieler case, « = the heat received frniii tlie sereeu, g = the heat received from the substance of the glass, S = the heat received from the sky, »ii = the portion of lunar heat transmitted by glass, and m-z = the portion of lunar heat absorbed by glass.
First Ktrji of uhxervulion. — Tlie bolometer is exposed to the radiation from the screen, which is interposed betwc en it and the sky. The heat received is then C -\- s.
Second step of ohsen'alion. — The screen is then withdrawn and the bolometer exposed to the moon. The heat re- ceived is C -|- Mil + i«2 + S.
The deilectiou of the galvanometer which is produced is due to the difference between these two amounts of heat or to nil + 1112 + <S' — ».
'Third itep of oliserrution. — The screen is again interposed, and the plate of glass, completely cutting oft' the radia- tion from the screen, is ])laced in front of the bolometer, which then receives the amount of heat C -\- g.
Fourth itip of ohserfntiDii. — The screen is now withdrawn and the bolometer again directeil toward the moon. The he.at from the sky, S, which consists entirely of radiations of long-wave length, is also completely cut otf by the glass, and the amount of heat received by the bolometer is C -f »»n -f- g, so that the resulting deflection of the galvanometer is proportional to (C -j- m.; + ff) — (C -|- g) = iii^.
The ratio of the two deflections obtained as above is the apparent transmissibility of glass for lunar heat, and it is therefore
= (,
nil +"11! + *' — s
If observations had been made without the use of a screen, by moving the siderostat mirror, the transmissibility would have been
JBi -I- nki
= f2
The quantity of heat, <S, depends upon the apparent temperature of the sky: that is, npon the temperature of the external air, and as this, except iu an unusual combination of circumstances, is lower than the temperature inside the building, S — 8 is negative, and consequently /i ]> t^.
TEMPERATURE OF THE SURFACE OF THE MOON.
MfasnremenU.
21
|
Radiatidii iiu-asiircd. |
Dclicctioii. 260 70 230 69 234 77 237 64 233 71 238 62 236 |
Amount transmitted. |
|
.29 |
||
|
Diiict lioat |
||
|
Hil"or ""lass |
.30 |
|
|
Diifct lieat |
||
|
Glass B |
.33 |
|
|
Direct heat |
||
|
Glass B |
.27 |
|
|
Diiect. heat |
||
|
Glass A Dii'fct heat Glass .\ Divfct beat |
.30 |
|
|
.26 |
||
|
■ |
From these ineasnreineTits it was coiicliuled that the Hilger jrlass transmitted 2ft percent., the glass A 28 per cent., ami the glass B 30 ])er cent, of the lunar radiation under the conditions iu question.
A similar series of excellently accordant observationson the same evening by another observer placed the trr.nsmissibility of the Ililger glass at 27 per cent., of glass A at 27 per cent., and of glass B at 26 per cent.
The most striking feature about these results i.s their very fair agreement among themselves and yet their discordance with the previons measures of June 21, which also exhibit no striking discrepancies of au order equal to that existing between the two sets of measurements. Ifc was therefore concluded that this discrepancy was in all probability chiefly due to purely local causes affecting the couditiou of the a])paratns at the time of experiment, which we "have reason to believe is in a large measure accounted for by the differing methods of exjiosure, and at the follow- ing lunation the measures were repeated, varying these conditions with especial regard to the fol- lowing points: (1) Temperature of different portions of the apparatus, particularly of the large concave mirror; (2) temperature of the glass; and (3) place at which the glass was interposed. For the piP'pose of varying tiie latter condition, the large pane of window glass, already referred to, was fixed in a frame so fastened to the large flat of the siderostat that the lunar rays incident on the flat were first obliged to pass normally throngh the glass, without, however, being inter- cepted by it on their way to the aperture in the wall of the building.* Tlie glass could be instantly withdrawn from the frame when desired and interposed immediately in front of the bolometer as in previous experiments, or elsewhere iu the i)ath of the rays. These later experiments were car- ried out with all due pi-ecautions, exposures bciing made only by inclining the siderostat mirror by means of its azimuth motion iu the manner x>revionsly desciibed. The transmission of the large pane for .solar rays was determined with special care by a long series of observations, and was substantially the same as that given by former measures. The same apparent transmissibility was found for all positions of the glass, whether in the open air above the siderostat mirror or imme- diately in front of the bolometer case inside the building.
Experiments on the eflect of varying the temperature of the glass and concave mirror by warming were only partially successful, since the immediate eflect iu either case was naturally that the progressive cooling of the heated object produced a violent "drift" of the galvanometer needle, so that measurements could only be resumed when the temperature had fallen nearly to that of the sujrounding objects. Within this limited range of temperature, however, the trans- mission of the glass did not ai)i)ear to vary as it presumably would have done had there been any change iu the bygrometric condition of the surface of the plates or other disturbing cause.
"Since glass is atUermanous to radiations from sources of such temperature as the b(dometer strips or the walls of the room, its position with reference to these might (conceivably) aft'oct the result. Although tlie mode of observa- tion was calculated to eliminate any such effect, the experiment of placing the glass outside the building was there- fore tried.
22 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
For the transmission of tlie large pane for lunar radiation were obtained the values:
Per cent.
Meaa of observation of November 20 12. 2
Mean of observation of December 2 14.5
Mean of observation of December 3 14. 9
Mean of all 13. 9
(the moon's zenith distance being about 45°.)
Observations on the variation of the coetficient of transmissibility of the lunar rays at differ- ent altitudes of the nioou have been made at every opportunity, Ijut the results are so dependent on fluctuations in our atmospheric conditions that they are at i)re.sent only to be interpreted as showing that, if there be a difference in transmissibility of glass for lunar rays at ditt'erent altitudes of the moon, this difference is not a conspicuous oiu^.
Among tlie substances, whose power of transmitting the lunar i-adiation was tested, was a very thin disk of polished ebonite (thickness = 0.28 millimeters) through which the moon, when viewed with the naked eye, ai)|ieared of a dark-red color. It was found by experiment with tlie bolometer that tliis ebonite disk transmitted CO per cent, of the moon's rays. Its transmission of tlie solar ra,')S was 32.4 per cent. The transmission of the large pane for solar rays was also carefully rede- termined, with the following results:
Per cent.
Mean of observation of November 26 75. 6
Mean of observation of December 3 75. 1
These values are quite in accordance with those iireviously given.
All of the later and more careful observations show, therefore, that, whereas nearly 70 per cent, of the total apparent solar radiation is transmitted by the large pane of glass, only about 14 l)er cent, of the total ajjparent lunar radiation is transmitted.
PRELIM IXAHY VBOTOMEiniC OBSERVATIOXS IN 18S:i.
The low transmissibility by glass whicli the lunar rays have been shown to possess by the experiments described in the first part of this paper is quite conftrmatory of the experimental results of Lord Rosse, though not necessarily of his inferences from them. As we shall see, it may be partly accounted for by the supposition that the rays which reach us have sufiered selective reflection at the surface of the moon. It is quite evident that, if selective absorption of heat take place, we ougUt to see it iu the study of those heat rays whiiih are also seen as " light." Moreover, as rays emitted from a source eveu of the temi)erature of boiling water can have nothing to do with vision, we shall not be liable to confound what we see with any efi'ect due to radiation from'the lunar soil, for what we thus observe must be due to retlected heat only (since "light" and "heat "are but names given to different manifestations of the same energy). Accordingly, if photospectro- metric observ^ations on homogeneous rays show a progressive selective reflection such that rays of low wavelength (such as are more absorbable by glass) are present in greater |)roportion after reflection from the moon than l)efore, we shall undoubtedly be justified iu concluding that the ettect observed by Lord Rosse is in part, at any rate, due to this cause, and not necessarily to the presence of heat of low refrangibility radiated from the lunar soil. From the fact that the lunar light is not white like the sun'.s, but yellowish (Sir J. Herscliel compares the moon's surface to that of sandstone rock), it was antecedently probable that such was the case. The fact has indeed been independently determined, but the writer was not familiar at this time with the work of others iu this direction. The following apparatus, which was fitted u]) in June, 18S3, was employed in the months of June, July, and October of that year for photometric comparisons of moon and sun light. It is not described more minutely because all the observations were afterward rei)eated with an imi)roved form of it hereafter described.
The lunar beam, reflected from the siderostat mirror, passed into the dark roonr, fell on a silveron-glass min-or of seven inches aperature and five feet focirs which formed a lunar image on
TEMPERATURE OF THE SURFACE OF THE MOON. 23
tlic liuvcr lialF of ;i slit, wlienee. tlic lif;lit passed tliron,<ili a eolliiiiatiiig lens, and fell upon a lar{;e, Itutlierl'iii'd liiatinji' of 17,L'!)(i lines lo (lie ineli, wliose dltlVaeted ra,vs were viewed by an observing telesoopo. Tlie iiielination of tl\e fjrating was deteiinined by a graduated circle and vernier, so that by use of tlii' eiistoinary forauila tlie exact wave len.utli of tlie color or line in the center of the tield could be eoni])ut(>(l. On the upper ]>art of the slit was a jirisni of total rellection which brought in the rays from an Argand burner arranged to slide at right angles to the axis of the colliinating teIes(!ope along a graduated scale. The amount of gas supplied to the burner was controlled by a meter. Accordingly, a spectrum from a tlame of standard and constant brightness was formed by the same grating in juxtaposition to the lunar s]>ectruui immediately under it in the api)arent field and viewed by the same eye-piece. The lam|> was now withdrawn or apitroached until some i)ar licular wave-length (c. (/., the yellow about 0''. (J) was Judged to be of like strength in either si)ectru in. Under these conditions if the grating was rotated so as to bring in more of the blue end of both si)ectra, the moonlight spectrum grew constantly brighter I'elative to that of the gas light, so that it was necessary to strengthen the latter light to re establish equality. The field was limited by a ■diaphragm to a narrow strip of both si>ectra, whost^ edges were brought as closely into juxtaposi- tion as possible, and numerous seiies of comparisons were taken througluint the visible si)ectrum, which after the requisite correctii)ns and reductions gave the relative intensity of the lunar spectrum in each i)art to that of the gas. The same ajjparatus was used for the solar conipaiisou in the same way, except that the stronger sunlight was allowed to enter through a smaller ai)erture and was diflused, instead of concentrated, by being allowed to fall on a convex silvered mirror. It was evident that the ])ropovtion of l)lue in the sunlight was greater than in the moonlight, as the fol- lowing results show.
Obsrrrafioii.s of June 'H)tli to 22d. (Corrections for altitude have not been ai)plied.)
For wave-length rj. .474. sunlight ii, 483,000 times moonlight. For wave-length .581, sunlight U.'52,140 times moonlight. For wave-length .625, sunlight 30,(i()0 times moonlight.
These comparatively rough preliminary values are uot believed to have any great (juantita- tive accuracy, but they at least show clearly that there is selective absorption of light (and hence of heat) throughout the visible lunar si)ectruiu, of such a kind that the rays less transmissible by glass will be found (so far as our investigation extends) in greater proportion in moon heat than in sun heat, irrespective of any question as to scjisible radiation from the lunar soil. It was evident that the photometric method was liable to error considerable enough to make, very con- siderable discrei)ancies between the work of careful observers, and the general lesults only are given above, because the work nf 1883 was supplemented by a tnore careful series of observations in 1884, which we now proceed to give in detail.
GENERAL CONSIDERATIONS.
Ziillner has shown that, owing to the irregularities of its surface, the full moon does not reflect as a smooth si)liere would do, but very nearly as a flat disk of like reflecting power, and filling the same angle. Such a disk, if it presented, as seen from the earth, the mean serai- diameter of li>' 3.5", and if it dillused all the solar energy which fell on it,* would send to us lyY^Tjo of what the sun does, which is the portion of the solar energy which we should leceive from such a moon, reflecting perfectly (hot specularly, but in all directions) all the solar energy which fell on it. The moon, however, is far from being a perfect reflector. The color of its surface is . comparable (as we recall) to that of sandstone rock, and hence it must reflect selectively, and, as far as we can see, in such a manner that the longer wave-lengths are in larger proi)ortiou in the reflected than in the original solar beam, in which, roughly speaking, the Inininous energy is about one half of the uou-luminous or dark beat. Since the moon then only imperfectly re-
' Consitleralde difft-reuce may exist even in values ol)taiued from such geometrical considerations. Thus Lam- bert's formula f^ives the numljcr tijJuu, which is nearly that used Ijy Lord Kosse ; and George P. Coiid (Memoirs ot American Academy, vol. viii) uses the value tsoiTO) where we have taken -grkuTi-
24 MEMOIPtS OF THE Js^ATIOXAL ACADEMY OF SCIEXCES.
fleets or diftuses, part of tbe solar energy must be absorbed and re-radiated as dark heat. We make no doubt, then, that the lunar soil radiates heat tovrard space. The real questions at issue are "At what temperature does it so radiate?" "Can we have any experimental knowl- edge of such dark beat radiation at the earth's surfacel" If we suppose, for instance, the lunar soil to be heated by the sim 50° C. above the temperature of surrounding space, then in the case of this very considerable supposed heating effect, the moon's surface will remain far below zero in the sunshine, and though it may be said in one sense to radiate beat to the earth, yet since it is in this case below the mean temperature of the earth's surface, we should obtain no sensible heat from it, even were our atmosphere altogether absent, while the actual presence of our atmosphere, athermanous, as it is generally believed to be to such radiations, wonld render their determination hopeless. Whether tbe moon be a perfectly diffusive body or the actually imperfectly diffusive one, we get the same amount of heat from it; for it will finally attain a condition of beat equilibriam in which it will send away as much as it receives. In the first hypothesis, what it sends away will be purely reflected or diffused energy, of wave-length corresponding to what it has received from the sun; in the second hypothesis, the radiant energy will be partly reflected, and partly that of much lower wave length emitted by the soil. Tbe second hypothesis, doubtless is tbe true one; but the question before us is, "Is this I'eradiated heat sensible ?"
From the fact that the lunar energy api)ears less traiismissible by glass than tbe solar it has been assumed that the entire effect is due necessarily to a large beat radiation from the lunar soil, which our atmosi)bere transmits and the glass stops. Before we accept this hypothesis we must repeat that it does not necessarily imi)ly this, for we have only to suppose the selective reflection exercised on the solar rays at the surface of the moon to be such as to send us in the reflected rays an undue proportion of those which glass absorbs, to account, at least in part, for the observed effect. We will pass, therefore, to a series of observations which show more clearly than any jet given that a selective absorption of such a character does actually take place.
I'BOTOMETIilC OBSERVATIONS IN 18S4.
Comparative photometric measures of tbe intensities of solar and lunar rays are of im- portance, as we ha\'e seen, to our heat determinations, and especially is this the case when such measures are combined with others (to be shortly given) of tbe comparative amounts of heat received from tbe sun and moon. The complete knowledge desirable would tell us of the special ratio of each separate heat or light ray, but even a knowledge of the ratio of tbe total sun- light to moonlight and tbe total sunheat to moonheat will be valuable. If, for instance, it were found by purely optical means that the intensity of sunlight was m times that of moon- light, and by an instrument like tbe thermoi)ile or bolometer, in which tbe registered effect of the radiation is propoi tional to the amount of energy which resides in it, that the beat received from the sun was only n times that from the moon, even such a result would enable us to draw some inference as to the general character of the lunar energy, and hence of the conditions of tem- perature of the moon's surface. For, in the case above stated (supposing »(>)(), tbe given relation between the ligbt and heat ratios could be explained only on the supposition that the energy was distributed differently in the two spectra, a larger portion of that residing in the lunar rays being unable to produce any physiological effect when received upon the retina or iiicai)able of being in- terpreted as light, and hence that tbe surface of the moon had either selectively reflected tlie solar i-ays or had added to them radiations from its own substance indicative of a considerable individual temperature. We have seen, however, that a difference in the direction of the above supposition is to be expected from the effects of selective reflection at the nioon's surface.
The chief objection to such a comparison between the light and heat ratios of the sun and moon is tbe difficulty of nniking the necessary measurements witb tlie requisite degree of accu- . racy; so that, unless the difference were extreme, it would be masked by the effects of the errors of observation. The photometric comparisons are generally made with the aid of an artificial source of light of intermediate brightness, which at once introduces a considerable degree of uncer- tainty into the problem on account of its variations in intensity. Differences in altitude ami changes in the state of tbe atmosphere have also great influence upon the result; and it has been shown by the writer bow great is tbe difficulty of making certain allowance for the effect of these
TEMPEEATUEE OF THE SUEFACE OF THE MOON. 25
unequal circunistauces by processes of inatbematical computation. Even for the relative total brightiioss of the sun and moon very discrepant results have been reached, which may be best exhibited in the form of a table of the principal detenninations.
300,000:1 (Lambert.)
400,000 : 1 (Lanibort, allowance made for various errors.)
300,000 : 1 (Bonj,'uet, Essai d'optiqiic, &,c.)
801, 000 : 1 ( Wollaston, Thil. Trans. (1&29), vol. 8.)
480,000 : 1 (Bond, Memoirs American Academy, vol. 9.)
618,000 : 1 (Zijllner, Photoraetrischo Uutersuchungeu, p. 10,5.)
350, 000 : 1 (W. II. Tickering, Pr. Amer. Academy, 1880.)
70, 000 : 1 (Sir William Thomson.)
There has been no essential improvement in such photometric processes as are here in ques- tion since the early measures by Bouguer and Lambert. Zolluer's ai-e perhaps made with more care than others, but giving all these values equal weights, we have 405,800 : 1 as the mean ratio. It is sufficiently evident that the limits of error are here wide, and wo shall adopt 40U,000 to 1 as the mo.st probable value.
Eecurriug now to the comparison of separate spectral rays in sunlight and moonlight, we find that investigations have been independently made by two competent observers.
In those of W. H. Pickering,* in which light from various sources was compared with that from a standard Argaud gas-burner at four different j)arts of the spectrum, there is a very great preponderance of violet in the solar rays as compared to the lunar. It is possible that the differ- ence is too great, but we have already remarked upon the exti'eme difficulty of real accuracy in such determinations, and our own earlier observations are of a like order of discrepancy.
Dr. H. C Vogeljt compared, by means of a spectrophotometer, in which a petroleum lamp served as a standard, moonlight and sunlight which had been reflected from various kinds of rock. As a result he fouud that a selective absorption of the more refrangible rays of the spectrum took place on reflection of the solar rays by the surface of the moon, although not sufficiently pronounced to indicate any very decided color in the substance of which it is composed. The moonlight agreed best with sunlight reflected from yellowish gray sandstone.
The spectrophotometer used at Allegheny in the later ob.servations (in 1884)f to determine the amount of the selective reflection under consideration was the result of the experience ob- tained in 1883, and at the same time not dissimilar in principle to those employed in the researches of Yogel and Pickering, the brilliancy of the two spectra being comjjared at dittereut i^oints by means of an artificial source of light of supposed constant inten.sity. This artificial source was a kerosene lamp in which the oil was kept at a constant level, with Argand burner, and screens so placed before the glass chimnej- as to limit the eftective part of the flame to a cylindrical portion 10 millimeters high, taken where it was brightest. The lamp was trimmed and cleaned before each set of observations, and although the constancy of its light seemed to be all that was desired, the quality was so dittereut from that of either of the two heavenly bodies to be compared that the accuracy of the observations was not so great as would have been obtained if a source like the electric light, for example, had been used.
In order to carry out the measurements, the intensity of the sunlight had to be diminished, and that of the moonlight increased until they were both compai'able with the standard. In doing this no attempt was made to determine the amount of diminution or increase, although a rough approximation to this is possible, but as only relative brilliancies in difierent parts of the two spectra were desired, attention was mainly paid to securing a convenient intensity in the light to be compared.
Plate 2 represents the arrangement of the apparatus. The light, reflected horizontally by the 12-iuch silvered mirror of the siderostat, enters the dark room by an aperture, A, in the north wall. Here, if it is sunlight which is being compared, all is stopped except what passes through a small cir-
' Proc. Amer. Academy, 1880, i). 236.
t Monatsberichte d. Konigl. Akademie d. Wissenschaft z. Berlin, Oct. 21, 1880. {These observations were conducted by Mr. J.E. Keelcr of this observatory. S. Mis. 69 4
26 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
cular aperture 4.86 millimeters in diameter, in the center of a cap covering the object-glass of a small telescope, D, of about 520 millimeters focus. On leaving the eye-piece of this telescope the sunlight is spread out into a diverging cone of rays, which at the distance of the photometer slit *S', 2610 millimeters beyond the eye-piece, has a diameter of 652 millimeters. Its intensity has therefore been weakened about 18,200 times (independently of the absorption of the glass, wliich is not a a factor in our qualitative determination).
S is the slit of a grating spectroscope. The collimator G has a focal length of 1254 millimeters and an aperture of 57 millimeters. The observing telescope T is much shorter, having a focal length of but 400 millimeters (in order tbat the head of the observer may not interfere), and is set at a fixed angle of about 49° to the collimator. A holder within the case at G carries a flat Row- land grating with a" ruled surface 51.6 by 35.0 millimeters, and with the number of lines per milli- meter equal to 568.4. Tliis grating, which gives very brilliant and very perfect spectra, was used in such a position that the normal to its surface fell between the two telescopes, the comparisons being made in the brighter first spectrum. Its angular position is indicated by a divided circle and vernier, reading to minutes on the outside of the case.
The lower part of the photometer slit is covered by a totally reflecting prism, P, which cuts off the sunlight entering there and substitutes for it the light from the standard lamp, L. Two spectra in close juxtaposition are therefore seen in the eye-piece of T, the upper belonging to the lamp and the lower to the sun. By means of a 2-millimeter blackened cardboard slit in the com- mon focus of the object-glass and eyepiece, the range of wave lengths included in the field of view was limited to 0''.0048, or about eight times the interval between the 1> lines.
The lamp has already been partially described. It was fastened to a slider, which could be drawn by the observer to and fro along a graduated scale, at right angles to the collimator so as to approach or recede from the slit, by pnlling a cord. A heavy screen which hung down to the level of the photometer scale concealed the lamp from the observer, who was thus unaware of its position while making a measurement (excei>tfrom the ajipearance of its spectrum in the eye-piece of the telescope) until the index had been read, and thus any bias resulting from a preconceived opinion as to the proper position of the lamp was avoided. The range of the scale was 20 deci- meters, and its zero-point was so adjusted that the reading of the index of the lamp-carriage was the distance of the center of the flame from the slit of the photometer. On account of the great difference in the quality of the lights compared, the range of the scale proved to be insufiBcient, and the wheel photometer, an instrament i)resently to be described, was used to diminish the more intense light by a given ratio.
When moonlight, instead of sunlight, was compared with the standard, the diminishing tele- scope was removed, and a telescope of 1,054 millimeters focus and 77 millimeters aperture, with the eye-piece removed, was placed on the axis of the beam from the siderostat, so as to form an image of the moon on the upper half of the photometer slit.
The wheel-photometer, referred to above, consists of two circular disks of sheet-zinc about twenty inches ia diameter, each pierced near the circumference by eighteen radial apertures separated by spaces of the same width. The two disks may be rotated past each other with con. siderable friction, enough to hold them firmly in relative position, and are held by an axis passing through their centers, by means of which, and a multiplying wheel connected with it, they may be rotated in a vert.cal plane with great velocity as a single wheel. If they are adjusted to coin- cide, and rotated in front of a source of light, they diminish its brilliancy one-half, although, on ac- count of the persistency of vision, the eye does not perceive any flickering or unsteadiness caused by the interruptions of the spokes. A graduated arc is attached to one of the disks, and an index to the other, so that the apertures may be adjusted to any width from the full opening down to zero. Thus the intensity of a luminous source may be diminished to any fraction less than one-half of its original value.
On looking into the eye-piece of this apparatus (Plate 2) two nearly square patches of light were s^eii, the lower belonging to the sun or moon, and the upper to the lamp. The color of the light would depend, of course, upon the position of the grating. The observations were made
TEMPERATCTKE OF THE SURFACE OF THE MOON. 27
by sliding the lamp along the scale, bj' means of its cord, until these two squares of light were of equal iiitonsity. Then, if the intensity of the standard is Icnown for all points of the scale, we obtain the intensity of the suuliglit or nioonliglit at that part of the spectrum. If the wheel- photometer was used, a proper factor must be introduced to give the degree of diminution caused by it. Eight points in the spectrum at which comparisons were to be made, which we may roughly designate by their aj)proximate colors, were selected. Their wave lengths, and the settings of the grating circle, together with those for several of the Frauenhofer lines, are given in the annexed table.
|
Point. |
Color. |
Line. ! Setting. Wave-length. |
|
1 2 |
Deep red j |
B... 84 5 0.687 C ... 84 35 0.656 84 47 0.649 |
|
3 4 5 6 7 8 1 |
Orange Yellow Grceu Bhie Bright violet .. Deep violet |
85 40 0.599 D... 85 49 : 0.589 85 52 1 0.586 (6)-- 87 8 1 0.518 F ... 87 42 1 0.486 88 0 0.470 , ... . 89 0 0.415'. |
|
1 |
A table giving the intensity of the illumination in the observing telescope, obtained from the photometer lamp for each decimeter of the lamp-scale, was next constructed from data obtained by observation. The assuni])tion which has been made in similar photometric measures that the intensity of the illumination is inversely proportional to the square of the distance of the lamp- flame from the slit, leads to results which may be considerably in error, particularly if some of the observations were made when this distance was small. The reasons for this are various. Jf, starting with the lamp at the end of its scale, we slide it gradually forward toward the slit, the intensity of the light in the observing telescope will increase gradually until the aperture of the collimator is filled, and then on closer approach the intensity no longer increases but remains constant, whereas by the law of inverse squares it should increase from a certain value up to infinity at the slit. In the apparatus used in these experiments this constancy of illnmination began at about 2 or 3 decimeters, and measurements made with a smaller scale reading than o decimeters were avoided as much as possible. On account of the small proportion of blue and violet rays iu the lamp-light, however, it was sometimes necessary to make the comparisons in the upper end of the spectrum with the lamp so near the slit that the value of its light intensity was subject to considerable uncertainty, and it is for this reason that the great difterence in quality between the standard and the lights to be compared is so prejudicial to the accuracy of the observations.
It was preferred, in making the measurements, to diminish as much as possible the violet of the sunlight or moonlight by means of the wheel-photometer, thus enabling the comparison to be made with the lamp at a greater distance from the photometer slit.
The edges of the lampflame are considerably more brilliant than the central portions. When the lamp is near the extremity of its scale, its effective brilliancy is the average of that of all its parts, but when brought up close to the slit, the effective rays are those from the central portions only. From both this and the foregoing reason, the decrease in the brilliancy of the light in the observing telescope as the lamp is moved away from the slit is less rapid than that required by the law of inverse squares.
The law actualij- followed was determined empirically by means of the wheel-photometer. A second kerosene lamp with Argand burner, quite similar to the standard lamp, was placed directly in front of the slit, at such a distance that when matched by the standard lamp the scale reading of the latter was a little less than 5 decimeters. Having determined this reading by taking the mean of five settings, the wheel-photometer with its index set to 10 (or with its apertures open to their full width), was interposed between the auxiliary lamp and the slit, cutting down the bril- liancy of the direct light to one-half; and the new position of the photometer lamp, when matched
28
MBMOIES OP THE NATIONAL ACADEMY OF SCIENCES.
with the diminished auxiliary, was determined as before by five settings. Tlie index of the wheel was then set to 9, reducing the intensity of the direct light to nine-twentieths, and soon until tlie reduction amounted to two-twentieths, when the limit of the lamiJ-scale was reached.
The following observations were made on November 5, 1884, each position of the photometer lamp being the mean of five independent settings, which sometimes, though very rarely, differed from each other by as much as 1 decimeter, the usual variation being from 1 to 5 centimeters. The comparisons were made in the yellow, experience having shown that equality was most accu- rately judged of in that color.
|
Setting of wheel-photo- meter. |
Intensity. |
Reading of lamp scale. |
|
T>ecimeters. |
||
|
No wheel _ . . . . |
1.00 .50 |
4.91 7.60 |
|
Wheel iudex at 10 |
||
|
Wheel index at 9 |
.45 |
8.06 |
|
Wheel index at 8 |
.40 |
8.34 |
|
Wheel iudex at 7 |
.35 |
8.90 |
|
Wheel index at 6 |
.30 |
9.74 |
|
Wheel index at 5 |
.25 |
10.84 |
|
Wheel index at 4 |
.20 |
12. 34 |
|
f Wheel index at 3 |
.15 |
14.76 |
|
Wheel index at 2 |
.10 |
18.34 |
|
No wheel |
1.00 |
4.70 |
These observations, when plotted, give points which fall very nearly on a smooth curve. From this curve we may then take the intensity corresponding to even decimeters on the lamp scale, the unit of intensity being one-twentieth of the intensity of the auxiliary lamp. Finally, we may express the intensity in terms of another pui'ely arbitrary unit ; namely, that of the standard lamp at a cjistance of 5 decimeters from tbe slit. We thus obtain the following table. The last column is the adopted value of the lamp intensity at each division of the scale, obtained by taking the mean of this and another similar set of observations.
|
Scale |
Intensitv in |
Intensity. |
Adopted |
Scale |
Intensity in |
Intensity. |
Adopted |
|
reading. |
twentieths. |
intensity. |
reading. |
twentieths. |
intensity. |
||
|
Decimeters. |
Decimeters. |
||||||
|
5 |
19.1 |
1.00 |
1.00 |
13 |
3.7 |
.19 |
.20 |
|
6 |
15.2 |
.80 |
.81 |
14 |
3.3 |
.17 |
.18 |
|
7 |
11.9 |
.62 |
.63 |
15 |
2.9 |
.15 |
.16 . |
|
8 |
9.1 |
.48 |
.56 |
16 |
2.6 |
.14 |
.14 |
|
9 |
6.8 |
..36 |
.38 |
17 |
2.3 |
.12 |
.12 |
|
10 |
5.7 |
.30 |
.32 |
18 |
2.1 |
.11 |
.11 |
|
11 |
4.9 |
.26 |
.27 |
19 |
1.9 |
.10 |
.10 |
|
12 |
4.2 |
.22 |
.23 |
20 |
1. 7 |
.09 |
.09 |
Plate 3 is a curve representing the intensity of the photometer lamp as a function of the scale reading, as determined by the experiments, and also the curve (dotted), on the assumption that the intensity varies inversely as the square of the distance from the slit. The less rapid decrease of intensity by the actual law is apparent. The unit of intensity in the last column, namely, that of the photometer lamp, at o decimeters from the slit, will be used throughout for all color.<i, no matter what their relative proportions in the lamp-light may be. The observations made on the moon on November 2, 1884, and those on the sun November 7, 1884, are given in full below. The observations of November 2, 1884, on moonlight, were made between the hours of 10 and 11 p. m.
TEMPERATURE OF THE SURFACE OF THE MOON.
29
Photometric observations on moonlight.
[Observer J. E. Kceler. All conditions favorable. The skj' "at first .slightly hazy, gradually becoming perfectly clear." At the time (10 h. 30 ni.) the moon's hour angle was 1 h. 3 m. and her declination -f 10"^, corresponding to a zenith distance of 34*^ and air-mass M=rl.21.]
|
Setting. |
|
o / |
|
84 5 |
|
84 47 |
|
85 40 |
|
85 52 |
|
87 8 |
|
87 8 |
|
87 42 |
|
88 0 |
|
89 0 |
Color.
Deep red
Uright red
Orange
Yellow
Green
do
Blue
Bright violet
Deep violet
Reading of lamp-scale .
Mean.
|
12.2 |
13.0 |
12.1 |
10.9 |
11.9 |
|
11.4 |
10.4 |
10.7 |
10.1 |
9.9 |
|
8.4 |
7.6 |
7.9 |
7.7 |
8.0 |
|
9.7 |
8.6 |
8.8 |
8.7 |
8.8 |
|
6.2 |
5.9 |
6.3 |
5.6 |
5.6 |
|
11.6 |
12.4 |
12.1 |
11.7 |
12.2 |
|
8.9 |
8.5 |
8.8 |
8.2 |
8.4 |
|
6.7 |
6.6 |
6.9 |
6.4 |
6.1 |
|
;i.-i |
3.0 |
2. 1 |
2.3 |
2.9 |
12.0 10.5 7.9 8.9 5.9 12.0 8.6 6.5
Kemarks.
Wheel before lamp, index at3.
Do.
Do. Wheel index at 5.
Do. No wheel.
Do.
Do.
2.8 I No wheel: faint.
These observations are reduced with the aid of the table of lamplight iuteusities on page 28. lu the following table the last column contains the intensity of moonlight in different parts of the spectrum, as compared with the standard lamp :
|
Wave- length. /' 0.G87 0. 649 0.599 0.586 0. 518 0. 518 0.486 0.470 0. 415 |
Mean lamp setting. 12.0 10.5 7.9 8.9 5.9 12.0 8.6 6.5 2.8 |
Talnilar intensity. . 230 .295 .513 .392 .829 .230 .428 .720 |
How modified by wheel. Reduced to ^(j do do Reduced to ^ |
Actual in- tensity. .035 .044 .077 .098 .207 .2.30 .428 .720 |
|
do |
||||
|
Not modified |
||||
|
do do rlo |
||||
In the observations of November 7 the sun was near the meridian (exact time not noted), and his declination being — 16°, his zenith distance was about 50°, corresponding to an air-mass of M=1.79. The condition of the apparatus was the same as in the previous measures. The sky was a " fair hazy blue."
Photometric observations on sunlight.
Setting. Color.
84 5'Deepred 12.2
84 47 Bright red 9. 0
85 40 Orange 15.4
Sj 52 Yellow 13. 5
87 8 Green 6.0
87 42 Blue 8.9
89 0 Bright violet 8.2
89 0 Deep violet 6.0
Reading of lamp-scale.
Mean.
|
13.1 |
12.0 |
11.2 |
11.2 |
|
8.7 |
8.6 |
8.0 |
S.8 |
|
l.*>. 7 |
10.2 |
14.8 |
1.=). 0 |
|
11.7 |
12.9 |
12.7 |
11.6 |
|
6.2 |
6.2 |
6.2 |
6.5 |
|
9.5 |
9.6 |
9.7 |
9.6 |
|
8.0 |
8.6 |
8.2 |
8.4- |
|
5.1 |
5.5 |
6.0 |
5.6 |
11.7 8.6 1,5. 4 12. 5 6.2 9.5 8.3 5.6
Remarks.
Wheel before lamp, index at 5.
Do. No wheel.
Do.
Do. Wheel before sun, index at 5.
Do.
Do.
These observations are reduced in the .same way as those given in the tirst example. It is evident that introducing the wheel photometer in the path of the sunlight increases the value of
30
MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES.
the light intensity at a given division of the lamp-scale by the same factor that it is diminished when the wheel is interposed between the lamp and the slit.
|
Wave- length. |
Mean lamp setting. |
Tabular in- tensity. |
How modified by wheel. |
Actual in- tensity. .061 .107 .152 .215 .774 1.400 1.856 3.544 |
|
u 0.687 0. 649 0.599 0.586 0.518 0.486 0.470 0.415 |
11.7 8.6 15.4 12.5 6.2 9.5 8.3 5.6 |
.242 .428 .152 .215 .774 .350 .464 .886 |
Reduced to J |
|
|
....do |
||||
|
....do ....do Increased to 4 |
||||
|
....do -..do |
Two more such complete sets of observations were made under favorable circumstances, one on the sun on November 1, and one on the moon on October 31. Other observations made under disadvantageous circumstances, such as a hazy or smoky sky, were rejected.
The diflereuces, which are sometimes considerable, between those results of these observations which should be identical, are duej to errors of observation, as well as to different conditions of the atmosphere at the times of observations, differences in altitude of the heavenly bodies observed and variations in the intensity and quality of the light from the photometer lamp. Since the effects of these sources of error, with, perhaps, the exception of that due to difference in altitude, do not allow of computation, the best we can do is to regard them as made under perfectly similar circumstances and combine them accordingly. We shall then at least know, from a consideration of the general effect of the actual differences in circumstances, in which direction the error of the combination lies.
The following table exhibits the mean values resulting from snch a combination. In the last three columns are given the intensities of the three kinds of light in terms of lamp light, cdl being supposed equal in the yellow. The fifth and sixth columns are obtained by multiplying the second and third columns throughout by a proper factor :
|
Wave- length. |
Moonlight. |
Sunlight. |
Lamp-light. |
Moonlight. |
|
0.687 |
.032 |
.055 |
1.00 |
.41 |
|
0.64U |
.041 |
.096 |
1.00 |
.52 |
|
0. 599 |
.006 |
.165 |
1.00 |
.84 |
|
0. 5«6 |
.079 |
.209 |
1.00 |
1.00 |
|
U.518 |
.190 |
.696 |
1.00 |
2.41 |
|
0.486 |
.370 |
1.092 |
1.00 |
4.69 |
|
0.470 |
.592 |
1.890 |
1.00 |
7.50 |
|
0.415 |
1.050 |
3.540 |
1.00 |
13. 29 |
Sunlight.
.26
.46
.79
1.00
3.33
5. 22
9.03
16.92
Plate 4 is a graphical reprsentation of this table. The intensity of lamp-light is repre- sented by a straight line everywhere at the distance 1 from the axis of A. The sunlight and moonlight curves intersect this line at the point A=0''. 586. They rise rapidly towards the violet end, but the sunlight ordinates increase faster than the moonlight ones. These curves show that the proportion of violet in sunlight is much greater than in moonlight, although as a quantitative determination the observations are not entirely satisfactory. The principal cause of error is, as already mentioned, the deficiency of violet rays in the light from the comparison lamp. The errors of observation become more apparent on eliminating this intermediate term, and conqjariug directly the light from the sun with that from the moon. From the curve in the figure we obtain the first part of the following table, and by a graphical construction of this part we get the last two col- umns from a smooth curve. This curve, as given by the table, is concave towards the axis of k It is quite certain, however, that if the observations had been perfect and made under
TEMPERATURE OF THE SURFACE OF THE MOON.
31
similar oirciimstances it would be convex. It is eviileiit that the siiiiliglit in these measures is at a great disadvantage in respect to the moonlight, especially in the upper regions of the spectrum, since the violet light from the sun, which was observed at a much lower altitude, had been more powerfully absorbed by the atmosphere. This absorption was even greater than could be exi)ected from the mere dilference in altitude, for the sUy at night was almost invariably better than in the daytime, and, moreover, the cloud of smoke, which always hangs over the city of Pittsburgh towards the south, gives an absorption for large zenith distances much greater than the mass of air traversed would iiroduce alone.
If the observations had been made under precisely similar circumstances, the preponderance of violet in the solar spectrum would be far more pronounced.
|
Sunliglit. |
Adopted |
Adopted . |
||
|
Wave |
■length. |
Sunlifjht. |
Moonlight. |
|
|
Moonlight. |
Moonlight. |
SunlTghT" |
||
|
/" |
||||
|
0.68? |
.65 |
.68 |
1.47 |
|
|
0.649 |
.88 |
.81 |
1.23 |
|
|
0.599 |
.95 |
.96 |
1.04 |
|
|
0.58fi |
1.00 |
1.00 |
1.00 |
|
|
0.518 |
1.23 |
1.18 |
.85 |
|
|
0.486 |
1.35 |
1.26 |
.79 |
|
|
0.470 |
1.35 |
1.31 |
.76 |
|
|
0.415 |
1.28 |
1.43 |
.70 1 |
In addition to this table we give another, containing the results obtained by different observ- ers, reduced by intepolation from smooth curves to the same points measured on in 1884. As some of these measurements were made under circumstances exactly opposite, as regards the rela- tive heights of the sun and moon, to those we have described, we may expect from a combination of them all to obtain a result more nearly free from the effects of unequal absorption of the light from the two bodies by the atmosphere.
Relative intensities of sunlight and moonlight.
Wave- length.
Pickering.
/' 0. 687 0.649 0.599 0.586 0..518 0.486 0.470 0.415
.48 .64 .89 l.O 2.2 4.6 6.3 13.
Preliminary
observations
of 1883.
Observations of 1884.
Vogel.
.7 1.0 6.5 9.5
13.
20.
.68 .81 .96 1.00 1.18 1.26 1.31 1.43
.90 .92 .98 1.00 1.26 1.40 1.54 2.10
Mean* by weights.
Moonlight.
Sunlight.
70 77 92 00 68 37 72 22
43 30
08 00 60 42 37 24
' The values in the sixth column have been used as ordinates for the curve. (Plate 5.)
In obtaining the column headed "Mean" the weight 5 has been given to each of the two preceding columns and the weight 1 to each of the others. The observations of Mr. Pickehixg on the moon were made under unfavorable circumstances, and the light ratio in the violet depends upon a single series of three readings. Those made at this observatory in 1883 were for the purpose of experimenting on the best arrangement of apparatus, and not made with a view to obtain the best quantitative results, while the values given by Dr. Vogel and by the Allegheny ob.servations of 1864 are the results of many and careful observations throughout the entire range of the spectrum. The weight which we have assigned to them would not therefore appear to be too great.
With the aid of this table we may make an efifbrt to draw the lunar energy curve. Within the limits of our observations an increase in energy in a definite part of the spectrum is followed by a proportional increase in brilliancy,* so that the figures in the last column, which represent
* With iutenser lights than we employ certain physiological phenomena affect this proportionality, which is here, however, sensibly exact.
32
MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES.
the light intensity ratio of moonlight and sunlight, may also be taken as the ratio of the ortlinates of the lunar and solar energy curves.
For the ordinates of the normal solar energy curve we may take the values given by the meau of all noon observations made with the spectro-bolometer at Allegheny during the spring of 1881. Then, multiplying each ordinate by the corresponding factor given in the last colurau of the pre- ceding table, we obtain the ordinates of the lunar energy curve. The results are exhibited below in tabular form :
|
Wave- length. |
Solar ordiuates. |
Lniiareuergy. |
Lunar ordinates. |
|
Solar energy. |
|||
|
/< |
|||
|
0.687 |
575 |
1.43 |
822 |
|
0.649 |
604 |
1.30 |
785 |
|
0. .^^99 |
624 |
1.08 |
674 |
|
0.586 |
622 |
1.00 |
622 |
|
0.518 |
590 |
.60 |
354 |
|
0.486 |
535 |
.42 |
225 |
|
0. 470 |
490 |
.37 |
181 |
|
0.415 |
300 |
.24 |
72 |
If we wish the lunar energy curve to represent the distributiou of the same amount of energy as the solar within the limits of the visible spectrum (say between Qi^.i and t'*'.7), we must multiply each of the lunar ordinates by the fraction fff, which is determined by plotting the curves and measuring the areas within the required limits. We obtain by this operation the following table, which is also graphically represented by the curves in Plate 6.
|
Wave- |
Solar |
Lunar |
|
length. |
1 ordinates. ! |
ordinates. |
|
M |
1 |
|
|
0.687 |
575 |
952 ! |
|
0.649 |
604 |
909 1 |
|
0.599 |
624 |
780 |
|
0. 566 |
622 |
721 |
|
0.518 |
590 |
410 |
|
0.486 |
535 |
261 |
|
0.470 |
490 |
209 |
|
0.415 |
300 |
83 |
An inspection of these curves shows at once the effects of the selective absorptiou undergone by the solar rays at the moon's surface. The maximum ordinate of the lunar curve falls much lower down in the spectrum, and there is a con-esponding reduction in the height of the curve 0%'er the violet end. The visible part of the normal siiectrum forms, however, so small a ])ortion of its entire length, that it would be unsafe to judge from the nature of the lunar curve obtained by optical means, as to its probable course at points very far below the limit of the visible red. Nevertheless, the evidence of these i)hotometric measurements as to the selective reflection exer- cised by the moon's surface is, as far as it goes, decisive, and it is shown to be in such a direction as to cause a preponderance in the lunar spectrum of the rays of long wavelength, and hence to tend to cause a smaller percentage of lunar rays to be transmitted by glass than of solar, and this independently of any effect from heat reradiated by the lunar soil. There is, theu, no doubt that the observed phenomenon of glass absorption already described is due in part to this cause, though in how large part we do not now determine.
ADOPTED HEAT-MEASUEES WITH BOLOMETER AND GALVANOMETER.
The galvanometer is so important an accessory of the bolometer, that we will describe the arrangement we have used to make our own most eflective.
The galvanometer employed is a Thomson differential astatic galvanometer, having a resist- ance of 20.35 ohms, and ori ginally made by Elliott Brothers, with a short suspending fiber, a damp-
TKMPEEATURE OF THE SURFACE OF THE MOON. 33
ing magnet sliding on a brass rod, and a system of five upper and five lower magnets connected by an alununum rod with an alnminnin vane, the time of a single vibration without damping magnet being G.5S seconds.
In ineparation for the extremely delic^ate final work on the moon, the following changes were made: (I have to express my great obligations to the kindness of Prof. Sir William Thomson and of Professor Rowland for valuable suggestions.) The most important of these improvements has been the replacing of the short fiber by one 33 centimeters in length (for the brass rod being substituted a hollow glass one, in the center of which is the fiber) ; and, second, the reconstruction of the needle.
In the new astatic system constructed at this observatory in November, 1884, the aluminum rod carrying the magnets was replaced by a hollow glass fiber. The aluminum vane, it occurred to me to replace by au insect's wing, and one was most advantageously made of dragon-fly's wings, (in which nature has supplied an admirably rigid and light construction). A minute platinum paddle at the bottom of the glass fiber, touching the surface of oil in an oil-cup, was supplied, and a new system of magnets. These are made by rolling soft sheet-steel, 0.076 millimeters thick and 5 millimeters wide and from 7 to 9.5 millimeters long, around a short straight piece of wire into minute cylinders, carbonizing them in fused ferrocyanide of potassium, and tempering them in mercury. The strength of one of the little magnets was found to be 874 Gaussian units, and of these there are in all twelve, six on each system.*
In forming the connections, it will be found advantageous to employ a battery of a consider- able number of cells (e. g. twelve, of a gravity battery), and to reduce the current by interposing resistance. Under these circumstances, it might appear that there was no advantage in using the current from twelve cells over that of one, if the current were as strong in either case. Such, however, is not the fact; for the accidental fluctuations due to the minute casual changes which take place in the most constant cell are obviously equalized by the use of a current which is the mean of that from a considerable number of cells.* Pains are taken to wrap every connection and binding post in cotton, and a great number of minute precautious, which are not here detailed, have been observed.
The damping magnet is arranged so as to take any position between the bottom of the glass rod and a point 1.46 meters above it, a graduated vertical scale being provided above the galva nometer rod. The mirror of the instrument is a minute silver-ouglass concave reflector, of 1-meter radius of curvature. The transparent scale, which is on the west, at 1 meter distance, is a portion of a cylinder of 1- meter radius, and is graduated in millimeters from 0 to 500. Accordingly, when the needle points north and south, and the optical axis of the mirror east and west, the image is at 250, at the middle of the scale. This image is a circle of light about 3 centimeters in diameter, with a central vertical line (the shadow of a wire).t With these values, to carry the image wholly off the scale demands a rotation of the needle through onlj' about 7 degrees. As a rule, this small maximum deviation, with the employment of a curved scale, renders reduction for arc unnecessary in such observations as these. The needle, when renderetl as astatic as possible, performs a single vibration in about a minute; but in this condition the directive force is apt to vary from one day to another, and the time of vibration, as a rule, to grow more ra^iid until a shorter period is reached^ at which it becomes relatively constant. For the purpose of forming an approximate estimate of the sensitiveness of the instrument, it may be stated that when making a single vibi-ation in 10 seconds a deflection of one millimeter division on the scale is given by a current approximately equal to 0.0000000013 ampere.
East of the galvanometer, and nearly in the prolongation ot the optical axis of the upper mir- ror, are two small bar magnets, on an independent stand, a minute movement of either of which serves to bring the image on to any point of the scale when necessary without altering the resist- ance in the resistance box.
* The device of the hollow magnets is cine to Mr. F. W. Very, of this Observatory, at whose suggestion also the number of battery cells was increased with great advantage. The actual construction and astaticising of the needles also has been chiefly due to Mr. Very's patience and skill.
tThe employment of a telescope and a flat mirror, reflecting the inverted scale, is in some respects preferable to this arrangement, which is continued in use, however, at present from its greater facility of adjustment. S. Mis. 69 5
34 MEMOIKS OF THE NATIONAL ACADEMY OF SCIENCES.
The adjustmeuts are coiuiuouly made so that heat falling ui)on the bolometer causes a deflec- tiou of the image to the south, thus increasing the reading on the scale, whose zero is at the northern end. It may be added, in further indication of the sensitiveness of the instrument, that on bolometer No. 1 (whose resistance is 80.5 ohms) by Matthiessen's table, the change of tempera- ture, corresponding to a change of resistance of 0.0001 ohm, is 0O.00032 C. Accordingly, when the needle is in such a condition of sensitiveness that it executes a single vibration in 10 seconds, and if we employ a current of 0.1 ampere, a change of one division on the scale corresponds to a change of temperature in the bolometer strips of 0^.000016 C. This result is to be uiulerstood as merely ajiproximate, and as indicating nearly the limit of sensitiveness attained in actual work at present. It need hardly be added that greater nominal setisitiveness can be obtained to almost any extent by increasing the time of swing: but the gain is apt to be only nominal, for we are to consider that, other things being equal, the efliciency of the instrument increases as the probable error diminishes, where this probable error is expressed as a fraction of the deviation in question. In fact, as the concentrated moonbeam drives the image off the scale altogether in the above condition of sensitiveness, it is necessary to employ the damping magnet, not to increase, but to diminish, the time of vibration, so that the nnage may remain on the scale. Under these latter conditions the probable error of a single observation is very small, i)robably not exceeding 2 per cent.*
DESCRIPTION OF BOLOMETERS EMPLOYED.
Bolometer No. 1, which has been chiefly used in measurements of total lunar radiation when concentrated by the concave mirroi-, and for comparative observations with the Leslie cube, has a square central aperture, 8.3 millimeters on a side, through which the blackened strips of the central or exposed arm may be seen, presenting to the incoming rays an ai'ea of 49 square millime- ters, and composed of 23 thin strips of blackened platinum, each about 0.001 millimeter thick, in two tiers, the rear ones covering the apertures left between the front ones. The other, or protected arm, is made up of 24 strips, an extra protected strip being introduced in the circuit of the exposed arm, to balance the resistance, which is 80.5 ohms for either arm. The case is a cylinder of ebonite, projecting so far beyond the strijis as to cut them off from all radiations, except those from the subject of experiment.
Bolometer No. 13 is composed of 8 side strips and 9 central ones, each 0.25 millimeter wide, the latter forming a band 2.3 millimeters wide and 10.3 millimeters high, with which measures in the lunar spectrum have chiefly been made. Each arm resists 38.4 ohms.
Our direct observations on the lunar heat may be grouped under six divisions. (1) Quantita- tive measurements of lunar heat as compared with solar; (2) comparisons of the moon's heat with that from a terrestrial source; (3) the comparative transmissibility of our atmosphere for lunar and solar heat; (4) comparative transmissibility of glass for lunar and solar heat; (5) heat ob- servations during a lunar eclipse; (G) the formation of a lunar-heat spectrum.
Class 1. — Quantitative measurements of lunar heat as compared with solar.
Let US expose the bolometer to the lunar radiation, either direct or concentrated, and note the i-esultant galvanometer deflection, and repeat the experiment the next day with the solar radiation, diminished in a known ratio. If the moon be full and at an equal altitude with the sun at the time of observation, we have the direct ratio of heat received from each at the earth's surface but it is to be remarked that we cannot confine these observations to the single night of full moon without giving inordinate time to the research (since they should be often repeated); while, if we take them at times much before or after the full, considerable errors may be introduced by our ignorance of the true law of the variation of the moon's heat with the phase. Where we have been obliged to use the latter class of obsei'vations, we have reduced them by Zollner's law. It is to be observed, also, that it is not only more than doubtful whether the transmissibility of the atmosphere
* It appears in Lord Rosse's observations that the mean of a series of 10 gave a jjrobable error of 19 per cent, with the thermoj>ilc and galvanometer then employed. Accordingly, if we do not consider constant errors, but only acci- dentiil ones, we find that, owing to the increased sensitiveness and steadiness of our .ajiparatiis, a single meaaurement with the present train is equivalent to several hundred ot that employed by Lord Eosse.
TKAll'KRATUltE OF THE SURFAC"!-] OF TJIF MOON.
35
is the same by uight as by day, but that other circuuistauces add to the difflculty iiufoiniiing exact couclusious.
The api)aiatus eiuployed in the following obseivatious for lunar rays consisted of the concave mirror and bolometer shown in Plate 1. These were used at night, while in the day the sun's rays passed through a narrow aperture and fell on the bolometer placed at a considerable distance in the divergent beam.
The following are the principal constants of the apparatus :
Let S=lunar apparent semi-diameter at the time of observation, obtained from the geocentric semi-diameter corrected for augmentation. /=the focal length of concave mirror=73.4 centimeters.
A=the radius of lunar beam falling upon the concave mirror=10.2 centimeters. This radius i.s limited by that of the hole in the north wall by which the beam from the siderostat enters. Let s be the semi-diameter of the lunar image in the focus of the concave uuri'or. Then
A 2
/sin S=s, and -, =concentration of lunar beam.
The absorption by the silver of the mirror aud the loss by non-perpendicular incidence of the rays on the bolometer strips are here neglected.
Again, let a be the semi-diameter of the aperture used for transmitting the solar rays, S' the solar semi-diameter, and d the distance of the bolometer strii)s from the diaphragui. Then TT {d sin S' + a) ^ttP, where I is the radius of the circle formed by the divergent solar beam at the distance of the bolometer strips, and, neglecting the effect of diffraction at the diaphragm, the
diminution of the solar beam = ,,. The ratio ^ to ,2 is that of sun heat to moon heat, or rather
that from an element of the center of the sun's surface to the mean value of the heat from the full moon. Observations of this kind were made on the following evenings, November 29, December 2, and December 3, 1884.
As an example we give that of December 2, 1884 :
|
Time. |
Zenith |
Deflec- |
Time. |
Zenith |
Deflec |
|
distance. |
tion. |
distance. |
tiou. |
||
|
]l. VI. |
0 ' |
h. m. |
0 ' |
||
|
6 24 (i 36 |
I 72 24 |
5 174 i 188 |
9 39 9 41 |
f 303 312 |
|
|
7 59 8 15 |
I 54 22 |
< 273 ) 285 |
9 45 9 47 |
■■ 3S 24 |
311 1 307 |
|
8 21 |
' |
f 295 301 |
9 51 |
30r) |
|
|
8 24 |
9 55 |
I 317 |
|||
|
8 27 |
> 52 05 |
311 ) 298 |
11 58 - |
f 320 |
|
|
8 30 |
12 02 |
1 332 |
|||
|
8 32 |
1 297 |
12 04 |
. 22 22 |
1 315 |
|
|
8 35 |
I 309 |
12 07 |
1 331 |
||
|
12 09 |
1 313 |
||||
|
12 13 |
I. 318 |
The sky during these observations was quite good and cloudless. A light haze having gath- ered shortly after midnight, observations were discontinued before the moon Iiad quite reached the meridian.
On the following day (December 3) observations were made on the sun at noon. The state of the sky appeared to be about the same as during the preceding lunar observations, and the battery current employed was adjusted to the same strength.
36 MEMOIKS OF THE NATIONAL ACADEMY OF SCIENCES.
The followiug observations were obtained:
|
Sun's hour angle. |
Deflection. |
|
.. 1 mm. -10 — 7 + 7 +10 + 15 |
163 181 170 196 174 |
|
Mean.. 176 |
One hundred and seventy-six divisions was therefore taken as the deflection produced by the sun at apparent noon, when bis zenith distance was 62° 43'.
On drawing a smooth curve through points given by the lunar observations in the first table we find that the deflection produced by the moon at the same zenith distance was 245 divisions. On the evening of December 2 the moon's geocentric semi diameter was 16' 47", and the semi, diameter at the time and i)lace of observation was 16' 55". The focal length of the concave mirror being 73.4 centimeters and the diameter of the moonbeam 20.3 centimeters, the concentration of the moonlight was
(20^)1 (^?I'_7qn ^
(73.4 + sin 16' 55"Y-{.722f- '^^''^
The aperture through which the sunlight was admitted was 0.486 centimeter diameter, and the bolometer strips, when exposed, were distant from it 653.5 centimeters. The sun's semi-diam- eter at noon being 16' 16".5, the approximate diminution of solar light and heat was
(«-*««)^ ^__(0A86): .00530
(653.5 X sin 16' 16".5f (6.674f
The moon was not quite full atthe time of observation. We find by Zollner's formula that if it had
245 been, the deflection produced would have been -wtv =272 div. We have, then, for the observed ratio
of radiation from the full moon to that of the sun, both bodies being at a zenith distance of 62° 43',
272 1 J, 530 ^ 1^ 176^790.5 100,000 96509
values which the reader is again reminded are presumably subject to large constant errors. The maximum total heat which we can by possibility receive from the moon, even in the absence of an absorbing atmosphere, as is shown elsewhere, is about 1-97000 of the solar heat. It is improbable that such a coincidence as that presented with the observed value just given is other than largely the result of chance, or rather of such constant errors tending in an unknown degree to increase the observed values.
Class 2. — Comparison of the heat from the moon with that from a Leslie cube.
On December 3, 1884, the temperature of the room being 0° C, the bolometer was exposed to the radiation from a Leslie cube filled with boiling water, which was observed through the circular aperture of a screen subtending the same angle as the cone of rays from the concave mirror used in
TEMrEKATUKE OF TUE SUKFACE OF THE MOON. 37
lunar measincinents. The following deflections were observed, the sensitiveness of the measuring apparatus being the same as during the lunar observations of the previous evening:
Teiiiperatiire Galvaiiome-
of tcr
Leslie cube. (k'lloctioii.
°C. Div.
95 408
9-2 400
b9 :i84
86 370
83 369
HI 353
73 '«t7
From a smooth curve we adojit 435 as the presumable deflection, which would have been ob- served under these conditions at 100° C. The screen itself acquired a minute amount of heat during the experiment, but the correction for this is negligible.
The bolometer strips attain thermal equlibrinm under ordinary circumstances within a traction of a second, while on account of the slowness of change of the temperature of the case, we can assume its radiation (0) to be constant during the experiment. The temperature of the bolometer strips may always be taken to be proportional to the angular area of the part of the surface radiat- ing to them, to its temperature, and to its emissive quality.
Thus the aperture of the moon bolometer occupies 0.00565 of the sphere. The temiierature of the room December 3, 1SS4, was 0°.0 0. If the aperture had pointed to a surface at the absolute zero, having the same emissive jjower as its case, a fall of temperature of 0.00565 multi- plied by 273° = 10.542 would have been experienced. We assume that, within the limits of this experiment, the iSTewtonian law of radiation holds. If the pointing had been to a surface at 100° C. of the same emissive power, the temperature of the bolometer would have risen 0°.565. Now, we have seen that a Leslie cube at 100° C. would have produced a deflection of 435 divis-
Qo_565 ions on the galvanometer. One division, therefore, indicated ^W— =0°.0013 change of temper- ature of the bolometer strips (the full sensitiveness of the galvanometer not being used). The deflection produced by the full moon on the previous evening, if reduced to zenith, would have been over 3.50 divisions, and the temperature of surrounding objects being 0° C. the effective radi- ation of the moon, if we suppose its emissive power the same as that of the case, was such as would
350 correspond to a temperature of jo^Xl00°i= + 80°.5 C, or 80o.5 C. above the temperature of sur- rounding tei-restrial objects, which happened to be zero Centigrade. This on the absolute scale gives 800.5+2730=3530.5; and if one-fourth of the lunar radiation is reflected sun heat the true aver- age temperature of the moon at the full is 80o.5 — j x353o.5 = — 7o.9 0. If we assume that one-half
only is reflected sun heat, we have — 99o.3 C, if that one-sixth is reflected, + 21o.C C.
A correction for atmospheric absorption which we have not applied would somewhat increase these values, but it is evident that not only the experimental conditions here do not favor accu- racy but that the results, such as they are, are subject to a wide latitude of interpretation.
Class 3. — Trassmissiox of lunar heat bv tub earth's atmosphere.
The remarks already made as to the difficulty of comparing observations at different altitudes but at different phases, when the law of change of heat with the phase is so imperfectly known, apply with peculiar force to this class of observations. Only a series of observations made exclu- sively on the full moon in favorable circumstances (and therefore occupying many years) could bring anything like satisfactory evidence. The reductions which we now give of the few values we possess lead to conclusions to which we cannot attach great weight.
The observations of December 2, 1884, are given below in tabular form, with the computa-
38
MEMOIRS OF THE NxVTION^AL ACADEMY OF SCIENCES.
tioiis nccessiiry for obtaiuiiig the coefficient of transmission by the atmosphere. This coefficient, as has been explained elsewhere*, is found by means of the formula
and from this may be found the original energy of the obser^^ed radiation before it entered the
atmosphere,
log iiJ^log rfi— ilf] /S, log f
although these formuliB are strictly ai)plicable only to homogeneous rays, and hence give only ap- proximate results. Each "detlection" is the mean of a number of observations made nearly at the same time.
Lunar heat ohncfMitions of Devemhcr 2. 1884.
[Height of barometer /j:=7.34 dcciuieters. ]
|
Deflection |
|||||||
|
Observa- tion. |
Time. |
Hour angle. |
Zenith distance. |
M. |
Mli. |
Deflection. |
corrected for change of phase. i |
|
h. m. |
h. III. |
O ' |
|||||
|
1 |
6 24 |
5 39 |
74 28 |
3.68 |
27. 01 |
174 |
183 |
|
f |
6 -M |
5 28 |
72 24 |
3.28 |
24. 08 |
188 |
197 |
|
e |
7 .59 |
4 09 |
.57 25 |
1.865 |
13. 69 |
273 |
284 |
|
d |
8 1.5 |
3 53 |
54 22 |
1.718 |
12. 60 |
285 |
294 |
|
c |
8 28 |
, 3 41 |
.52 05 |
1.627 |
11.94 |
302 |
311 |
|
h |
9 46 |
' 2 26 |
38 24 |
1.277 |
9.37 |
309 |
315 1 |
|
a |
12 0.5 |
0 13 |
22 29 |
1.080 |
8.00 |
323 |
323 \ |
The comparison of observ^ations made at great and small zenith distances is also exhibited in the form of a table.
|
Obser- |
|||
|
vations |
d, |
d- |
Log di |
|
com- |
|||
|
pared. |
|||
|
a and g |
323 |
183 |
2. 5092 |
|
a and /" |
323 |
197 |
2. 5092 |
|
a and c |
323 |
284 |
2. 5092 |
|
6 and g |
315 ,183 \ |
2. 4983 |
■Load, Log
dz
-Lo:
/LogdA \Log dij
2.2625 :— .2467 2.2945 -.2147 2.4533 :-. 05.59 2.2625 -.2358
9. 3921 9. 3318 8. 7474 9. 3726
Log (^2 A
1. 2790 1.21162
0. 7551
1. 2465
Log (Log t)
Log t
Logt.
Log E.
E.
8. 1131— .0130 .971 8. 1256— .0134 ,.970 7. 9923i— . 0098 1.978
8. 12611— .0134 .970
I
.1040 2.6132 410 . 1072 , 2. 6164 413 .0784 1 2.5876 i 387 . 1256 i 2. 6239 i 421
The average value of t is 0.972, which is the fraction of the lunar radiation transmitted by a column of air capable of supporting 1 decimeter of mercury. The fraction of a vertical beam transmitted by the entire depth of the atmosphere would be ^'•'^=.806.
The correction due to the change of the phase of the moon during the course of the night's observations is taken from a curve based on the formula of Ziillner.
CLA8.S 4. — CCMPARATIVE TIIANSMISSION OK GLA.SS FOR LUNAU AND SOLAU HEAT.
The pieces of glass used were the same as those employed in the preliminary experiments. They were A, B, and the "large window pane." A series of observations made by moving the sidero- stat mirror so as to expose alternately to the adjacent sky and to the moon gave, as has already been said, systematically different results from those obtained by the interposition of a screen and other modes of observation. For reasons already given, the values found by alternate exposure to the moon and sky are preferred. We give as an example the observations of December 3, 1884, on the sun, and of November 20, 1884, on the moon, the general disposition of the apparatus em ployed being that indicated in plate 1, and the glass, thoroughly dried and cleaned, being in ev-
• American Journal of Science, Vol. 125, page 176.
TEMPERATURE OF TIIK SURFACE OF THE MOON.
39
ery case allowed to comuiunicate its own temperature to the bolometer before being exposed to the lunar or solar rays.
Traiismimioii of xohir nuliulioii hi/ i/hiss.
[ Dt'cembt'i- 3. 1884. Sun's zonitli distance at apparent noon ()d° 43'. Siinhcuiii tliniinislu'il in intensity to about 0.00530. The transmission is obtained by dividinj; the detloction, when tlio niys pass tlmnigli glass, by tlieniean of the adjacent dellei-t ions in the direct solar beam.]
|
Mean time. |
Deflection in direct .solar beam. 163 |
Dellection with glass interposed. |
I'rans of so at ion |
misBioD ar radi- >y glass |
|
h. )». 11 40 |
1 |
|||
|
11 42 |
125 |
6.727 1 |
||
|
11 43 |
181 170 |
|||
|
11 57 |
||||
|
11 59 |
133 |
0 727 |
||
|
12 00 |
196 174 |
_ ... .- |
||
|
12 05 |
||||
|
12 07 |
130 |
(J. 791 |
||
|
12 08 |
155 |
|||
|
12 10 |
123 |
0. 794 |
||
|
12 12 |
155 |
|||
|
12 13 |
112 |
0.725 |
||
|
12 15 |
154 |
|||
|
12 16 |
119 |
6.761 |
||
|
12 17 |
159 |
|||
|
12 19 |
118 |
0.7.35 |
||
|
12 20 |
162 |
|||
|
Mean. |
||||
|
0.751 |
Traiisiiiisniun of Iniiiir rndiai'ion bi/ glasx. [November 26, 1884. A good sky. External temperature — 5"^. 0 C. Barometer, /3^7.26 decimeters ]
|
Mean |
Moon's dis- |
Moon's |
1 Air |
Deflection |
Deflection through |
glass. |
Trana- |
|
uieridian. |
tauce. |
Mi3. |
lunar beam. |
Glass outside. Glass |
inside. |
niissiou. |
|
|
h. m. |
h. m. |
||||||
|
, 5 56 |
0 48 |
c |
240 |
||||
|
6 00 |
0 44 |
44i |
10.2 |
22 |
.090 |
||
|
: 6 07 |
0 38 |
35 |
.139 |
||||
|
6:il |
0 34 |
2.57 |
|||||
|
6^19 |
0 26 |
29 |
.114 |
||||
|
6.24 |
0 21 |
30 |
.119 |
||||
|
6 31 |
0 14 |
251 |
|||||
|
6 53 |
0 00 |
43i |
10.0 |
260 |
|||
|
7 00 |
0 13 |
26 |
.102 |
||||
|
; 7 04 |
0 17 |
(2 lavers=lS) |
|||||
|
1 7 07 |
0 20 |
28 |
.112 |
||||
|
7 14 |
0 28 |
44 |
10. 1 |
247 |
|||
|
7 19 |
0 33 |
34 |
.140 |
||||
|
1 7 25 |
0 39 |
30 |
.127 |
||||
|
7 31 |
0 42 |
44* |
10.2 |
231 ' |
|||
|
9 12 |
2 20 |
53 |
12.1 |
227 |
|||
|
9 17 |
2 25 |
.54 |
12.3 |
29 |
. 135 |
||
|
9 21 |
2 29 |
54* |
12:5 |
•2C, |
. 126 |
||
|
9 26 |
2 33 |
55 |
12.6 |
196 |
|||
|
9 33 |
2 40 |
56 |
12.9 |
26 |
.131 |
||
|
9 36 |
2 43 |
56* |
13.1 |
25 |
. 13(1 |
||
|
9 40 |
2 47 |
57 |
13.4
|
192 |
i . |
Lnnat radiation: Mean transmission (glass outside) 119
Mean transmission (glass inside) 126
Mean of all observations 122
There is very little difference between the results for transmission with glass inside and out- side the building, and this little may be entirely accounted for by the diflusiou of the rays by the
40 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
irregular surfaces of the glass pane, which produces larger loss when the latter is ontside at a dis- tance from the iubtrument.
The solar energy which falls on the luoon may be divided into two portions: «, that which is reflected or dilfused ; h, that which is absorbed by the lunar soil and reradiated. We may form some rude « priori notion of the relative value of these from the following considerations : Were the full moon a perfectly diffusive body and reflecting according to the law established by ZoUner's experiments, it should behave nearly as aflat disc would do, and return to us such a portion of the sun's energy as the angular area of its disc bears to that of the hemisphere gyioo? (" )• Hence we may take this fraction to express the ratio of total lunar radiation — i.e.,{a+ b) — in terms of solar radi- ation. The ratio of lunar to solar luminous radiation is here taken to be (roughly) j o orroo — ^"t the ratio of lunar nonluminous to solar nonluminous radiation, owing to the selective absorption of the lunar surface, is probably indefinitely greater. This latter ratio is unknown, but the larger it is the smaller is the portion which we must assign to radiated heat. If, for instance, the per- fectly diflusive moon sends us -^ of the total solar I'adiation, and the ratio of lunar to solar radia- tion within the limits of the solar spectrum be -^j ^ is the proportion which is diffused or reflected to us (rt), and 1—'^ is that which is absorbed and radiated [b). Now, « is a little less than 100,000, and m varies with the degree of selective reflection in the lunar surface. If m be 000,000, one-sixth of the lunar radiation is reflected or diflused solar energy, and five-sixths absorbed and radiated from the soil. If m be 300,000, one-third of the energy is reflected, &c., and somewhere between these two values it seems probable that the ratio sought will lie. The heat sent earthward by the radiation from the lunar soil is almost certainly greater than that reflected or diflused ; but our at- mosphere is, according to what we have been hitherto accustomed to think, comparatively opaque to the first class of heat (that radiated from the soil) and comparatively translucent or diatherman- ous to the.second, so that there seems an a priori probability that the true ratio between a and 6, as it would present itself to an observer outside our atmosphere, will be altered by its absorption, and that actually observed at sea level be something different. It seems certain, at any rate, that the radiation of the lunar soil must be of a quality to which glass is nearly opaque, since the glass which we have employed in our own experiments is nearly opaque to the radiation from a source at lOOoC
Class 5.* — Heat observations during a lunar eclipsk.
The only lunar eclipse observed at Allegheny was that of October 4, 1884. The eclipsed moon rose behind clouds, and the first observation, obtained when the penumbra was already pass- ing off, was made while the moon was still partly obscured by haze. Under these circumstances little interest attaches to the observation, which need not be cited in detail. The inference from it, so far as any could be drawn, was that about the same amount of heat was received as was to have been expected had there been no previous eclipse.
KEVIEW.
Let us now review our sources of information and weigh the imperfect and sometimes contra- dictory results each has brought us.
(1) Direct measurement of lunar heat as compared with solar. — Our direct comi)arison indicates that we receive nearly the whole proportion of solar energy from the full moon that we should ex- pect to get from a diflusive disk of the same angular aperture. This heat must in reality be partly diffused and partly radiated, and we do not know (from the present observations) in what propor- tions these two kinds enter. So far as the observation itself is reliable, we may, however, infer that our atmosphere is permeable to most of the lunar heat of either kind, but the method is unfortun- ately subject to such large sources of constant error, that we cannot derive great confidence from the apparent agreement of different observations or even of different observers. It may be said, however, to create a certain presumption that the earth's atmosphere is diathermanous to heat of lower wave-length than has been heretofore snpposed, and of lower wavelemiihthan appears to reach us from the sun.
" Clnss (i, «i*c ii'fi'fi.
TEMPERATURE OF THE SURFACE OF THE MOON. 41
(2) Comparison ofmoon''s heat with that of Leslie cube. — If we may draw any infi^reiice from tbis class of observations it is that the sunlit surface of the moou is not far from the freezing tem- perature, but not so far below as we might expect to find that of an absolutely airless j)lanet.
(l?) Transmission of lunar heat by the eartKs atmosphere. — Our observations indicate a not ma- terially greater coetlicient of transmission for lunar heat than for solar; and though their limited number and the uncertainty of the correction for change of heat with phase render more certainty as to the fact desirable, we may (accepting them as probable) reason thus.
Previous observations both at Allegheny and Mount Whitney have shown that the solar rays are transmitted with greater and greater facility (except for cold bands) as the wave-length increases up to the point (near /. = 3" ) where they suddenly disappear altogether. This shows either that (1) the solar heat, which according to the customary assumption exists to an unlimited wave- length before absorption, has here been cutoff hy a suddenly absorbent action, like that of a cold baud extending indetinitely below 3*^, or (2) that, either through a precedent absorption of such rays in the sun's own atmosphere or their non-existence, no solar rays below S** present themselves to our atmosphere for admission.
The flrst view is that which I have treated as most in accordance with received opinion. It is not, however, the only one, since the second is not to be absolutely rejected, considering our experimental ignorance of the laws of radiation from gaseous bodies for great wave-lengths. Of these two hypotheses we see that, accoiding to the first, our atmosphere is quite opaque to all heat below S**, and the writer's (unpublished) experiments show that heat above this point must come almost wholly from a source nuch above 100° C. In this view, then (unless we agree that the radiations from the lunar soil correspond to a source much above 100° C), we conclude that sensibly none of them pass our atmosphere, but that what we receive is diffused and reflected heat coming within the range of the known solar energj' spectrum, and transmitted with nearly the same facility as solar heat, or if with a little greater, because lowered in wave-length by selective reflection at the lunar surface, not by absorption and reradiatiou from the lunar soil.
In the second view, for anything we have absolutely known to the contrary, our atmosphere may be permeable to radiations of any wave-length below Si^, and we could draw no certain infer- ence, even if the lunar radiation were more distinctly difierent in transmissibility than it is.
As a matter of fact, with the actually limited difl'erence in the character of its transmissibility, a difl'erence which, as so far determined, is of the same order as that of the error of observation, we have no ground then from this present class of observation (i e., class 3) for any absolute con- clusion one way or the other. But we repeat it seems to be a probable inference from our whole work that the earth's atmosphere is more diathermanous to heat of extremely low refrangibility than has heretofore been supposed.
(■4) Comparative transmission of glass for lunar and solar heat. — The evidence here, which at flrst seems to so directly support the view of a sensible radiation from the surface of the moon, proves on examination to be subject to other interpretation, for the observed effect is almost cer- tainly due in part to a degradation of wave-length by selective reflection from the lunar soil.
We can draw no absolute conclusion, then, from this evidence at first in appearance so prom- ising, though we may say that it certainly indicates an increased probability for the view that radiations from the lunar soil may be transmissible by our atmosphere.
(5) Observations during a lunar eclipse. — If our own observations in this respect are imperfect, those of Lord Rosse before cited are on the other hand clear. They appear to bear but one inter- pretation, that all heat from the moon disajipears immediately that it passes into the earth's shadow, and there is no evidence of any being retained, for any sensible time, more than if it were reflected.
It is so difficult to conceive that while the moon has been storing heat during many days of sunshine, it can part with it instantly, so that the temi^erature of the whole earthwaid surface of the i)lanet disapi)ears in an inappreciable interval, that most will see in this observation an argu- ment against the existence of any such heat sensible to us at any time whatever.
(G) Formation of a lunar heat spectrum. — The observations made here with the lunar heat spec- trum are as yet incomplete. With improving experience and apparatus, we hope to make others which shall give information of a character no other means can furnish. (See note, infra.) S. Mis. 69 6
42 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
CONCLUSION.
While we Lave fouud abuudaut evidence of heat from the uioou, every method we have tried, or that has heeu tried by others for determiuiug the character of this heat appears to us incouclu- sive; and, without questioning that the moon radiates lieat earthward from its soil, we have not yet found any experimental means of discriminating with such certainty between this and reflected heat that it is not open to misinterpretation. "Whether we do so or not in the future will probably depend on our ability to measure by some process which will inform us directly of the wave-lengths of the heat observed.
Note added February, 1885. — Since the above paragraph was written, we have succeeded in obtaining measures with rock-salt prisms and lenses in a lunar heat spectrum. These difiticult measures must be repeated at many lunations before complete results can be obtained; but, con- sidering their importance to the present subject, we think it best to state now in general terms, and with the reserve due to the necessity of future experiment, that they indicate two maxima in the heat curve, one corresponding within the limits of errors of observation to the solar curve maximum, the second indefinitely lower down in the spectrum, corresponding to a greater amount of heat at a lower temperature. Exactly what temperature this latter corresponds to, we have no present means of knowing. We have succeeded, however, in forming a measurable heat spec- trum from the surface of a Leslie cube containing boiling water, and the maximum ordinate in the Innar heat curve appears to be below the maximum ordinate in the hot water curve. The inference from this is, of course, that the temperature of the lunar soil is, at any rate, below that of boiling water and in an indefinite degree.
We cannot close this note without calling attention to the remarkable fact that we here seem to have radiations from the moon of lower wave-length than from the sun, which implies an appar- ent contradiction to the almost universally accei)ted belief that the sun's emanations, like those from any heated solid body, include all low wave-lengths representing temperatures inferior to those certainly emitted.
13 f > H H
>•
a
w
>■
H
•a
> a
mmm.
I
?
H O
o
Cn
I
Intensity.
Oi
a
a
I
s
o •5
>v u o
o
s
H W
Cji
O
I
20-
-1 i L
J-7^
Plate 4.— Relative Intensities of Sunlight, Moonlight, and Lamplight.
Plate 5. — Curve showing the Ratio of Sunlight to Moonlight in Different
Parts of the Spectrum.
Plate (j, — Solar and Lunar Energy Curves.
NATIONAL ACADEMY OF SCIENCES.
VOL. Ill
THIRD MEMOIR.
ON A METHOD OF PRECISELY MEASURLNG THE VIBRATORY PERIODS
OP
TUNIN^G-FORKS, ETC.
43
ON A METHOD OF PRECISELY MEASURING THE VIBRATORY PERIODS OF TUNING-FORKS, AND THE DETERMINATION OF THE LAWS OF THE VIBRATIONS OF FORKS; WITH SPECIAL REFERENCE OF THESE FACTS AND LAWS TO THE ACTION OF A SIMPLE CHRONOSCOPE.
By Alfred M. Mayer.
This research was carried on with funds from the Bache endowment to the N'ational Academy of Sciences. Its object was to arrive at a method of preciselj' measuring the vibratory periods of tuning-forliS, and to determine the laws of the vibrations of forks, with the special reference of these facts and laws to the uses of the tuning fork as a chronoscope in measuring small intervals of time.
The method devised is to make a clock, at each second, flash a spark of induced electricity on the trace made by a style attached to the prong of the vibrating fork F. P, Fig. 1, is the pen- dulum armed with a triangular piece of platinum foil, which, at each second, cuts through a globnle of mercury contained in a small iron cup, .U. This cup is so made that the globule can be regulated as to size and height by means of a screw-collar. Fresh mercury was placed in the cup at each experiment. The tuning-fork F is screwed into a board, H, which is hinged at h. This board rests against a screw-stop, E. C is a cylinder of brass, rotating on an axle, on one end of which is cut a screw, which runs in a nut at T. (See upper figure of Fig. 1.) The end of a prong of the fork is armed with a small triangle of thin elastic copper foil, about --}„ millimeter thick, and weighing only one milligram. The surface of the prong is well washed with ether, and then the foil is cemented to it with shellac. The point of this style just touches the camphor-smoked surface of paper, which tightly and smoothly envelops the cylinder C. The primary coil of an inductorium, I, and the clock (through P, and the globule of mercury, M) are placed in the circuit of a voltaic cell, B. In the secondary circuit of the inductorium is the fork F and the cylinder C, the thickness of the jiaper on the latter separating the point of the style on the fork from the surface of the brass cylinder. The fork is thrown upward, around the hinge /;, vibrated by drawing a bow across a prong; then depressed till the board jB" comes against the stop -B. The cylinder is rotated, and the trace of the fork is made on the paper, as shown in upper figure of Fig. 1. At each second, when the platinum-tipped pendulum leaves the globule of mercury, a spark flashes from the point of the style and makes a single minute and circular white spot on the blackened paper. This spot must be bisected by the trace of the fork. The center of the spot is generally marked by a minute perforation.
To obtain the results just described, it is necessary to fulfill certain conditions in the experi- ment, which, if neglected by experimenters, they would hastily regard the method as inaccurate. These conditions are as follows: (1) The globule of mercury siiould be small and rigid; that is, it should not vibrate when the platinum tip cuts through it. This condition is attained bj' screwing up the collar on the small cup M till only a small portion of the mercury is above the upper face
45
46 MEMOIRS OF THE NATIONAL ACADEMY OP SCIENCES.
of the cup. This adjustment has to be made with great care. The spark which at each second passes between the i)latinum tip and the mercury rapidly oxidizes the latter, and the mercury must be renewed at each experiment. (2) The paper on the cylinder must be smooth, thin, but not glazed. It required many days of experimenting before I succeeded in getting a paper which gave the results I sought. The best paper is a very thin printing paper with a smooth, un glazed surface. (3) The style on the fork must be very light and elastic. The best for this purpose is made out of thin hard-rolled copper or aluminium. (4) The spark given by the inductorium must be of the character already described. If the discharge of the inductorium be not composed of a single sparic, and its impress on the paper a minute circular spot bisected by the trace of the fork, it will be useless to expect accurate results from this method.
To reach these conditions cost much time, and it may be interesting to describe some of the variations in the character of the discharge of an inductorium when excited by various strengths of current, and when condensers of vai-ious areas are or are not in the secondary circuit.
The flash of an inductorium appears composed of a single discharge ; but only in certain conditions is it really composed of a single spark. If the discharge be obtained through the style on the fork with a current traversing the coil of a strength approaching that used in the usual electrical experiments with it, several flexures of the trace of the fork will be obliterated by the discharge deflagTating the carbon on the paper. This effect is produced by a multiplicity of dis- charges, following each other with such rapidity, and of such strength, as to denude the paper of carbon, to some extent, on either side of the trace. The breadth of carbon removed and the fuzzy character of the contour of these traces give them the appearance of caterpillars.
To obtain an analysis of these complex actions I devised the following method of experi- menting, shown in Fig. 2: A revolving brass cylinder, similar to the one used in our appa- ratus just described, was covered with thin printing paper, and the latter was well blackened by rotating the cylinder over burning camphor. The paper was then removed from the cylinder and cut into disks of about 15 centimeters in diameter. When one of these disks is revolved about its center with a velocity of about 20 times per second, it is rendered very flat by centrifugal action. It can then be brought between points or balls, even when the latter are separated by no more than .75 millimeter. When in this position the discharge between the points or balls perforates the disk and leaves a permanent record of its character, of the duration of the whole discharge, and of the intervals separating its constituent flashes .and sparks. To obtain the time of rotation I presented momentarily to the rotating disk a delicate point attached to the prong of a vibrating fork of known period of vibration. The axis of the sinuous trace thus made by the fork is traced by a needle point applied to the rotating paper disk. Drawing radii through symmetrical intersec- tions of this axis on the sinuous line, we divide the disk ott' into known fractions of time. The disk is now removed from the rotating apparatus and the carbon is fixed by floating the disk for a moment on dilute spirit varnish. When the disk is dry it is centered on a divided circle provided with a low -power micrometer microscope, and the duration of the whole discharge and the inter- vals of time separating its components can be determined to the oiioo of a second. I here give three typical experiments with this method, which will show the characteristics of the discharge of an inductoriiim :
1. Discharge of a large inductorium (striking distance, 45 centimeters between brass points) between platinum points 1 millimeter apart. no jar or condenser in secondary circuit.
The platinum electrodes were neatly rounded and formed on wire 1% millimeter in diameter. After the discharge through the rotating disk nothing was visible on it except a short arc formed of minute, thickly-set white dots; but on holding the disk between the eye and the light, it was found to be perforated with 33 clean, round holes, \nth the carbon undisturbed around their edges. The portion of the discharge which makes these holes lasts „-3 second, and the holes are separated by intervals which gradually decrease in size toward the end of the discharge, so that the last spark-holes are separated about one-half of the distance separating the holes made at the begin- ning of the discharge. The average interval between the spark-holes is 7-^ second. After this
MEASUEING THE VIBRATORY PERIODS OF TUNING-FORKS. 47
portion of tlie discharge has passed tbere is a period of quiescence lasting about y-jVo second; then follows a shower of minute sparks, which forms the short dotted line already referred to. This si»iirk-shower lasts ^rio of "^ second, and is form(\d of 30 sjiarks; hence the average interval sepa- rating these sparks is ^iiVo second. The intervals sejjarating these sparks arc, however, not uni- form, Imt are smaller in the middle of the spark-shower than at the beginning or at the end of this piit'iiomcnoii. This sjiark shower, indeed, is a miniature of the phenomenon obtained when a Lejden Jar is placed in tlie secondary circuit of the coil, and which will be described in the follow- ing experiments. The above determinations of intervals of time in the discharge are the mean of measures on six disks.
2. Discharge of large indxjctorium betaveen platinum points one millimeter apart,
WITH A LEYDEN jar OF 242 square CENTIMETERS SURFACE IN THE SECONDARY CIRCUIT OF THE COIL.
After this discharge through the disk a very remarkable appearance is presented. The dis- charge in its path around the rotating disk dissipates little circles of carbon. There are 91 of these circles, each perforated by 4, 3, 2, or 1 holes. I have to frame a new nomenclature to describe this complex phenomenon. I call the whole act of discharge of the coil, the (lischargc. Those separate actions which form the little circles by the dissipation of the carbon we will call flashes, and the perforations of these circles we call spa rl- -holes. The dischai-ge in the above experiment lasts -2-4- second. The flashes at the bi'ginniug of the discharge are separated by intervals averaging 5^5 second up to the tenth flash ; after this the intervals of the flash rapidly close up, so that during the fourth fiftii of the discharge they follow at each ^^g^ of a second. During the last fifth of the discharge the intervals between the flashes gradually increase, and the last flash is separated from its predecessor by y^oo of ^ second.
The appearance of the carbon-covered disk, after one of the discharges just described has passed through it, is giveu in Fig. 3.
On diminishing the current in the primary coil of the inductorinm I found that the number of flashes in the discharge diminished, so that at last I obtained a discharge which consisted of but one flash perforated by one minute spark-hole. Also, if the current remain the same and a i)ortion of the secondary circuit be divided, and gradually separated more and more, the number of flashes in the discharge will be diminished and the whole energy of the discharge concentrated in time. l>ut no rule can be given for any special coil to obtaiu from it such a discharge as is alone useful in the work on the forks, and the current must be gradually varied by resistances in the primary circuit of the inductorinm, and the area of the condenser in the secondary circuit, till the conditions for any special coil are obtained which cause it to give a s[)ark which makes a minute circular and well-defined mark directly in the trace of the style of the fork. In the inductorinm used there is 150 feet of wire in the primary circuit and eight miles in the secondary. The condenser in the secondary circuit was formed of tin-foil separated by panes of glass, and had an area of 50 square inches.
STUDY OF THE EFFECT OF VARYING A3IPLITUDES OF VIBRATION OF THE FORK ON ITS VIBRATORY PERIOD; AND ON THE EFFECTS OF VARYING PRESSURES OF THE STYLE ON THE PAPER-COV- ERED CYLINDER.
The experiments on this fork of Kceuig's were made not so much for the determination of its vibratory period at a given temperature, as to discover any effect on the vibratory period caused by ditterence of amplitude of vibration, and by varying jiressures of the tracing style on the smoked paper. This series of measures is given as an average example of series of similar sheets on which we have made measures. It will be observed that the vibration-numbers opposite the successive seconds, given in the first column, are alternately small and large. This is due to the fact that the center of the globule of mercury is not exactly on the vertical of the jjenduluTu, but by taking
48
MEMOIK3 OF THE NATIONAL ACADEMY OF SCIENCES.
the mean of two successive secouds we have the mean number of vibrations for those seconds. These means are given in column 3.
Table I.
(1)
8
9
10
11
12
(2)
(3)
255. 256. 255. 256. 254. 256. 2.54.
254. 257. 254. 257.
00 90 05 90 90 90 70 15 95 10 90 10
255. 95 255.97 255. 90 255. 92 256. 02 256. 00
(1) The mean of 1st and 2d secoDds= 255.95. Amplitude of vibration of 1st second ^2.03 millimeters. The mean of Uth and 12th secouds = 256.00. Amplitude of vibration of 12th second = .63 uiillimeter.
From this observation one might conclude that the number of vibrations increased with a diminished amplitude, but the following observations show that this is not a just conclusion :
(2) Mean Of 1st and 2d second8=255. 97. Mean of 7th and 8th secouds=25.5. 97.
(3) Mean of Ist and 2d seconds=256. 05. Mean of 11th and 12th second8=256. 00.
(4) Mean of 1st and 2d seconds=256. 17. Mean of 9th and 10th seconds=256. 20.
Amplitude of vibration of 1st second=l. 19 millimeters. Amplitude of vibration of 8th secoud:= . 59 millimeter. Amplitude of vibration of 1st second=2. 39 millimeters. Amplitude of vibration of 12th 8econd= . 61 millimeter. Amplitude of vibration of 1st 8econd^2. 07 millimeters. Amplitude of vibratiou of 10th 8econd= . 78 millimeter.
From the above measures we conclude that diflerences of amplitude of vibration in a fork, arranged as in the experiments, has no appreciable effect on its vibratory period.
Many measures were made on records obtained with varyiug pressures of the tracing style against the smoked pajier; but the slight variations of those pressures which could be obtained within the range of elasticity of the delicate style used gave no diflerences in the number of vibra- tions from which we could detect any influence of varying pressures of the style.
KPFEOT OF TEMPERATURE ON THE VIBRATORY PERIOD OF FORKS.
To determine the effect of variations of temperature on the vibratory periods of steel forks, I bought two sets of Kcenig's forks of the CT, harmonic series to known diflerences of temperature, and then determined how much they were thus thrown out of unison by the ob.servation of the number of beats thus can.sed in one minute of time.
Instead of heiiting or cooling one set of the forks by automatic thermostats, which method had several objections in principle and great diflicultits in the way of experimenting, I decided to wait for a favorable spell of weather, which we often have in April, when the air is still and misty and a drizzling rain occurs. In such weather the air is nearly constant in temperature. During such favorable conditions for the work, when the atmosphere varied only a few degrees in tem- perature during two days of mist and rain, I opened the windows of a room which contained one of the sets of forks and allowed them to remain there for a night and part of a day before begin- ning the experiments. In an adjoining room, kept at as nearly an equable temperature as possible, I placed the other forks. After the respective temperatures of these rooms had not varied perceptibly during three hours, I opened the door between the rooms just enough to hear clearly tlie forks of one room when stationed near the forks in the other. The temperature of the hot room was 66° Fahr., that of the other room was 41° Fahr.
Simultaneously sounding in order the two corresponding forks of the series, I obtained the
.MEASURING THE VIBRATORY PERIODS OF TUNING-FORKS. 49
following results. Tlio boats were timed with tlie aid of a stoi)-\vat(;li registering to oi)e-teiith of a second. After each observation the (h)or was closed and lilteen niiiiiites alloweil to elajjse before bej^inniiig the observations on the two forks ne.\t in order. I should here remark, however, that tlie order in which tlie forks were experimented with was tlie reverse of that given in the table, that is to say, the experiments began with the f/?':, fork, of highest pitch; because the smaller mass of the higher forks would be most attecte<l by any change of temperature from interchange of air of the rooms. I, however, observed no change in tlie tem])erature of the rooms ilnriiig the experiments.
Table II.
Tlio two IT: folks gave 11. (j beats iu 60 seconils for a difference of 25° Falir. The two VT^ forks gave '-j;t.O beats in 60 seeoiuls for a difference of ih'^ Fahr. Tlie two SOLz forks gave '26.0 beats in 60 seconds for a dift'ereuce of 25° Fahr. The two Ul\ forks gave 'i'i.h beats in 60 seconds for a difference of 25° Fahr. The two Mli forks gave 67.6 beats in 60 seconds for a difference of 25° Fahr. The two VTi forlvs gave 81.5 beats iu 60 seconds for a difference of 2.5° Fahr.
The forks in the cold room were a set recently received of KcENia; those in tlie warm room were a set of his forks which had been in constant use for several years and had become worn and somewhat rusted. To ascertain the difference in the numbers of vibrations of cou'esponding forks of the two sets, when at the same temperature, 1 had kept them for a day in the room which had the teminratnre of 06° Fahr., and after they had remained at this temperature during four hours we simultaneously sounded the two corresponding forks of tiie two sets with the following results:
Table III.
New rr,. fork g.ive 2..3 beats in 60 seconds, with old VT. fork. Old f.nk Mat.
Kew CTj fork gave 5.0 beats iu 60 seconds, with old {/'J'n fork. Old fork flat.
New SOL^ fork gave 2.0 beats in 60 seconds, with old .vOii fork. Old fork sliar)).
New [Tj fork gave no beats in 60 seconds, with old [?T, fork. Old fork in unison.
New JZ/i fork gave 12.0 beats in 60 seconds, with old MU fork. Old fork tlat.
New J7Ts fork gave 12.0 beats iu 60 seconds, with old UT:, fork. Old fork flat.
Coireeting the ob.servations of the number of beats given in Table II by the determination of beats contained in Table III, we have tlie actual numbers of beats iier minute given V)y the forks for a difference in temperature of 25° Fahr., if the fork had been strictly in unison when tit the same temperature, as follows:
Table IY.
The two VT2 forks g.ave 9.:i beats in 00 seconds for a dill'eieuce of 25- Fahr. The two fTj forks gave 18.0 beats in 60 secouds for a dift'ereuce of 25° Fahr. The two .SOL;, forks gave 28.0 beats iu 60 secouds for a <liti'ereiice of 25° Fahr. The two UTi forks gave 34.5 beats in 60 seconds for a difference of 25° Fahr. The two illi forks gave 45.6 beats in 60 seconds for a difference of 25° Fahr. The two J'T:, forks gave 6'.t.6 beats in 60 seconds for a difference of 2.5° Fahr.
I'rom the above determinations it follows:
Table V.
— , -|-, 1" Fahr. gives JJTi fork -\-, — , .00600 of a vibration per secovd. — , +, 1° Fahr. gives X'l\ fork -i-, — , .01200 of a vibration per secoud. — , -|-, 1° Fahr. gives SOL^ fork +, — , .018660 of a vibration per secoml. — , +, 1° Fahr. gives VT^ fork +, — , .023000 of a vibration per second. — , -|-, 1° Fahr. gives Mh fork +, — , .0:)0400 of a viliration per second. — , -I-, 1° Fahr. gives IT:, fork +, — , .0463:i:J of a viliration per .second.
S. Mis. fiO 7
W..1...II.. «
t;f :;^'"^: >
r !.'»'• (w
m:
f :. %
^- ■ *--
48
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
the mean of two successive seconds we have the mean number of vibrations for those seconds. These means are given in column 3.
Table I.
1 256. 00
(1) The mean of 1st and 2tl second8= 255.9.5. Amplitude of vibration of 1st second = 2.03 millimeters. The mean of lltli and 12th seconds = 256.00. Amplitude of vibration of 12th second = .63 millimeter.
From this observation one might conclude that the number of vibrations increased with a diminished amplitude, but the following observations show that this is not a just conclusion :
(2) Mean of 1st and 2d secouds=2.55. 97. Amplitude of vibration of 1st second=l. 19 millimeters. Mean of 7th and 8th seconds=25.5. 97. Am])Iitude of vibration of 8th secoud= . 59 millimeter.
(3) Mean of 1st and 2d seconds=256. 05. Am]ilitude of vibration of 1st second=2. 39 millimeters. Mean of 11th and 12th seconds=256. 00. Amplitude of vibration of 12th 8econd= .61 millimeter.
(4) Mean of 1st and 2d seconds=256. 17. Amplitude of vibration of Ist secoiid=2. 07 millimeters. Mean of 9th and 10th seeonds=256. 20. Amplitude of vibration of 10th 8econd= .78 millimeter.
From the above measures we conclude that differences of amplitude of vibration in a fork, arranged as in the experiments, has no appreciable effect on its vil)rator,y period.
Many measures were made on records obtained with varying pressures of the tracing style against the smoked paper; but the slight variations of those pressures which could be obtained within the range of elasticity of the delicate style used gave no differences in the number of vibra- tions from which we could detect any influence of varying pressures of the style.
KPFECT OF TEMPERATURE ON THE VIBRATORY PERIOD OF FORKS.
To determine the effect of variations of temperature ou the vibratory periods of steel forks, I bought two sets of KtBiiig's forks of the TJT2 harmonic series to known differences of temperature, and then determined how much they were thus thrown out of unison by the observation of the number of beats thus caused in one minute of time.
Instead of heiiting or cooling one set of the forks by automatic thermostats, which method had several objections in principle and great ditlicultiis in the way of experimenting, I decided to wait for a favorable .siiell of weather, which we often have in April, when the air is still and misty and a drizzling rain occurs. In such weather the air is nearly constant in temperature. During such favorable conditions for the work, when the atmosphere varied only a few degrees in tem- perature during two days of mist and rain, I opened the windows of a room which contained one of the sets of forks and allowed tbem to remain there for a night and part of a day before begin- ning the experiments. In an adjoining room, kept at as nearly an equable temperature as possible, I placed tiie other forks. After the respective temperatures of these rooms had not varied perceptibly during three hours, I opened the door between the rooms just enough to hear clearly the forks of one room when stationed near the forks in the other. The temperature of the hot room was 60° Fahr., that of the other room was 41° Fahr.
Simultaneously sounding in order the two corresponding I'orks of the series, I obtained the
v^J' !>> ^
^::#
S'^'
^ i£
^ ♦ ^.
* t
V * « f *
]\IKA8URIN(! THE VIBKATOIJY PERIODS OK TrNlNd-FOHKS.
49
following results. The beats were timed with the aid of a stop-watch registering to oue-tenth of a second. After eacli observation the door was closed and fifteen minutes allowed to elai)se before beji'inning the observations on the two forks next in order. 1 slioidd here remark, however, that the order iu which the forks were experimented with was the reverse of that given in the table, that is to say, the experiments began with the UT-, fork, of highest i>iteh; because the smaller mass of the higher forks would be most affected by any change of temperature from interchange of air of the rooms. 1, however, observed no change in the temperature of the rooms during the experiments.
Table n.
Tlic two IT, forks gave 11. C liciits in CO scconils for a diftVienee of 25° Falir. Tlie two VTs forks gavo 2'S.O beats in 60 seconds for a difference of 2r>° Fahr. The two SOL3 forks gave 26.0 beats in 60 seconds for a difference of 25° Fahr. The two U'l\ forks gave 32.5 beats in 00 seconds for a difference of 2.5° Fahr. The two Alii forks gave 67.6 beats in 60 seconds for a difference of 25° Fahr. The two f'T"-, forlvs gave 81.5 beats iu 60 seconds for a difference of 2.5" Fahr.
The forks iu the cold room were a set recently received of KceniCt; those in the warm room were a set of his forks which had been iu constant use for several years and had become worn and .somewliat rusted. To ascertain the difference in the numbers of vibrations of corresponding forks of the two sets, when at the same temperature, I had kept them for a day in the room which had the temperature of 06° Fahr., and after they had remained at this temperature during four hours we simultaneonsly sounded the two corresponding forks of the two .sets with the following results:
TABLE in.
New f'Tj fork g.ave 2.3 beats in 60 seconds, with old CTj i'cirli.
New CTa fork gave 5.0 beats in 60 seconds, with old f 7':, fork. New SOLn fork gave 2.0 beats iu 60 seconds, with (dd SOL-, fork.
New UTi fork gave no beats in 60 seconds, with old UT., fork.
New .I//4 fork gave 12.0 beats in 60 seconds, with old MJt I'ork.
New VT-, fork gave 12.0 beats in 60 seconds, with old f/T;, fork.
Old fork flat. Old fork flat. Old fork .sharp. Old fork in unison. Old fork flat. Old fork flat.
Coirectiug the observations of the number of beats given iu Table II by the determination of beats contained in Table III, we have the actual numbers of beats per minute given by the forks for a difterence in temperature of 25° Fahr., if the fork had been strictly in unison when at the same temperature, as follows:
Table IV.
The two UT.2 forks g.ave 9.3 beats in 60 seconds for a dilfereuce of 25° Fahr. The two UT:i forks g.ave 18.0 beats in 60 seconds for a difference of 25° Fahr. The tvro SOL:i forks gave 28.0 beats iu 60 seconds for a difterence of 25° Fahr. The two UTi forks gave 34.5 beats in 60 seconds for a difference of 2.5° Fahr. The two Mli forks gave 45.6 beats in 60 .seconds for a difterence of 25° Fahr. The two FT:, forks gave 69.6 beats iu 60 seconds for a difterence of 2.5° Fahr.
From the above determinations it follows:
Table V.
— , +, 1° Fahr. gives UT-, fork +, — ,
— , +, 1° Fahr. gives UT-i fork -)-, -,
— , +, 1° Fahr. gives SOL^ fork +, -
— , +, 1° Fahr. gives f/r< fork -f , -,
— , +, 1° Fahr. gives Mh fork +, — ,
— , +, 1° Fahr. gives I'T, fork +, — ,
S. Mis. 09 7
.00600 of a vibration per second.
.01200 of a vibration per second. .018666 of a vibr.ation per second. .023000 of a vibration per .second. .030400 of a vibration per second. .046333 of .'i vibration per s<'Cond.
50
MEMOIRS OF THE NATIONAL ACADE.MY OF SCIENCES.
The above resiilt.s may be rediieed to a more general statement by giving the eti'ect of a change of 1° Falir. on the forks' vibratory period, as follows:
Table VI.
+ 1- Falir. diiiiinisbcs VT.: fork's vibratory period (ji? second) ^lijj part. -|- 1° Falir. diiniuishes VTi fork's vibratory period (jj^ second) -jrk^^ part. + 1'^ I'alir. diminishes .S'OXs forlc's vibratory period (^ Jj secoud) xyi^it part. -f- 1° Fabr. dimini.sbes VTt fork'.s vibratory period (j{-j second) ytitt part. + 1° Falir. diminishes Mlt fork's vibratory period (^^^y second) yxosi part. 4- 1" Fabr. diminishes JJ'T,, fork's vibratory period (xoW second) yjluo part.
From Table YI it is .«een that the effect of a change of temperatnre on the vibratory period is the same for all forks made of the same steel and similarly shaped. The diflerences among the fractions of a vibratory period are small and evidently owing to the necessary errors of observa- tion. I have great confidence in the accuracy of this determination. Tlie mean fraction of the vibratory period which one of Ka-nig's forks gains or loses by a diminution or increase of 1° Fahr. is irxiTfTPart, or .00004038.
THE LAW OF THE ErNNlNlr DOWN IN THE AMPLITUDE OF A FORK'S VIBRATION.
Twelve sheets were carefully taken of the traces of an J'Ti fork of ll'S vibrations per second. The fork was vibrated with a bow and the cylinder turned as niiiformly as possil)le by the hand. The seconds were mariied off on the traces of the fork by the break circuit of the clock. At or near each second mark on the sheets was measured with a microscope micrometer the amplitude of the vibration. The whole number of the sheets furnished over two hundred measures, giving the connection between the time the fork liad run and the amplitude of its vibration at the end of that time. A curve was then plotted giving their relations. Its discussion showed that it was a logarithmic curve, which has the following expression : )/=(1.119)\
EFFECT OF THE SUPPORT OF A FORK AND OF THE SCRAPE OF ITS TRACING-STYLE ON ITS
VIBRATORY PERIOD.
These experiments on the effects of the support and sci-ape of the fork were made in connec- tion with Prof. Albert A. Michelson with special reference to the period of vibration of the fork he used in timing the rotation of the mirror he employed in his e.xperiments on the velocity of light. The fork was an TT, of Kceni"-.
No. 1.
Temp. SC^ Fahr. 80
15x.0l2^.180=correction for tcuiiieratnre
(1).... 0.3 (0).... 1289. 2
(2).... 256.1 (7). ...1535.3
(3).... 511.7 (8). ...1791. 5
(4).... 767.9 (9)....2U47. 1 (5) .... 1023. 5
(7)— (1)— 6^255.83 (8)— (2)-^6=2o5. 90 (9)— (3)— 6=255. 90 (10)— (4)— 6=255.93 (11)- (5)^6=255. 92 (12)— (6)— 6=256.01 (13)— (7)— 6=255.95
|
Table VII. |
||||
|
—65=15 ;uiiieratnre. |
T. (1).. (2).. (3).. (4).. |
■nip. 81^^ 0.6 .. 256.7 .. 512.4 .. 768.3 |
No. 2. Fahr. 16x.012=.192 |
81-65=16 |
|
(11)).... 2303. 5 (11). ...2559.0 (1-2).... 2825. 3 (13).... 3071.0 |
(5).... 1024. 5 (6) .... 1280. 6 (7). ...1.536. 2 (8).... 1792. 3 |
(9). ...2048.6 i (10). ...2304. 9 (11). ...2560.2 |
.Mean 2.55.920
Corr. for temp. .. . +.180
2.56. 100 Coir, for clock ... — . 028
256. 072
(6)— (2)-^4=255. 97 (7)-(l)^6=256.93 (8)— (2)— 6=255. 93 (9)_(3)— 6=256. 03 (10)-(4)— 6=2.56. 10 [(ll)-(5)-6=25.5.95]:'
|
2.55. 91)2 |
|
|
Corr. for temp.. |
.. +.192 |
|
Corr. for clock.. |
256. 154 .. —.028 |
256. 126
MEASURINd TlIK VIBKATOKY I'EIUODS OF TUNING-FORKS.
Tai!LE Vll— Ooutiiifiul.
51
(1) (^)
(4)
(o)
|
... |
0.1 2.54.5 |
|
... |
7()l). 3 1023. 5 |
(0).
. . 1535. 2 ..17iH1.3 ..2047. (•
(10).... 230,'. 1 (H)
(12)....2S14.0 (13)....3U7I.l
(7)— (1)— 0=255. 85
(H)-(2)— 6=255. 97
(9)— (D— 8=255.86
(101— (4)— 6=255.97
(12)- (4)— 8=255.96
(13)— (5)— 8=255. 95
Meau 255.927
CoiT. for teuip. . .. +.192
Coir, forelock.
256. 119 . —.028
256. 091
(7)— (1)— 6=256. Oil
(8)— (2)^6=255. 9S
(9)— (3)— 6=255. 9N
(10)— (4)— 6=255.97
(11)— (5)— 3=2.55.95
Mean 2.55. 976
Corr. for temp .. +.120
Corr. for clock.
256. 096 . —.028
256. 068
|
(1).- |
.. .03 |
(6).. |
(10).. |
..2307.2 |
|
|
(2).. |
.. 258.4 |
(7).. |
. . 1536. 1 |
(11).. |
..2560.0 |
|
(3).. |
.. 512.1 |
C^)-- |
..1795.0 |
(12).. |
..2819.3 |
|
(4).. |
.. 771.1 |
(9).. |
..204e. 1 |
(13).. |
..3072.3 |
|
(5).. |
. . 1024. 1 |
(")-(l)— 6=255.97 (*^)— (2)— 6=2.56. 10 (9)— (3)— 6=256. no (10)— (4)— 0=250.02 (II)— (5)— 6=255.97 (12)-(4)— 8=256.02 (13)— (7)— 6=256. 03
Mean
Corr. for temp.
Corr. for clock
.256.016 . +. 120
256. 136 . —.028
256. 108
|
Temp. 75" Falir |
No. 5. 75—65=10 |
10x.012r- 120 |
|
(1).... 0.5 (2).... 2.53. 6 (3).... 512. 3 |
(5).... 1024. 3 (6) (7).... 1.536. 5 |
(9).... 204^. 2 (10).. ..2301. 3 ! (11). ...2.560.(1 ■ |
Temp. 75° Falir.
No. 6.
75—65=10
10x.012=.120
(1).... 0.7 (2). ...258.6 (3).... 512. 7 (4).... 770. 5
(5) ...1024.7 (6).... 1282. 7 (7).... 1536. 6 (8).... 1794. 5
(7)— (1)^6=255.98
(8)— (2)— 6=255.98
(9)— (3)— 6=2.56. 00
(10)-(4)— 6=2.56. 02
(11)— (5)— 6=255.98
(12)— (6)^6=256. 03
(9).... 2048. 7 (10).... 2306. 6 (U).... 2560. 6 (12)....281-.9
Meau 255. 998
Corr. for temp... +. 120
2.56. 118 ( 'orr. for clock ... — . 028
256. 090
Temp. 75° Fahr.
No. 7. 75—65=10
(1)... (2)... (3)... (4)...
10x.012=120 Temp.76J Fahr.
0.1 (5) 1023.7
2.57.9 (6) 1281.6
512.11 (7).... 1536.0
770.0 (8).... 1794.0
(7)— (1)— 6=2.35.98
(8)-(2)— 6=2.56.02
(9)— (3)— 6=255. 92
(10)— (4)— 6=2.56. 05
(11)— (5)— 6=256.05
(12)— (6)— 6=256. 12
(9).... 2047. 5 (10).... 2306. 2 (11). ...2.560.0 (12). ...2818.3
Meau 256.020
Cori'. for temp ... +. 120
256. 140 CoiT. for clock ... — . 028
256.112
No. 8. 70—65=11
11X.012=132
(1)..-. 0.0 (5).... 1023. 7 (9).... 2048. 1
(2).... 254. 1 (6;.... 1278. 1 (10)
(3).... 512.0 (7).... 1.536.2 (11) ....2559. 9
(4).... 766.0 (8)... .1790.1
(7)— (1)— 6=256.03 (8)— (2)— 6=256. 00 (9)— (3)— 6=256. 02 (8)— (4)— 4=256. 02 (11)— (5)— 6=2.56.03
Mean 2.56.020
Corr. for temp.. . +. 132
Corr. forelock. .
256. 152
. —.028
256. 124
52
MEMOIRS OF THE NATIONAL ACADEMY OV SCIENCES. Table VII — Continued.
|
Temp. 81^ Fahr. |
No- 9. 81-65=16 |
16 X. 012=. 192 |
Tcniii |
SIJ Fabi- |
No. 10. 81-65=10 |
16x.012=.]92 |
|
(1).... 0.8 (2).... 257.2 (3).... .512.7 (4).... 768.9 |
(5).... 1024. 3 (6) -..1280. 7 (7).... 1536. 3 (8).... 1792. 5 |
(9).... 2048. 4 (10).... 2304.0 (11). ...2.560.2 |
(1)-.. (2)-- (3)... (4)... (5)... |
. 0.6 . 2.58.1 . 512. C . 770.0 .1024.1 |
(6).... 1281. 9 (7) . . . . 1535. 9 (8).... 1793. 8 (9).... 2047. 5 |
(10).... 2305. 7 (11).... 25.59. 7 (12). ...2817.3 (13). ...3071.5 |
(7)— (1)— 6=255.92
(8)— (2)^6=255. 88
(9)— (3)— 6=255. 95
(10)— (4)— 6— 255.85
(11)— (5)— 6=255.98
Meau 255.916
Corr. for temp . . . -|-.192
. (7)— (1)— 6=255.88
(8)-(2)^ 6=255.95
(9)— (3)— 6=255.82
(10)— (4)— 6=255.95
(11)— (5)— 6=25.5.93
(12)— (6)— 6=25.5.90 (13)— (1)— 12=2.5.5.91
256. lOS Corr. for clock . . . — .028
256. 080
Mean . . '.
Corr. for temp . . .
Corr. for clock . . .
.2.55.906 . +.192
256. 098
. —.028
256. 070
The mean value of tlie above- determiued ten means is as follows:
|
(1).... |
-.2.56.072 |
|
(2).... |
..256.126 |
|
(3).... |
-.256.(191 |
|
(4).... |
..256.108 |
|
(5).... |
..256.068 |
|
(6).... |
..256.090 |
|
(7).... |
..256.112 |
|
(8).-.. |
..2.56.124 |
|
(9).... |
. . 256. 080 |
|
(10).... |
..256.070 |
|
Correction for effects of .support |
256. 094 — . 026 |
|
ami scrape. |
|
|
•>'fi nr^ J Number of vibrations of fork ou -OD. vor, ^ i-esouaut box at 65° Fabr. |
|
The coirectiou — .026 lor the effect of support and scrape of style of fork was determined as follows:
The standard TIT-^ fork was placed in the same support {H of Fig. 1) which held it while it made its record on smoked paper, but fork vibrated freely, that is, it did not trace its vibrations on the paper. Another similar Ul\ fork was screwed on its resonant bo.\ and its prongs loaded with wax till it made al)out five beats per second with rtrst fork. The beats were counted by coincidences with the one-tifth second beats of a watch.
Table VIII.
Coiucidenoe.s were marked at 32 secomls; :i9 .seconds; 43.5 seconds ; 49 seconds; 54.5 seconds; 61.5 seconds.
61.5 — 32^29.5; 29.5— 5^5. 9^time of one interval between coincidences.
Kksumi':.— (1)=5.9 seconds; (2)=6.2 seconds; (3)=6.2 seconds; (4)=6.2 seconds. Mean=6.13=timo of one interval between coincidences.
In tbis time, tbe watch makes 6.13x5=30.65 beats, and the forks make 30.65+1^31.65 beats. Hence tbe number of beats per second is 31.65— 6.13=5.16:i.
We now made similar experiments to tbe above, with tlie dirt'erence that the standard UT3 fork was allowed to make its trace on the smoked j)aper, as it did when we determined its rate of vibration.
MEASUKING THE VIBKATOKY PERIODS OF TUNING-FOEKS. 53
TA15LK IX.
Ooiucitloucos wevo marked at 59 seconds; at 4 seconds; at 1(1.5 seconds; at 17 seconds. 77 — 59=18; 18-f-3=G.n=tiuie of one interval.
Kesum6. — (1)=6.0 seconds; (2)^6.0 seconds ; (:5)=6.7 .seconds; (4)=6.3 seconds; (5)=6.5 seconds ; (r))=U. 7 sec- onds; (7)=G.O: meau=6.:!l .seconds.
(i.31Xo— :il..'i5 :U. 55+1.00=32.55
32.55—6.31= 5. 159 With fork free= 5. 103
Effect of scrape = — .004 Circumstances as in tirst case, except that both forks were on their resonant boxes.
Table X.
Coincidences were observed at 21 seconds; at 26 seconds; at 36 seconds; at 44 seconds; at 51 seconds; at 00 seconds.
60 — 21=39; 39— 5=7.S^tinic of one interval.
R^SUM]?;. — (1)=7.8 seconds; (2)^7.1 seconds; (3)=7. 6 seconds; (4).=7. 4 seconds; (5)=7.2 seconds ; inean=7.42 seconds.
72.42x5= 37. 10 + 1.00
38. 10
38.10—7.42= 5.133 Above= 5. 159
Kii'ect of sniiport and scrape= — . 026
From the esperimeuts it appears that the effect of the ^vork of the fork in traciiio' its record oil the smoked paper covering the cylinder, is only — .OOi of a vibration; a (iiiantity so small as to be negligible, as will appear further on where we give the probable error of the mean determina- tion of the numbers of vibrations per second of various forks.
The difference in the number of vibrations given bj- the fork when vibrating on its resonant box and when vibrating while screwed into the hard wooden support [H, Fig. 1), amounts to — .02G less .004, or — .0J2. This result was not anticipated, and it shows how careful should experimenters be in describing minutely the cliaracter of the sui)i)ort of the fork when they give the value of its vibratory period.
DcUrminatwH of the numbers of vibration per second of European forks of various standards of pitch
[Scut me by Mr. Alexander J. Ellis, F. K. S. ]
These forks were the si fork of 1789, of the Gha2)elle Versailles; the A fork of 1812, of the Con.servatoire ; the ^4. fork of 1818, of the Theatre Feydeau; tb-e A fork of 1820, of the Tuilleries, and a C fork made by Marloye of Paris.
The determination of the pitch of these forks was made with special care, and these measures may be regarded as the limits of accuracy of our method, so far as I have been able to deal with it. The fractions of vibrations on the records were read otf with a microscope-micrometer, and the corrections for temperature and rate of clock were carefully obtained.
54
MEMOIRS OF THE NATIONAL ACADE3IY OF SCIENCES.
Table XI.
Table XII.
[Conservatoire (A) fork of 1812.]
|
Ore; |
r^ |
.' o |
« a |
|||||
|
a; |
+- tn |
V |
o § |
a c3r • |
||||
|
G |
o Sf^ |
|||||||
|
rate, si real. |
factor ect rec rate. |
d corree ur rate. |
erature ion -f- 65). |
a a o ■" ■*. .'S a ^ .».> g § a |
||||
|
o |
a. a |
o |
lock con for |
o |
B si. |
|||
|
M |
^ |
H |
o |
o |
M |
-^._'^. |
H |
r- |
|
O J,' |
||||||||
|
ij |
65 |
+5. 30 |
. 99721 |
438. 12S |
439. 354 |
. 000 |
439. 354 |
|
|
65 |
+5.30 |
. 99721 |
iSf. 075 |
439.301 |
.000 |
439. 301 |
||
|
>■> |
64.75 |
+5. 30 |
.99721 |
438. 161 |
439. 387 |
^.005 |
439. 382 |
|
|
:i |
63.6 |
+5. 30 |
. 99721 |
438. 134 |
439. 360 |
-.028 |
439. 332 |
|
|
4 |
63. 6 |
+5. 30 |
. 99721 |
438. llh |
439. 344 |
-. 028 |
439. 316 |
|
|
439. 337 |
.a
J^
Table XIII.
[Theatre Feydeau (A) fork of 1818.]
° F.
63.4
63.4
63.4
63.4
63.8
63.8
63.8
63.8
64.5
64.5
64.5
64.5
o p o
« o 5
+5.2
+5.2
+.5.2
+5.
+5.
+5.
+5.
+5.
+5.
+5.
+5,
+5,
. 99721 . 99721 . 99721 . 99721 . 99721 . 99721 .99721 . 99721 . 99721 .99721 . 99721 . 99721
m
432. 812 432. 799 432. 809 432. 800 432. 847 432.818 432. 844 432. 825 432.799 432. 837 432. 805 432. 828
434. 023 434. 010 434. 019 434.011 434. 058 434. 029 434. 055 434. 036 434 010 434. 048 434.016 434. 039
I
|
iL ^ |
|
|
ss. |
a cs,- o a. .ii |
|
•l* , |
a ao |
|
^+ ; |
x'S^ |
|
rat ou 5). |
a ° 4i |
|
i-T |
rt 5 2 |
|
- ^ 1 |
Z i^ a |
|
a g;:^ |
-^ X +.> |
|
. H 1 |
>■ |
|
1 -. 031 |
433. 922 |
|
—.031 |
433. 979 |
|
-.031 |
433. 988 |
|
—.031 |
433. 980 |
|
— . 023 |
434.035 |
|
-.023 |
434. 006 |
|
—.023 |
434. 032 |
|
—.023 |
434. 013 |
|
—.010 |
434. 000 |
|
-.010 |
434. 038 |
|
—.010 |
434. 006 |
|
—.010 |
434. 027 |
|
434. 008 |
MEASURING THE VIBRATORY PERIODS OP TITNINd-FORKS.
55
|
TAliI.E XIV. |
|||||||||
|
_ |
IT |
lillcries (A) fork of 1820.J |
|||||||
|
;_ |
.— |
J, o. |
i" 3 |
||||||
|
•B |
"*" ^ |
3 |
S 5 |
||||||
|
i |
3 S |
ti |
5 + |
a ill ;>f III 6.5° |
|||||
|
1 |
a; |
a; |
■t: a |
lock fa correct for rate |
o |
ecord c( for ra |
pi |
ibration second ( time at |
|
|
to |
H |
H |
O |
O |
a: |
K |
•^ |
||
|
OJi- |
|||||||||
|
.s |
1 |
65. |
5 |
+4.9 |
. 997->l |
421. 589 |
422. 769 |
- .01 |
422. 759 |
|
o |
65. |
5 |
+■4.1) |
. 99721 |
421.597 |
422. 776 |
— .01 |
422. 766 |
|
|
( |
:i |
()•">. |
5 |
+4.9 |
. 99721 |
421. 626 |
422. 806 |
— .01 |
422. 79(> |
|
.:> |
I |
(!5. |
8 |
+4.9 |
. 99721 |
421.6^2 |
422.812 |
— . 015 |
422. 797 |
|
2 |
/jr |
H |
+4.9 |
. 99721 |
42l.6:ir, |
422. 81li |
— . 015 |
422. 801 |
|
|
( |
:! |
H |
+ 4.9 |
.99721 |
421.641 |
422. 821 |
—.015 |
422. m-> |
|
|
<s |
1 |
:, |
+4.9 |
.99721 |
421.6i;7 |
422. 847 |
- .01 |
122. 8:i7 |
|
|
'A |
■2 |
5 |
+4.9 |
. 99721 |
421. 609 |
422. 788 |
— .01 |
422. 778 |
|
|
} |
:! |
5 |
+4.9 |
. 99721 |
421. 624 |
422. 804 |
— .01 |
422. 794 |
422. 793
Table XY.
[Marloye (C) fork.]
|
; |
z — |
- |
w r |
|||||
|
4-i |
||||||||
|
£ |
'5 |
li |
? ■ |
Ceo — o |
||||
|
c3 |
a, g |
3 o |
||||||
|
S |
^ ;; |
^ |
■2 o |
•^?a= |
||||
|
i |
5 |
_o |
lock con for: |
o |
§=2 |
ibra sec tim |
||
|
XJi |
H |
H |
5 |
O |
K |
03 |
H |
[ |
|
I |
O Ji". |
i |
||||||
|
3 |
1 ' |
69. 25 |
+3.48 |
. 99723 |
2,55. 167 |
2,55. 876 |
+. 051 |
255.927 |
|
4 |
1 |
69. 5 |
+3.48 |
. 99723 |
255. 224 |
255. 933 |
+.054 |
255. 987 |
|
6 |
1 |
71 |
+3.48 |
. 99723 |
2.55. 187 |
255. 896 |
+. 072 |
255. 968 |
|
2 |
71 |
+3. 48 |
. 99723 |
2.55. 120 |
255. 829 |
+.072 |
25.5.901 |
|
|
. |
1 |
60 |
+4. 35 |
. 99722 |
255. 208 |
255. 919 |
— . 0.57 |
255. 8()2 |
|
/ ' |
2 |
liO |
+4. 35 |
. 99722 |
255. 219 |
255. 930 |
—.057 |
255. 873 |
|
8. |
1 |
i;i |
+5. 00 |
. 99721 |
25.5. 212 |
255. 926 |
-.048 |
255. 878 |
|
-> |
61 |
+5. 00 |
. 99721 |
255. 221 |
255. 935 |
—.048 |
255. 887 |
|
|
2.55.9111 |
Tbe Ueterniiuatious of the number of vibratious per second of tlie .4 forks have to be cor- rected by +.04-4 for the cfl'ect of the weight of the tracing style. The correctiou was too small to be determiiied iu the case of the C fork.
The separate detei'miiiations of the number of vibratious of the Oiiapelle Versailles fork and those of the Theatre Feydeaii fork are numerous enough to give some idea of the probable error of a single determination and of the error of tbe mean of the determinations when these are dis- cussed by the method of least squares.
From this discussion it appears that for the Chapelle Versailles fork, the probable error of a single determinations: i .019 of a vibration ; the probable error of the mean determination= + .0053 of a vibration.
From the experiments on the Theatre Feydeau fork, the probable error of a single determina- tion= i.014 of a vibration; tbe probable error of the mean determination^ ±.004 of a vibration.
These results show tliat the method is quite accurate, and certainly sufidciently so for the determination of the pitch of a standard fork, and for all purposes when the fork is used as a chronoscope iu the measure of small intervals of time. If the error of the determination of the pitch of these two forks — when corrected for eflects of support and S(;rape, which is a constant
56 MEMOIRS OF THE NATIONAL ACADEMY OF SGIENCES.
readily determiued — should only equal Tb%o> or ^ Jo "f ^ vibration in one second, a variatiou of that amount would be produced by a cliauge of temperature of only one-fourth of a degree F. in the Theatre Feydeau fork, and if measured in beats would amount to the difference in the pitch of two forks, which, when sounded together, would give oue beat in 200 seconds.
On the uses op the tuning-fork as a chronoscope. — Various forms of chronoscopic apparatus contain a vibrating foi'lc as a register of time. The majority of these are costly, by reason of the attempts of the iuventons to obtain regular rotations of cylinders or disks by means of clock-work, when really all such appliances are useless. The fork itself, if only allowed to register its own trace on the revolving cylinder or disk, will give all that is desired without such adjuncts, for the accuracy of its registratiou has no connection with the rotation of the cylinder on which it leaves its record, and it matters not whether the latter be revolved quicker or slower, regularly or irregularly, so long as the motion is appreciably uniform during the trace of one flexure of the fork ; this duration in the case of an VTi fork would be oidy the oi,y of a second, and in that minute interval it would not be possible to get a measurable variation in velocity unless we did our best to attain it. Any ordinary care in the rotation of the cylinder by hand will give waves which at and near the spark-mark will be found to be similar and equal, and therefore no error can be made in the measure of the fraction of a wave.
The numbers of vibrations of a fork per second can be determined to ^^-^ of a vibration, or, to be surely within bounds, say to the '^Jii^ of a vibration, by the method we have described in this paper. This will give the time record with an A fork of WO vibrations per second to ttoto of a second.
It is not necessary to make any correction for the effect of the scrape or weight of tracing style or for the effect of the kind of support of the fork, for the number of the fork's vibrations per second is determined while the fork is on the same support it has when used as a chronoscope and while the fork is making its record; in other words, the number of the fork's vibrations per second are determined in the cruet conditions in which it is used as a chronoscope.
The arrangement of such a chronoscope is of the sinqjlest character. Fig. 4 shows it. As an example, we will suppose that we are to determine the initial velocity of a rifle-ball. 7> is a voltaic cell, whose current goes thi-ough the primary coil of the inductorium /, then to the target T formed of a metal plate (or a screen of wire, if we are determining the velocity of a caunou ball). This plate is very slightly inclined forwards, so that its upper edge presses very slightly against an adjusting screw at A'. The abutting surfaces of this screw and the plate are amalgamated to insure good elastic contact. The bottom of the plate rests in a siuall trough of mercury. The current passes to this trough and out of the plate at the adjusting screw S, thence to the make- circuit lever J\r(\ and back to the battery 7>. Oue pole of the secondary circuit of the inductorium is connected with the fork F, the other pole with the rotating cylinder C. The make-circuit lever is formeil in this manner: It moves around a center at 0. On its lower side are two platinum lugs. By the motion of the lever around O, eitlier one or the other of these lugs are brought in contact with two platinum contact-pieces, e and c, which are insulated from the plate and standard on which the lever is supported.
The chronoscopic apparatus haviug been arranged as in the diagram, the fork is raised on the hinge h (see Fig. 1) and vibrated with a bow. The cylinder is revolved and the fork brought down on its smoked paper surface. At the word "Are," the rifle is discharged. The fine wire or thread ir is cut by the ball, and the weight j) which it supported and which brought the left hand platinum lug onto the left hand insulated contact-piece, falls; then the spring ,v (or, better, a rubber band), which opposed the action of the weight, swings the right hand lug on to the right hand contact-piece. When the ball cut the wire, the primary circuit of the inductorium was broken, and a spark, at that instant, passed from the style of the fork and made a spark- hole in its sinuous trace. But the spring .v at once made contact again, and the circuit was made through the right-hand lug c. The ball, therefore, reaches tlie target-plate T with the circuit closed, and when it strikes 2* the plate is thrown from the contact-screw 8, and a second break takes i)lace in tlie primary circuit and another spark passes from the style of the fork. By counting the number of waves and measuring with a microscope-micrometer the fraction of the
MEASURING THE VIBEATOUV I'EKIODS OK TUNING-FOEKS.
57
wave iu the trace of tlie fork, wo liave the time it took the ball to go over the kuown distance from the wire w to the target T.
As an example of such work, we here give ex])erimeiits we made on tlie velocity of the rifle- ball of A5 inch caliber of the United States Army cartridge. This ball weighs 405 grains, and the powder driving it weighs 70 grains.
Table XVI.
Xiiiiilior of experiment.
(1) (2) (3) (•1) (5) (6)
11.31 11.34 11.30 11. '.^8 11.35 11.3-2
c
a'
Seconds. .04418 . 04429 .04414 . 04406 . 04433 . 04421
Feet. 1,:«8.0 1,354.7 1,359.3 1,361.7 1, 3.53. 3 1, 357. 1
1,3.57.3
Feet. +0.7 —2.6 +2.0 +4.4 —4.0 —0.2
The tifth column gives the ditterences of the separate determinations, and 1,3.57.3 feet the mean velocity of the ball per second. The average difference amounts to only 2.3 feet.
EXPERIMENTS WITH THE CHEONOSCOPE ON THE VELOCITIES OF FOWLING-PIECE SHOT OF VARIOUS SIZES PROJECTED WITH VARIOUS CHARGES OF POWDER FROM 12 AND 10 GAUGE GUNS.
The guns used iu these experiments wei-e "choke bore," of the Colt Arms Manufacturing Company, of Hartford, Conn. They had rebounding locks. The primary current of the induc- torium passed through a break-piece fixed under the rebounding hammer, so that at the instant the cartridge was exploded the electric current iu the primary circuit of the inductorium was broken and then immediately formed again. The current which passed through this break-piece was led by a wire to an upright piece of tin plate, whose front surface leaned against a thick copper wire. Another wire led from the tin plate (which stood in a shallow trough of mercury) back to the battery.
The following tables give the results of our experiments:
TABLE XVII.
[lO-gauge Colt gun; 5 drams Curtis & Harvey powder; l^^-ounce shot.]
|
Size of shot. |
Velocity 30 yards. |
Velocity 40 yards. |
Velocity 50 yards. |
|
No.l Buck FF |
1153 1147 1146 1066 1012 995 900 |
1067 1132 1126 1015 |
|
|
BB No.3 |
|||
|
928 |
|||
|
No.6 No.8 No. 10 |
963 880 803 |
859 775 716 |
S. Mis. m-
58
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
TABLE XVIII.
[lO-gange Colt gun; 4 drauis Curtis & Harvey jiowder; IJ-ounce shot.]
|
•Size of shot. |
Velocity 30 yards. |
Velocity 40 yards. |
Velocity 50 yards. |
|
No.lBiKk FF BB No.3 No. 6 . - |
1067 1017 1000 989 966 920 848 |
1018 1009 967 911 883 874 756 |
|
|
967 897 872 806 776 669 |
|||
|
No.8 |
|||
|
No. 10 |
Table XIX.
[la-gauge Colt gun ; 3J- drams of Curtis & Harvey powder ; IJ-onnce shot. ]
|
Size of shot. |
Velocity 30 yards. |
Velocity 40 yards. |
Velocity 50 yards. |
|
BB No. 3 No. 6 No. 8. |
862 844 825 816 796 |
795 754 739 749 680 |
667 690 600 < 607 610 |
|
No. 10 |
Table XX.
[12-gauge Colt gun; 4 drams Curtis & Harvey powder; IJ-ounce shot.]
|
Size of shot |
Velocity 30 yards. |
Velocity 40 yards. |
Velocity 50 yards. |
|
No. 8 |
847 748 |
722 6.07 |
671 596 |
|
No. 10 |
Bach measure of velocity given in these tables is the mean value obtained from several experi- ments, varying in number from three to six. The headings " velocity 30, 40, 50 yards," mean that the numbers under them give the average velocities of the flight of shot over those distances, and not the velocities at 30, 40, and 50 yards from the gun.
It will be observed that the shot used were Nos. 10, 8, 6, 3, BB, FF, and No. 1 Buck. They were so selected because a pellet of any number in the above series weighs nearly double the pre- ceding one. Thus a pellet of No. 8 weighs double one of No. 10, a pellet oi' No. 6 weighs double one of No. S, and so on. These relations of weight among the pellets were obtained so that I could readily reach the relations existing between the velocities and the weights of pellets. The shot used was kindly furnished me by Tatham & Bros., of New York, who used carefully gauged sieves in their manufacture. The powder used was Curtis & Harvey's Diamond Grain No. (J. The powder and shot in each cartridge had been carefully weighed out in an accurate balance.
A glance at the tables at once shows the rapid increase in the velocity of the shot from No. 10 up to No. 3. With the heavier pellets the increase is less marked. Thus the table headed "10 Colt gun; 4 drams, Curtis & Harvey, 1:^ shot," shows that No. 8 shot has 72 feet per second velocity over No. 10 shot, and No. 6 has 46 feet over No. 8, while No. 3 has only 23 feet over No. 6, and BB shot gains only 11 feet over No. 3.
The relations between velocity and weight of pellet shown in this table may be taken as a type of all the experiments, and I have graphically shown their relations in the accompanying curve.
MEASURING THE VIBRATORY PERIODS OP TUNING-FORKS. 59
The divisions on the scale, measured on the axis of ordinates, give the velocity per second of the pellets. One unit on this axis equals 20 feet, and a unit on the axis of abscissas equals one unit of weight of pellet. The weight of a pellet of No. 10 shot is here taken as the unit of weight. The numbers of the shot are written under the axis of abscissas, the velocities along the axis of ordinates- My friend Professor Rice, of the United States Naval Academy, who had previously made sim- ilar experiments with a Le Bouleng^ chronoscope, and who took great interest in these experiments, found that the curve here given is very nearly the curve of secants, and the formula for it is:
« -1^.7.
T = sec. — 0 a
where x is the velocity and y the weight of a pellet, and a h and n undetermined constants.
So far as the experiments with these two special guns show, there is a marked superiority in the 10 over the 12 gauge, when each is loaded with the same weight of powder and shot- Thus, with the same charges, viz, 4 drams powder and 1^ ounces of shot tired from the 10 gauge, gives a velocity of 100 feet per second more than that given by the 12gauge gun. This fact is conclusively shown in the comparison of the figures in the two tables XVIII and XX, and the ditference in velocities is in favor of the 10 gauge in each of the sixty experiments which were made to get the numbers contained in the lines opposite No. 8 and No. 10.
With No. 10 shot the mean velocity given by the 10 gauge gun over the first .30 yards is 848 feet. With the same charge in the 12 gauge the velocity is 748 feet ; showing a difi'erence of 100 feet in favor of the 10 gauge. With No. 8 shot the experiments show a ditierence of 72 feet. The average difference in favor of the 10 gauge in the flight of shot Nos. 8 and 10 over 40 yards amounts to 110 feet.
If we assume, as we may without grave error, that the penetration of shot varies as the square of its velocity, these experiments will give the relative penetrations of the 10 to the 12 gauge gun about as 9 is to 7.
That the 10-gauge gun shows such marked superiority over the 12 may be accounted for by the fact that the same charge occupies less length in a 10 than in a 12-gauge, and hence there are fewer pellets in contact with the barrel of the former than of the latter to oppose by their friction the projectile force of the powder. Also, as these choke-bores are contracted two sizes at their muzzles, the action of the choke on the pellets in a 10-gauge, will, I think, be more effective than in the case of a 12, the pellets in the latter being more crowded together and conflicting in their actions than in the case of their discharge from a 10 bore. Also, some effect in favor of the lOgauge may be owing to the fact that in this gun the powder is exploded nearer the center of the charge, and thus there is less chance of it blasting before it unburnt powder contained in the portion of the charge removed from the point of ignition.
I also venture to predict that with the same weight of barrels the 10-gauge will not heat as much as the 12, because the motion of the shot lost in the 12gauge must appear in the form of heat.
The simplicity and inexpensiveness of the chronoscope we have described in this paper, its accuracy, and the ease with which it is used must commend it to all who will give it a trial under the conditions of its action which we have endeavored to set forth in this paper. Another of its advantages is that its records on the paper covering the cylinder are easily rendered permanent by drawing the uusmoked side of the paper over the surface of a dilute solution of photographic negative varnish contained in a wide shallow dish. On the records may be written with a blunt style the nature of the experiments they i-ecord before the carbon is fixed by the varnish, and *hen they can be bound togetner in book-form for preservation and reference.
S. Mis. 69
DO
k
^.5.
8. Mis. Ot)
rig. 4.
l^Sf.S.
2am 990
oso
S30 910
690
ero
650 830
308 e 3
S. Mis. 69
3B
JF
NATIONAL ACADEMY OF SCIENCES.
VOL. III.
FOURTH MEMOIR.
THE BAUME HYDROMETERS.
61
THE BAUME HYDROMETERS.
JtEAD AT TUE PHILADELPHIA MEETIKd. 1881.
By v.. V. Chandleu.
In 1768, Autoine Bauiiie, a cUemist in Paris, published an account of two new instruments which he had devised for determining the specific gravity of liquids.
These instruments met with speedj' acceptance on the part of practical men, and are now more extensively used in manufacturing establishments than any others.
Acids, alkalies, sugar solutions, petroleum oils, &c., are almost exclusively described in degrees Baum^.
The degrees on the Baume scale are entirely arbitrary, and bear no obvious relation to the specific gravity of the liquid.
Baum^'s hydrometers are instruments of even divisions. The special recommendation which has led to their extensive use among practical men is the simplicity of the numbers representing the specific gravity of the liquid. For liquids heavier than water the entire range is from zero to about 70 degrees. For liquids lighter than water, 10 to 80.
The numbers, therefore, are very easy to remember, and far more convenient on that account than the number expressing the true specific gravity, which for a liquid heavier than water would be 1 and a decimal of three figures usually, as for example 1.237.
Although Baum6 described with great accuracy the method which he employed for securing the scale for his hydrometers, and it would seem, therefore, as though no difficulty existed to pre- vent the reproduction of his instruments, nevertheless it is a fact that among instrument-makers the scale has been so far modified from time to time that we have the greatest variety of instru- ments purporting to be Baume's, each one of which has a set of degrees of an entirely difiereut value from that exhibited by any other.
I have found twenty-three different scales, published by as many different writers, for liquids heavier than water, the highest of which gives as the value of 66° Baume 1.8922; the lowest 1.730, no one of which can be said to be correct, or to have been obtained by following Baume's directions.
For liquids lighter than water I have found eleven scales in which the value of 47° Baume varies from 0.7978 to 0.7909.
Baume's directions for the construction of his instruments are very simple, and it is almost incredible that such deviations should have occurred in connection with the instruments.
It has often been suggested that .the only safe plan is to abandon the use of them entirely, and rely upon instruments which record at once the true specific gravity, referred to that of water as a unit.
The answer to this is that practical men will not abandon them, having become wedded to them, and preferring them on account of the simplicity of the numbers involved, and it would be impossible to induce them to give them up.
63
64 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENUES.
Table I. — Value of degrees Baumefor liquids heavier than water, given by different authors.
P - ^ £
.. 0000 1. .. 0072,1. .. 0145 1. .. 0219 1. .. 0294 1. .. 0370 1. .. 0448 1. ,. 0526 1. .. 0606 1. .. 0687 1. . 0769 1. . 0853 I. ,. 0037 1, . 1023 I. .11111. . 1200 1. . 1290 1. . 1382 1. . 1475 1. . 1570 1. . 1666 1. . 1764 1. . 1864 1. .19651. . 2068 1. . 2173 1. .22801. . 2389 1. . 2499 1. .26121. . 2727 1. . 2844 1. . 2962 1. . 3083 1. . .■)207 1. . .■(333 1. . 3461 1. . 3o92;l. . 3725 1. .3861il. . 3999 1. .4141 1. .42851. .4433 1. . 4583 1 . 4735 1 . 4893 1 . 5053 1. . .5217 1. . 5384 1. . 5555 1. . .5730 1. . 5909 1. . 6096 1. .6279 1. . 6471 1. . 6667 1. . 6868 1. . 7074 1. . 7285 1. .75011. . 7722 1. . 7950 1. . 8184 1. . 8423 1. . 8669 1. . 8923 1. .9180 1. . 9447 1. . 9721 1. . 0003 1 Il
1.000
.C20
So 0
|
Q |
|
|
□0 |
3 II |
|
C |
|
|
a |
a "3
.140
261 .
275'"
286
298!
.309]
321
334 1
346|
359
372 '■
384
398'
412,,..
426
440l
4.54;i.4oi 470 1. 466 485 1. 482 501 1.500 516 1. 515 5321. 532 549 1. 5.50 566 1. 566 583,1.586 601 1.603 6I8!1. 618
638
659l 6781... 698 . 7181.717
739
760,
782'
804
827
850 ]. 849'
874
898'
922
947,
973
000
,295
. 000 1. c . 007,1. C .014 1.( . 022:1. ( . 029 1. ( . 0361.( . 044il.C . 052 1. ( . 060 1. ( . 067 1. ( . 0751.{ . 083'].( . 091 1. ( . 100 I. ( . 108 1. ] .116 1.] . 125 1. 1 . 134 1. 1 . 143 1. 1 . 1521 1 .I6I1I. 1 .1711.1 .180 1.1 . 190 1. 1 .1991.5 .210,1.5 .221il.£ .23111.5 .242J1. S .252 1.5 .26III. 5 . 27511. 2 .286' I. 5 . 298il.2 . 309!l.a .32l!l.a . 334il.a .346,1.3 . 359!l.a .3721.3 . 384 1. a . 3981. 3 .412 1.4 .426 1.4 .410 1.4 .454 1.4 . 470 1. 4 .4851.4 .5011.5 . 516 I. 5 . 532 1. 5 .5491,5 . 506 1. ."i ..583 1.5 , 601 1. e . 618 1. 6 .637 1.6 , 6.56 1. 6 , 676 1. 6 695 1. 6 ,7151.7 ,7361.7 , 7.58 1. 7 ,779 1.7 ,8011.7 , 823 1. 8 , 847 1. 8 , 872 1. 8 . 897 1. 8 ,9211.9 , 946 1. 0 ,9741.0 . 002 2. 0 .031 ... .059 .. .087 ..
l.OOOOl. 1.0069. 1.0140 . 1. 0212 . 1.0285|. 1. 0358 1. 1.0433 . 1. 0509 . 1.0586'. 1.0665;. 1. 0744 1. 1,0825! 1. 0906; . 1.0989 . I. 1074' 1. 11.59 1. 1. 1246 . 1. 1335 . 1. I424I . 1.1516'. 1. 1608 1. 1. 1702 1.1798,. 1.1895,. 1. I994I. 1. 2095 1. 1.2197:. 1.2301!. 1. 2407 . . 1.2514 1. 2624 1. 1.2735 ., 1. 2849 1. 2964 1. 1.3081 ., I. 3201 1. 1.3323 1. 1. 3447 1. 1.3.574 1. 1.37031. 1. 3834 1. 1.3968 1. 1.4104 1. 1.4244 1. 1.43861. 1.4530 1. 1.4678 I. 1. 4829 1. 1.4983 1. 1.51401. 1. 5301 1. 1. 5465 1. I. 5632 1. I. 5802 1. I. 5978 1. 1.6157 1. 1.6340 1. 1.6527 1. 1.67191. 1.69151. I. 7115 1. I. 7321 1. 1.7531 1. 1.7748 1. I. 7968 I. 1.81941. I. 8427,1. L 8665|.. 1.8909'.. I.9I6I1.. 1.9418.. L. 9683' . 1.9955,.. !.0235!.. !.0523[.. !.0819..
036 1.023
S a la
161 1.16;
209 1
262 1
296
326' 332 345
357 370 383 397 410 424 438 453 1, 468 ' . 483 1. 498 . 514 ' 530 !l, 546 . 563 i. 5S0 . 597 ' 615 1, 634 . 6.52 671 . 691
711 1. 732 . 753 774 . 796 819 8426 1.
1.000 1.008 1.015 1. 022 1.029 1. 036 1. 1. 0431 ■ - 1.051].. 1. 059 1. 1. 067! . . 076 1, 075 1. ...'1. 083| . ...]l. 091:1. ...'1.099',. -.-!1.107!., 1141.1161. ... 1.125 ...1,134 .. 1.143 1.152 1. 161 1, 1. 1701, 1.1801 1. 190 1 1.2001,
1.000
023
Wxi i S^
r-o ! r XT
.2101.210 . 1. 220 .1.230 .11.241 II. 252 . 260 1. 263 ....1.274 .... 1.285 ....'1.296]1. . . . . 1. 308 1.
3151.3201. .... 1. 332 1. .... 1.3451. .... 1.3.581. 1.371 1.
3751.384 1. .... 1.3971. .... 1.410 1. .... 1.424 1. ... 1.438 1.
466 1. 4.53 1. .... 1.468 1. .... 1.4831. .... 1.4981. ...1.514 1.
5241.530 1. ....1.546 1. ....!1..563 1. .... 1. 580 1. .. .:1.598:i.
6181.0161. .... 1.634,1. ,...;1.653l.
...]1.6721. ,...'1.6911.
7251.711:1.
...]1.7321.
...]l.753 1.
.. 1.7751.
... 1.7971.
. .'1.8191.
842 1. 842 1.
...!1.866 .
...11.8911 .
... I, 916!..
... 1. 942; . .
... 1.968'..
...1.995]..
...2.023!..
...2.052
...2.081
260
273
2841.
2961.
307]l.
3151.
329 1.
33»]l.
3591.
3721.
375 1.
399,1.
4131.
4271.
441, 1.
453 1.
466 1.
4821.
600,1.
5161.
5321.
5501.
666 1.
5861.
603 1.
6181.
639 1.
660 1.
682 1.
703 1.
725 1.
744 1.
764 1.
783 1.
8031.
8221.
8421.
000!l. 0000 007;i. 0069! 0141.0139! 022:1.0211! 029 1. 0283 037'l. 03.57 0451.0431: 0521.0.507 060 1. 0683 067 1. 0661 075 1.0740 083 1. 0820 091 1.0902 100 1. 0984 108 1. 1068, 116 1.1153 1251. 1240 134:1. 1328, 1421.1417 1521.1507; 162 1. 1600 1711. 1693' 180 1.1788! 100 1. 1885 200'1. 1983! 210(1.2083! 22011.2184 2311. 2288 241 1. 2393: 252:1.2,500' 263:1.2608' 274,1.2719 285!1. 28:;l! 297,1.2946 1. 3063 1.3181 1. 3302 1.3425 1.3551! 1. 3679 1. 3.SO9' 1. 3942 1. 4077 1.4215' 1.4356 453 1. 45U0 468:1.4646 48311.4793; 498 1. 4949
1. 5104 1. 5263 1. .5425
563 1. 6591;
1.5760, 1.5934 1.6111 634 1.6292' 6.52 1, 6477! 671 1.6666 691 1.6860' 711 1,7058 7,12 1,7261 753 1. 7469 774 I. 7682, 796 1.7901 8191.8125 842 1. 8354 1. 8589 - 1. 8831 . 1. 9079 . 1.9333 . 1.9595 ,
1, 9863 . 2,0139 .
2. 0422 . 2.0714,.
. 0000 1 . 0069 1, .01391, .0211 1, .02831 . 03.56 1, .0431,1, . 0,506 1, , 05S3]l, .0661 I . 0740 1 . 0820 1. . 0901 1. . 0983 1. . 1067 1, , 1152 1. , 1239 1 , 1326 1, ,14151. , 1506 1, ,15981, .1691 1. .17861. . 1883 1. .19811. .2080:1. .21821. .2285,1. . 2390 1. .24971 .2605 1 .2716,1. .28281. . 2943]1. .30.191, ,3177:1, .3298,1, . 342l!l, . 3546,1. . 3674!l. . 3S04'1. .3937,1 ,4072 1, .421 01, . 4350 1 . 4193 1 ,464111, . 4TWI 1. ,4941 1, , 5007 1, . 5255 1. . 5417 1 , 5583 1 . 6752 1 . 5925 1 .61111 1 . 6282 I . (i4C.7 1, , 6656 I. , i;84!l 1. ,7(147 1. , 72.".() 1. .'4,57 1. .7609 1. . 7888 1. .8111 1, , 83411 1. . 8574 1. .88151, . 9062 1, . 9316 1. , 0577 1, . 9844 1, ,0119 2. . 040: , 060312. ,0992
0000 1. 0070 1. 0141 1. 0213 I. 0280 1. 0:1601. 0435,1. 0611 1. 0588 1. 0666 1. 0745 1. 0823 1. 0906 1. 0988 1. 1071 1. 1155 1. 12401. 1326;l. I414I1. 1504:1. 1696 1. 1691) 1. 1785 1. 1882 1. 1981 1. 2082 1. 2184 1. 2288 1. 2394 1. 2502 1. 2612 1. ^24 1. 2838 1. 2954,1. 3072 1. 3190 I. 33111. .3431 1. 3559 1. 3686 1. 3815 1. 3947 1. 4082 J. 4219 1. 43,59 1. 4,50ri. 4645 1. 4792 1. 4942 1. 6096 1. ,5253 1, .54131. 5576 1. 5742 1. 5912 1.
Bii.';6 1.
0204 1. 6446 1. 6632 1. 6823 1 , 7019 1. 72_'0 1. 7427 1, 76411 1. 78,38 1 8082 1, 8312 1. 8.348 1. 87!IU 1, !i038 1, 9291 1, 9548 1. 9809 1. 0073 1. 034(1 2. 001012.
00001. 0068, 1, 01381. 0208,1, 0280 1. 03,53' 1. 0426 I. 0501 1. 0576:1, 06,53 1, 0731 1. 0810,1, 0890 1, 0972 1, 1054,1, 11381, 1224 1, 1310 1, 1398 I 1487 1 1.578 1, 1670 1 1763 1, 1858 1, 1955 1, 2053 1, 21.53 1, 2254 1, 2357 1 2462 1, 25691 2677 1, 2788 1, 2901 1 3015 1, 31311, 32.50 1 3370 1, 3494 1, 3619 1 37461 3876 1, 40091, 41431 4281 1 4421 1, 4,364 1 4710 1, 4860 1 5012 1, 51671. 53251, 5487 1 5632 1, 5820 1 3993 1 CI 69 1 0349 1 6333 1 6721 1 6914 1, 711l]l 73I3]l. 7.520 1. 7731 1. 79481. 81711. 83981. 86.32 1, 8871 1, 91171 9370 1, 9629 1, 9895 . 0167 . 0449'.
096 .. 104 . 1 131. 1115! 1.
121 ].
130 .
138: !.
147 ].
1571.15431
160 !.
176 ].
185 !.
195 |.
205 1. 2007 1
216'
225
235
245
2561.2509;!
267, .
278'
289
300 , .
3121.3055il
324 '.
337 ., 349 .. 361! 375 1. 3650
388;
401
414
428
4421.4303
4.56
470 ....
485
500
515 1. 5021 1
531!
546
562
578
.6961.5816
615
634
6.33
6711 '.
690 1, 66981
709
729 .
750
771' ].
703 1.7686!!
. 1110
815 1.789
839
■864
883
909 1. 8796
935
960
* Calculated b.v tlie compiler, alculated by the formula : n= == Bau(Q6 degree. 68 was taken for " (i" whenever the corresponding Sp. Gr. appeared
I> V rf
XorE. — Whore the modulus was not given, it was calculated by the formula: n= - - in which a ;
modulus; P .specific gravity
THE HAUMK 1 1 V DKO-AriOTKHS. (55
Tlic only tliiiiji to be done is to coirec^t tin- iiiiieciuacies aiul estahli.sli b.v some coiiiiieteiit aiitlioiity ail aiitliorized and acceiited standard of values for tlie Banni(5 scales.
Hauint''s inetliods were lirst described in I'Arnnt Ci>urcur towards tlie close of ITtlS. Tliey have been repeated in the several editions of liis Rienicnts de Pharniacie. In the eighth edition of this work, published in Paris in 17!tT, he st;ites tliat he constructed his instruments in this way =
(1) For the hi/di-onteter far l!<iiiiils licariir thiiii water he prepared a solution of salt (u)ntaiiiing tifteen (15) parts of salt by weight in eij;lity-five (85) parts of watei- by weight. He describes the salt as "very pure'' and "very dry," and states that the experiments should be made in a cellar iu which the temperature is 10° Keauniur, equivalent to 12.0° Centigrade and to 54.5° Fahrenheit. The zero ou the scale indicate.s the point to which the instrument sinks in distilled water (at the temperature above stated), the 15 mark the point to which it sinks in the 15 percent, salt solution. Witli a pair of dividers the space between "0" and " 15" is divided into fifteen equal i)arts, and degrees of the same size are coutiiiued above " 15."
Baum^'s idea was that each additional degree ou this scale would indicate one additional per cent, of salt, which of course is not quite correct, but the directions given are sufficiently simi)le to enable any person to reproduce the instrunieut.
(2) For the hydrometer for liquids tighter thati ia(ter he uses a 1(1 per cent, solution of salt prepared in the same way, and hy means of it fixes the zero point on the hydrometer. He uses distilled water for the " 10" point, and obtains a scale as iu the case of the other instrument, but running in the opposite dii'ection.
With so .simple and direct a statement as this it is remarkable that it has been possible to get .so far away from the true Baume scales. In looking over the literature of the subject 1 find that these discrepancies have arisen fiom various causes — either neglect to follow Baum^'s directions, or a deliberate attempt to improve the scales.
(a) Baume conveys the idea that each degree represents 1 per cent, of salt, and he even sug- gests that in order to obviate errors due to irregularities in the stem of the instrument, a series of solutions may be prepared, the first containing 1 per cent, of salt and 99 jier cent, of water, the second 2 per cent, of salt and 98 per cent, of water, and so on, and that the degrees 1, 2, &c., can l)e marked by the use of these solutions.
(b) Acting still further on this suggestion of Baume, many instrument makers gave up pre- paring the 15 per cent, salt solution altogether for fixing the " 15" mark, using instead the 10 per cent, solution and fixing by it the " 10" mark, thus making one solution answer for both instru- ments.
(c) It was found at an early day that oil of vitriol generally stood at about 66 on the Baume instrument; so many instrument makers fixed the 66 mark by immersing the instrument in oil of vitriol. As a matter of fact oil of vitriol is a variable substance. It never contains 100 per cent, of sulphuric acid^usually only from 92 to 96 per cent. It consequently has a variable specific gravity, and its use for the 66° mark introduces varying errors.
SCALKS FOR LIQUIDS HEAVIER THAN WATER.
I submit herewith a table — -'Table No. I" — containing twenty-three different scales of values for the degrees on the instrument for liquids heavier than water, and another table — "Table No. II" — containing the eleven scales for liipiids lighter than water.
METHODS I:MFL0YED IN SECTRINCi THE SCALES GIVEN IN TABLE I.
(1) Delezennes. 66o=1.8922. The mark for 10° was found by a 10 per cent, salt solution at 10° E. (Wagner Jahresb., 1869, vol. 15, 236.) This scale appears in Journal de Pliys., vol. 94, 204; Bache & McCulloh, 1848, 116: Dingler's Polyt. Journal, 1865, 2 vol., 176, 4.55; Handwor- terbuch der Chemie, 1859, vol. 2, 1, 179; Knapp, Chem. Tech.
(2) Ziurek. 66o=1.8.50. No method given. This scale appeai-s in Technologische Tabellen, 1863, 35.
(3) D'Arcet. 66° = 1.84'.i (calculated). The point 66° B. was obtained in sulphuric acid of spe- cific gravity 1.830, but it is assumed that it is not pure hydrate, but contains about 6 to 7 per cent.
S. Mis. 69 9
66 JVIEMOIRS OF THE XATIONAL ACADEMY OF SCIENCES.
more water tbau the liydrate H^ SO^. (Muspratt, vol. (i, 357.) This scale appears in Bull. Soc. IikI. (le Miilliouse, 1872; Muspratt, 187!l, vol. (5, 359.
(4) Gilpin. 6(io = 1.848. The mark 10° was found by a 10 per cent, salt solution at 10° R. (Wagner, Jabresb., 186!>, vol. 15, 236.) Tbis scale appears in Henry, 1810; Cbiklreii, 1819; Ann. de Chimie, vol. 23, 1797; Haudwiirterbucb, vol. 2, 1; Bacbe & McCullob, 1S4S; Knapp, Chem. Tecb., vol. 1, part 5; Journal de Pbysique, 1797.
(5) French Codex (Holland). 6Co = 1.847. In the Holland scale, the lo^ was obtained by a 10 l)er cent, common salt solution at 10° R. (Bacbe & McCullob. Reports on Sugar and Hydrome- ters, 1848, 84.) Tbis scale appears in U. S. Dispensatory, 5tb, 7tb, 8tb, lltb, 12tb, 13tb, and 14th editions; Pbarmacopiea Batava, 1805; Bacbe & McCullob, 1848; Neues Handworterbucb, 1871; Dingler's Polyt. Journal, 1870.
(6) H. A. Mott, jr. 66o=1.8461. Was deduced by Doctor Pj le, of Philadelphia, and the table calculated to 0.5 by Doctor Mott. (Letter from Dr. M. to Dr. C. F. C, Nov. 8, 1881.) This scale appears in Mott, Chemist's Manual, 1877.
(7) Daltou. 660=1.8460. The poiat 66° was obtained in sulphuric acid of specitic gravity 1.830 (see D'Arcet). (Muspratt, 1879, vol. 6, 357.) This scale appears in Muspratt's Technische Cheraie, 1879, vol. 6.
(8) Bourgougnou. 66o=1.8427. This table is calculated according to the formula —
p^ 144.3 144.3 -fZ
in which P = density ; f?=degree Baume. This formula is obtained when Gay-Lussac's method is used with sulphuric acid of specific gravity 1.8427 at 15° C. (Tucker, Manual of Sugar Analysis, 1881, pp. 108, 109.) Tbis scale appears in Proc. Am. Chem. Soc, vol. 1, No. 5, 1878; Tucker, Manual of Sugar Analysis, 1881.
(9) Bineau. 66o=1.8426. lu Bineau's tables, which Otto has calculated for 15° C. according to Bineau's own statements, the specific gravity of the sulphuric acid (Schwefelsaiirehydrates) at 15° C. =1.8426. (Wagner, Jabresb., 1S69, vol. 15, 238.) This scale appears in Muspratt, 1879, vol. 6, 358 ; Agendas Dunod, 1877 ; Lunge, 1879, vol. 1.
(10) Yauquelin. 66^=1.842. The point 66° was obtained in sulphuric acid of specific gravity 1.830 (see D'Arcet). (Muspratt, 1879, vol. 6, 357.) Tbis scale appears in Ann. de Chimie et Physique, 1 series, vol. 76; Bull. Ind. de Miilhouse, 1872; Muspratt, 1879, vol. 6, 359.
(11) Morozeau. !!6C'= 1.842. Calculated by Morozeau by the formula
'M'{v'-n)
y-
n'd' — n(l—x{d'—d)
n, «', and ,r are the degrees of the instrument corresponding to the specific gravities, d, d', and y. The 660=1.842 at 10° E. Tbis number is accejited because it corresponds to the highest specific gravity of "acide sulfurique hydreux," because it is given by Theuard and because it seems gen- erally accepted. In giving to ,r the values 1, 2, 3, up to 75, the corresjjonding values of y have therefrom been deduced. (Journal de Pharmacie, Paris, 1830, vol. 16, p. 488.) Tbis scale appears in Journal de Pharmacie, vol. 16, 488; Knapp, Chem. Technologic; ficole Centrale Lyonnaise.
(12) Custom in France. 66o=1.842. Tbis table is based on Yauquelin's table. (Bull. Soc. Ind. de Miilhouse (42) 1872, p. 211.) This scale appears in Bull. Soc. Ind. de Miilhouse, 1872.
(13) J. Kolb. 660=1.842. 66o=pure sulphuric acid of specific gravity 1.842. (Lunge Soda Industrie, 1879, vol. 1, 24.) This scale appears in Bull. Soc. Ind. de Miilhouse, 1872; Roscoe and Scborlemmer, 1877; Wurtz, Diet, de Chimie, 1876; Lunge, Soda Industrie, 1879, vol. 1; Deut. Chem. Kalendar, Dresden, 1877 ; Wagner, Chem. Tech., 1875 ; Muspratt, 1879, vol. 6, 359. Nos. 10, 11, 12, and 13 all give 66° Baume=1.842, though differing in other terms.
(14) H. Pemberton. 66o=1.8354. Calculated by H. Pemberton in 1851, and adopted as stand- ard by the Philadelphia College of Pharmacy the same year. This scale appears in U. S. Dispen- satory, 12th, 13th, and 14tb editions.
THE BAUMfi: HYDIiOMETERS. 67
(15) .Mauul'acturiiig Chemists' Association, U. S. A. (i()0=1.835. Calculated by A. H. Elliott from the data given by tlie eoinmittee on "What is oil of vitriol?" in 1875,
(ifjo H = e2SO, !t;5. 5
H.,0 (i. 5
1(10.0
This scale appears in a separate sheet published by the association. In a report of the Coni- inisi?ion on "What is oil of vitriol?" previously published, a tal)le ditl'ering slightly from this is jmblished.
(16) Schober and Pecher. (j(jo = 1.8340. The mark 10'^ was obtained by a 10 per cent, salt solution of specitic gravity 1.07-t and the scale calculated by the formula
](),> + , {p-\)
in which S = specitic gravity of the fluid, />=specitic gravity of salt solution, ;(=degrees. (Dmg- ler's Polyt. J., 1828, vol. '21, 63.) This scale appears in Dingler's I'olyt. J., vol. 27, 63; Hotfmann- Schaedler Tabellen, 1877; Knapp, Ohem. Tech.; E. L. Schubarth, vol. 1, 47.
(17) Huss, Edinburgh Disjjensatory. 66° = 1.8312. Calculated by Iluss and published in Duncan's Ed'b'gh Disp., 1830. This scale appears in Duncan's Ed'b'gh Disp., 1830; V. S. Dispen- satory, Sth, 7tb, 8th, nth, 12th, 13th, and 14th editions.
(18) Gerlach. 66°= 1.8171. Based on a 10 per cent, salt solution of specific gravity 1.07311 at 14° R. (Dingier Polyt. J., 1870, 198, 315.) Thi.s scale appears in Dingler's Polyt. J., 1870; Post, Chem. Tech. Analyse, 1881, Part 1, 438; Lunge, Soda Industrie, 1870, vol. 1.
(19) Chemiker Kalender. Berlin. <i6o = 1.815. No method stated. This scale appears in Chem. Kalender, Berlin, Dr. Biedermaun, 1881.
(20) " Baume Original Scale." As calculated by Gerlach, 1870. 66o=1.7897. Based on the specific gravity of a 15 per cent, salt solution hi vacuo at 15° C. = 1.11146. This scale appears in Dingler's Polyt. J., 1870, vol. 198, 316.
(21) Baudin. 66o=1.786 (calculated). A 15 per cent, salt solution of specific gravity 1.111 was employed for the 15 mark, at 15° C. (Chemical News, 1870, vol. 21, 54.) This scale appears in Chemical News, 1870, vol. 21, .54.
(22) Francceur. 66o=1.767. The 15 mark was obtained by a 15 per cent, solution of rock salt dissolved in distilled water at maximum density specific gravity = 1.1094. (Francieur, Memoire, sur I'Areometrie, 1842, Paris, 26.) This scale appears in Watts' Diet., vol. 3, 209 ; Johnson's Cycl., vol. 2, 1062; Fownes' Chemistry, 12th ed. ; Ure's Diet., vol. 1; Handwdrterbuch der Chemie, vol. 2, 1 ; Knapp, Chem. Tech. ; Bache & McCulloh, 1848.
(23) Bohnenberger. 66o=1.730 (calculated). Probably a 15 per cent, salt solution at 11.5° R. was employed for the 15 mark. (Wagner, Jahresb., 1869, vol. 15, 235.) This scale appears in Handwiirterbucb der Chemie, vol. 2, 1; Practical Magazine; Dingler's Polyt. J., 1865, vol. 176; Tiib. Bliitter, vol. 2, 457 ; Knapp, Chem. Technology.
THE TRUE Sf'ALE FOR LIQUIDS HEAVIER THAN WATER.
As no one of these twenty-three scales had been obtained by following Bauiii^ exactly, it was deemed advisable to repeat his experiments.
Three solutions were prepcired by following exactly the directions of Baume, each one con- taining 15 per cent, of salt and 85 per cent, of water by weight. For the first solution chemically pure sodium chloride was employed ; for the second, " solar salt," from Syracuse ; for the third, " factory -filled dairy salt," from Syracuse. The specific gravity of these solutions was carefully determined at 10° Reaumur. The results are given in Table III, together with the results obtained by several friends who have rei)eated this experiment, and also of several chemists who have pub- lished their results.
68
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
Taisle if. ^'ahle of degrees Banmr for liquids lighter than icnter, given hy different authors.
[(■..iiipiliMl liy C. F. Cliandl.r ami V. G. Wiecliiiiniiii, ISsl',]
S2r a.,
|
n |
|
|
% |
S |
|
^ |
g |
|
a |
-* |
|
^ |
|
|
10 |
|
|
r> |
5i |
|
C-l 1^ |
|
|
« |
US
H o
|
?ix |
a |
|
oi; |
p.? |
|
0 0 |
|
|
^1 |
fi-" |
|
.a . |
|
|
■ ^ |
y.rH |
w
10
u 12
13 14 15 10 17 18 19 30 21 '>2 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43
01)00 1. 9932 0. 9865 0. 9799 0. 9733 0 9609 0. 9005 0. 9542 0. 9480 0. 9420 (I. 93590. 9300 0. 9241 0. 9183 0. 9125,0. 9068 0. 9012 0. 8957 0. 8902 0. 8848 0. 8795 0. 8742 0. 8090 0. 8639 0. 8588 0. 8538 0. 8488 0 8439,0. 8391 0. 8343 0. 8295 0. 8249 0. 8202 0. 8156 0.
000 I. 990 0. 985 0. 977 0. 970 0. 963 0. 955 0. 949 0. 942 0. 935 0. 928 0. 922 0. 915 0. 909 0. 903 0. 897'0. 892 0 886 0. 88010. 874 0. 867 0. 8610. 8.50 0. 852 0. 847 0. 842 0. 837 0. 832 0. 827 0. 822 0. 817 0. 814 0. 8110. 808 0.
000 1.00001. 993 0. 9931 0. 980 0. 9864 0. 979 0. 9797 0. 973 0. 9731 0. 967 0, 9006 0. 9011 0. 9003 0. 954 0. 9539 0. 948 0.9477 0. 942 0 9416 0. 935 0. 9355 0. 929 0. 9295 0. 924 0. 9230 0. 918 0 9177 0. 912 0. 9120 0. 900 0. 9063 0. 901:0.9007 0. 895 0. 8951 0. 889 0. 8890 0. 8810.8842 0. 879 0. 87S8 0. 873 0. 8735 0. 808 0. 8683 0. 863 0. 8032 0. 858 0. 8580 0. 853 0. 8530 0. 848 0. 8480 P. 843 0.84310. 838 0. 8382 0. 833 0. 8334 0. 829 0. 8287 0. 824 0. 8239 0. 819 0. 8193 0. 815 0.8147 0.
000 1. 993 0. 9S7 0. 98IJ 0. 974 0 907 0. 9010. 954 0. 94.S 0. 941 0. 935 0. 9290. 923 0. 917 0. 9110. 906 0. 900 0. 895 0. 8890. 884 0. 878 0. 873 0. 868 0. 863 0. 858 0. 852 0. 847 0. 842 0. 837 0. 832 0. 828 0. 823 0. 819 0. 814 0.
000 1. 993 0. 980 0. 879 0. 973 0. 906 0 960 0. 9530. 947,0. 9410. 9350. 929 0. 923 0, 9170. 9110. 905'0 900 0. 894 0. 889,0. 883.0. 8780. 8720. 867 0. 862 0. 857 0. 852 0. 847 0. 842 0. 837 0. 832 0. 827 0. 823 0. 818:0. 813 0.
COOOl 9928 0. 9800 0. 9800 0. 9729 0. 9666 0. 9605 I). 9535 0. 9470 0. 9417 0. 9343 0. 9283 0. 9221 0. 9178 0. 9112 0. 9067 0. 8997 0. 8949 0. 8900 0. 8824 0. 8773 0. 8720 0. 8064 0. 80110. 8583 jo. 85200. 84600. 84300. 8373 0. 8306 0. 8272 0. 8237 0. 8104 0. 8125 0.
0000 1, 9929 O 9859 0, 9790 0, 9722 0. 90550. 9589 0. 9524 0. 9160 0. 93960. 9333 0. 9272 0. 92110. 91510. 9091 0. 9033 0. 89750. 8918 0. 8861 0. 8800 0. 8751 0. 8090 0. 8643 0. 8590 0. 8537 0. 8486 0. 8435 0. 8384 0. 8334 0. 8285 0. 8236 0. KI88 0. 81410. 8094 0.
|
^2 |
1' : |
|
6g |
15 |
|
2S |
fl"^ |
|
M |
£ |
s:
0000 1. 993 1 0. 9861 0. 9793 0. 9724 0, 9057 0. 9591 0. 9526 0. 9162 0. 9399 0. 9336 0. 9274 0. 9212 0. 91510. 9aqi 0. 9033 0. 8974 0. 8917 0. 8860 0. 8804 0, 8748 0. 8693 0. 8638 0. 8584 0. 8.531 0. 8479 0. 8428 0. 8378 0. 8329 0. 8281 0. 8233 0. 8180 0. 8139 0. 8093 0.
p--~ is.
moo I If: cj
|Otc
; o —
HOO fCO ^
%]
000 1.0000
993 0. 9929 986 0. 98.59 979 0. 9790 1 972 0. 9722 ' 900 0 -9055 959 0. 9589 952 0. 9523 946 0. 9459 94" 0. 9395 933 0. 9333 927 0.9271 9210.9210 915 0.91.50 909 0. 9090 903 0. 9U32 898 0. 8974 892 0. 8917 886 0 8860 8810.8805 875 0. 8750 870 0. 8695 864 0. 8641 1 859 0. 8588 854 0. 8536 849 0. 8484 844 0. 8433 838 0. 8383,
833 0. 8333 829 0. 8284
834 0. 8235 819 0. 8187 814,0.8139 809 0. 8092
0.81110. 0. 8066 0. 0. 8022 0. 0. 7978 0. 0. 7935 0. 0. 7892 0. 0. 7849 0. 0. 7807 . 0. 7766' . 0. 7725 . 0. 7084, 0. 7044, . 0. 7604! . 0.7565;. 0 75261 . 0. 7487 . 0.7419 . 0.7411 .
805 0.810(1. 802 0. 806 0. 799 0. 801 0. 797 0. 797 0. 795 0. 792 0. 793 0. 7S8io. 791 0. 784:0. .. 0. 78ll0. ... 0. 776|0. .. 0. 77ro . . 0.769,0. , ... 0.763 0.
0. 759I0.
... 0.755 0. , .. '0.7510. . . . 0. 748 0. ... 0.744 0. ... 0.740'0. . ... 0.736 0.
8102 0. 8057 0. 8013 0. 7969 0. 7925 0. 7882 0. 7839 0. 7707 . 7756 7714. 7674 . 7633 . 7593' 7554 - 7515'- 7470 7438 . 7399 . 7862.
|
m |
M |
|
CC |
ci |
|
rt t- |
|
|
'•^rr |
II <=> |
|
c |
|
|
'Z'^ |
|
|
i^ |
|
|
C=^ |
p |
|
n |
|
|
U |
|
|
0 |
|
|
Cl |
.0 |
|
« |
- ' |
810 0. 809 0. 8084 0. 805 0.804 0.80410. 800 0. 800 0. 7995 0. 796 0.795 0.7940 0.
2 0. 791 . 787 0. 787 . 782 0. 783 . ... 0. 778 . ... 0.774 . . . 0. 770 . - - - 0. 700 . ... 0.702,.
0.758.
0. 7.54' .
0. 730' . . 0. 740 .
0. 742 .
0. 738, .
:0.735|. . O.731I.
. 0. 7271 .
8017 0. 8001 0. 7956 0. 79110. 7866 0. 7823 0. 7779 0. .... 0 . . . . 0.
0.
.... 0.
0.
0.
.... 0.
0.
0.
0.
0.
10.
8047 0. SOOl 0. 7956 0. 79110. 7860 0. 7821 0. 7777 0. 7733 0. 7089 0. 7646 0. 7603,0. 75600. 7518;o. 7476 0.
3'-
7435 7394 7354
7314 7275
. 0.724 .0.720 . 0. 716 . 0. 713
. 0. 709 0.706
. 0. 702 .
0. 699 . . 0.696,.
. 0. 6891 .
0. 686: .
.0.682.
802 0. 8045 800 0. 8000 796 0. 7954 791 0. 7909 787:0.7865 782 0 7821 778 0. 7777 773 0. 7734 709 0. 7092 765 0. 7050 700 0. 7608 7.50 0. 7567 752 0. 7520 748 0. 7486 744 0. 7440 739 0. 7407 735 0. 7368
0. 7329
... 0.7290 . . . . 0. 7253 . ... 0.7216 . . 0.7179 . ... 0.7142
0.7106
0. 7070
. -. 0.7035 ... 0.7000
0. 6905
0. 6930
. .. 0.6890 . . . . 0. 6863 ... ,0.6829 ... 0.6796 ....10.6763
I Bachc & McCulloIi, 1848; Watt's Diet., 1865, vol. Ill : U. R. Petroleum Assn, 1861: Haudworterbueli ikTChemie, 1859, vol. II, 1 : Dinc'ers Poly. .loiirual, 1870, vol. 198 : Tucker, Manual of Sugar Analysis, 1881 ; Johuson's Cycl., Vol. II, 1870; Fowne.s Chemistry, 12th ed., 1877; Cre's Diet., vol. I, 1807; Neues Haiidworterhueb, 1871, Vol. I; Deut. Chera. Kalender, Dresdeu. 1877. '^ Trans. Pbilos., 1794; Anuales de Chiniie, 1797: Cliildrcn. 1819: Baebe & McCulloh, 1848. achemiker Kalender, Bi'rlin, IS81, 1882. J Hoflmann-Sibaedler, Tabidlen, 1877 ; Diufjler's Poly.Jonr- nal. Vol. XXVII, 1828. »Baelio& McCuIIoli, 1848 ; Pharmaiopcea Batava, 1805 su. S. Dispensatory, 11th, 121h. 13th, 14tb eds. : Neue.5 Haud- wiirterbueh, 1871, Vol. I. ' Bollev Handbueb der Chem. Tecbnolocie, 1865 « Baebe & McCullob, 1848 ; Ilandwiirterbueb der Chemie. Vol. II, 1, 18.')9. ' Dunean's Edinburgh IMsp., 1830 ; I'. S. Dispensatory, 5th, 7tb. 8lh. 11th. 12th, 13tli, 14th eds, "'Ziurek, Teihnologisclie, Tabellen Jt N'otizen, 1803. "Philadelphia Coll. Pharmacy ; V. S. Disp., 12tb, 13tb, 14tb eds. : Mott, Chemist's Manual, 1877.
.P(d-10l
Note. — The modulus for each scale was calculated by the formula, n=
[gravity.
The calculation..! were in each case made on the 47tli Haume degree.
1-1'
, in \\hicb n —modulus: il ^ Baunie degree : /*— specific
Table III. — Si>ecific grarifi/ of a 15 per cent, solution of common saltatW^Ji. ( = 12.5° (7.— 54.5° F.)
|
No., |
Specific gravity. |
By \\lioin calculated. |
|
1 |
1. 1122 |
Cliaiullci' and Wicclimaiiii. |
|
2 |
1.1121 |
do. i |
|
:! |
1.1120 |
do. |
|
4 |
1.1122 |
do. |
|
.'S |
l.lliC) |
do. |
|
!■ G |
1.1121 |
I'rot'. Hinu'v Moitoii. |
|
i 7 |
l.lllSl |
Dr. Hermann Eudenianii. |
|
8 |
1.1110 |
Dr. Arno Helir. |
|
i) |
1.1110 |
M. ]!;iiidiii (CliPiii.News, 1870, XXI, 54). |
|
1(1 |
1. 11(172.-. |
I'rof. t'oiiliiT, Ibid. |
|
1 11 |
1. 11140 |
Dr. Geilach (Zcit. Anal. Cheiuie, 1865, IV, 1). |
|
! 12 |
1. IKiO |
E. Soubeirau (Traits de Pliarinacie ;!'«""' ed.. 1847, 1, 1;!)- |
|
Vi |
1. 1094 |
Fraticoeiir (Meiiioire .siir rAnioniitric, Paris, 1842, 20). |
|
1. 1118988 |
Average. |
sail.
NoTK.— 1 and 2 were chemically pure salt; 3 and 4 were Syracuse solar salt; 5 was Syracuse factory-tilled dairy
THE BAUMl^. HYDROMETERS.
69
It should bi^ remarked that in tlie above table tlie iininber by Raiidiii was obtained by weij^li- ing tlie sohition at 15° centigrade instead of 12.5, and Oerlaeli's result was obtained by weighing at 14° centigrade, and calculating what the specitic gravity wouhl be at 15° centigrade in vacuo.
Franconir determined his si)ecific gravity at the niaxiinnni density of water.
Xone of these determinations were rejected, however, in making up tlie table, as the nnmlicrs are so nearly alike. We may fairly assume that the average is practically 1.1119.
Table IV exhibits a scale which has been carefully calculated by Mr. Wiechmann from the actual average as given on Table III, by the formuhe
Pxd 'P-1
P=
n—d
fn which P=tlie specific gravity; (/ = the Bauiui? degree; n=the modulus.
Table IV. — Vabtr of decrees Bannu' calculdfaJ from ()° — \, and ir)°=:l.ll 189SS ht/ the modidiis 14y.049()!(, till- i:tj)i'rimriit(il irork hiiriiuj been conducted in exact accordance witli Haum^^n original directions.
[Temperature 10° R. =12.5° C.=54.5'^ F.]
Baiiiiie degiees.
Spec! He aravitv.
Baume Specitic ilegrees. j gravity.
10
11
12 i:i
14
ir.
U) 17 L« lit
|
1 . 00000 |
20 |
1. 15497 |
|
1. 00675 |
21 |
1.16399 |
|
1.011560 |
22 |
1. 17316 |
|
1. 02054 |
23 |
1. 18246 |
|
1.02757 |
24 |
1. 19192 |
|
1.0:!471 |
25 |
1. 20153 |
|
1.04194 |
26 |
1.21129 |
|
1. 04927 |
27 |
1.22122 |
|
1.05671 |
28 |
1.23131 |
|
1.06426 |
29 |
1.24156 |
|
1.07191 |
30 |
1. 25199 |
|
1.07968 |
31 |
1.26260 |
|
1.08755 |
32 |
1.27338 |
|
1.09555 |
33 |
1.28436 |
|
1. 10366 |
34 |
1. 29552 |
|
1.11189 |
35 |
1. 30688 |
|
1. 12025 |
36 |
1.31844 |
|
1.12873 |
37 |
1. 33021 |
|
1. 13735 |
38 |
1. 34218 |
|
1. 14609 |
Baume degrees.
39 40 41 42 43 44 45 46 47 48 49 .50 51 52 53 54 55 56
Specific gravity.
1.35438 1. 36680 1. :57945 1. 39234 1. 40547 1.41885 1.43248 1. 44638 1. 46056 1. 47501 1.48975 1.50479 1. 52014 1. 535S0 1.55179 1. .56812 1. .58479 1. 60182 1. 6Ut23
Banm^ degrees.
Specific' gravity.
58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76
63701 65519 67378 (19279 71223 73213 75250 77335 79470 816,57 83899 86196 88551 90967 93446 95989 98601 01283 04038
It will be .seen by comparing Table IV with Table I that this scale corresponds most closely with No. 20, which is entitled "Bauine's original scale," and which was calculated by Gerlach iu 1870 — Dingler's Pol. J., vol. 198, 314 — and was based upon the specific gravity 1.11146 for the 15 jier cent, salt solution. The observation, however, was made at 14° centigrade and was then cal- culated for 152 centigrade in vacuo, while Baume's directions are to use a 15 per cent, salt solution at 10° Reaumur iu the atmosphere. It will be seen that neither this nor any other of the twenty- three scales published in Table I has been obtained by strictly following Bauine's directions.
SCAX.BS FOR LIQUIDS LIGHTER THAN WATER.
For the purpose of a.scertaining the exact value of Baume's degrees lor liquids lighter than water, three 10 per cent, salt solutions were carefully prepared, using as before chemically pure salt, "Solar" Syracuse salt, and Syracuse "Factory-filled dairy salt." The results are exhibited in Table V, together with results obtained by other chemists.
70
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
Table V.
Specific iji-ailty of a 10 per rent, solution of com men fiuU at 10° K. (=12.5'-' C. =54.5'= F.)
1. 1. 0738 Ch.aiuller iiud Wiechmauu.
2. 1.0737 Chandler and Wiechmaun.
3. 1.0741 Chandler and Wieclimann.
4. 1.07303 Schiiber and Peeher (Din};l. Pol. .!., 1828, XXVII, 65).
5. 1.07518 Schober and Peeher. C. 1.07372 SchoUer and Peeher.
7. 1.073464 Dr. Gerlach (Zeit. Anal. Chemie, 1865, IV, 8).
8. 1.073405 Dr. Gerlach (Zeit. Aual. Chemie, 1865, IV, 8).
9. 1. 073.50 Franeienr (M6nioire snr I'Areonietrie, Paris, 1842, 26).
1.0737665 Average.
Note. — 1 was chemically pure salt; 2 was Syracuse solar salt; 3 was Syracuse factory-filled dairy salt; 4 was rock salt; 5 was chemically pure salt ; 6 was commercial salt.
The average of these determinations gives as the specific gravity of a 10 per cent, salt solu- tion 1.0737665, and the modulus is= 145.56289, computed according to the formula
'H =
P (d-10) 1-p
in which P=the spec^iflc gravity, (l=the Baum6 degree, /( = the modulus.
With tlie use of this modulus tlie following table (Table VI) has Vieen calculated by the formula
(H-10)+f?
in which P=the specific gravity, (/=the Ban me degree, »i=the modulus.
Table VI. — Valut of degrees Bamne calculated from Oo=;i.0737665 and 10o=l hy the modulus 145.56289, the e.iperimental worl- harhiy been conducted in exact accordance with Baume''s original directions.
[Temperature 10° R.=12..5^ C=54..5'^^ F.]
|
Bannie degree. |
1 Specific 1 gravity. \ |
|
10 |
1. 00000 0.96679 ; 0. 93571 0. 906.57 0. S7919 0. 85342 0. 82912 0.80616 0. 78443 0.76385 0.74432 0.72577 0.70811 0. 69130 |
|
15 |
|
|
20 |
|
|
25 |
|
|
30 |
|
|
35 |
|
|
40 |
|
|
45 |
|
|
50 |
|
|
55 |
|
|
60 |
|
|
65 |
|
|
70 |
|
|
75 |
|
On comparing Table VI with Table II it will be seen that it agrees most closely with the first scale, which is Francceur's, and which has been adoi)ted by the United States Petroleum Associa- tion.
CONCLUSION.
In conclusion I would suggest to the Academy that, owing to the very extensive u.se which is made of the Baum6 instruments, it would be eminently projier to consider the propriety of legis-
THE BAUMR HYDKOMK/rEKS. 71
latioii oil Mil' part of Congress, or some other means, for ostablisliiiig a fixed value to the two .scales of tlie Haiimc iiKstruineiits, and I will ofl'er at the proper time the following resolution:
'■'■Resolrcd, That a committee be appointed to consider what action, if any, is desirable, with a view to establishinj; a legal value for the degrees of the Baume and other hydrometers of arbi- trary scales; the committee to report at the next meeting."
NoTK. — This resolntiiin was adopted, and the I'ollowiiif; comniitteo was appoiiitiMl : Julius E. Hilgard, Superiu- tendent riiited States Coast Snive.v, Washington, D. C. ; Henry Morton, President Stevens Institute, Hoboken, N. J. ; C. F. Chandler, Professor of Chemistry, Coluniliia College, New York.
I would further state that 1 am very largely indebted to my assistant, F. G. Wiechmann, Ph.B., for the experimental and historical data contained in the preceding tables.
NATIONAL ACADEMY OF SCIENCES.
VOL. Ill,
FIFTH MEMOIR.
ON SMALL DIFFERENCES OF SENSATION.
S. Mis. 69 10 73
ON SMALL DIFFERENCES OF SENSATION.
JtEA r> nCTORElt 17, 1884.
By C S. Prtrce and J. JASTRfiW.
The physiological psychologists assunie that two nerve excitations alike in quality will only ])ro(luce distinguishable sensations provi<le(l they differ in intensity by an amount greater tiian a lixe<l ratio. Tlie least pereejitible dift'ereu'ce of the excitations divided by half their sum is what they call the UnterschiedsHchwelle. Fechner* gives an experiment to prove the fact assumed, namely: He finds that two very dim liglits placed nearly in line with the edge of an opaque body show but one shadow of the edge. It will be found, however, that this phenomenon is not a clearly marked one, unless the lights are nearly in range. If the experiment is performed with lateral .shifting of one of the lights, and with a knowledge of the effects of a telescope upon the appear- ance of terrestrial objects at uight, it will be found very far from conclusive.
The conception of the psychologists is certainly a difficult one to seize. According to their own doctrine, in which the observed facts seem fully to bear them out, the intensity of the sensa- tion increases continuously witli the excitation, so that the least increase of the latter must pro- duce a corresponding increase of the former. And, indeed, the hypothesis that a continuous in- crease of the excitation would be accompanied by successive discrete increments of the sensation, gratuitous as it would be, would not be sufficient to account for a constant Unterschiedsschwelle. We are therefore forced to conclude that if there be such a phenomenon it has its origin, not in the faculty of sensation, but in that of comparing sensations. In short, if the phenomenon were established, we should be forced to say that there was a least perceptible dift'erence of .sensation — a difference which, though existing in sensation, could not be brought into consciousness by any eftbrt of attention. But the errors of our judgments in comparing our sensations seem sufficiently accounted for by the slow and doubtless complicated process by which the impression is conveyed from the periphery to the brain ; for this must be liable to more or less accidental derangement at every step of its progress. Accordingly we find that the frequencies of errors of different magui- fudes follow the probability curve, which is the law of an effect brought about by the sum of an infinite number of infinitesimal causes. This theory, however, does not a<lmit of an Unterschieds- schirdlt. On the contrary, if leads to the method of least squares, according to which the multipli- cation of observations will indefinitely reduce the error of their mean, so that if of two excitations one were ever so little the more intense, in the long run it would be judged to be the more intense the majority of times. It is true that the astronomers themselves have not usually supposed that this would be the case, because (apart from coustaut errors, which have uo relevancy to the pres- ent question) they have supposed this extreme result to be contrary to common sense. But it has .seemed to us that the most satisfactory course would be to subject the tpiesfiou to the test of direct ex])eriment. If there be a least perceptible difference, then when two excitations differing by less than this are presented to us, and we are asked to judge which is the greater, we ought to answer wrong as often as right in the long run. Whereas, if the theory of least squares is correct, we uot
' Elemente der Psychopliysik, I, p. 242.
76
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
only oiiglit to answer right oftener tban wrong, but we ouglit to do so in a predictible ratio of cases.*
We have experimented with the pressure sense, observing the proportion of errors among judgments as to which is the greater of two pressures, when it is known tliat the two are two stated pressures, and the question presente<l for the decisiou of the observer is, which is wliich ? From the probability, tlius ascertained, of committing an error of a given magnitude, the probable error of a judgment can be calculated according to the mathematical theory of errors. If, now, we find that when the ratio of the two ])ressures is smaller than a certain ratio, the erroneous judgments number ouehaJf of the whole, while the mathematical theory requires them to be sen- sibly fewer, then this theory is plainly disproved, and the maximum ratio at which this phenom- enon is observed the so-called UnttrHchu'dHnchwcUe. If, on the other hand, the values obtained for the probable error are the same for errors varying from three times to one-fourth of the i)robable error (the smallest for which it is easy to collect sufficient observations), then the theory of the method of least squares is shown to hold good within those limits, the presumi)tiou will be that it extends still further, and it is possible that it holds for tiie smallest diffei'ences of excitation. But, further, if this law is shown to hold good for differeuce so slight that the observer is not conscious of being able to discriminate between them at all, all reason for believing in an Uuttr- schicdsschwdh' is destroyed. The mathematical theory has the advantage of yielding conceptions of greater detiniteness than that of the physiologists, and will thus tend to improve methods of observation. Moreover, it affords a ready method for determining the sensibility or fineness of perception and allows of a comparison with the results of others; for, knowing the number of errors iu a certain number of experiments, and accepting the conclusions of this paper, the calcu- lated ratio to the total excitation of that variation of excitation, in judging which we should err one time out of four, measures the sensibility. Incidentally our experiments will afford additional information upon the value of the normal avei-age sensibility for the pressure sense, which they seem to make a finer sense than it has hitherto been believed to be. But in this regaixl two things have to be noted : (1) Our value relates to the probable error or the value for the point at which an error is committed half the time; (2) in our experiments there were two opportunities forjudg- ing, for the initial weight was either first increased and then diminished, or riec versa, the sub- ject having to say which of these two double changes was made. It would seem at first blush that the value thus obtained ought to be multiplied by -/^ (I.41I) to get the error of a single judg- ment. Yet this would hardly be correct, because the judgment, in point of fact, depended almost exclusively on the sensation of increase of pressure, the decrease being felt very much less. The ratio ^2 (1.414) would therefore be too great, and 1.2 would perha])s l)e about correct. The advantage of having two changes in one experiment consists iu this: If only one change were employed, then some of the experiments would have an increase of excitation only and the others a decrease only ; and since the former would yield a far greater amount of sensation than the latter, the nature of the results would be greatly complicated; but when each experiment embraces a
* The rule for tiuding this ratio is as follows: Divide the logarithm of the ratio of excitatiixis by the probable error and multiply the quotient by 0.477. Call this jnoduct t. Euter it iu the table of the integral Ot, given in most works on probabilities; St is the proportion of cases iu which the error will be less than the ditt'erence between the given excitations. In all these cases, of cour.4e, we shall answer correctly, and also by chance in one-half of the remaining cases. The proportion of erroneous answers is therefore (1— Ot)— 2. In the following table the first col- umn gives the i|niitient of the logarithm of the ratio of excitation, divided by the iirobable error, and the second column sliows the proportion of erroneous judgments :
|
0.0 |
0.50 |
|
0. 0.'-. |
0.49 |
|
0.1 |
0.47 |
|
0. ar> |
0.43 |
|
0.5 |
0.37 |
|
1.0 |
0.25 |
To guess the correct canl out of a ])ack of tifty-two once in eleven times it would bo necessary to have a sensation amounting to 0.:17 of the i>roliabIc error. This would be a .-eu.sation of wliicii we sliouhl i>robably never become aware, as will appear below.
SMALL DIFFERENCES OF SENSATION.
77
double cliauge this dirterence in the iiinomit of seI^s;lti()ll caiiscd by an increase and decrease of pressure attects every experiment alike, and the liability to error is constant.*
Throughout our observations we noted the degree ofeonfidenee witii w hicli the ob.server gave liis judgment upon a scale of four degrees, as follows:
0 denoted absence of any preference for one answer over its opposite, so that it seemed uou
sensical to answer at all.
1 denoted a distinct leaning to one alternati\e.
2 denoted some little confidence of being right.
'3 denoted as strong a contidence as one would have about such sensations. We do not mean to say that when zero was the recorded confldence, there was absolutely no sensation of preference for the answer given. We only mean that there was no sensation that the observer noticed when attending to hjs feelings of this sort as closely as he conveniently could, namely, closely enough to mark them on this scale. The scale of confidence Hnctuated cousiderablj'. Thus, when iMr. Jastrow passed from experiments upon differences of weight of 0(1, 30, and 15 on the thousand to differences of 20, 10, and 5 on the thousand, although the accuracy of his judgments was decidedly improved, his contidence fell oil' very greatly, owing to his no longer having the sensation i)roduced by a difference of (jO present to his memory. The estimations of contidence were also rough, and might be improved in future work. The average marks seem to conform to the formula —
P
»(=clog
-P
where m denotes the degree of confidence on the scale, /> denotes tlie probability of the answer being right, iuid c is a constant which may be called the index of confidence.
To show that this (orniula approximates to the truth, we compare it with the average marks assigned to estimates of differences for which more than a hundred e.ijperiments were made. Mr. Jastrow's experiments are separated into groups, which will be explained below.
First (iroiip.
|
Ratio iif )ir('s.siires. |
Peii'ce, observer. |
.Jastrow, |
ibserver. |
||
|
(=1. 25. |
<■=!. 5. |
0=0. 0. |
|||
|
Meaii couthlciice. |
Mi'aii ooiiliileiicc. |
Mean ciiiilidoiKc. |
|||
|
01jserve<]. |
Calculated. |
Observed. Calculated. |
Observed. |
Calculiited. |
|
|
l.oi.-. i.o:!0 1.060 |
0.14 0. :io 0.70 |
0.10 0. :» 0.70 |
0.30 0.2 0.40 : 0.4-.J 0. 85 0. 87 |
0. 34 0. r,o 1. 02 |
O.2.- ('..'6 1.-..2 |
|
Ratii> iifiiretsurrs. |
- |
Jastrow, |
observer. |
|
|
c=(i. ar,. |
(■=0. 4. |
|||
|
Mi'au conlidrnce. |
Mean ciiTiliili-iue. |
|||
|
Observed. (1 (Ml |
Calculated. |
Oliserved. |
Calculated. |
|
|
1.00.") |
0. 03 |
II. (10 (1. (ir> 0. CO |
0. 06 0.12 0.30 |
|
|
1.010 |
(1.07 0.06 |
|||
|
1.020 |
0.12 |
0.12 |
• Tlie number of errors, when au increase of weight was followed by a decrease, was slightly le.ss than wben.the tirst chauge was a decre.ase of pressure.
78
MEMOIRS OF TUE NATIONAL ACADEMY OF SCIENCES.
The jndgiiients cnniiciiited witli any ,<jiveii deftrec of confidenee were more likely to be rialit with greater dittereuces thau with smaller ditt'ereuceti. To show this, we give the tVeqiieiicy of the dittereiit marks in Mr. Jastrow's second, third, and fourth groups.*
The apparatus used was au adaptation of a "Fairbanks" post-oflice scale; upon the end of the beam of which was fixed a square enlargement (about one-half inch square), with a flat tojt, which served to convey the pressure to the linger in a manner to be presently described. This was tightly covered witli an India-rubber cap, to ]n'event sensations of cold, &c., from contact A\ith the metal. A kilogram i)laced in the pan of the balance brought a pressure of one fourtli
" The rt-snlt of our oliservntions on the confidence connected with the judgments is lis t'ollows:
[Subject, Mr Peirce.]
|
y:iri;itions. |
A \ era go confidence. |
Nnmber oC sets of 50. |
|
|
(10 |
Grams. |
.67 |
7 |
|
no.. 15 |
.28 .15 |
5 |
[Snliject, Mr. .I:iRt.ro\v.]
|
.yo |
|
|
.51 |
|
|
.30 |
|
|
.11 |
|
|
.(« |
I'J |
|
.00 |
10 |
fiO. 30. 15. 20. 10.
In 1,125 experiments (subject, Mr. Peirce) — variations 15, :50, and BO gr.ain.s^tliere occurred confidence of '^, 3» times (3 per cent.) : of 2, 102 times (9 per cent.) ; of 1, 282 times (25 per cent.): of 0, 700 times (03 per cent.). In these experiments there were 332 (2!l per cent.) errors committed, of which 1 (0.3 per cent.) was made in connection with a confidence 3; 10(3 per cent.) with a confidence 2; 51 (15 per cent.) with a confidence 1; 270 (81 per cent.) with .a confidence 0. From which we find that in connection with a confidence of 3 tliere occurred I error in 35 cases (3 per cent.): with a confidence of 2, 10 errors in 102 cases (10 per cent.); with a lonfidence of 1, 51 errors in 282 cases (ly per cent.) : with a confidence of 0, 270 errors in 700 cases (38 per cent.).
, In 1,975 experiments (snliject, Mr. .lastrow) — variations 15, 30, and 00 gr.ams — there occurred confidence ol' 3, 02
times (3 per cent.) ; of 2, U)0 times ( 10 per cent.) ; of 1, 594 times (:i0 per cent.) ; of 0, 1,123 times (.57 jjcr cent.). In
• these experiments there were 451 (23 per cent.) errors committed, of which 2 (0.4 per cent.) were made in connection with a confidence of 3; 12 (3 per cent.) with a confidence of 2; 97 (22 per cent.) with a confidence of 1, 340 (75 per cent.) with a confidence of 0. Again, in connection with a confidence of 3, errors occurred twice in (ji cases (3 per cent.) ; with a confidence of 2, 12 times in I'.Mi cases (C per cent.) ; with a confidence of 1, 97 times in .504 cases (10 per cent.); with a confidence of 0, 340 times in 1,123 cases (30 per cent.).
In 1.075 experiments (subject, Mr. .lastrow) — variations 5, 10, and 20 grams — there occurreil confidences of 3, Miun' ; of 2, none ; of 1, 115 times (7 per cent.) ; of 0, l,.'i00 times (93 per cent.). In these experiments there were 5.38 (32 iier cent.) errors committed, of which 10 (3 i)er cent.) occurred in connection with a confidence of I : .522 (97 per cent. ) with a confidence of 0. Ag.ain. in connection witli a confidence of 1, errors occurred 10 times in 115 cases (14 per cent.) : with a coulidence of 0, 522 times in 1,.5()0 cases (34 per cent.).
Siiiind group.
Ratio of weight.s. i Mark 0. ! Mark 1. Marl; 2. ' M.ark 3.
1.015 \ ll'I'isl't
I 00 wrong
j 100 riglit ( 35 wrong
S 80 right \ 8 wrong
1.030. 1.060.
|
51 riglit |
:l right |
1 right |
|
17 \\ rung \ 72 right; |
2 wrong 23 riglit' |
0 wrong 2 right |
|
1 1 wrong 75 right, 1 wrong |
1 wrong 54 right 2 wrong |
0 wrong 24 right 0 wrong |
SMALL Dil'KEKKNCKa OF SE:NttATlOiJ. 71)
of if.s wci^lit ii|)(>ii llic liii.ucr. Tlii' (litri'iciitiiil pressure was ])i(){luc<'(l by lowerinj;' upon llie pan of the balanee a smaller pan into wliieli tlie proper \veij;hts eould he (inuly fixed; this litth' |)au hiid its bottom of cork, and was placed upon a piece of Hatinel which <!onstaiitly remained in the ])an of tiie bahuu'e. It was lifted oft' and on by means of a fine Indiaruliber threatl. whieli was so mueli stretched by the weight as certainly to avoid any noise dv Jar fiom the momentum of the descending pan. A sufficient weight eonld also be hung on I lie beam of the balance, so as to take oH" the entire pressure from the Hnger at the end of each e.\i)erimeut. This weight could be applied ov removed by means of a cam acting upon a lever; and its bearings ui)on the beam were guarded by India-rubber. It was found that the use of this arrangement, which removed all annoying irregularities of sensation connected with the removal and replacement of the greater (initial) i)ressure, rendered the results more uniform and diminished the probable error. It also shortened the time necessary for performing the experiments, so that a series of 2") experiments was concluded before the effects of fatigue were noticeable. It may be mentioned tliat certain causes tended to the constant decrease of the probable eiTor as the experiments went on, these mainly being an increased skill on the part of the operator ami an eilucafion of the sensibility of the subject. The finger was supported in such a way as to be lightly but firmly held in jiosition, all the muscles of the arm being relaxed; and the India-rubber top of the brass enlargement at the end of the beam of the balance was ne\(U- actually separated from the hnger. The i)rojecting arm of a filter-stand (the height of which could be adjusted) with some attachments not necessary to detail, gently prevented the finger from moving upwards under the pressure exerted by the weight in the i)aii. In the case of Mr. Peirce as subject (it may be noted that Mi'. Peirce is left- handed, while Mr. .Jastrow is strongly right-handed) the tii> of foiefinger, and in the case of Mr. Jastrow of the middle finger, of the left hand were used. In addition, a screen served to prevent the subject from having any indications whatever of the movements of the operator. It is hardly necessary to say that we were fully on our guard against unconsciously received indications.
The observations were conducted in the following manner: At each sitting three ditt'erential weights wei-e employed. At first we always began and ended with the heaviest, but at a later period the plan was to begin on alternate days with the lightest and heaviest. When we began with the heaviest 2i) observations* were made with that; then 2.5 with the middle one, and then 25 with the lightest; this constituted one-half of the sitting. It was completed by three more sets of 2o, the order of the weights being reversed. When we began with the lightest the lieaviest was used for the third and fourth sets. In this way 150 experiments on each of us were taken at one sitting of two hours.
A pack of 25 cards were taken, 12 red and 13 black, or vice vermi, so that in the 50 experiments made at one sitting with a given ditt'erential weight, 25 red and 25 black cards should be used. These cards were cut exactly square and their corners were distinguished by holes punched in them so as to indicate the scale of numbers (0, 1, 2,3) used to designate the degree of confidence of the judgment. The backs of the.se cards were distinguished from their face^. They were, in fact, made of ordinary playing-cards. At the beginning of a set of 25, the i)ack was well shuffled, and, the operator and subject having taken their places, the operator was governed by the color
Third and fonitli (/I'diijis. [Marlis 2 mid '■> do not oecur.]
KiUio of wtriiilits. Sliirlv 0. Mark 1.
f.UO;
S '.iW right' :!-i right
UIM light 2 liglit
'M''i wKiiig f wroii'
'•"^•^ I l'J2 wi-oiig :;0 wrong
1 A.,„ S :i'J^> 'iglit IW right
^•"~ ;( l:n wrong (i wrong
At tirst a short pause was made in the set of 2.'), at the optiou oi the subject ; later this was ilisjiiustil « ilh.
80
MEMOIRS OK THE NATIONAL ACADEMY OF SCIENCES.
of tlic .siicce.s.sivi' cards in choosing wlietlier lie should lirst diminish the weight and then increase it, or rice rcrsu. If the weight was to be first increased and then diminished the operator brought tiic juessurc e.vertfd by the kilogram alone upon the finger of the subject by means of the lever and cam mentioned above, and when the subject said "change" he gently lowered the differential weight, resting in the small pan, upon the pan of the balance. The subject, having appreciated the sensation, again said "change," whereupon the operator removed the differential weight. If, on the other hand, the color of the card directed the weight to be first diminished and then increased, the operator had the dift'erential weight already on the pan of the balance before the pressure was brought to bear on the finger, and made the reverse changes at the commai.d of the subject. The subject theu stated his Judgment and also his degree of confidence, whereupon the total jires.snire was at once removed by the cam, and the card that had been used to direct the change was placed face down or face up according as the answer was right or wrong, and with corner indicating the degree of confidence in a determinate position. By means of these trifling devices (he imi)ortant object of rapidity was secured, and any possible psychological guessing of what change the operator was likely to select was avoided. A slight disadvantage in this mode of pro- ceeding arises from the long runs of one particular kind of change, which would occasionally be [iroduced by chance and would tend to confuse the mind of the subject. But it seems clear that this disadvantage was less than that which would have been occasioned by his knowing that there would be no such long runs if any means had been taken to prevent them. At the end of each set the results were of course entered into a book.*
The following tables show the results of the observations for each day :
|
Date. |
Ra |
tio-sof pre.ssiires. [Subject: Mr. Peirce.") |
||||
|
1.100 |
1.080 |
1.060 |
1.050 |
1.040 |
1.030 |
1.015 |
|
December 13 |
1 4 errors.
|
8 errors. 11 4 14 l."S 12 6 |
15 errors. |
1 |
||
|
16 20 29 16 15 |
21 errors. 28 28 20 22 |
|||||
|
|
||||||
|
Jannary 22 | |
||||||
|
Meaus Calculated from |irob:t- ble eiTor=0.M5l Average coufdrnrf. Observed |
||||||
|
2 |
4 |
10.4^1.0 13 |
15 1 19.3±1.4 |
21.6±1.1 |
||
|
4.6^1.0 |
7.2±1.6 |
10.7±0.8 12.7±2.1 |
14. 9-1-2. 2 17. 2^0. 9 |
21.0-tl.l |
||
|
1.9 1.3 |
0.9 1.0 |
0. 7 0. fi |
0.3 |
0.3 0.3 |
0.2 0.2 |
|
|
Calculated .'. |
0.7
|
0.6
|
0.5 |
The numbers in the columns show the number of errors in fifty experiments. With the aver- age nnmber of errors in a set of fifty we compare the theoretical value of this average as calculated by the method of least sipiares. The number .051 thus obtained in this case best .satisfies the mean number of errors. The numbers attixed with a sign denote, in the upjier row the observed [a posteriori) probable error of the mean value as given, in the lower row the calculated (n priori) proliable error. The last two lines give the average confidence observed and calculated with each variation of the ratios of pressure. It will be seen that the correspondence between the real and theoretical numbers is close, and clo.sest when the number of sets is large. The probable errors also closely correspond, the observed being, as is natural, slightly larger than the calculated probable erroi's.
* In the experiments of December, 1883, and Jannary, 1884, the method as above described was not fnlly perfected the most, important fault being th.at the total weight instead of being removed and replaced by a mechanical device, was taken off by the operator pressing with his finger upon the beam of the balance.
SMALT. niKFKRKNOES OF SENSATION.
Till' t'olldwiiiR i.s a siinilar tabic for Mr. Jastrow a.s .subject:
Ratios of pressures. I.IUO 1.(180 1.0(iU I.O.-iO 1.040 l.Oai t.O-J(» 1.01.-, l.OKl 1.00.-,
81
iiiitt-.
Deo.iiilier 10 :>
IVieiiiliir 13 1 '.I l.'>
Deceinber 17 ] 14
December -.30 | 10
.laimary :i | 8
Jamiarv 10 j 7
.1 an iiarv 1.') .... 12
19
ir,
January V!2 . . January 2i . . February 11 . February 17 . February 18 . February 24 .
March 4
March :
11 4 1
2:! 17 14
i:!
(;
10
11
7
10 II
8
Ki
i:!
March 18 14
March 19 1 11
March 23 14
March25 I 12
March 30 1 H
March 31 10
April2 11
April3 9
April (i I'f
April 7 0 -> 7
24 17 22 IG 18 18 17 17 1.5
14
I(i 17 19 21 17 16 16 15 17 18 15 15
2b 18 18 18 21 21 21 20 21 17
Means.
«.6
19 15.0 11.6 , 11.4 , 18.9 I 16.H 20.5
It would obviously be uiilair to compare these numbens with any -set of theoretical uumbers, since the probable error is on the decrease throughout, owing to ett'ect.s of practice, etc. For various reasons we can conveniently 8tou[) these experiments into four groups. The first will include the experiments from December 10 to January 22, inclusive; the second from January 24 to February 24, inclusive; the tiiird from Marcli 4 to March 25, inclusive; the fourth from March 30 to the end of the work.
The mean results for tlie different groups are exliibited in the following tables:
First groiij).
[I'n.bable error=0.05.]
Ratios of Nuinbeiof pre.ssnres. sets of .-|0.
I. 100 1.080 1. 060 1.050 1. 040
i.ii;!0
1.015
Average number of errors.
Average eouliiU'ii^
Calculated ()bser\e(l. fioni proba- (.)bser\e(i. Caleulatol. ble error.
11.0 J 0.7
19
15
1.3. 8 J 1.5
20. 8^ 1. 1
4.4~tl.4 7.0J^1.7 10.44-0.7 12.54:2.1 14.7^2.2 17. 0-tO. 9 21.0-tl. 1
0.9 0.9 0. 85 0. 35
0. :!
0.5 0.3
1.5 1.2
0. 9 0.7 11.6 0.4 0.2
Sccoiut (/roup. [Probable error=0.0235.]
S. Mis. G9-
1 . 060 1.030 1.015
—11
|
2. 2 j-0. 3 |
2. |
1+0 |
4 |
1. |
0 |
1. |
■-' |
|
9.4-0.6 |
9. |
6+0 |
< |
0. |
55 |
0. |
6 |
|
17. 0-1-0. 3 |
16. |
6+1 |
0 |
0. |
3 |
0. |
3 |
82
MEMOIRS OV THE :NATrONAL ACADEMY OF SCIENCES.
Third grotqj. [Probable enor=0.02.]
|
Ratios of pressMics. |
Number of sets of 50. |
Average number of errors. |
Average coiitit |
ence. |
|
|
Observed. |
Calculated from proba- ble error. |
Observed. Call |
ulated. |
||
|
1.020 1.010 1.005 |
6 6 4 |
12. 8 ±0. 3 17. 7-1-0. 6 20.7-1-1.7 |
12. 5±0. 8 18. 3-1-0. y 21.6±1.2 |
0. 12 0.07 0.00 |
0.12 1 0.06 ' 0.03 1 |
|
Fourth gronp. [Probable error=0.0155. |
] |
||||
|
l.OHO |
1 1 6 1 6 6 |
0 5 10. 0-1-0. 5 14 16 20. 8±0. 4 |
0. 8±0. 6 4.8-bl.4 y. 6-tO. 8 12. 8±2. 1 16. 5±0. 9 20. 6±1. 0 |
1 1. K |
|
|
1.030 1.020 1.015 1.010 1.005 |
0.5 0.1 0.1 0.05 0.00 |
0.4 0.2 0. 13 0.12 0.06 |
The tables show that the numbers of errors follow, as far as we cau convenieutly traue them, the numbers assigned by the probability curve,* and therefore destroy all presumption in favor of an Untvrsvhwdsiicluvdlf. The introduction and retention of this false notion can only confuse thought, while the conception of the mathematician must exercise a favorable influence on psychological experimentation. t
The quantity which we have called the degree of confidence was i^robably the secondary sen- sation of a difference between the primary sensations compared. The evidence of our experiments
*Iu the tables of the third and fourth groups, there is a marked divergence between the a priori awA. a posteriori probable error, for the average number of errors iu 50, makiug the observed probable error too small. This can only be partly accounted for by the fact that the subject foriueil the unconscious habit of retaining the number of each liind of experiment in a set and answering according to that knowledge. In point of fact the plus errors and minus errors separately do not exhibit the singular uniformity of their sums, for which we are quite unable to account. Thus iu the fourth group we have :
Number nf -\- and — errors.
Date.
1.020
March 30 — 4, + 7
March 31 — 7, -|- 3
Aiuii 2 — 1,+10
April 3 ! — 4,-i- 5
April ti —6,4- 6
April 7 —5,+ 9
1.010
1.005
|
—6, -1-10 |
-13,4- « |
|
—5, 4-10 |
— 6, 4-15 |
|
—8,-1- 9 |
— 8, 4-13 |
|
—4, -f 14 |
—10,4-10 |
|
-8,4- 7 |
-10,4-11 |
|
-8,4- 7 |
- 8, 4- 9 |
tThe conclusions of this paper are strengthened by the results of a series of experiments on the color sense, made with the use of a photometer by Mr. Jastro w. The object was to deterraiue the number of errors of a given magnitude, and compare the numbers thus ascertained with the theoretical numbers given by the probability curve. A thousand experiments were made. Dividing the magnitude of the errors from 0 to the largest error, made into 5 parts, the number of errors, as observed and calculated, that occur in each part are as follows:
Observed
Calculated . . .
These numbers would be in closer ac,;ordance if the probable error were the same throughout, as it is not owing to the effects of practice, &a. Moreover, the experiments were made on dift'erent colors — 300 on white and 100 each on yellow, blue, dove, pink, green, orange, and brown. These experiments were not continuous.
|
199 213 |
181 197 |
217 209 |
213 181 |
190 200 |
SMALL DIFFERENCES OF SENSATION. 83
seems clearly to be tliat this seiisatioii has no SckwiUi; and vanishes only when the diffeienee to which it refers vanishes. At the same time we found the subject often overlooked this element of his field of sensation, although his attention was diretrted with a (;ertain stren.nth toward it, so that he marked his contidence as zero. This haijpened in eases where the judgments were so mneli alfected by the diftereiice of pressures as to be correct three times out of tive. The general fact has highly important practical bearings, since it gives new reason for believing that we gather what is i)iissing in on(! another's minds in large measure from sensations so faint that we are not fairly aware of having them, and can give no account of how we reach our conclusions about such matters. The insight of females as well as certain "telepathic" i)henoinena may be explained in this way. Such faint sensations ought to be fully studied by the i)sychologist and assiduously cultivated by every man.
NATIONAL ACAI3EMY OF SCIENCES.
VOX.. 11 1
SIXTH MElMOIR.
DESCRIPTION OF AN AliTICULATE OF DOUBTFUL RELATIONSHIP FROM THE TERTIARY REDS OF FLORISSANT. COLO.
DESCRIPTION OF AN ARTICULATE OF DOUBTFUL RELATIONSHIP FROM THE TERTIARY BEDS OF FLORISSANT, COLORADO.
JtEAD AT WASffimiTON, At'lilL 20, 188;!
By Sami'ei. H. Scuddek.
Amoug the remains of auimals in my bauds I'ouud iu the aucient lake basin of Florissant are about forty specimens of an onisciform arthropod, about a centimeter in length, whose affinities have jiroved very perplexing. This does not result from poorness of preservation, for among the numerous specimens apparently all the prominent external features are found completely pre- served, and even the course of some of the internal organs may occasionally be traced; but it presents such anomalies of structure that we are at a loss where to look for its nearest kin.
It appears to be an aquatic animal. Its body consists of three large subequal thoracic joints, and an abdomen about half as large again as any one of them, with occasional indications of a feeble division into four segments. These are the oidj' jointed divisions that can be found in the body, there being no distinct head. The thoracic segments are so considered because each bears a pair of legs, which occur nowhere else. Their dorsal plates are large, flat longitudinally, and arched transversely; smooth, and deeply and narrowly notched in the middle of the front margin.
Fig. 3.
Fig. 2.
Fig. 1, dorsal view; tig, 2, lateral view: fig. 3, transverse sectional view of Planoceph- alus aneUoidea from the oligocene of Florissant, Colorado, restored, and magnified about six diam- eters.
Fig. 1.
The tirst plate, in which the median notch is more conspicuous and open than in the others, also narrows and becomes more arched in front, so as to form a sort of hood. The legs are very broad and compressed, and adapted to swimming, which was apparently their use, as there would be no need of such compression to crawl into chinks when the body is so much arched. They consist of a femur, tibia, and two tarsal joints, terminated by a single curved claw. The femur is very large, subovate, inserted (presumably by a coxa) in large cavities, those of opposite sides sepa- rated by their own width, and situated a little behind the middle of each segment. The tibia is also very large and subovate, but more elongated and squarer at the ends, being about twice as long as broad, and fringed on the anterior edge by a row of delicate hairs as long as the width of the joint. Of the two tarsal joints, the basal is a little the larger, being both longer and stouter. Each is armed at the tip internally with a tolerably stout spine of moderate length, and together they are a little longer than the tibia, much slenderer, and quadrate iu form. The terminal claw
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is about lialf as long as the teriuiual joiut. The hind legs are somewhat stouter and the middle pair a little shorter than the others; but otherwise they closely resemble each other.
The dilterent segments of the thorax, as stated, are protected above by the development of distinct chitinous plates, the lower edges of which are clearly marked, and extend downward to the concealment, on a si(ie view, of the lower part of the body. The abdomen, however, seems to have no such specialization of the integument of the upper surtace. It is stout, apparently well rounded transversely, and tapers to a i.roduced but blunt tip, which is armed with a pair of slightly recurved stout claws, two or three times longer than the leg-claws, arranged as if to drag the body backward. The abdomen is faintly divided into four segments, often entirely obscured. Of these the terminal usually appears shorter than the others, which are subequal.
These divisions of the body are all that appear to have belonged to the animal; and it is the most remarkable fact in its organization that it certainly had no distinct chitinous head. This is the more surprising from the clearness with which the thoracic segments are marked. All that one can lind preserved is what appears to be a ring of buccal plates terminating anteriorly the alimentary canal, and which was evidently capable of being thrust forward a long distance beyond the body. If it were not for the unusual preservation of the alimentary canal we should be forced to consider the head as lost from all the specimens, notwithstanding the nearly perfect preserva- tion of the other parts; but in several specimens the alimentary tube can be traced with ease half throvh the body, terminating in front in these more or less clearly preserved chitinous plates, arranged to form a circle a little smaller than the coxal cavities. What is most remarkable is the extension of this alimentary tube and accompanying buccal plates like a ])roboscis far beyond the limits of the body; sometimes forward (apiiarently through the anterior notch) to a distance in front of the first segment equal to half the length of the latter; more often directed downward as well as outward, perhaps between the front legs, ami occasionally extending beyond the body to nearly or (pnte th' mfin- Inuith of the same. It seems to leave its direct course within the body at about the middle of the'tirst thoracic segment, directly in front of which position the buccal plates appear in one or two specimens, apparently in the position ot repose. The various i)Ositions in which these buccal plates are found outside the body, both when their connection with the tube is traceable and when it is obscure or fails, shows how perfectly movable a proboscis the creature possessed. The external parts of the head, then, may be said to have probably been composed entirely of a flexible, extensible membrane capable of protrusion as a fleshy i)roboscis, separated by no line of demarkation from the first thoracic segment, and bearing as appendages only a series of buccal plates for mouth-parts, and beyond this nothing— neither cranium, eyes, antenuie,nor palpi. In the absence of eyes, one would naturally look for the development of tactile organs ot some sort; but nothing of the kind is discoverable on the most careful special search, unless such an office may be performed by long delicate hairs which seem, in some few instances, to be scattered dis- tantly over the projected mouth-tube.
A special study of the buccal plates in the twenty-four or twenty-five specimens which best show them gives no very satisfactory explanation of their form and relations. They have been said to form a ring, because in a considerable number they are so arranged; but it may be doubted whether this appearance is not due to the flaking of the chitinous parts. Like the lips of the notches of the thoracic segments, the buccal apparatus was evidently more dense and thicker than other te-umeutary parts, for these are darker colored than the other parts and often carbonaceous in this condition the central portions seem liable to flake away and leave the thinner edges with ragged fragments of the carbonaceous inner portions attached, thus frequently lormmg a sort ot irregular ring of dark chitiue. On the other hand, it is just as common for fragments to become chipped out from the edges, or for rounded bits to fall out here and there, producing thereby an almost endless varietv of present appearances. Among these it is difficult to trace tlie clew to the original arrangement and form of the plates. One might anticipate that these would have occurred around the central orifice of a proboscis; and if anything of this sort was present it would appear the most probable (though extremely doubtful) that there were four subtriangular plates ol pretty large size, the lateral the larger, nearly meeting by their tips at the center. From specimens, however, which are least broken, it would seem quite as probable that the api)aratus consisted of two attiiigeiit or overlapping circular plates, placed transversely, densest centrally, wliich by tlieir
DESCKIPTION OF AN ARTICULATE OF DOUBTFUL RELATIONSHIP. 89
consolidation form an oval rounded mass. How such a pair of plates, or compound plates, could Lave subserved any purpose in tbe procuring of food, I cannot understand, but that such is their iu)t uufrequent appearance, especially when seen through and protected by the thoracic shield of the first segment, is nevertheless the fact. It is to be hoped that other specimens may set this matter at rest. Those at hand allow no more definite statement than has been made. About three-fourths of the specimens of this species show the buccal plates more or less distinctly. In all but three they lie outside the body, usually at a distance from it of about half the length of tlie first thoracic segment. In a fourth specimen they lie half protruding at the front edge of the body.
These buccal plates, as already stated, are the only hard parts of the head, and the onlj- append- ages. Indeed, the only claim this portion of the body has to be called the head at all is that it is certainly the anterior extremity of the digestive canal. On account of this peculiarity of the oi'ganizatiou of the head, the creature, which is certainly widely different from anything known, may be called Planocephalus (TtXaydco, neqiaXij), and on account of its onisciform body, Piano- cephalus aselloides.
The first impression the sight of this strange headless creature conveys is that of an isopod crustacean. But tbe limited number of legs at once puts its reference to the Crustacea out of question, since no abdominal legs at all are present. Even in the parasitic Crustacea, where some of the legs are aborted, the same is the case with the segments themselves and with the joints of the legs which remain. The clear distinction which obtains between the thoracic and abdominal regions, and the limitation of the jointed legs to a single pair on each thoracic segment seems to lead one strongly to the conviction that these important elements of its construction place it among insects. Tbe structure of the legs and the small tapering abdomen furnished with small anal appendages tend to the same conclusion.
Where among insects it should be placed is more questionable. Thinking it possibly a larval form, careful search has been made among all the groups into which it could by any possibility be l)resumed to fall, viz, among the Neuroptera and Coleojitera, but nothing in the slightest degree seeming to be related to it could be found, and its conspicuous size rendered it the less probable that a kindred form would be overlooked. On account, however, of its apterous character, and the discovery in recent years of certain (surious types of animals (all of them, however, very minute) whose afflnities have provoked more than usual discussion, my attention was early drawn toward certain resemblances which Planocephalus bears to the Pauropidie among Myriapods and to the Tbysanura, and here, if anywhere, its aflflnities seem likely to be found.
Its passing resemblance to the obtected forms of Pauropoda which Ryder has published under the name of Eurypauropodidre is certainly very considerable, especially when it is remembered that the young of Pauropoda bear only three pairs of legs. The position of the more mobile part of the head of Eurypauropus beneath the cephalic shield is the same that the head of Planoceph- alus bears to the first thoracic shield ; and the mouth-parts in both are confined to a somewhat similar circular area; there are no eyes in either, and the legs terminate in a single curved claw.
On the other hand, not only are antenufe of a highly organized character developed in Pau- ropoda, but the upper portion of the head carries a cephalic shield as large and conspicuous as the others ; two pairs of legs are developed in the adult on every or nearly every segment of the body, and always on the abdominal to the same extent as on the thoracic segments, no abdomen being distinct from a thorax as in Planocephalus, but all the joints of the body entirely similar ; the legs of the Pauropoda are formed on the myriapodal type, consisting of cylindrical undlfterentiated joints, while those of Planocephalus are hexapodal in character, having a clearly defined femur and tibia, and a two-jointed tarsus conspicuously smaller and shorter than the preceding joints, of different form and apically spiued.
The closer, therefore, we compare these two types the less important seem the points of resem- blance, and the more important the points of divergence between them; for in the clear distinction of the thorax and abdomen, the absence of abdominal legs, and the structure of the legs them- selves— fundamental features of its organization — Planocephalus clearly belongs to the true hex- apod type of insects.
Its probable reference to the Thysanura may be defended on both negative and positive grounds. There is no other group of hesapods to which it could be considered as more likely to S. Mis, 69 12
90 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
belong, and there are some special thysauuran features in its structure, anomalous as it is. Since Packard lias sbown the reasonableness of placing the Symphyla ( = Scolopendrella) of Ryder in the Thysanura, with theCollembolaand Cinura as co-ordinate groups, the range of the Thysanura has been extended, and as a group of equivalent taxonomic value to the larger divisions of winged insects it has seemed itself to gain a better ratio vivendi. It is not necessary, therefore, in consid- ering the relations of Planocephalus to Thysanura as a whole, to limit ourselves to points of com- parison which it may have to one or another of its subordinate groups, but consider any points of resemblance we may find to any of these groups indifferently. The tlioracic segments remind us not a little of some Cinura, while tlie abdomen as a whole recalls many of the Collembola, its approximated pair of specialized anal ai)pendages being also like the variously developed organs of all Thysanura and unlike anything we can recall in any niyriapod. The legs, in the develop- ment of the basal Joints and in the smaller double jointed tarsus, are ciosely related to those of some Cinura — built indeed upon the same general pattern, excepting that in Planocephalus they are specially developed for swimmjng. In the claw of our fossil genus we have something decidedly thysanuriform. We have heretofore spoken of the two tarsal joints as each armed apically with an interior spine ; but that of the final joint arises from the base of the curving claw^, and takes on more or less its direction, though only half as long as it, causing it to resemble very closely the smaller digit of the claw of both Collembola and Cinura, which is always inferior to the larger, and not infrequently, as in Lepidocyrtus, etc., straight instead of curved.
Of course, the rudimentary character of the head and the entire obliteration of the cephalic plates renders our fossil very distinct from any known type of Thysanura. But these features separate it quite as widely from any other group that may be suggested for it, aud taking into account the considerable develoi)ment of the thoracic portions, we must look upon Planocephalus as in some sense a degraded form, descended from a type in which the head was developed at least to some extent; and this renders it more probable that we have here found its proper place. More- over when we examine the mouth-parts of Podura, we find them partially withdrawn within the bead, reduced in external presentation to a small circle at the end of a conical protrusion of the under side of the head. Take away the cephalic plates, withdraw the mouth-parts to the same protection of the first thoracic segment which tliey now enjoy under the cephalic dome, imagine further that the mouth-parts could be protruded to their original position when covered by a cephalic shield, and we have about the same condition of things we find in Planocephalus; indeed the extensibility of the mouth parts beyond the thoracic shield seems quite what one might expect after the loss of the hard parts of the head; and the mouth-parts of Planocephalus bear much the same relative position to the first thoracic shield which those of Podura bear to the cephalic shield.
Assuming, then, that Planocephalus is a true hexapod, its general relations are certainly with the Thysanura rather than with any other gruui); while tlie character of the legs, the half devel- oped double claw, aud the anal appendages specialized to peculiar use are characters which are positively thysauuran. Add to this that we find in Podura something in a remote degree analogous to the extraordinary mouth-parts of Planocephalus, which we should in vain seek elsewhere, and the probability that we find here its nearest allies is rendered very strong; and the more so from the diversity of form aud type in this group since the addition to it of Scolopendrella. The dis- covery of a co'lophore or something homologous to it would, we conceive, be decisive on the point; but the lateral preservation of nearly all the specimens of this fossil, aud the obscurity of the base of the abdomen in nearly all, not only forbid its determination in those yet found, but render it doubtful if it will ever be discovered.
The position of this g.roup among the Thysanura must be an independent one, between the Cinura and the Symphyla, and of an equivalent value to them. For such a group the name of Ballostoma is proposed, in reference to the remarkable power it possessed of thrusting forward the gullet and mouth-parts. It would be characterized by the peculiarity named, by the lack of any chitinous framework of the head, the equal development of three thoracic segments developed dorsally as shields, and all separated from a cylindrical abdomen, which is armed at tip with a pair of hooks for crawling; legs largely developed and with expanded and fiattened femora and tibire, the tarsi two jointed. The principal points toward which attention should be dii-ected for the more perfect elucidation of its structure are the buccal plates aud a possible collophore.
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A^OL. Ill
SEVENTH MEiAlOIR.
THE STRDCTIJRE OF THE COLUMELLA AURIS IN THE PELYCOSACRLi
91
THE STRUCTURE OF THE COLUMELLA AURIS IN THE PELVCOSAURfA
HEAD OCTOBER 16, 1884.
By E. D. Cope.
lu a specimen of the Permiau reptile Clepsydrops lepiocephalus Cope,* the columella anris was fouud nearly in its normal position. It was found lying on tiie internal side of the normally joined squamosal and (pxadrate bones, the greater part of it within the former, but the distal extremity overlapping the superior part of the latter. These elements have lost their attachment to the cranium proper, so that the connection of the columella with the latter is not visible.
The columella is of unusual size as compared with other bones of the skull. Thus while the vertical length of the premaxillary bone is M. .060, and its width at the third tooth is .022, and while the vertical length of the quadrate bone is .085, the dimensions of the colnniella anris are as follows :
Length on inside of curve 072
Greatest d ameter just below stapes 021
Distal diameters \ =■
\ short Oil
°^"-"^&:;:;:::;;:::;;:::;:::;::;::::::::::::::::::::::S5
) long 029
Diameters of disk of stapes : , _,,
( short 021
The shaft is slightly curved. The proximal extremity is divided by a fissure which is at right angles to the long transverse diameter. The smaller of these divisions is the more prominent, and its free extremital angle is formed by the continuous concave edge of the shaft. It bears the same relation to the shaft as the head of a rib does to its shaft (Fig. 1). The other proximal division occupies the position with reference to the shaft that the tubercle does to the rib. It is much larger than the inner head of the columella, and its face looks away from that of the head at an angle of 120°. Its long diameter diverges from that of the head by an angle of about 145°. Its free surfaceis a wide oval, and is concave, forming a basin-shaped lid to the foramen ovale of the internal ear. It thus represents the expanded proximal extremity of the stapes of other vertebrates. The base of this stapedial portion is perforated in the direction of its long diameter by a canal. One foramen of this canal is situated on the external edge below the external extremity of the oval basin. The other foramen issues in a groove, which continues for a short distance on the inner side of the bone from the fissure which separates the epicolumella from the stapes. This canal is, no doubt, that for the mandibular artery, and represents the foramen of the stapes, which is present in many Mam- malia (Fig. 1 e e).
The distal extremity of the shaft is concave, and shows an articular surface of ridges and pits (Fig. I c). The coai'seness of the latter indicates that the distal element attached at this point was cartilaginous, at least at the point of attachment. It will then resemble the corresponding part in the Crocodilia and Lacertilia, whicli connects the columella with the membranum tympani.
The points above determined as to the structure of this element permit of a number of inter- esting deductions.
First. This columella possesses what has not been previously observed in reptiles and higher
* Proceedings American Philosophical Society, 1884, p. 30.
94 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
vertebrates, au osseous counection, distinct from that formed by tlie stapes with the foramen ovale of the OS petrosuui. From this it follows that the stapes cauuot be regarded as the proximal extremity of the visceral arch of which the colaraella forms a part, as its appearance in other rep- tiles would lead us to infer. It also lends support to the view of Salensky, which is accepted by Fraser, that the stapes is not an ossification of the cartilage of the visceral arch, but is an ossifi- cation of the tissue surrounding the mandibular artery.
Second. That the stapes resembles that of the Mammalia, and differs from that of other rep- tiles in the perforation below its head.
Third. That it is succeeded distiilly by a cartilaginous element, as in many other reptiles, which is the triangular ligament of Cuvier, and is functionally the analogue, and xjrobably the homologue of the malleus of the Mammalia.
The homology of the proximal extremity of this columella may now be considered. It cannot be the suprastapedial cartilage of Huxley, since that is a superior process of the distal cartilagi- nous element or malleus. It appears to be unrepresented in the reptilian columella, and I have therefore called it the epicolumella'' (Figs. 1, Ecol).
In order to obtain some light on the homologies of the parts of this element, I have compared it with the corresponding parts in various species of reptiles and batrachians, several of which have been figured by Messrs. Huxley, Peters, and Parker. I have examined the ear bones and cartilages of the Heloderma siisjyectum, and append herewith the result of my observations :
The columella has the length usual in the Lacertilia, ceasing a short distance proximad to the eustachian foramen. The cartilage, which continues in the same straight line, is divided at the eustachian foramen, one process passing downwards on its anterior border, the other forming its superior border. The posterior branch continues downwards for a short distance and terminates in a point, wbich is connected by a short ligament with the extremity of the pterygoid bone (Fig. 2 hi). Immediately exterior to it, a slender, rod-like ligament descends in close contact with it. It extends farther, howevei', reaching the articular bone of the lower jaw immediately posterior to the cotylus for the quadrate (Fig. 2 el). Its subsequent course will be mentioned below. It a])pears to be the ligament which Peters has represented as continuous with the descending process of the stapedial cartilage, and on which he based his belief in the continuity of the latter with the cartilage of Meckel. Its superior connection is, however, not with any part of the ossicula auditus, biit it can be traced to a point above the external extremity of the exoccipital bone.
The stapedial cartilage extends beyond the superior edge of the large eustachian foramen to the membranum tympaui, and is there decurved, extending in contact with it for 2-3 yam. and terminating in an acute ajjex. Near the point where it reaches the membrane it sends a branch upwards and backwards (Fig. 2 sst,) the suprastapedial cartilage, which forms a slender rod. The suprastapedial reaches inwards, and terminates at a point on the inferior side of the exoccipital bone at a point a little within opposite the origin of the inferior branch. It is only connected with the horizontal cartilage below it by membrane, and it does not form a fan-shaped plate as represented by Peters in Stellio and Huxley in Hatteria.
The following are the connections of the cartilages with adjacent elements : The distal extremity is acuminate and lies for a short distance on the membranum tympaui, where it terminates without continuation. From the convexity of the curve formed l)y the inferior edge of the cartilage where it turns upwards, backwards, and inwards to foi^ni the suprastapedial, a narrow and weak band descends. It passes along the posterior border of the eustachian foramen, and terminates on the superior edge of the mandible. As it descends it thins out and becomes undistinguishable as a distinct rod or band. The slender rod already described as descending to the mandible from the descending process of the cartilage along the inner border of the eustachian foramen is figured by Peters iu Uromastii sjyinipes.^ He describes "it as a fibrous thread, which was formerly cartilag- inous and connected the malleus with Meckel's cartilage." According to the figure it is not con- tinuous with the inferior process of the cartilage ("malleus"). In Heloderma suspeftmn it passes anterior to the cartilage, in close contact with it, to a point superior to the suprastai^edial process,
'Americau Natnralist, 1884, p. 1254.
t Mouatsbeiichtc Akademie Berlin, 1874, 44 f. B.
CTUEE OF THE COLUMELLA AURIS IN THE PELYCOSAUEIA.
95
and then turns towards tb« base of the sluill. I trace it directly to a foraniou on the superior edge of tlie sphenoid. It is clearly the facial portion of the seventh nerve (tensor tympani), as described by Fischer and Stannins,* and has nothinj;- to do with the auricular bones and cartilages. The only connection, then, with inferior arches which lean detect in this species is the fibrous one with the mandible, and I am doubtful of the significance of this.
It does not seem practicable to recognize the suprastapedial in the epicolumella of Clcpsydrops hptocephalus.] It would require an excessive shortening of the columella, which might readily be the condition of things in Clepsydrops. But it would require that the suprastapedial should be ossified, and separated by suture from the remainder of the cartilage. Until some form is found ill which this cartilage is segmented such a hypothesis has no foundation. The homology of the epicolumella with the incus is, on the other hand, almost certain; first, by the evident propriety of the exclusion of the stajjcs from the question, on account of its position, and by the history of its origin as shown by Salensky; second, on account of its position relative to both the stapes and the malleus. This being the case, the result follows that the doctrine of Peters that the quad- rate bone is not the incus, as was maintained by Reichert, is the true one. J
Efol
Epol
EXPLANATION OF PLATE.
Fig. 1. Coh\me\laanT\so( Clepsydrojyslepiocejihulus; internal side. Fig. la, external side; 1ft, proximal extremity ; Ic, distal extremity ; st., head of stapes; Etoh, epicolumella; d, distal articular surface, especially represented in Fig. , Ic; c c, toramiua of stapedial can.al. All tigures aie half natural size, excepting Ic, which is natural size. — From the proceedings of the American Philosophical Society, 1884, p. 46.
Fig. 'i. Auricular bones and cartilages and adjacent parts of Selodeniia suspect urn Co\)e,§ twice natural size. Bo., hasioccipital bone; J?i-o.,cxoccipital ; y., quadrate; J/n., mandible; P/., pterygoid ; J/. Pf., interual pterygoid muscle ; VII, seventh nerve; Col., columella auris; HsI., hypostapedial process of auricular cartilage; Sst., suprastapedial process; Est., epistapedial process; HI., hypostapedial ligament; El., epistapedial ligament.
* Zootomie der Fische, p. 154.
tSuch a hyjiothesis is suggested after inspection of Huxley's figure of these parts in Hatteria, in Anatomy of Vertebrated Aninuils, p. 77, Fig. A. See also American Naturalist, 1884, p. 1253; Proceeds. Amer. Philosoph. Soc, 1884, p. 41.
{See Proceedings Amer. Philosoph. Society, 1884, p. 41, where Peter's view Is maintained.
§ I owe the specimen dissected to my friend Horatio N. Bust, who obtained it on the Gila River, Arizona.
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VOL. III.
EIGHTH MEMOIK.
ON THE STRUCTURE OF THE BRAIN OF THE SESSILE-EYED CRUSTACEA.
S. Mis. 69 13 97
ON THE STRL CTUHE OF THE BRAJN OF THE SESSILEEYED CRUSTACEA.
READ AT WASHIXUTON, APRIL 14, 1864.
U,V A. S. Packaud.
The following- descriptions aud notes liave grown out of :iu attempt to compare the nervous system, particularly the brain and other ganglia of the head, of the eyeless species of cave inhabiting Arthropods with their oat of-door allies. We have begun with the structure and morphology of the brain of Aselliis communis Say as a standard of comparison with that of the blind Asellid, Gecidotcva sijiqia Pack., which is so common in the brooks of Mammoth and other caves and in the wells of Southern Indiana and Illinois. Studies of this nature are, it seems to us, well calculated to throw light on the origin of the cave forms, and to show what great modiftcatious have been produced iu these organisms by a radical change in their surroundings ; consisting, as it does, nminly in the absence of light, and perhaps of the usual food, or at least the usual amount of food.
It is plain enough that the species of Gecidotsea are simply eyeless, slender, depauperated Aselli, which have originated from some one of our out-of-door species within a comparatively recent time, at least since the river-terrace epoch of the Quaternary Period. The facts bearing upon the general relations of the blind to the eyed Asellida^, and a discussion of the change iu form of the body and its appendages, and of the causes of the transformation of the species and genus, are reserved for another occasion.
My present purpose is simjily to describe aud depict the brain and other nerve-centers of the head oi AsdJus communis Say aud Gccidotaa styyia Pack.
I. The bkain of Asellus communis.
The nervous system of tlie European Asellus ((quaticui Linn, has been referred to by Leydig aud also by Sars, who published a tigure of the nervous system as a whole. Leydig's " Vom Bau des thierischcii Korijcrs^'' gives a careful and comprehensive general account of the nervous system of Arthropods, the most complete and authoritative, up to ISOA, we jiossess, supplemented as it is by his excellent Tn/eln ron veigleicluiidcn Anatomic, published iu the same year (18(Ji). According to Leydig, in the Isopoda (Oniscus, Porcellio) the optic lobes are very large and overlie the cerebral lobes.
In Asellus aquaticus the abundant fat body around the ventral cord belongs to the blood sinus which envelops the nervous cord. Of this form Leydig has little to say, remarking that he did not examine the* entire ventral cord, but only sections, which agree iu appearance with those of the land wood-lice.
Sar's tigure of the brain of Asellus aquaticus is drawn on a small scale, is rather indiffereut, aud does not show more than the cerebral lobes and optic nerves. He evidently did not i)erceive the other ganglia.
Leydig's valuable figures of the biaiu of Oniscus murarius show that he did not study the nervous centers of the head by means of longitudinal sections, aud that he simply dissected the brain from above, a dorsal view showing tiie large optic lobes to be mostly above and iu front of the smaller cerebral lobes, while the ganglion, e, in his tigure 8 (Taf. VI), which he denominates nehcnlappen, is probably one of the antennal ganglia. The other ganglia of the head he does not represent, nor speak of in his Vergieichende Anatomic.
9a
100 MEMOIES 01<' THE NATIONAL ACADEMY OF SCIENCES.
The other sketches of Isopod brains by Brandt and Ratzeburg, Eathke, Lereboullet, and Milue- Edwards, as well as those in our "Zoology,''* are drawn on a small scale, are iu some cases rather indifl'erently drawn, and only represent a dorsal view, the antenna! and those ganglia posterior to it being concealed from view in dissecting from above downward. t
The observations I have made are based on vertical, longitudinal sections kindly made for me by Mrs. C. O. Whitman, under the direction of Dr. C. O. Whitman. The sections were thin, clear, well-mounted in Canada balsam, iu consecutive order, and made from alcoholic specimens, which bad, however, been kept for several years, though the uerv^ous system had beeu well preserved,
THE HISTOLO(HCAL ELEMENTS OF THE GANGLIA.
Unlike the central nervous system of Vertebrates, in which there are but two kinds of nerve tissue, viz, ganglion cells and fibers, there are in the Asellidae, as in insects and Decapods, three kinds of elements in tlie brain and other ganglia, viz: (1) ganglion cells; (2) nerve fibers; and (3) Leydig's puntzsuhstam {ma rksuhstx nz of Leydig and Kabl-Riickhard, nnd especially Dietl), which might be called the myeloid tissue or substance.
(1) GaiHjHoit cells. — These have not, as iu the brain of the lobster, a simple nucleus and nucleolus, but they usually have numerous, from 10 to 20, nuclei, the nucleolus of each nucleus readily receiving a stain and forming a distinct dark mass. They resemble those of the locust.:]: They are, as a rule, much smaller, however, tlian in the locust. As seen in most of the sections they appear to be spherical, being cut through transversely by the microtome, but as shown by Pig. 3a they are of the usual pyriform shape. In size they are very much smaller than those of the lobster and much more uniform in size, very few of the cells being twice as large as those of the average size; as already remarked, the nucleus in the gauglion cells of the American lobster are almost uniformly simple and homogeneous, with a single nucleolus. The largest ganglion cell of the lobster's brain which we have found is six times as large as the largest ganglion cell ot Asellus.
The ganglion cells appear to be entirely unipolar; no bipolar or multipolar cells were observed, though special search was made for them. Nothing noticeable was observed in respect to the nerve-tibers. The j)uii]d.sul>st(tii:, marksuhstdiiz or myeloid substance, as we may designate it, dif- fers iu its topographical relations from that of the brain of Decapoda. This myeloid substance, which seems to be peculiar to the worms, mollusks, and esi)ecia!ly the Crustacea and insects, has beeu most thoroughly studied by Leydig. This is the central liuely-granular part of the brain, in whicli granules have short irregular fibers passing through theui. In iiis Vom Ban dex thierischen Korpers, p. SO, Leydig thus refers to it:
111 tbe brain aud ventral ganglia of the leech, of insects, iinaiii tlio brain of tin- Gasrropcxls (Schnecken; loViserve that the stallis (stiele) of the {janfjiion-celts iu nowise imiuediately arise as neive-libfi-s, but areplaiitetliu a molecular ni.ass or jxiKktsuhxIan: sitnateil in the center of the ganglion, aud merged with this substance. It follows, from what I have seen, that there is no donlit Ihiit ilie origin of (he ne.n/t-Jilitrs firxt taken place from this central jiiiiiklniihstam.
This relation is the rule. But there also occur in the uerve-ceuters of the invertebiates single detinitely situated ganglion cells, whose coutiunatious become nerve-fibers without the intervention of a superadded iiuuktsubstanz.
L(\vdig subsequently (p. 91) further describes this myeloid substance, stating that the gran- ules composing it form a reticulated mass of fibrilhe, or, in other words, a tangled web of very line fibers.
We at present consider that by the passage of the continuatiou of the ganglion cells into the 2>^inktxnbst(im this colli ill nation becomes lost in the tine threads, aud on tbe other side of the 2>'inktsnl»ilnn: the similar tibrillar substance forms the origin of the axis-cylinders arranged parallel to one another; so it is as good as certain Ihot the xinf/lc axin- ei/lindcr derices its fibrillar snbslance as a mixinre from the moat dirersc yaniilion cells.
The myeloid substance iu the brain of Asellus is not however differentiated into distinct spher- ical masses, the punktsubstanzballen of Krieger (Balken of Dietl) or whitish ball like masses
' Fig. 255, Idolaa inorata, and Fig. 2.3(1, Scrolls, drawn by ,T. S. Kiugsley.
t Since this essay has been prepared I have obtained Dr. Btdlouci's excellent memoir on the nervous system of SjihaToiiia, iu which he figures and describes the brain and nervous system in general of that Isopod.
t Second Report United Slates Entomological Commission, ch. xi. The Urain of the Locust, 1880 (PI. xi. Fig :!b--3e).
STRUCTUKE OF THE BUAIN OF TUB SESSILE-EYEl) CRUSTACEA. lOl
\vliii;lj arc so characleri.stic of the brain of the Decapod C'riistacea and tbe iiiscict.s; and in this resi)ect there is probably a wide ilittereuce between the brain of Decapoda aud Edrioplithahnata.
HISTOLOGICAL TOPOGRAPHY OF THE NEHVK TISSl KS.
(1) Tht (jaiKjlion nils. — These cells form a cortical layer envelopinj>()ii all or nearly all sides the central myeloid mass. The cells being distinct aud more or less loosely arranged readily take a deep carmine stain, while the much more dense myeloid mass remains white ami unstained.
The ganglion cells are collected into more or less definite mas.ses, enveloi)ed by connective tissue, the latter as it were forming a mesh, inclosing spherical masses of ganglion cells. In a ver- tical sectiou, such as that represented by Figs. 2 and 3, passing through the anterior and middle i)art of the brain aud in the horizontal sectiou (Fig. — ), while the ganglion cells are seen to be packed more or less solidly around the central myeloid portiou, they are also seen to be disposed iu more or less distinct lobular masses, which are iuclosed by connective tissue. Seven or more distinct lobes or subspherical masses of these ganglion cells may be distinguished on each side of the brain.
As seen iu Figs. 2 aud 3, the uppermost or dorsofroutal lobes are the double sets filling the upper or dorsal lissure between the right and left lobes of the brain and marked a and h ; h is divided into two sublobes, the upper (/>') being small, flattened, and l.\iug on the dorsal and inner edge of the central lobe. The third set is a double lobe, c e' ; these may be c;illed the dorsolateral set; they are more or less counected with the lateral lobes d rf', aud the latter with the e.xteruo- commissural set of lobes {e e'). On the dorsal side of the brain near the base of the optic ganglia are two sets, one above and one below (;/) the base of the optic ganglion; tiie exact relation of these to the others is not very plain from our sections, but they are in front of and external to the outer edge of the lobes of the brain.
The optic ganglion is enveloped by a lobulated mass of ganglion cells exactly like those of the brain proper, aud these lobes {U i k, Fig. 27) which envelop the myeloid mass cau be distinguished from the outer one at the beginning of the outer division of the nerve fibers sent to the eye from the ganglion cells.
(2) The ncr Pi- fibers. — The ftbers arising from the ganglion cells form the commissures which unite the brain with the suboesophageal and succeeding ganglia; and also the commissures between the two cerebral lobes.
One set of fibres arise in the dorsofroutal group of ganglion cells (Fig. 3, / />), to become lost iu the myeloid substance. The fibers are seen to pass down, and to form a part of the subtesophageal commissure, although we did not trace them to the last abdominal ganglion. Judging from Michel's observations on the commissural flbers of Orycivs nanicorni-s,* there is little doubt but that in all Arthropoda certain nerve-fibers arising in the pro cerebral lobes pass uuiuterruptedly to the last ventral ganglion.
It will be further seen by reference to Figs. 2, 3 ( Asellus), aiul especially Fig. 27 (Cecidotaia), tliat the fibers arising from certain of the gaugliou cells in lobes c and c' pass into the cerebral lobe in two directions, some connecting the two lobes, forming the transverse commissure, while others ])ass dowu aud ruu parallel with the fibers from the dorsofroutal lobes and aid iu building up the subtesophageal commissui-es. The latter commissure is also re-enforced by fibers from the lateral lobes d d\ e eK
From what we have seen in the sections represented by the camera sketches referred to (Figs. 2, 3, and 27), aud from what is known of the cells and flbers of other Arthropods, there is no doubt but that all the ganglion cells give rise to flbers, some of which at least pass directly through or above or around the myeloid substance of the cerebral lobes aud form the commissures. This independence of the myeloid substance appears to be more general in the Asellidie, at least this we would infer from Leydig's statements previously quoted. When we look at Fig. 1, which is a composition (drawn, however, with the camera) from the sections represented by Figs. 5 and 8 we see that the two main longitudinal commissures pass above the seven postceiihalic ganglia rei)re- sented in the figure. Those ganglia are masses of myeloid substance, with a cortical layer of gan-
" Michels. Beschreibung eles Nervensystems von Oryctes nasioornis in Larven, Puppeus uuil liiiferznstand. Zeits. f. wisseus. Zoologie., xx.\iv, 641-702. 1880.
102 MEMOIRS OP THE NATIONAL ACADEMY OP SCIENCES.
glioii cells, froui wliich fibers arise after passing tlirongli tlie myeloid substance; there becoming broken ui> into a tangled mass of flbrillic, whicU unite tinally to form the tibers constituting the nerves of the appendages. Without doubt also a few commissural fibers from the procere- bral lobes pass into each jjost-cerebral ganglion so as to afibrd the means to the cerebral lobes [primi inter pit res, as happily styled by Leydig) of coiirdinating the nervous power of the other ganglia, their histological and morphological ecjnivaleuts. It should be said that although Leydig's view as to the relations of the nerve-flbers to the myeloid substance may be the correct one, yet though it may apply to tlie Annelids, it may not be so general an occurrence in the Arthropods. It seems to us, thougli we are still open to conviction, that the transverse and longitudinal commissural tibers, which und(jubtedly arise from the cortical ganglion cells, have little or nothing to do with the myeloid substance. This latter substance does not exist in the nervous system of the vertebrates, and just what its nature and function clearly are in the invertebrates has yet to be worked out. In the hands of a skillful and expert histologist, much light will yet be thrown upon this difiieult subject ; certainly the present writer has not the qualitications for the task. His own opinion from what little he has seen is, that the myeloid substance is tbe result of the splitting u]) into a tangled mass of very tine fibrilhe of certain of the tibers thrown off from the mono-polar ganglion cells, i.e. such tibers as do not go to form the main longitudinal commissures. It should also be borne in mind that in the embryo the ganglia are composed of ganglion cells alone, with few if any primitive tibers.
MORPHOLOGY OF THE BRAIN.
The brain of the Isopods and Amphipods is a syiiccrcbrnm, though far less complicated than in the Decai)oda. It will be remembered that Professor Laukester in his memoir on Apus desig- nates the suni)le brain of that crustacean as an archicercbrum, while the composite brain of " all Crustacea, excepting Apus, and possibly some other Phyllopods," he denominates a syncerebrum. In our Monograph of N. A. Phyllopoda, p .403, we adojjted the view that the brains of all Crustacea except the Phyllopoda and Merostomata were syncerebra, and we divided tlie syncerebrum into three types; adding that the syncerebrum of sessile eyed Crustacea (Edriophthalma) was built on a ditt'erent jilan from that of the Decapoda.
Pig. I has been drawn to give a general view of the nervous centers of the head, including the tirst thoracic segment and its ganglion. It has been drawn with the camera from a number of sections, especially those represented by Pigs. 5-8, so that it is believed to be approximately correct and not merely a schematic plan. The section passes through the head on one side of the u^sophagus, which of course is not rex>resented in tiie sketch; being so near the median line it does not involve the optic lobes and eyes, which, especially the latter, ai'e on the extreme side of the bodj', so that these organs could not well be shown in the drawing. The general relation of the nervous system to the body walls, to the stomach and the ai>pendages are made obvious in the sketch, and their description need not detain us. It should be borne in mind that the mouth and cBsophagus open between the mandibles They are shown in Pig. 5. The end of one of the ovarian lubes is seen to overlie the pyloric end of the stomach ; it does not ijass into the head. The drawing ol the heart is somewhat diagrammatic, as it was not well shown in the sections, but its position is believed to be approximately correct. The sympathetic nerve was not discovered.
As seen in Pig. 1, the brain or supra(esophageal ganglion is a composite mass or group of four i)airs of ganglia, /. c, (1) the brain proi)er or procerebral lobes, (2) the optic ganglia, (3) the tirst antennal, and {4) the second antennal lobes. These lobes are quite separate from each other in the Isopoda and Amphipoda as comi)ared with the Deuapoda.
THE PROCEREBRUM OR PROCEREBRAL LOBES.
These constitute the brain proper, and have been usually called the "cerebrum" or "cerebral lobes." As, however, they are not the homologiies of tlie lobes of that name in Vertebrates, either stiucturally or functionally, we would suggest that the ganglion be termed the i>rocerebrum and the individual lobes the procerebral lobes, not only in allusion to its position in advance of all the
STRIICTUKK OF THE BRAIN OF THE SESSILE-EYED CRtJSTACiOA. 103
otluT o-aiig-lia, but siiuio it stands as the cnoi-dinatiiis", rosnlatiiiii' gaiiiilioii, tlic first in ini])()rtanre ot all till' jjans'lia.
As regards size, the i)rocerebral lobes are more than double that of the other ganglia; they bulge out dorsally and backward, so as to conceal from above the antennal and mandibular ganglia. Plate 1, Fig. 3, represents a seistion throngh the lobes in front of the commissure, showing at a, b, the dorso-frontal group of ganglion cells, those nearest the myeloid substance sending fibers downward (/'/() to form a part of the a'sopbageal commissure. At Fig. 3, a section farther back and passing through the commissure, the fibers are seen to pass directly through the myeloid substance along the inner side of the commissure. Fig. i represents a still more posterior section ; this shows distinctly the origin of the fibers of the transverse commissure (tr. c) from the ganglion cells of the upper and outermost portion of the lobes. The commissure is seen to be composed of three bundles of fibers — an upper, middle, and lower or ventral ; the space between the upper and middle bundles being tilled with myeloid substance.
Vertical sections of the procerebral lobes are seen iu Figs. 5 to 8. Fig. ."), which passes through the median line of the head, through the mouth, (esophagus, and the median line of the stomach, shows the procerebral lobe ou one side of the commissure; and, Ijelow, the second maxillary and maxillipedal ganglia. Fig. 7, passing through one side of the first antennal ganglion, shows the procerebral lobe nearly separate from the antennal lobe. Fig. 8 represents a section passing through the main commissure and a portion of the procerebral lobe.
Horizontal sections from the top of the head downwaT'ds are seen in Figs. 9 to 18. Fig. 0 represents a section through the upper part of the procerebral lobes; Fig. 10, thiough the lobes above the transverse commissure ; Fig. 11, through the entire procerebrum, near the origin of the optic ganglia and optic nerves.
THE OPTIC GANGLIA AND OPTIC NERVES.
The eyes being smaller in Asellus than iu most other genera of Isopods, particularly Oniscus and PorceUio, the forms figured and described by Leydig; the optic ganglion and nerve are also much smaller, while the eyes being set farther back on the sides of the head, the ganglion and nerve are directed obliquely backward, so that a series of verticofrontal sections pass through the brain before reaching the optic nerve. PI. IV, Figs. 19-21, represent these organs. Fig. 19 shows the procerebral lobes, and on the left the optic ganglion and the optic nerve leading to the eye. Fig. 20 represents a section just behind the procerebral lobes, passing through the hinder edge of the cortical layer of ganglion cells. Fig. 21 is an enlarged view of the sam e. The optic lobe is divided into two parts, the inner connected with the iirocerebral lobe, with an abuudant supjjly of ganglion cells, while from the smaller, outer division arise the fibers which unite to form the optic nerve, which divides at or just beyond the middle into several branches sent to the eyes. Tliese branches are seen to end iu slightly bulbous expansions among the small retina cells, forming the deep brown pigment-mass in which the lenses are imbedded.
TItc first antennal ganglia (Figs. 1, 7, and 12). — The relations from a side view to the other parts of the brain are seen in Figs. 1, 7, and 7a. It will be seen that the ganglion is much freer from the procerebral lobes than in the Decapoda. It may be seen from above, when looking down upon the brain, projecting somewhat in advance of the procerebral lobes, the first antennal nerve arising from the upper and anterior side, ascending a little at its origin, and passing horizontally into the base of the antenna. Fig. 12 represents a horizontal section through the lobes, showing the gan- glion cells, the myeloid substance, and the origin of the antennal nerves.
The second antennal lobes (Figs. 1, 7, 7a, 14 to 10). — The second antennal ganglion lies directly beneath the upper or first antennal lobes, and appears to be slightly larger than the latter, the nerves being larger, corresponding to the much larger size of the second antenna. It will be seen by reference to Figs. 11 to 10 that the oesophagus passes between the lower part of the lobes, which are almost wholly separate. (Figs. 17 and 18, which represent sections just below that represented by Fig. 10, are introduced to show the o-sophageal commissures and their ganglion cells on each side of the cesophagus.)
104 MEMOIRS OP THE NATIONAL ACADEMY OF SCIENCES.
The first suhcesoplMf/cdl or mandibular ganglion (Figs. 1, 6, 7, 22, 23, md. g.). — This is rather hirger than eitlier of the anteniuil ganglia, as its rehitious to the braiu are well seen in the sections represented by Fig. 0. By reference to the sections represented by Figs. 5 and 6, it is clearly seen to lie directly under the aiitenual ganglia, and to be separated from the brain proper by the short (esophageal commissures. It is therefore the first subnesophageal ganglion, givin g oft' but a single pair of nerves, those supplying the large tripartite mandibles.
The ganglion lies in front of the main longitudinal commissure, and in position in front of the lower side of the stomach, being situated in an inclined plane, nearer vertical than horizontal The sections represented by Figs. 22 and 23 pass through a portion of it, and in them is well seen, the mode of origin of the large mandibular nerves.
The first and second maxillary ganglia. — These are situated widely apart, neither coalescing with the other ganglia in front or behind. The first maxillary ganglion (Figs. 1, 8, 22, 23, mx.g.) is situated nearer the mandibular than the second maxillary ganglion, as seen in Figs. 1, 22, and 23. It lies in an inclined plane, and is much smaller than any of the other postcesophageal ganglia, as it innervates smaller appendages.
The second maxillary ganglion (Figs. 1, 8, 22, 23, jhj;^ (/.) is situated next to the maxillipedal ganglion, and like that lies in a horizontal position. It is of nearly the same size but a little smaller than the ganglion next behind it, and the commissures connecting it with the maxillipedal ganglion are very short.
The maxillipedal ganglion (Figs. 1, 8, 22, 23 mxp. g.) is a little larger than its near neighbor, the second maxillary ganglion, inasmuch as it innervates the large maxillipedes.
At some distance behind this ganglion and situated in the first thoracic segment is the first thoracic ganglion supplying the nerves to the first pair of feet. It is a little larger than the max- illipedal ganglion.
The main longitudinal commissures (Figs. 1, 22, 23) pass over the ganglia, and are united in the head, except at two points indicated by the clear spaces in the figure, behind which point we have not traced it. Sars, however, represents the main longitudinal commissure behind the head as double.
In the section represented by Figs. 22 and 23 the limits of the mandibular and first maxillary ganglia are not definite, and they are seen to be connected by a bridge or tract of myeloid sub- stance. Towards the second maxillary ganglion the fibers in the section are fewer and lower together, and are seen in some cases to enter the myeloid substance, but in others to pass over it. The ganglion cells of the maxillipedal ganglion are more numerous than those about the myeloid mass of the second maxillary ganglion
From the foregoing facts it will be seen that the brain of the AselUdw is composed of four precBSophageal p lirs of ganglia, situated at greater or less distance apart from each other, being a very loosely constructed syncerebrum compared with that of such Decapods as have been thus far examined. The mouth-parts in the Asellidw, if not all Isopoda, are not innervated from a single subtesophageal ganglion, but each appendage, beginning with the mandibles, is supplied by a nerve arising from a separate ganglion. Thus there are eight ganglia of the first order in the head of these Isopods, our observations not referring to any secondary ganglia, which may or may not exist in connection with the brain or sympathetic nervous system. It will be remembered that in the Decapods, the lobster for example, the brain innervates the eyes and an tenure, while the only other ganglion in the head is the suboesophageal, from which the mouth appendages are all innervated ; thus there are but two nerve-centers in the head of adult Decapods; the subtesophageal ganglia being concentrated probably during embryonic or larval life.
II. The brain of the eyeless form C^cidot^a.
It is a matter of great interest to know just what, if any, changes take place in the braiu or nerve-centers of the head of the eyeless forms related to Asellus; whether the modification is confined to the external parts of the eye, or to the optic lobes and nerves alone.
It is well known that a blind Asellus-like form is abundant in the brooks and pools of Mam- moth and other caves in Kentucky and Indiana, as well as in the wells of the cavernous and adjacent
STEUCTUKE OF THE BEAIX OF TDK SESSILE-EYED CRUSTACFA. 105
regions. The loroK'^iiigobsorvntioiison tlie Imiiii and eves of tlic coiumoii Asclliisof our brooks and ponds were made to atiord a basis ofeoiuparison with the siinihir parts in tlie eyeless form.
(JiBcidotiea in its external shape is seen to be a depauperate AseUus, wiili the body, iiowever, inueli hmser and slenderer than in tlie eyed form, and witli sU'nderer apiienda^es. It is not usually totally ey<'Iess. In a number of specimens from a well at Normal, 111., kindly sent us b^' iMr. S. A. Forbes, a minute black speck is seen on each side of the iiead in tiie positions of the eyes of Asellns, just above the posterior end of the bas(> of the mandibles. In some specimens these Ijlack dots are not to be seen; in others they are visible, but fainter than in others. In twelve si>ecimens which I collected in Shaler's Brook in Mammoth Cave I could detect no traces of eyes, and infer that most, if not all, the Mammoth Cave specimens are totally eyeless. It I lins ai)pears that <litiler- ent individuals have eyes either (juite obsolete, if living- in eaves in total darkness, or, if living in wells, with eyes in different degrees of development up to a certain stage — that representeil by black dots — which, however, are so easily overlooked, that we confess, after handling dozens of specimens, we did not suspect that the rudimentary eyes existed, until our attention was called to them by Dr. C. O. Whitman when he sent the slides. The European CwcUlota'u forelii is also said to be blind. The specimens we received through the kindness of Professor Forel, which were, unfortunately, dried and spoiled, seemed to be entirely eyeless, though special search was not made for the eye specks.
It will be seen that the eyeless Ca^cidotwa differs from AseUus as regards its brain and organs of sight, in the complete loss of the optic ganglioD, the optic nerve, and the almost and sometimes quite total loss of the pigment-cells and lenses.
After a pretty careful study of numerous vertical sections of the brain of Ca'cidotcvu styyia as compared with that oi Asellus communis we do not see that there are any essential ditt'erences, ex- cept in the absence of the oj)tic ganglia and nerves. The proportions of the procerebral lobes, of the ganglion cells, their number and distribution, the size of the transverse and longitudinal com- missures are the same. The head and brain as represented is smaller than in Asellus, the form itself being considerably smaller.
Fig. 25 represents a section through the middle of the procerebral lobes, which may be com- pared with that of A.sellus, Fig. 4. Another section a little posterior is represented by Fig. 26. Fig. 27 is an enlarged view of a section still further back, which shows that there is little, if any, difference between the brain at this point and that of Asellus represented by Fig. 3. In this sec- tion it is easy to see that the ganglion cells on each side of the ijrocerebral lobes send libers directly through the myeloid mass to form the transverse commissures. The section at this point does not show the fibers arising from the fronto dorsal group of ganglion cells; but traces of them are seen in Fig. 28, which represents a section corresponding to that indicated by Fig. 3.
Careful examination of the sections passing behind the procerebral lobes and oesophageal com- missures failed to show any traces of the optic ganglion of either division, or of the ganglion cells and myeloid substance composing it. Every part connected with the optic ganglia seems to be totally abolished. The same may be said of the optic nerve throughout its length. The amount of time spent in examining the numei-ous well cut, thin, and beautifully mounted sections made by Ur. Whitman, or under his direction, enables us to attirm jiositively that the entire nervous portion of the optical organs are wanting. And we are glad to add that Dr. Whitman also observed to us the absence of the optic nerves.
With the eye itself it is different. The modification resulting from a life in total darkness has left traces of the eye, telling the story of degeneration and loss of the organs of sight, until but the merest rudiments of the eye remain as land marks pointing to the downward path in deg- radation and ruin taken by the organs of vision as the result of a transfer to a life in total or par- tial darkness, as the case may have been, in the well-iidiabitiug or cave-dwelling individuals.
Fig. 29 represents a section through the head of Ccccidotwa stytjia behind the procerebral lobes and oesophageal commissures, showing the absence of any traces of the optic ganglia or optic nerves, but indicating the rudiments of the eye, show ing that the pigment mass of the retina and the lenses exist in a very rutlimeutary condition, while the optic nerve and ganglion are entirely aborted.
S. Mis. 69 14
lOB MEMOIRS OP THE NATIONAL ACADEMY OF SCIENCES.
Figs. 30 and 31 re.preseut eularged views of the riidiiueatary eye of two diflerent specimeus of C. stijijiii from Maiiiinoth Cave. In the sections represented by Fig 30 a h we see tliat the number of f;icets lias been reduced apparently to two (b), the rudiiuentary lenses being enveloped by a black pigment mass. Tbis section, examined by Tolles' i A, is maguifled and drawn to exactly the same scale as that of the eve of Asellus represented by Fig. 21. In that figure may be seen the uormal size of the lenses and of the retina cells. It will be seen that in C;eci(lot;ea the retina cells are broken down and have disappeared as such, and that the rudimentary lens (or the hyaline l)ortion we sujjpose to be such) which the retinal pigment incloses is many times smaller than in the normal eye of Asellus.
On comparing the eyes of the two specimens as shown in Figs, ola and 32a, it will be seen that the eyes in one are considerably larger than iu the other specimen. Fig. 32/; shows that in the eye of tlii* individual there were at least four lenses, if not more, not included in the section. At the i)oint indicated by 32(Z on the t dge of the eye one lens is indicated (though the divisions are wanting), not wholly concealed by the pigment of the retina; a more magnified view is seen at Fig. 32e. The four sections a-d passed through the eye, the section in front and behind not touching the eye itself.
It thus appears from the obsei'vations here presented that the syncerebrum of the blind Ca'ci- dota'a differs from that of the normal Asellus in the absence of the optic ganglia (both divisions) and the optic nerves, while the eyes are exceedingly rudimentary, the retinal cells being wanting; the black i)igmeut mass inclosing very rudimentary minute lens-cells, which have lost their trans- verse zonular constriction or division ; the entire eye of Ctecidotsea finally being sometimes wanting, but usually microscopic in size, and about one-fifth as large as that of the normal Asellus.
TLe steps taken in tlie degeneration or degradation of the eye, the result of the life in dark- ness, seems to be these : (1) the total and nearly or quite simultaneous loss by disuse of the optic ganglia and nerves; (2) the breaking down of the retinal cells; (3) the last step being, as seen in the totally eyeless form, the loss of the lens and pigment.
That these modifications in the eye of the Ctecidotiea are the result of disuse from the absence of light seems well proved ; and this, with many parallel facts in the structure of other cave Crus- tacea, as well as insects, arachnids, and worms, seems to us to be due to the action of two factors: (a) change in the environment; (b) heredity. Thus we are led by a study of these instances, in a sphere where there is little, if any, occasion for struggling for existence between these organisms, to a modified modern form of Lamarckianism to account for the origination of these forms, rather than to the theory of natural selection, or jjure Darwinism as such.
BIBLIOGRAPHY OF WORKS ON THE NERVOUS SYSTEM OF CRUSTACEA.
GENERAL.
Belloxci, G. Intoruo alia struttiua e alle coiinessionl del lobi olfattorii negll Artropodl suiieiiori e iiei veite- lirati. 2 tav. 4. Ivi, 1882.
Berger. UntersucliUDgeii Uber den Bau des Gehirus uud der Retiua der Artbropodeu. Arbeitou des zool. lusti- tiits zu Wieii, Heft 2.
Nachtrag zu deu Uutersuchuugeu uber deu Bau des Gehirus uud der Retiua der Artbropodeu. Ibid.,
Heft :?.
Ehrenbeug. Beobachtung ciuer bisber unerkauuteu Strnctur des Seeleuorgans. 1836.
GUENACHEH, H. Untersucbuugen iiber das Seeorgau der Artbropodeu, iusbesondere der Spinueu, lusecteu, iiud Cru.staceen. Gilttingeu, 1879.
Hannover. Rechercbes microscopiques sur lo systeme uerveux. 1857. Hr;LMHOLTZ. De fabrica systeniatis nervosi evertebratoruni. Diss. Berolini, 1842. Leydig. Lebrbucb der Ilistologie des Mensclien uud der Tbiere. 1857.
Vom Bau des tbieriscbeu Korpers. Erster Baud. 1864.
Tafelu zur vergleicbendeu Auatoiuie. Erstes Heft. 1864.
Milne-Edwards, F1. Histoire uaturelle des Crustacfe. Tom. i-iii. Paris, 1834-1840. Remak. Ueber d. lubalt der Nervenpriuiitivruhren. Arcbiv f. Anat. u. Pbys., 1843. Waltek. Mikroscopiscbe Studieu iiber das Centralnervensystem wirbelloser Tbiere. 1863.
STUUGTURK OF THE liKAlN OF THE SlOSSl LE-EVEU (JUUSTACKA. 107
CIRRIPEDIA.
HltANlvr, !•;. I'cboi' dim Nerveiisystcm fl(M' Lepas aiiatitVru (aiiiXt<imiscliliistol(if;i.sclK' Untersiicliiiiij;). Mol.in^cs l>iiiU)j;iiliU's, vii. Bull, dc I'Acail. iiiii>.,x\% St. I'otorsbiiri;. June, 1870.
Crvir.u. G. Mt'inoire snr los Mollusciiics. Paris, 1817.
Cl.Al'S, C Dii' Cypris-iilmliclie Larve (Piippi;) ilor Cirniicdicii iiiiil ilii-c Viiwandlunn in ilas I'rslil/i'inli' ■riii<'i-. Suliriltoii dor Gcsollscliaft ■/.. ge.s. Xatnrw. Warliiiru'. Supii.-Ifi'l't \-. Mailiiu's "• I.iipzig, 18(11). (liraiii i C larva (ir(.'iiii- chodcvina.)
Dakwix, C. a mouograph of the sub-class Cirripodia. 1851, ISoH.
Ki.N'GSl.KY, J. S. Barnacles. Auiorican Naturali.st, xi, 10:i. 1877, and Paidcard's Z(ii)l(ij;y, Fij;'. )i\>x. (N'cr\ (ins .sys- ti-m of Lopas faseicularis.)
Maktin St.-Angk. Monioire sur I'organisation des Cirripodcs. Paris, 18:>5.
Wy.max, J. Proet'odinss Bo.ston Soc. Nat. Hist. Anitu'. .Jour. Sei. Arts, xxxix, 182. 181(1. (Nervous .syslmi nl' Otioii I'Hi'iVrii.)
ENTOMOSTRACA.
C'LAUS, C. Beitriige znr Kenntuiss der Kntoniostrakeu. Marburg, 18(iO. (Nervous system of .SViyj/i/n'/id /«/(/<'»».)
Die freilebenden Coijopoden. Leipzig, 1803. (Nerv^ons .system of Copilia, Coryea'id;e, Sapliirella, Cala-
uella, Cetochilus, Sapliirina, Dias longiremis. )
Uebcr die Entwielvclung, Organization und systematisclie .Stelluug dcr Argiiliilen. Zeits. wissens. Zoo].,
XXV, 1875. (Nervous system of Argulus foliaceus and eorcgoni.)
Gegenbaur. Mittlieil. iib. d. Organization von Phyllosoma und Sappliirina. Arcbiv f. Naturge.scjiiciile, Taf. V, tig. 1, 1858.
NonDMAXX. Jlikrographische Beitriige. Heft 2, 1832.
Zexkeu. Anat. syst. Studien iiber die Krebsthiere. Arebiv f. Natnrg., Taf. vi, tig. 13, 1854.
BRANCHIOPODA.
Brongxiart, a. H^moire sur la.Limnadia. M^m. du Mus(?um, vi, 1820.
Claus, C. Zur Kenntui.ss des Baues und der Entwicklung vou Brancliipus stagnalis und Apns c.-mcriforuiis. Abh. k. liesell. Wissens., Gijttingen, Bd. viii, 1873. (Brain of young B. stagnalis and A. cancriformis. )
Zur Keuntniss der Organization und des feineren Baues der Dapbniden und verwandler Cladoeereii.
Zi'its. wissens. Zool., xxvii, 1876. (Brain of Daphnia.)
Untersuchnugen zur Erfcuscbung der genealogiscben Grundl.age des Crustaceen-Systenis. Wieu, ls7(i.
(Nervous sy.steni of young Estberia ticinensis.)
Gkube, A. E. Bemerkungen Tiber die Phyllopoden. Archiv f. Natnrg., xix. Berlin. 18,53. Nervous .systcai of Limnetis.
.JoLY. Recbercbes zool., anat. et pbys. snr 1' Jsaura cycladoidcs. Annales d. Sc. Nat., 184.J.
Laxkester, E. R. Observations and refleetious on tbe appendages and on tlie nervous syslem of .\iins eaueil- formis. Quart. Jour. Micr. Sc, April, 1881.
Ley-dig, Fk. Naturgeschicbte der Dapbniden. Tlibingen 1860. (Braiu of several species of Dapbuia, Snla, Lyn- oeus, Pasithea, Bosmina, Polyphemus, and Bythotrephes.)
Verg. Anatomie. 218, 1864.
Ueber Artemia salina u. Brancbipus stagnalis. Beitr. z. anat. ICenutniss dieser Tbiere. Zeits. f. wissen.
Zoologie, 1851.
Miller, P. E. Danmarks Cladocera. Kroyer's Tid.sskrift, Ser. iii, Hind v, 18t;^-;i. (Brain of Bytbotrepbes, Podon, Evadne, Leptodera.)
Packard, A. S., jr. Mouogr.apb of tbe Pbyllopod Crustacea of North America, witb remarks on tbe ordiT Pliyllo- carida. Twelfth Annual Rep. U. S. Geol. Surv. Terr., 1883. (Nerv. system of Apus lucasanus. PI. xxxii, lig. 1. In this tigure tbe lower loop between the liver and oesophagus should be removed and tbe commissure extended froju above to take its place. Nervous system of EstUeria mexicana and Branchipus verualis. Plate xxxiii.)
Sp^vngexberg, Fk. Bemerkungen zur Anatomie der Limnadia Hermanni Brongn. Zeits. wLssens. Zool., xxx, Supp., 474, 1878. (Nervous system described at length.)
Weismaxx', A. Ueber Ban und Lebeuserscheinungen von Leptodora liyalina Lilljoborg. Zeits. wissens. Zool., xxiv, 1874.
Zaddach, E. G. De Apodis cancriformis. Anatome et Ilisloria evolntionis. Bonna-, 1841. (Nervous system of Apus cancriformis.)
PHYLLOCARIDA.
C'l.AT'S, C. Untersuchungen zur Erforschung der genealogiscben Grundlage des Crustaeeen-.Systems. Wiiui, 1876. (Nervous system of Nebalia geoti'royi.)
Packard, A. S., jr. Mouograph of tbe Pbyllopod Crustacea of North America, witb remarks on tbe order Phyllo carida. Twelfth Ann. Rep. U. S. Geol. Snrv. Terr., 1883. (Brain and nervous system of Nelialia bipes.)
108 MEMOIRS OF THE NATIOISrAL ACADEMY OF SCIENOES.
EDKIOPHTHALMA.
At'DonX KT Milne-Edwa1!DS. Aiinales <les So. Nat., xiv, 1828. (Nervous system of Talitrus and C'yraothoa.)
Bklloxci, G. Sistcmo nervoso c organi dei sensi della. Spba?roma serratum. Constar, Roma, 1881.
IShan'dt VXD Ratzuukg. Medicinisehe Zooloijie, 1829. (Nervous systeui of Oiiisens. )
BiiUSKLlus. Beitrag ziir Kenutiuss vom iuueren Ban der Amphipoden. Archiv f. Naturgesch., 1859.
Cl.ADS, C. Uiitersiichuiigeu ziir Erforsch. d. Geuealog. Gnindlage des Crust. Syst. Wieii, 187(i. (Brain aod organ of lii'aring of O.'cycoplialns figured.)
Dn i-A Vai.lktte, G. De Ganimaro putcauo. 1857.
Doiinx, A. Natnrgcschiebie dor f'aprella. Zeits. wissens. Zool.,xvi, 245, 1863. (Includes that of Cyamus oeti.)
Uutersucliungen iiber Bau und Entwicklnng der Arlhropodon, 4. Entwickhing und Organization un
I'r.iui/a ( Aneeus) mnxillaris. 5. Zur Kenntniss des Baues von Parautliura costana. Zeits. wissens. Zoologie, xx, 1870.
FiiiiV u.vi> Leuckart. Lelirliucli der Zootomie. 195, 1847. (Nervous .system of Idotbea and Caprella.)
Gamhoth, a Beitmge zur Kennlniss der Natnrgeschichte tier Cajirellen. Zeits. wissens. Zoologie, xxxi. (Brain (if Caprella .■eqnililjra.)
GEHSTAECKEii, A. Bronu's Classen und Ordnungeu der Tbierreicbs. Artbropoila. Abtb., ii, 1880.
KiN'GSLEY, J. S. Figures of the nervous systeui of Idota'a irrorata and Serolisguadicbaudi. In Zoology for bigb sebocds and colleges, by A. S. Packard, Jr. New York, 1878.
LEiiEJioULLET, A. M^ui. snr la Ligidia Persoonii Brdt. Annales des Sc. Nat., xx, 1843.
Mdmoire sur les Cru.stac^s de la Famille des Cloportides qui habiteut les environs de Strasbourg. M^ni.
Soc. d'Hist. Nat. Strasb. Strasbourg, 18.'i3. (Nervous system and brain of Oniscus murarius.)
Lk.ydig, Fr. Vom Bau des thieriscben Korpers. Handbuch der vergleicbenden Anatomie. Bd. 1. Tilbingen, 1864. (Nervous system of Asellus aqnaticus, Porcellio scaber and Oniscus murarius, Armadillo described.)
Tapleu zur Vergleicbenden Anatomie. Heft 1, Zum nervensystem und den Siunesorgauen der Wiirnier
und Gliederfiissler. Tiibiugen, 1854. (Nervous system of Porcellio scaber ; brain aud eyes of Oniscus murarius figured.)
Pagbn.stecher. Pbronima sedentaria. Ein Beitrag z. Auat. ii. Pbys. dieses Krebscs. Arcbiv fiir Naturges- cbichte, 1861.
Rathke, H. Nueste Sclirift. d. Naturg. Gesellsch, in Danzig, 1820. (Nervous system of Idotbea.)
■ De Bopyro et Nereide. 1837.
Rextsch. Homoiogeuesis. Beiti'. z. Natur- u. Heilkunde, 1860. (Nervous system of Gammarus ornatus.)
Nova Acta Nat. Cur. xx, 1843. (Aega, etc.).
RfiussKL ))E Vanz^me. Annales des Sc. Nat., i, 1834. (Nervous system of Cyamns, "beautiful lignre" Leydig.)
StraUlSS-Durckheim. M6m. sur les Hiella. M^m. dn Museum d'hist. Nat.,xviii, 1829.
Treviranus. Vermiscbte Scbriften Anat. n. pbys. Inhalts. 1816. (Nervous system of Oniscus and Cyamus.)
Sars, G. O. Histoire naturelle des Crustac^s d'eau douce de Norv^ge. 1"^ Liv. Lee Malacostraoes. Avec 10 PI. Cbristiania, 1867. 4°. (Nervous system of Asellus aijuaticus.)
STOMAPODA.
Bei-lonci. Morfologia del sistema nervoso centrale della squilla mantis. Annali del Museo civico di storia naturalo di Geuova, XII, 1878. (See al.so under General, Bellonci's Memoir ou Squilla in Intorno alia struttura artropodi, &c.)
Nuove Ricercbe snlla Struttura del Ganglio ottico della Squilla tnaiilis. Mem. Acad. Sc. Inst. Bologna,
iii, 419-426, Tav. 1-3, 1882.
CuviER, G. Lefons sur I'anatomie compar^e, 1809.
DELLE Chiaje. Descrizioue e notomia degli animali invertebrati della Sicilia citeriore. Napoli, 1841-'44.
SCHIZOPODA.
Frey. De Mysidis flexuosi anatomi, 1846.
aud Leuckart. Beitriige zur Kenntniss wirbellos. Tbiere, 1847.
DECAPODA.
Belloxci,G. Sui lobi olfattorii del Nepbrops norvegicus. Memorie dell'Acc. d. Scienze di Bologne. 1880. Brandt und Ratzeburg. Mediziniscbe Zoologie, 1829.
Cartjs, G. Lebrbueb der vergleicbende Zootomie, 1818. Zweite Aufl., 1834. CuviEU, G. Lefons d'auatomie comparee. Paris, 1809.
DiETL, M. J. Die Organization des Artbropodengehirns. Zeits. f. wissen. Zoologie, xxvii, p. 488, 1876. Haeckkl, E. Ueber d. Gewebe des Flu.sskrebses. Arcbiv f. Anat. u. Pbys., 1857. Hannover. Rechercbes microscopiques sur le systi'me uerveux, 1844.
Home, E. On tlie internal structure of the human brain, when examined in the microscope, as compared with that of fishes, insects, and worms. Phil. Traus., 1824, PI. 4, Fig. 3.
Krieger, K. R. Ueber das centrale Nervensystem des Flusskrebses. Zool. Anzeiger, 1. .Jahrg., Nr. 15, 1878.
STRUCTURE OF THE BRAIX OF THE SESSI I.E-EVED ORUHTACEA. 109
KitlKiiAU, K. R. Ui'bi'i' <las CciitniliU'iveiisystciM ties Miisskrelisos. Zeits. f. wisseii. Zoolojfio, xxxiii, p. r>27, Jan. 23, IrttiO.
KnoiiN. ITcber die yerdauui)i;siiervon (les Krebses. Isis, 1834.
Le.moixe. Eeclierchos pour servir a I'histoire tics systiMiies ih'imiin musrulain' ot slaiidnlairo do rccrevissfi. Ann. des sciences nat. 5'" s6r. Zoologie, ix, 1868.
Mri.i.Kit. .Ton. Acta Acad. Ca'saieo-Lcopold., XIV.
NewI'OHT. (i. Phil. Traus., 1834. (Nervous system of Houiariis. )
Ofsiaxnikoi'F, Ph. Recherclies sur la structure intinic. du systcmc ucrvcux des Crustaccis et iMiucipalpiucnt, dii lioiuard. Ann. des sciences nat. 4"^ s(^r., Zoologie, xv, ISlil.
Ueber die fciuerer Structnr des Kopfganglions bei den Knd)sen, besonders beini Pali minis iDCiiKta. Jleni.
Acad. imp. sc. St.-Petersbonrg, vi, No. 10, 1863.
OwF.x. R. Lectures on tlie comp. anatomy and physiology of the invertebrate animals, 1843.
Packard, A. S. Zoology for colleges, 1879. Brain of Candjarus and the blind Orcoiiectes peUiicidiis, brieliy described and tignred. Kig. 21)9.
SCHLEMM. De hepate ac bile Crustaceorum, 1844.
Swan. Comparative anatomy of the nervous system, 1835.
Valkntixe. Nova Acta Nat. Curios, xviii, 183G.
ViALl.AXES, H. Etudes histologifjues et organologicines sur les Centres nerveux et les organes des Sens des Ani- maux articutes. Premier menioire. Le Gauglimi optiqne de la La,ngouste (I'liliiiiiriis niti/nris). Annales desSciences Nat. vi' serie. Tom. xvii, July, 1884, 1-74.
Weber, E. H. De aure et auditn homiuis et animalium, 1820.
Will. Archiv fiir Anat. n. Phys., 1844.
WiLLl.s. De anima brutorum, 1(174.
YUXG, E. Kechercbes sur la structure intime et les fonctious du systeme nerveux central chez les Crustacea d(?capodes. Arcbives de Zoologie esp. et g^n., vii, 1878.
De la structure intime du systfeme nerveux central des Crustacds d^capodes. Comptes reudus, Ixxxviii,
1879.
MEROSTOMATA.
Milne-Edwards, A. Recherches sur Fanatomie des Limules. Annales des sciences nat. Zoologie, xvii, Nov. 1872.
P.iCKARD, A. S., jr. On the development of the nervous system m Limulus. American Naturalist, ix, 422. July, 1875.
Structure of the eye of Limulus. Amer. Nat., xiv, 212. March, 1880.
luterual structure of the brain of Linnilus. Amer. Nat., xiv, 445. June, 1880.
The anatomy, histology, and embryology of Limulus polyijhemus. Anniversary memoirs of the Boston
Soc. Nat. Hist. 1880.
Vander Hoe yen, J. Recherches sur I'histoire naturelle et I'anatomie des Limules. Leyde, 1838.
EXPLANATION OF PLATES. Plate I. — Asellus communis.
Fig. 1. LoDgitiidinal .section through the head on one side of mouth and oesophagus, showing the brain or procerebrum {pern), first and second autennal ganglia; mandibular, first and second maxillary, the maxillipedal ganglia and nerves passing to the antenna> and mouth-parts x 1| in(^h A.
Fig. 2. Section through the procerebral lobes in front of the optic nerves X i A.
Plate II. — Asellus communis.
Fig. 4. Section of the procerebrum posterior to Fig. 3, x i A.
Fig. 3. Section through procerebrum and main commissure X i A, .3a, ganglia cells from lobe b. X i C.
Fig. 5. Section through the median line of the head, involving the oesophagus and one of the procerebral lobes.
Fig. 6. Section through the head, x i A.
Fig. 7. Section of the head passing through one side of the tirst autennal ganglion and .showing the origin of the first
antennal nerve; also the second antennal ganglion, and mandibular ganglion {md.rj) X i A.
Fig. 7a. Section passing near 7 and through the main commissure.
Plate III. — Asellus communis.
Fig. 8. Section passing through the main commissure from the procerebral to the Ist pedal ganglion. Fig. 9-18. Horizontal sections from the top of the head downwards X z A.
110 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
Plate IV. — Asellus communis.
Fig. 19. Transver.se section of the head tliroughthe proeerebral lobes and through the eyes and optic nerves and com- missures X i A.
Fig. 20. A section back of the procerebruui passing through the optic ganglion, optic nerve and eye.
Fig. 21. Same section as in Fig. 20, enlarged X i A, re, retinal cells ; op, n, optic nerve; h, i, k, masses of ganglion cells.
Fig. 22. Horizontal section through the main commissures and the first and second m.axillary ganglia, and niaxillipedal ganglia, and showing the origin of the mandibular nerves. X i A.
Fig. 2o. The same section as in Fig. 22, enlarged, x '- A.
Plate V.— C^cidot^a stygius.
Fig. 25. Transverse section through the procerebruui and commi.ssures. x ■; A.
Fig. 26. .Section a little posterior to that of Fig. 25. X + A.
Fig. 27. Enlarged sketch of section still farther back, x i A.
Fig. 28. Enlarged sketch of section still farther back. X i A.
Fig. 29. Section behind procerebruui and showing the rudimentary eye, but entire ab.sence of the optic ganglion and
optic nerve. Fig. 30. Section through the eye. x ^ A.
Fig. :il. Section through the eye of another individual. X i A. c, lens. X i c. Fig. 32. Section through a ventral ganglion. Fig. 33. Section through a ventral ganglion. Fig. 34. Section through a ventr.al ganglion under the stomach. Fig. 35. Section through a ventral ganglion under the stomach.
Note. — All the figures drawn by the author with the camera lucida.
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MEMOIRS
OF THE
NATIONAL ACADEMY OF SCIENCES.
"V^oliame III
WASHINGTON:
GDVKKNMENT PRINTING OFFICE. *
1886.
:\4:emoirb.
Page.
IX. Co>fTRiBUTioNs TO Meteorology; by Elias Loomls 1-66
X. On Fi.AMSTEEn'.s Siar.s "Observed, but not Exlsting"; by C. H. V. Peters 69-63
XI. Corrigenda IN Various Star Catalogues; by C. H. F. Peters 87-97
XII. Ratio of Meter to Yard ; by C. B. Comstock 101-103
XIII. On Composite Photography as Applied to Craniology ; by J. S. Billings : and on Meas-
uring THE Cubic Capacity of Skulls; by Washington Matthews 105-116
XIV. On a New Craniophore for Use in Making Co.mpositk Photographs of Skulls; by J. S.
Billings and Washington Matthews U'.»-120
XV — I. Ox the Syncarida, a Hitherto Undescribed Synthetic Group ok Extinct Malacostra-
coos Crustacea; by A. S. Packard 123-128
II. On the Gampsonychid.e, an Undescribed Family of Fossil Schizopod Crustacea. Plate
III, Figs. 1-4; VII, Figs. I, 2; by A. S. Packard 129-133
III. On the Anthr\cakid.e, a Family of Carboniferous Macri'rous Decapod Crustacea; by
A. S. Packard , 135-139
XVI. Ox THE Carboniferous XiPHOSUROUs Fauna of North America ; by A. S. Packard 143-157
XVII. On Two New Forms of Polyodont and Gonorhynchid Fishes from the Eocene of the
Rocky Mountains; by E. D. Cope. 161-165
Notes on the Third Memoir, Page 45, Part I; by Alfred M. Mayer li)7-169
NATIONAL ACADEMY OF SCIENCES.
VOL. III.
NINTH MEMOIR
CONTRIBUTIONS TO METEOROLOGY.
PREFACE.
Fifty years ago, when a tutor in Yale College, I became greatly interested in Redfield's inves- tigations resjjecting tlie laws of storms; and from that time to the present day I have uever lost luy interest in meteorological phenomena. In 183G I was appointed jmifessor of natural philos- ophy in Western Reserve College, and was sent to Europe to purchase instruments for my ilepartment. Among my purchases was a superior set of meteorological instruments, and on my settlement in Ohio I commenced a meteorological journal, embracing daily observations of the barometer, thermometer, &c., and I also made hourly observations for thirty-six hours at the equi- noxes and solstices, according to the scheme proposed by Sir John tierschel. In October, 1837, a hurricane of considerable violence passed within 5 miles of Hudson, and I improved the opportu- nity to malie a careful survey of its track, with special reference to deciding between the conflict- ing views of Kedtield and Espy, but the materials for this purpose were not as complete as I had expected. In order to obtain fuller materials for this purpose I resolved to select some storm of unusnal violence and collect all the information possible respecting it, and to make a thorough examination of its phenomeua. I selected the storm of December 20, 1836, and succeeded in obtaining a consideiable mass of observations relating to it. The results of this investigation were published in the Transactions of the American Philosophical Society, and seemed to show that neither the views of Redfield nor Espy were wholly correct, and that much remained to be learned respecting the laws of our winter storms. I found it impossible to obtain observations respecting the storm of December, 1836, which would enable me to make so complete an investiga- tion as I desired, and I waited in the hope of being more successful with some future storm.
In February, 1842, a tornado of unusual violence passed within 20 miles of Hudson. As soon as I received tlie news, I started out with chain and compass to make a thorough survey of the track, and succeeded to my entire satisfaction. As the tornado passed over a forest of heavy timber, I had the best opportunity to learn the direction of the wind from the prostrate trees; and by measuring the direction of the trees as they lay piled one upon another, I determined the successive changes in the direction of the wind. The facts demonstrated incontestably that the movement of the wind was spirally inward and upward, circulating from right to left about the center of the tornado. This tornado was but an incident in a great storm which swept over the United States, and I resolved to collect all the information possible respecting the general storm. In this attempt I met with fair success, and in discussing the observations I adopted methods which are now familiar to all the world, but which were new to me, and which, so far as I know, had not at that time been employed by any other person. The results were published in the Transactions of the American Philosophical Society. This investigation showed conclusively that Eedfield was mistaken in supposing that in all great storms the wind revolves in circles about the center ; and also that Espy was mistaken in supposing that the air moves toward the center in the direction of radii.
After completing this investigation, I desired to apply my new methods of research to another violent storm, but the labor and expense involved in collecting my materials induced me to wait, hoping that as the number of observers increased more abundant materials might be obtained, and with a less expenditure of time andmoney. In 18.56, during a somewhat extended tour through Europe, I improved the o])portunity to collect observations respecting a storm which prevailed in Europe soon after ihe American storm of December, 1836, and which some persons supposed to have been connected with the American storm. Qn my return to the United States these observa- tions were carefully discussed and the results were published by the Smithsonian Institution.
7
8 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
Tears rolled ou, and the favorable opportunity wbicb I bad looked for to enable me to resume my investigations of tbe pbenomena of storms did not come. Tbe Smitbsonian Institution bad indeed organized a large body of meteorological observers, but most of tbe observers bad no barometer, and many of tbe barometers wbicb were used were unreliable. At lengtb tbe Signal Service was organized, and now came tbe opportunity for wbicb I bad been waiting tbirty years, but bad almost despaired of living to witness. As soon as I had obtained one daily weatber map for two years I commenced a careful examination of tbese maps, for tbe purpose of deducing from tbem general laws. As tbe observations multiplied, I was enabled to undertake tbe investigation of new questions, and tbe results are contained in a series of papers published in tbe American Journal of Science, and entitled " Contributions to Meteorology." These papers have attracted considerable attention in Europe. Tbe first nine papers were translated into French by M. Brocard^ and were published in Paris bj^ tbe late Abb^ Moiguo, under the title of Meteorologie Dynamique A very full abstract of several of these papers has been published in Italian by Dr. Ciro Ferrari, of the meteorological oflflce at Home, in a pamphlet of 92 pages, with numerous plates. Notices of most of tbe papers have from time to time appeared in various scientific journals of Great Britain and the Continent of Europe.
Tbe subjects investigated in these contributions were taken up without any regard to systematic order, and the later results, having been derived from a much greater mass of materials, will sometimes be found not to harmonize entirely with the results published in my earlier iiajXTS. Under tbese circumstances it has been thought desirable to revise tbe entire series of papers, and reduce them to a more systematic foim, improving the opportunity to combine new researches on points heretofore neglected, and to deduce all results from the entire series of observations now available, not only from the United States but from Europe and other parts of tbe world. Tbe present memoir contains the first chapter of this revision, and it is designed that other chapters shall follow as rapidly as my strength will permit.
E. L.
CONTRIBUTIONS TO METEOROLOGY.
By Elias Loomis.
AREAS OF LOW PRESSURE — THEIR FORJl, MAGNITUDE, DIRECTION, AND VELOCITY OF MOVE- MENT.
1. Tbe pressure of the atmosphere is coutinually chauging. In the michlle and higiier latitudes of tlie Northern Hemisphere these cliaiiges are very great and sometimes very sudden. In the northern jiart of tlie United Slates tlie barometer frequently rises a half inch above its mean height, and it has been known to rise a whole inch above tiie mean. It frequently sinks a half inch and sometimes more than an im^h below the mean. These changes take place simul- taneonsly over regions of vast extent. In order to exhibit these plienonieua in tlie simplest manner, we draw lines connecting all tliose places where the pressure at a given instant is the same. Such lines are called lines of equal pressure, or isobaric lines, or simply isobars. Plate I shows the isobars for the United States on the loth of January, 1877, at 4'' 35'" p. m., Washington time, the isobars being drawn at intervals of one-tenth of an inch. It must be understood that the barometric observations here represented are not the actual readings of the barometer, but a correction has been applied to all of them to reduce them to sea-level. We see that the region over which the pressure was less than 30 inches, is of an elongated form, about 1,000 miles in diameter, measured in a direction from XW. to SE., and about 1,800 miles in diameter measured in a direction from SW. to NE. This region, over which the pressure is less than the mean, is called an area of low pressure; tlie point wliere the barometer is lowest is called the center of the low area; and on the Signal Service maps this center is marked Low.
2. If the atmosphere were of uniform density from the surface of the earth to its upper limit, these differences of pressure wouhl indicate differences in the height of the atmosi)here; and if an observer could be elevated above the earth so as to see the whole area of low i)ressure at one view, be would notice a depression in the upjjer surface of the atmosphere somewhat similar to that produced when a vessel of water is rotated rapidly about a vertical axis. The upper surface of the atmosphere over the low area would appear dei)ressed below a horizontal surface, and would appear to slope upwards from the low center. This slope is called the atmospheric gradient, or barometric gradient, and the steepness of the slope is indicated by the increase of height in a given distance, or the change of barometric jiressure in a given distance. The unit of distance now generally adopted is a degree of the meridian, or 60 nautical miles. We notice that on Plate I the gradient is uot the same in all directions from the low center, but is steepest on the northwest side. Here the isobars are crowded close together, their average distance from each other being 43 nautical miles. The change of pressure for a distance of 60 nautical miles, measured iu a direction perpendicular to the isobars, is 0.14 inch, and this is the barometric gradient for that part of the low area. This is a very steej) gradient, and only occurs in the case of violent storms.
3 The direction of the wind within this low area is indicated by arrows, and the velocity of
the wind by the number of feather* on the tail of each arrow ; one feather indicating a velocity
not exceeding 5 miles per hour; two feathers indicating a velocity from 5 to 10 miles per hour .
three feathers a velocity from 10 to 15 miles, and so on up to ten feathers, indicating a velocity
S. Mis. 154 2 9
10
MEMOIRS OF THE NATIONAL ACADE.MY OF SCIENCES.
from 45 to 50 miles per lioiir. We see tliat (with a few exceptions, whicb may generally be ascribed to local causes) the winds all have a tendency inward toward the low center, and at the same time tiiey circulate around this center in a direction contrary to the motion of the hands of a watch. We also see that the average velocity of the wind is greatest on the northwest side, where the gradient is steepest, and that the winds are generally feeblest where the gradients are least. This remark must not be construed as applicable rigorously to the observation.s at each locality, but rather to the average velocity of the wind over a considerable district.
4. This storm was attended by a great fall of rain and snow, the precipitation at Louisville Ky., having been 1.56 inches during the nine hours preceding 4'' 35™ p. m., January 17, and 2.13 inches during the seventeen hours jireceding 4'' 35'" p. M. The greatest rain fall was pretty near the center of low i)ressure, and was situated upon the southeast side of it. The area over which there was a fall of at least a quarter of an inch of water (in the form of raiii or snow) was G50 miles in diameter, measured in a direction from NW. to SE.; and 1,2.50 miles in diameter, measured in a direction from SW. to NE.
5. The contrasts between the temperatures prevailing on tlie op])osite sides of the low center were uncommonly great. On the northwest side the thermometer was extremely low, viz, at Pembina, — 22°; at Breckenridge,— 21°; at Fort Garry, — 18°, and at Yankton, — 13°. On the southeast side of the low center the temperature was unusually high for midwinter, viz, at Key West, 85°; at Pnnta Rassa,740; at .Tacksonville and New Orleans, 73°; at Savannah and Augusta, 70<5. Thus at the same instant of time, from Key West to Breckenridge (distant 1,700 miles), the dift'erence of temperature was 106^, showing an average diflerence of one degree for each 16 miles of distance. In the neighborhood of the low center, the contrasts of temperature were still more remarkable. At Memphis, the thermometer stood at 01°, showing a ditterence of temi)erature from Yankton to Memphis (distance 690 miles) amounting to 74°, being an average difference of one degree for each 9 English miles of distance. It wilt be seen hereafter that the phenomena here noticed are in their main features characteristic of the violent storms of the United States, particularly during the colder, months of the year.
6. The isobars represented on Plate I are not circles. Occasionally we find examples iu which the isobars about a low center approach more nearly to a circular form, but the Signal Service mai)s do not, on an average, show more than one case in a year in which the isobars do not differ sensibly from circles.
From an actual measurement of the greatest and least diameters of the isol)ars represented on the Signal Service maps for 7'" 35™ A. M. during a period of three years, the following average results have been obtained:
The average ratio of the longest diameter of the isobars to the shortest was 1.94.
In 59"! per cent, of the whole imniber of cases, ( 1.5
33 I the ratio of the longest J 2 •
11 ( diameter to the shortest | 3
nJ
was greater than
7. The longest diameter of the isobars may be turned in any azimuth, but it is most frequently directed towards a point somewhat east of north. The following table shows the number of cases in a hundred in which the longest diameter of the isobars was directed towards each of the ten- degree intervals of azimuth, counting from the north point around by east towar<ls the south:
|
Azimuth. oo to 10° 10 to 20 20 to 30 |
Cases per cent. |
Azimuth. |
Cases per cent. |
Azimuth. |
Cases per cent. |
Azinnitli. |
Cases per cent. 6 4 3 |
Azimuth. |
Cases per cent. |
Aziiiinth. |
Oases per cent. 3 3 4 |
|
7 8 7 |
30° to 40° 40 to .50 50 to 60 |
15 10 9 |
60° to 70° 70 to 80 80 to 90 |
3 7 4 |
90° to 100° 100 to 110 110 to 120 |
120° to 130° 130 to 140 140 to 1.00 |
1 3 3 |
150° to 100° 160 to 170 170 to 180 |
The point towards which the hmgest diameter is most frequently directed is N. 36° E. If we make a separate comparison of the cases occurring in the Mississippi Valley and those near the
CUNTRIBUTIONS TO METEOROLOGY. 1 1
Atlantic (-(uist, we liiul that tli(> aveia<;o direction oftlie loiij^est diameter of llie isobars is sensibly the same for both regions.
8. The irrej-nlaiit.v in tlie form oftlie isobars abont a low center appears to bo generally dne to the unequal force with which the wind on dilferent sides presses inward towards th(> center of the low area. The depression of the barometer in a low area is considered to l)edue mainly to the detlectiiij; force arising- from the eartli's daily rotation u])on its axis, as will lie more fully explained hereafter.
If the wind jiressed in with equal force on all sides towards the low center, and there was no disturbance from local causes, we might expect that the isobars would be exact circles, were it not that the deflecting force arising from the earth'srotation increases with the latitude. It seems, then, well nigh impossible that the isobars should ever be exact circles. The magnitude of the average ditierence between rhe greatest and least diameters of the isobars, together with the marked preference which the longer diameter shows for a particular i>osition in azimuth, indicates that the form of the isobars is not wholly determined by an accidental difference between the velocities of the wind on the ditt'erent sides of the low center.
9. If we examine the cases in which the elongation of the isobars is greatest we may learn something of the causes which produce this elongation, and which determine the position of the longest diameter of the isobars. Plate 1 1 exhibits a case of this kind which occurred March 8, 1877, at 7'' ou" A. M., when a low center was situated between two centers of high pressure not very remote from each other. In cases of this kind, we generally find that the gradients are niuch the steepest in the direction of the high centers, and hence tiiere results a (compression of the isobars ill the direction of a line joining the high centers, and an elongation of the isobars in a direction periieudicular to this line. Cases of this kind are of common occurrence in the United States. A low area is almost invariably ibilowed by a high area, which is generally situated on its northwest side; and tin? low area is generally preceded bj' a high area on its east or southeast side. Such was the case iu the storms represented on Plates I and II. This position of the low center with reference to the high areas causes the longest diameters of the isobars to incline in a direction somewhat east of north.
10. Over the Atlantic Ocean and also over Europe, areas of low pressure resemble the low areas of the United States in their main features, but exhibit several points of ditierence which ordinarily are pretty clearly marked. Plate III exhibits the isobars for a storm which prevailed over the Atlantic Ocean February 5, 1870. The least diameter of this low area was -!,.380 English miles, and the longest diameter was probably about 3,000 English miles. At the center of this low area the barometer stood at 27.33 inches, and the gradient, where steepest, amounted to 0.71 inch for one degree, and on the southeast side oftlie low center the average gradient up to the isobar of 30 inches was 0.25 inch, and this is nearly double the gradient shown on Plate I. If w e compare Plate III with Plate 1 we perceive that iu the Ibimer the isobars approach nearest to the figure of a circle ; the low area has greater dimensions ; the depression of the barometer at the center is greatest ; and the barometric gradient is the stee]iest. In each of these four particulars we generally find a well-marked difference between the low areas of the Atlantic Ocean and those of the United States. This difleience ajijiears from a comparison of Hoffmeyer's weather charts (1874-1876) with those of the United Stales Signal Seivice. From a comparison of the isobars on Uofluieyer's charts during a period of three years, I have obtained the follo-nung results. The average ratio of the longest diameter of the isobars to the shortest is 1.70:
Iu 54 Jper tcut. ot the whole number of cases, 17 " - - -
54 ) per eeut. ot the whole number of cases, ( 1.5 17 > the ratio of the longest diameter to •? 2 1 S the shortest was greater than ( 3
If we compare these results with those already given for the United States, we jierceive a marked deficiency of very elongated low areas over the Atlantic Ocean.
11. The longest diameter of the isobars over the Atlantic Ocean may be turned in any azimuth, but (as in the United States) it is most frequently directed towards a i)oint somewhat east of north. The lollowiug table shows the number of cases in a hundred in which the longest diameter of the
12
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
isobars was directed towards each of tbe ten-degree intervals of azimuth, counting from the north point around by east towards the south :
|
Azimuth. |
Cases per cent. |
Azimuth. |
Cases per cent. |
Azimuth. |
Cases per cent. |
Azimuth. |
Cases per cent. |
Azimuth. |
Cases per cent. |
Azimuth. |
Cases per ceut. |
|
0°tolOo 10 to 20 •>0 to 30 |
8 7 7 |
1 30oto40°: 8 40 to 50 ! 9 50 tofiO 8 |
60° t<i 7IP 70 to 80 80 to 90 |
5 6 6 |
1 90° to lOQc 1 lOu to 110 110 toiao i |
3 o 2 |
120° to 130° 130 to 140 140 to 1.50 |
4 6 4 |
1,50° fo 160° 160 to 170 170 to 180 |
2 2 8 |
We see that over the Atlantic Ocean the directions of the longest diameters of the isobars are somewhat more equally distributed in azimuth than they are in the United States; nevertheless the quadiant from SOo to ITOOof azimntb contains only one third of the wliole number of cases, and the center of the region of greatest frequency is N. 35° E., which corresponds almost exactly with the direction already found for the United States.
12. If we examine the cases in which the elongation of the isobars is greatest we shall tiiid that the position of the longest diameter of the isobars is intimately connected with the position of the neighboring areas of high pressure. Plate IV shows the isobars for May 31, 187.5, over the Atlantic Ocean and Northern ICurope. This plate is coi)ied from the series of Uanisli weather maps which were issued by Cai>tain Hofl'meyer from December, 1873, to No\ ember, 187li, and which are now continued under the joint sui)ervision of the Danish Meteorological Institute and the Hamburg Meteorological Observatory. The isobars represent the atmospheric pressure in millimeters, and are drawn at intervals of 5""". The barometric observations are all reduced to sea-level, and to the temiierature of zero on the centigrade thermometer. Isobars less than 760'"™ are represented by broken lines; isobars of 760""" and n])wards are represented by continuous lines. The direction of the wind is indicated by arrows, and its force is indicated by the number of feathers on the tail of the arrow, according to a scale of 1 to 6 (1 representing the feeblest wind and 6 the strongest).
We find on this i)late an area of low ]>ressure stretching from SW. to NE. over a distance of 4,000 miles, and having a breadth from NW. to SE. of 900 miles. The lowest isobar is 740".'"' (20.13 inches). On the north side of this low area is an area of high pressure (highest isobar shown on the map being 770'"'" or 30.32 inches). On the south side is also an area of high i>res- sure (highest isobar 765'""' or 30.12 inches), and on the east side is a third an-a of high pressure (highest isobar shown on the map being 770""" or 30.32 inches). The situation of these high areas with reference to the low area is somewhat similar to that represented on Plate II.
13. Within the trojiics we occasionally find areas of low pressure in which the winds are very violent and the gradients are very steep, but the geogra]jhical extent of the low area is much less than in the great storms of the middle latitudes. Plate V shows the isobars during a violent storm which passed over the Philii)pine Islands (Asiatic Archijielago) November 5, 1882. On the north and south sides the gradient amounted to 9""" for a half degree, which is at the rate of 18'"'" (=:0.71 inch) for one degree ; and this is equal to the steepest gradient shown on Plate III. The greatest velocity of the wind re|H)rted was 45 meters pe'r second, or 100 miles per hour, which is greater than any wind reported during the storm repiesented on Plate HI ; yet the diameter of this low area, measured from north to south, did not much exceed 500 miles. The cyclones of the tro])ics frequently exhibit a violence greater than is ever known in the storms of the middle latitudes, but their geographical extent is comparatively small. It will be noticed that on Plate V the winds all incline inward, as on Plates I and III, and show a tendency to circulate about the low center from right to left, but the inclination inward is more strongly marked than in most storms of the middle latitudes.
14. The lower i^ortion of Plate V exhibits the changes of barometric pressure, and also the changes in the direction and force of the wind as shown by self-registering instruments at Manila iluring the progress of the storm, this place being situated very near the path of the center of low pressure. The pressui'e in millimeters is indicated on the left margin of the plate; the velocity of the wind is shown on the left margin in meters per second ; the hours are shown at the top of the
CON'TRIBDTIONS TO METEOROLOGY.
13
oliait from Novciiibci- 4, 5 a. M., to Novoiiihor 0, it A. M. ; tlic <lir('(!tioii of the. wiiiil for t'ii<;li lioiir is sliown at tlie bottom oi' tlic cliart; and tlie rainfall is shown on the lower i)art of the chart as measured at intervals of three hours. The teini)erature is show n in centigrade degrees on the right margin of the cliart, and also the relative humidity.
15. The term loir, as used in the preceding ])ages, is to he understood in a relative sense, and does not necessarily indicate that tiie barometer is below its mean height. The characteristic feature of an area of low pressure is a general nioveinent of the winds inwaiil, and at the same time circulating from right to left about the low center. Such a movement of the winds is found to prevail in the violent cyclones of the West India Islands, and such a system of winds is called a cyclonic system, or simply a cycloiu^; and an area of low barometer over which such a system of winds i)revails, is called an area of cycdonic winds, or simply a cyclonic area. The barometer at the center of such an area may stand as high as '.M inches, and occasionally it stands as high as .30.1, or 3(1.2, or even higher. Plate VI shows the isobars for the United States on the morning of January 5, 1.H82, at which time the barometer stood above 30 inches over nearly the whole of the Unitf^d States, with an area of high pressure (30.8 inches) over the river Saint Lawrence. Near latitude ii)° the isobars 30.4 and 30..5 were separated by an interval of over 800 miles, and between them was an area nearly 400 miles in diameter, within which the pressure was less than 30.4 inches.
On the morning of January 4 there was an area of low pressure over Arkansas (the pressure at the center being a little below 30 inches) and it was surrounded by a distinctly marked system of circulating winds. During the next twenty-four hours this low area advanced about 450 miles toward the northeast, and during this time the barometer had been continually rising, and the system of circulating winds was generally supplanted by feeble winds froui some northern quarter. At only one station on the morning of January 5 was the wind within this area reported from the south. The isobar of 30.4 inches included a region over which the pressure was lower than the pressure immediately surrounding it, that is, the pressure was relatively low, but there remained only a slight trace of the system of circulating winds which had previously prevailed. The term cyclonic area, when applied to a system of circulating winds with jiressure above 30 inches, is more descri]itive than the term low area; but both of these terms are in common use.
10. A comparison of Plates 1 to VI shows that we may have deep cyclones as seen in Plates I and III, or shallow e.^ clones as seen in Plate VI, and there is a corresi)onding difference in the velocity of the winds in the two cases. The winds shown in Plate I were very strong, particularly on the northwest side of the low center, being 48 miles an hour at Dodge City, 36 miles at Yankton, 32 miles at Leavenworth, and 31 miles atEscanaba. The winds represented on Plate III were still more violent, five vessels having reported the force of the wind as rising to 10 on Beaufort's scale, which is considered to be equivalent to a velocity of C5 miles per hour; and one vessel rejjorted the force of the wind as 12 on the same scale, indicating a velocity of 90 miles pei' hour. Within the low area represented on Plate VI the highest wind reported was at Nashville, C miles per hour, while at Cohnnbus and Louisville the velocity was 4 miles per hour; at Cincinnati and Indianapolis, 3 miles per hour; and at Knoxville only 1 mile per hour.
17. When an area of low juessure is very much elong.ated we frequently (iud two cyclonic centers included within the same area of low pressure. Plates I, II, and III show only one low center, but Plate IV shows two centers of cyclonic movement within the same area of low pressure, besides three less important centers on the lower iiart of the chart, and each of them is attended by a system of feeble winds circulating about it. When there are two cyclonic centers within the same area of low pressure these centers are generally of unequal depth ; but sometimes they are
|
Miles per hour. |
1 |
Miles per hour. |
Miles per hour. |
||
|
Sandy Hook, N. J Cape' May, N.J Erie, Pa Barne<;at, X. J Cape Lookout, N. C . . |
74 70 4-^ 40 Sri |
Buffalo, N. Y Cleveland, Ohio Albary, N. Y New York City Cape Heury, Va |
Kitty Hawk, N. C Moroantown, W. Va-. . Alpena, Mich Atlautif City, N. ,J Norfolk, Va" |
32 32 30 30 30 |
14
MEMOIRS OP THE NATIONAL ACADEMY OF SCIENCES.
sensibly equal, as sbown iu Plate VII, which represents the isobars over the eastern i)art of the United States ou the morning of December 9, 187(5. Here we notice a center of high pressure (30.4 inches) ou the western side of the low area, and on that side of the low area the gradients are very steep, and the wind velocities are very high, as shown in the preceding table.
This table shows the wind velocities reported at 7'' 35"' A. m., but these were uot iu all cases the highest velocities reported during the progress ot this storm. The following table shows the highest velocities reported :
|
Miles per hour. |
Miles per hour. |
Miles per hour. |
|||
|
Sandy Hook, N.J Cape May, N.J Newport, R. I |
84 72 60 60 54 50 |
Boston, Mass . ... |
50 50 49 48 45 43 |
Philadelphia, Pa New Haven, Conn Portland Me . |
42 40 3H 36 36 35 |
|
Wood's Holl, Mass Grand Haven, Mich Erie, Pa Baruegat, N. J Eastport, Me |
|||||
|
New Yorl- City Marquette, Mich Cape Lookout, N. C ... |
Rochester, N. Y Oswego, N. Y . . : Port Huron, Mich |
The winds reported in the neighborhood of New York City are the highest winds that I have found reported at any of the Signal Service stations since the commencement of the observations in 1872, with the exception of Mount Washington.
Over New England the isobars are very much elongated iu a direction nearly perpendicular to a line joining the high and low centers. Within the isobar 29.2 we find two isobars of 29.1; and at the most northerly' stations the winds ajipear to be mainly controlled by the northern center, and at the more southerly stations the winds are mainly controlled by the southern center. Between two neighboring centers of low pressure we generally find the directions of the wind to be irregu- lar, at certain places being mainly controlled by one of the centers, and at other places being mainly controlled by the other center.
18. Sometimes within a large area of low pressure we find three centers of cyclonic movement of the winds. These cyclonic centers are generally of unequal depth, but occasionally we find them sensibly equal. Plate VIII shows the isobars over the Atlantic Ocean and Europe on the morning of March 12, 1876. This plate is constructed on the same plan as Plate IV. Here we see three low centers, and the lowest isobar about each of them is 730'"™, and we noti(te a high area (770""") on the west side, another high area (770""") on the southwest side, and a third high area (770""") on the northeast side. The winds over a large portion of this low area are extremely violent, particularly on the south and west sides of the low center which prevails over England, where the winds rise to 6 (on a scale of 1 to 0); and on the northeast side of this center, to a distance of about 360 miles, the winds appear to be controlled by this center. A little further to the northeast the winds are controlled by the low center over Sweden, but on the north side of the Swedish low center the winds are generally feeble, and are mainly controlled by the third low center on the northwest of Norway.
19. Occasionally, within a large area of low jircssure, we find four or five or even more cyclonic centers, and when the number of centers is so great it seldom occurs that they are all of equal depth. Plate IX shows the isobars over Euro])e and the Atlantic Ocean, on the morning of March 9, 1876, The princii)al center of low pressure (71.5"'"') is north of Scotland, and about this center the winds are very violent, rising to number 6 on a scale 1 to 6, and the gradients are steej), particularly on the western side. The cyclonic motion of the winds is strongly marked, the circulation of the winds about the low center being very decided, while the inward tendency is not as great as is generally found in cases where the winds are less violent. On the eastern side of this ])rinci[)al cyclonic center the winds are more feeble, and here we find four minor centers of cyclonic movement. Near St. Petersburg is a low center (740'"'"), about which the cyclonic movement of the winds is distinctly marked. Near the parallel of 50° is a third low center (745™™), where the winds are generally feeble, but they show considerable cyclonic tendency. South of the Black Sea is a fourth low center (75»»"'"'), where the observations are few, but those which are represented ou the chart show a distinct cyclonic tendency; while over the Caspian Sea is a fifth
CONTRIBUTIONS TO METEOROLOGY. 15
low center (755"""). On tlie iiortliwest side of tliis ininiense area of low ])ressnre is au area of higli pressure (775"'"'), a!ul on the southwest side is another area of hit;ii pressure (775'""'). On the east side the highest isobar represented is 705""", but the length of this isobar and its relation to the low i)ressnre on the western side lead us to expect higher i)ressure further east, and by consnlting observations in Asiatic Russia (not represented on tiie niaj)) we find that tiie pressure continued to increase in advancing eastward.
20. Sometimes we find areas of low pressure of greater extent than any of the preceding, and showing numerous centers about which the winds circulate with considerable force, when the barometric^ dejiression is considerable, but feeble when the dei)ression is small. The international weather maps show numerous examples of this kind. According to these maps, on the morning of June 7, 1882, there was an area of low pressure which covered the whole of Asia, and aitpareutly extended from the equator to a considerable distance beyond the North Pole; it covered the whole of Europe with the exception of a very small i)ortion of its southern margin; it covered the northern part of the Atlantic Ocean, and reached across the central portion of North America to the Pacitic Ocean, extending thus through about 320 degrees of longitude. The principal low center (29.2 inches) was north of the Caspian Sea; a second low center (29.4 inches) was over the northern part of India; a third loiv center (29.6 inches) over the Gulf of Saint Lawrence; a fourth low center (29.8 inches) over China; a fifth low center (29.8 inches) northeast of Japan; and if the observations were sutliciently numerous, there is little doubt that several other subordinate low centers would be exhibited. A center of high pressure (30,4 inches) was found over the Atlantic Ocean near latitude 35°; a second center of high jjressure (30.2 inches) over the southeastern part of the United State.- ; and a third center (30.2 inches) over the easteru part of the Pacilic Ocean near latitude 30°. The area of high pressure formed a belt following the parallel of 30° or 35°, and extending through at least 240° of longitude, but interrupted by the Asiatic Continent.
21. Plate IX illustrates the tendency to the formation of subordinate centers of cyclonic action, whenever within a very extensive area of low i)ressure the winds are comparatively feeble. When this tendency is slight it simply causes a little distortion in the isobars without the formation of a distinct area of cyclonic action. There are few cases of great storms in which we do not find some distortion of the isobars which may be ascribed to this cause. In Plate III most of the isobars are uncommonly symmetrical, but we notice a distortion of the isobar 30.0 inches over Spain, and the winds in this neighborhood indicate a feeble center of cyclonic action. The same remark is illustrated by Plates IV and VIII.
22. From an examination of the Signal Service maps, we find that in the United States au area of low barometer, with only one system of cyclonic winds, frequently has a diameter of 1,600 English miles. From Hofliueyer's charts we find that over the Atlantic Ocean such an area frequently has a diameter of 2,000 English miles. Areas of low barometer, having several centers of cyclonic action, may have a diameter of 6,000 English miles, and may form a belt extending, nearly (if not entirely) around the globe, between the parallels of 40 and 50 degrees.
Direction of movement of areas of lotc pressure.
23. Areas of low pressure seldom remain stationary in position for many hours. The center of low pressure generally changes its position steadily from hour to hour, and everywhere we find a marked uniformity in the direction of this movement. Plate X shows the tracks of a large number of centers of low pressure, for the United States and the adjacent districts. This plate is not designed to indicate the track which storm centers most frequently pursue, but rather to give an example of all the more important tracks j)nrsued by storm centers, as delineated on the Signal Service maps. The tracks represented on the northern part of the chart are those which most frequently occur, while those on the southern part of the chart are comi)aratively infrequent. We perceive that north of the parallel of 30° storms generally travel from west towards the east; but in some places they deviate to the south of east, and in other places they deviate to the north of east. On the southeast poi'tion of the chart we notice several tracks which are directed towards the northwest.
24. A chart which represents storm tracks for the entire northern hemisphere is best adapted
16
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
to suggest the cause of tlicse movements. Plate XI affords an example of nearly all the different storm tracks delineated ou the international maps of the United States Signal Service for a period of more than four years. We perceive that north of the parallel of 30° storm tracks in all longitudes almost invariably i)ursue an easterly course, but generally they show an inclination towards the north of east ; while witbin the tropics storm tracks almost invariably tend westerly, with au inclination towards the nortli of west. We also notice that none of the storm tracks delineated on the chart reaches down to the equator. The lowest latitude of any center of low pressure which has been distinctly traced is (i.io N., and there are eight cases of cyclonic storms whose paths have been traced to points south of latitude 10° N.
25. It is not, however, to be uiulerstood that at the equator the wind does not sometimes rise to the force of a gale, but rather that a i-egular system of cyclonic winds, with a considerable depression of the barometer, has never been known to prevail directly under the equator. Hard gales and violent squalls of wind do however sometiuies occur directly under the equator. This is shown by various logs quoted in I'iddingtou's Memoirs. The following is an exauiple from the log-book of the Winifred, quoted in I'iddington's Eleventh Memoir, pages 30 to 40 :
|
Lat. |
Long. |
Bar. |
Wind. |
. |
|||
|
184:! |
|||||||
|
Nov.'ifi, iionn. |
it-' JO' N. |
85° 4fi' E. |
29.80 |
E. |
Stvont; sqnallN .iikI lieavv r.ain. |
||
|
27, |
7 4 N. |
85 56 |
29. 67 |
ENE. |
Suddi'ii aud dangtirons gusts and violent H<iiiall3. |
||
|
28, |
li |
4 27 N. |
85 58 |
29. 65 |
NW. |
Mo.st tfiTitic .snualls. Reduced sail t" donlde reef tops |
lil. |
|
29, |
it |
1 20 N. |
8R 30 |
29. 59 |
NNW. |
Succession of dangerous s(|nalls. |
|
|
:)0, |
(( |
1 1 S. |
86 0 |
29. 64 |
W. |
Violent and territic squalls. |
|
|
Dec. 1, |
(1 |
:? 1.^. S. |
86 56 |
29. 67 |
NW. |
Violent varying .squalls. |
|
|
2, |
»( |
4 21 S. |
87 34 |
29. 74 |
Calm weather. |
The following is from the log-book of the Pyzul Curreem lor the same period :
|
Lat. |
Long. |
Wind. |
||||
|
1843. |
||||||
|
Nov. 27, noon. |
.5°11'N. |
83° 36' E. |
NNW. |
Heavy .squalls. |
||
|
28, " |
2 6 N. |
83 40 |
W. by S. |
Fresh gale. |
||
|
29, " |
0 54 S. |
84 31 |
W. |
Fresh gale, incre:ising \vi(li |
lieuA'v squalls to a strong |
sale. |
|
30, " |
3 .50 S. |
85 27 |
W. |
Fresh gales. |
||
|
Dec. 1, " |
5 39 S. |
85 37 |
NNW. |
Strong sea from WSW. |
||
|
2, " |
6 41 S. |
85 1 |
NNE. |
Heavy head sea. |
These observations show that directly under the equator we may have winds of a dangerous violence, accompanied by frequent (ihanges in direction, indicating somewhat imperfectlj' a cyclonic character, and accompanied by sudden oscillations of the barometer, which are very unusual near the equator. Within six degrees of the equator the depression of the barometer has, however, never been found sufBcientlj' great, and the depression has not been maintained with suflicient steadiness to enable us to identify an area of low pressure in its progress from day to day.
26. Although violent gales do sometimes occitr directly under the equator, they are of very rare occurrence. This is shown by Maury's Storm Chart of the North Atlantic Ocean, which gives th(i number of gales which have been observed on the Atlantic Ocean in different latitudes from the equator as far north as latitude (JOO. Ou this chart the ocean is divided into squares by parallels of latitude drawn at intervals of five degrees from each other, and meridians of longitude at intervals of five degrees. The following table presents a summary of the results of this chart. Eath S(]uare of the table ('ontains three numbers. The, first shows the nuniber of observations within the given S(inare, each observation representing a period of eight hours. The second shows the number of gales reported, and the third shows the average number of gales occurring in a hundred observa- tions. Thus in the square included between the parallels of 40° and 45° of north latitude, and between the merulians of 45° and 50° west longitude from Greenwich, the first number is 1,863,
CONTRIBUTIONS TO METEOROLOGY.
17
whicli shows the iiumher of obstTVittioiis obtaineil in that squiue. The seeoiid number jh -!S(», which deuotes the iiuiiiber of sales reported; thi^ third number is 15, which denotes that tlie number of gales was 15 per cent, of tht^ wliole number of observations.
Table I. — Gales on the Atlantic Ocean by Maury's Storm Chart.
60°
55°
50°
45°
40°
35°
30°
25°
20°
15°
10°
.5°
0°
80° 75° . 70° 65° t)0° 55° 50° 45° 40° 35° 30° 25° 20° 15° 10°
5°
0°
|
60 |
102 |
123 |
117 |
78 |
30 |
||||||||||
|
16 |
38 |
35 |
31 |
12 |
3 |
||||||||||
|
27 |
37 |
28 |
27 |
15 |
10 |
||||||||||
|
1.50 |
420 |
510 |
694 |
850 |
932 |
1270 |
1393 |
583 |
|||||||
|
.57 |
111 |
140 |
169 |
159 |
117 |
152 |
133 |
46 |
|||||||
|
38 |
26 |
27 |
24 |
19 |
12 |
12 |
10 |
8 |
|||||||
|
126 |
288 |
919 |
1242 |
l.WO |
1740 |
1627 |
1539 |
1478 |
1312 |
920 |
313 |
||||
|
11 |
28 |
121 |
209 |
369 |
277 |
242 |
165 |
160 |
156 |
85 |
13 |
||||
|
9 |
10 |
13 |
17 |
24 |
16 |
15 |
n |
11 |
12 |
9 |
4 |
||||
|
1820 |
3249 |
2544 |
2679 |
2419 |
1863 |
1581 |
1119 |
732 |
396 |
269 |
168 |
128 |
67 |
0 |
|
|
126 |
260 |
266 |
269 |
•241 |
280 |
234 |
127 |
66 |
58 |
44 |
16 |
9 |
1 |
||
|
7 |
8 |
11 |
10 |
10 |
15 |
15 |
11 |
9 |
15 |
16 |
9 |
8 |
1 |
||
|
243 |
4193 |
2974 |
1797 |
1393 |
1100 |
773 |
480 |
349 |
242 |
341 |
268 |
302 |
340 |
334 |
225 |
|
8 |
607 |
475 |
393 |
177 |
115 |
62 |
28 |
27 |
23 |
35 |
5 |
24 |
7 |
9 |
14 |
|
4 |
14 |
16 |
22 |
13 |
10 |
8 |
6 |
8 |
9 |
10 |
2 |
8 |
2 |
3 |
6 |
|
1534 |
2265 |
1645 |
766 |
723 |
860 |
986 |
893 |
747 |
392 |
175 |
129 |
223 |
77 |
3 |
|
|
126 |
231 |
137 |
65 |
72 |
71 |
60 |
48 |
27 |
25 |
4 |
0 |
9 |
0 |
0 |
|
|
8 |
10 |
8 |
9 |
10 |
8 |
6 |
5 |
3 |
6 |
2 |
0 |
4 |
0 |
0 |
|
|
1945 |
1393 |
1137 |
948 |
394 |
351 |
564 |
726 |
958 |
663 |
209 |
153 |
87 |
|||
|
81 |
30 |
57 |
17 |
17 |
6 |
5 |
9 |
61 |
6 |
8 |
0 |
6 |
|||
|
4 |
2 |
' |
2 |
4 |
a |
1 |
1 |
6 |
1 |
4 |
0 |
7 |
|||
|
316 |
380 |
262 |
650 |
637 |
267 |
262 |
452 |
806 |
()64 |
338 |
13(5 |
15 |
|||
|
12 |
9 |
4 |
7 |
6 |
6 |
9 |
18 |
4 |
25 |
0 |
0 |
0 |
|||
|
4 |
2 |
2 |
1 |
1 |
2 |
3 |
4 |
0 |
■ 4 |
0 |
0 |
0 |
|||
|
243 |
320 |
152 |
183 |
459 |
541 |
326 |
302 |
449 |
711 |
638 |
159 |
6 |
|||
|
4 |
2 |
0 |
0 |
1 |
4 |
1 |
10 |
6 |
13 |
8 |
0 |
0 |
1 |
||
|
2 |
1 |
0 |
0 |
0 |
1 |
0 |
3 |
1 |
2 |
1 |
0 |
0 |
|||
|
65 |
0 |
53 |
53 |
96 |
387 |
594 |
508 |
415 |
667 |
8.35 |
622 |
225 |
|||
|
0 |
0 |
1 |
0 |
1 |
0 |
1 |
0 |
3 |
9 |
21 |
0 |
0 |
|||
|
0 |
0 |
2 |
0 |
1 |
0 |
0 |
0 |
1 |
1 |
3 |
0 |
0 |
|||
|
23 |
0 |
289 |
668 |
632 |
739 |
1667 |
1109 |
483 |
716 |
80 |
70 |
||||
|
0 |
0 |
0 |
0 |
0 |
3 |
5 |
0 |
0 |
0 |
0 |
0 |
||||
|
0 |
0 |
0 |
0 |
0 613 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
||||
|
95 |
421 |
1004 |
2004 |
1262 |
335 |
107 |
362 |
233 |
|||||||
|
0 |
0 |
0 |
0 |
3 |
0 |
0 |
0 |
1 |
0 |
||||||
|
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
The following table jjreseuts a suniniary of the results for all parts of the Atlantic Ocean for each five degrees of latitude :
Table II. — Summary.
Latitude.
Equator to 5°N.
5 N. to 10 N.
ION. to 15 N.
15 N. to 20 N.
Obs.
6,436 6,476 4, 520 4,489
|
Gales. |
fiatio. |
|
4 |
.0006 |
|
8 |
.0012 |
|
36 |
.0030 |
|
49 |
.0109 ; |
Latitude.
Ol.s.
Galea.! Batio.
20° N. to 25° N. I 5, 185 100 1 .0193 25 " to 30 9, .528 303 .0318
30 " to35 11,418 I 875 I .U766
35 " to 40 !l5,354 |2,009 ' .1308
Latitude.
40° N. to 45° N. 45 " to 50 50 " to 55 55 " to 60
Obs.
19, 034
13, 074
6,792
510
Gales. Ratio.
1,997 .1049
1, 836 I . 1404
1,084 .1.596
135 . 2647
From this table we see that on the Atlantic Ocean, between the equator and latitude 5° N., gales occur on an average somewhat less frequently than once a .year; and from latitude 5° to
S. Mis. 164 3
18
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
latitucJe 10° N. tbey occur a little more frequently tlian ouee a year. From latitude 10° N. to lati- tude 15° N. tbere occur on an average nine "ales annually ; and as we advance northward the fre- quency of gales iucreases with the latitude up to latitude (W° X.
27. On Maury's storm chart for the eastern half of the North Pacific Oci-an among 17,854 observations between the equator and 5° N. latitude, 35 gales are reported ; and between 5° aud 10° N. latitude among 9,352 observations, 33 gales are reported. These observations indicate that in the low latitudes of the Pacific Ocean gales are somewhat more frequent than over the Atlantic Ocean. It appears evident that in both oceans, within 6° of the equator, gales are of extremely rare occur- rence, and wheu they do occur the depression of the barometer is small, and the cyclonic character of the winds is indistinctly marked. North of the parallel of 6° the cyclonic character of the winds becomes more distinct, and areas of low pressure can be identified iu their progress from day to day.
28. The tropical cyclones which have been found to pursue a westerly course are limited to two districts: 1. The Atlantic Ocean, aud chiefiy its western part near the West India Islands. 2. Thei'egion south of the continent of Asia. Tropical cyclones have never been observed iu any l)arl of the Pacific Ocean, with the exception of its western portion near the continent of Asia aud the neighboring islands. I have made a careful study of the cyclones of each of these localities. Table III exhibits some of the particulars resi>ecting each of the cyclones originating near the
Table III. — Course of cyclonen originating near the West India Islands.
No.
Date.
1 1780,
2 ! 1780, 1H04, 1821, 1827, lc3ll, 1830, 1830, 1831,
10 1831. U 1831, la ; 183.^,,
13 I 1835,
14 1837,
15 I 1837,
16 ; 1837,
17 I 1837, 1837, 1839, 1842, 1842, 1844, 1840, 1S46, 1847, 1848, 1848, 1850, 1851, 1853, le53, 1853, 1866, 1867,
35 1871,
36 1871,
37 1873,
38 i 1873, 1»73, 1874, 1875,
Oct. 3 Oct. 12 i Se)>t. 3 .Sept. 1 Aujr. 17 Aug. 12 , Aug. 22 Sept. 29 Jau. 13 JUUI.-23 Aug. 10 Aug. 12 Sept. 3 July 26 Aug. 2 Aug. 12 Aug. 24 Sept. 27 Sept. 12 Aug. 30 Oct. 2 Oct. 4 Sept. 11
Oct Oct. Aug Aug, Sept Aug. 16 Aug. 30 Sept. 26 Sept. 29 Oct. 1 Oct. 29 Juue 1 Sept. 5 Aug. 18 Aug. 20 Oct. 6 Feb. 7 Sept; 14
16.5° 11.8
15.7 21.7 14.8 17.3 22. 3 20.2 30.0 10.3 12.3 16.3 12.4 11.0 17. 3 17.6 32. 7 15.7 18.5 21.6 20.0 18.6 13.8 14.2 12.8 15.0 15.0 16.0 13.5 12.5 28.8 13.9 19. 0 18. . 23.5
Course whilei a g
moving 'Z-.-^
westward. .- J?
o ~-
W. 31^' N. W.30 N. W.27 N. W.29 N. W.23.5 N. W.27 N. VV. 33.5 N.
w!V4..'i'N] W.25.5 N. W. 17 N. VV.38 N. \V.29 N. W. 31.5 N. W.20 X.
\V.'24 N."
W. 26 N.
W. 1 N.
17.8 20.4 35.0 12.9
iC'ourse while
moving I eastward.
23.3 31. 2 31.2 30.0
23. 8 31. 4
18.7 26.4
20.4 16.6
117.8
30.3;
30. 4| 30. 0!
... I 30.7
W. 62 N. W.60 N. W. 11.5 S. W.28.5N. W.22 N.
W.5 N.
W. 15 N. W. 12.5 N.
\V. 9 N. \V.15 N.
W.2 S. W. 14 N.
8.3
io.o
10.3 21. 2
E. ai.fto N. ■E. 39.5 N.
E. 46 N. E.55 N. E.43 N. E.37 N. E.40 N. E.43 N. E. 53.5 N.
30.0
31.7
26.2 32. 2
E.24.5 N.
E.47 N.
E. 17.5 N.
.... E. IbN.
.... E.54N.
29.2 li;.47 N.
30.0 E. 60.5 N.
27.4 29. 0
E.22 N. E.24 N.
17.5 27.3, E.34 N. 25. 3 31. 7 1 E.24.5 N. -.29.2 E.27 N.
15.0,26.4'
15..-,!....;, 12. 3,31. 5i
E.25 N.
20. 0 25. U 21. 3 24.0 23.0
\V.32 N. W.51 N. W.28 N.
W. 22 N.
112. 3 33. Oi
!l0.5l34.3
9.5I24.3
1 . . . . |26. 5' 125.1,28.5
E. 45 N. E. 38 N. E.37 N. E,41 N. E.45 N. E.45 N. E.24 N.
f^-^ ^ ^
17. 2 18.1 25. L)
Kaiu-fall
Hard rain . . . Hard rai n . . . V. banl raiu Hard rain ..
10.0 Hard raiu ... 16. 3 V. hard raiu.
16.01 Raiu
29.6
16. 6 Snow
Hard rain . .
Rain
Hard rain . ..
V. hard rain.
Hard rain . . .
Rain
Hani niiu . . . 13. 4' Hard raiu . ,. . . . . i Hard rain . . .
Rain
Hard lain . ..
Hard raiu ..
Hard raiu . . .
Raiu
Raiu
Investiga- tors.
17
10.6 30.4
14. 3| 23. 5
18.7 28.4
30. 0
23.
Hard rain
Raiu
Raiu
V. hard raiu V. hard r;iiu. Hard rai u . . .
Raiu
V. bard rain. Rain
15.0; Raiu . ,18.4 Raiu ,
16.4 30.1 23. 5 29.6 Hard rain
V. liard rain Hard niin . . Raiu
I
Eeid
Reid ....
Redfield.
Redfield. j Redfield. I Redfield.
Redfield.
Redfield. [ Redfield.
Redfield.
Redfield.
Redfield. I Reid ....
Reid
I Reid
Reid ....
Reid ....
Reid....
Reid ...
Redfield.
Redfield .
Redfield .
Redfield.
Redfield.
Reid
Reid
Maury ..
Redfield.
Redfield .
Redfield -
Redfield.
Redfield.
Buchan .
Eastman
Sig. Serv
Sig. Serv
Sig. Serv
Toj'ubee
Sig. Serv
Sig. Serv
Sig. Serv
Where recorded.
Law of Storms, p. 273. Law of Storms, p. 273. Jo. Sci.,v.20,p. 17. Jo. Sci., V.20, p. 17. Jo. Sci.,v.31,p. 123. Jo. Sci., v.20, p. 34. Jo. Sci., v.20, p. 39. Jo. Sci., v.20, p. 42. U. S. Naval Mag, 1836. Jo. Sci., V. 31, p. 123. Jo. Sci., V. 21, p. 192. Jo. Sci., V. 31, p. 124. Law of Storms, p. 36. Law of Storms, p. 48. Law of Storms, p. 48. Law of Storms, p. 69. Law of Storms, p. 109. Progress, p. 13. Progress, p. 39. Jo. Sci., V. l,p.2. Jo. Sci., V. 1, p. 153. Jo. Sci., V. 2, p. 312. Jo. Sci., V. 18, chart. Jo. Sci., V. 18, chart. Progress, chart. Progress, p. 337. Phys. Geog.,p.60. Jo. Sci., V. 18, p. 176. Jo. Sci., V. 18, chart. Jo. Sci., V. 18, p. 1. Jo. Sci., V. 18, p. 180. Jo. Sci., V. 18, p. 178. Haudy Book, p. 151. Pamphlet. Report lf)72, p. 282. Report 1874, map. Report 1873, p. 1029. Jo. Met. Soc, V. 2, p. 15. Monthly Map, 1873. Report 18T4, map. Monthly Map, 1875.
CONTRIBUTIONS TO METEOROLOGY. l9
West India Islands, and lor which definite )>atlis liave been determined. (Jolumn 1 shows the number of reference ; column 2 gives the date of commencement of the storm so far as ascertained ; column 3 shows the latitude of the storm's center, when it first became violent; column 4 shows the average course of the storm while moving west \\ard; column .") shows the hourly velocity of progress in the preceding i)art of its course; column (i shows the latiiude at which the storm was movinjr due north ; column 7 shows the average conrsi^ of the storm after turning eastward, until it reached the ])aralle] of 40°; column S shows the hourly velocity of ])rogress during the pre- ceding i)eriod; column t) shows whether lain was mentioned as accomi)auying the storm; column 10 gives the name of the person by whom the phenomena of the storm were investigated, and column 11 shows where the record of the inv(>stigation maybe found.
29. It will be noticed that the least latitude of any storm path here recorded is 10°; that is, over the Atlantic Ocean no storm path has been traced within 10° of the equator.
The courses of the storms nientioned in this table (while moving westward) range from 11^° south of west to 62° north of west. In two cases the course was a little south of west ; in a third case the course was only one degree north of west, and in a fourth case the course was only five degrees north of west. Tropical stoi ms do therefore sometimes travel towards the equator, and it maybe suspected that this directioii occurs more frequently than the table would indicate, since many of the storms here recorded would never have been selected for investigation if they had not advanced into the middle latitudes. The average course of the storms here enumerated, while they were moving westward, was west 26° north ; and the average hourly velocity in this part of their course was 17.4 miles.
The average latitude of the storm's center when moving due north was 29^°, and the latitudes range from 23^° to 34°. During the three summer months the average latitude is 30°. 6; in Septeuiber it is 29°. 7, and during the other months of the year 2()°.7, indicating that the i)oint where the course changes from west to east is somewhat more northerly in summer than in winter. The average course of these storms while traveling easti^ard to the parallel of 40° was E. 38J° N., ranging from 17° to 60°. The average hourly velocity in this part of their course is 20.5 miles, which is a little less than the average velocity of storms in the United States for the months of August and September, according to the Signal Service observations. It will be seen from column 9, that rain generally accompanies cyilones. In three of the cases I have found in the published reports no mention of rain, but it is presumed that this is simply an oversight, since in most of the other cases rain is only incidentally mentioned. In all the iuvestigatious of Redfield and Reid the circumstances upon which they insist as specially important are the direction and force of the wind, and it is only by consulting the extracts from .he log books which they have furnished us that I have discovered anj mention of accompanyiug rain. It is believed that tropical cyclones never occur without rain, and generally the rain is described as descending in torrents. The letter V, in column 9, signifies very.
30. In order to obtain more complete information respecting the tracks of tropical cyclones in the neighborhood of the West India Islands, I have compared all the storm tracks delineated on the maps of the Monthly Weather Review, and also these delineated on the international charts.
20
MEM(JIRS OF THE NATIONAL ACADEMY OF SCIENCES.
The following table shows the leading particulars respecting those storms whose course was for some days towards the west:
Table IV. — American .storms advancing westerly.
|
No. |
Date. |
Latitude. Beg. End. |
Longitude. . Beg. End. i |
Course. |
Veloc- ity, miles. |
Subsequent course. |
|
|
1 |
1873, |
June 1.1- 2.3 |
240-32'^ |
80C-86^ |
NNW. |
12. 5 |
Became extinct. |
|
•2 |
Oct. 2 - 4.2 |
22-24 |
82- 86 |
NW. |
9.5 |
Moved NE. |
|
|
»» |
1874, |
Feb. 7-8.1 |
24-27 |
62- 83 |
NNW. |
15.4 |
Moved NE. |
|
4 |
July 2.3- 4.2 |
27-29 |
87- 98 |
WNW. |
13.1 |
Became extinct. |
|
|
5 |
Sept. 4.3- 5.3 |
25-32 |
65- 70 |
NNW. |
22. 5 |
Moved NE. |
|
|
6 |
1875, |
Sept. 8.3-17.1 |
14--J9 |
.59- 96 |
WNW. |
13.2 |
Moved NE. |
|
7 |
1876, |
Sept. 15 -18.1 |
21-43 |
69- 80 |
NNW. |
25. 9 |
Moved E. |
|
8 |
1877, |
Sept. 22.2-30.3 |
12-26 |
65- 88 |
WNW. |
U. 1 |
Moved NE. |
|
9 |
1878, |
Aug. 12 -18 |
14-21 |
75- 97 |
WNW. |
14.4 |
Unkuown. |
|
10 |
Sept. 1-8 |
U-28 |
.59- 81 |
WNW. |
9.3 |
Moved N. |
|
|
n |
Sept. 12 -18 |
14-29 |
47- 60 |
NW. |
9.6 |
Moved NE. |
|
|
12 |
Sept. 24 -30 |
14-28 |
70- 73 |
NNW. |
.5.3 |
Moved NE. |
|
|
13 |
Sept. 29 -34 |
22-30 |
.i8- 70 |
NW. |
9.1 |
Moved NE. |
|
|
14 |
Oct. 9 -13 |
1.5-26 |
40- 52 |
NW. |
7.2 |
Moved NE. |
|
|
15 |
Oct. 13 -la |
17-30 |
36- 55 |
NW. |
13.2 |
Moved N. |
|
|
16 |
Nov. 25 -30 |
l.:,-17 |
52- 73 |
W. |
11.7 |
Uukiiown |
|
|
17 1879, |
Aug. 13 -17 |
18-30 |
60- 77 |
NW. |
8.2 |
Moved NE. |
|
|
18 |
Aug. 15 -16 |
14-14 |
43- 51 |
W. |
(?) |
Unknown. |
|
|
19 |
Aug. 20 -23 |
16-29 |
87- 94 |
NW. |
8.2 |
Moved E. |
|
|
20 |
Oct. 3-7 |
1.5-31 |
78- 90 |
NW. |
8.1 |
Became extinct. |
|
|
21 |
Oct. 10 -17 |
14-43 |
70- 90 |
NW. |
11.1 |
Moved E. |
|
|
22 |
1880, |
Aug. 6 -14.2 |
12-32 |
77-103 |
WNW. |
12. 9 |
Disappeared. |
|
23 |
Aug. 15 -19 |
13-20 |
62- 78 |
WNW. |
12.0 |
Moved NE. |
|
|
24 |
Aug. 24 -31 |
26-33 |
60- 89 |
WNW. |
10.0 |
Disappeared. |
Column 1 shows the number of reference ; column 2 shows the dates of beginning and end of the observed movement as long as the course continued westerly ; column 3 shows the latitude at the beginning and end of tliis portion of the path ; polnnni 4 show.s the longitude at the beginning and end of this portion of the path; column 5 shows the prevalent direction of the path while moving westerly ; column 6 shows the average velocity of progress of the storm center (in miles per hour) wliile the course continued westerly ; column 7 gives a brief indication of the subsequent course of each storm. On Plate XH, Fig. 1, tliese tracks are delineated, and are designated by the same numbers as in the table.
31. The general results of this table correspond very closely with those deduced from Table III. The lowest latitude of any storm center shown in this table is lO^.C N. The lowest latitude shown in Table III is 10o.3 N. The average velocity of these storms while moving westerly was 11.9 English statute miles per hour; the average velocity of the storms mentioned in Table III while moving westerly was 17.4 miles per hour, lu nine of these cases the course of the storm became due north before reaching the parallel of 30°, and tlie average direction of these storms in the early part of their course was west 20^.5 uorth.
Storm No. IS api)areutly advanced directly west, and storms Nos. 9 and 16 apparently moved for a day or two a little south of west. Table III shows thiity one cases in which the course of storms was towards the uorth of west, and only two cases in which the course was south of west, viz, one case in which the course was two degrees south of west, and the other eleven degrees south of west. From the two tables we perceive that the ca.ses in wliii'h tropical storms move in a direction north of west are fifteen times as frequent as the cases in which they move in a direction south of west, and in none of the cases here reported was the southerly motion very decided.
32. In order to determine whether during the period here considered there may not possibly have been other storms which moved in a direction corresponding moi'e nearly with that of the northeast trade winds. I have made a careful comparison of the international observations. Five sixths of ail the storms enumerated in Table TV occurretl in the months of August, September, and October. 1 therefore selected these three months for special comparison. For the years lS76-'77-'78 and '79 the barometric curves were drawn for these months for all the stations reported in the International Bulletin, between the equator and latitude 26° N.
CONTRIBUTIONS TO METEOROLOGY. 21
A.U exauiination of these curves shows that at all of these stations the fluctuations of the barometer were very small, particularly for the stations nearest to the equator. At Paramaribo, latitude 5° 45' N., the entire range of the barometer for tiiese twelve months was only 0.20 inch, and there was no oscilliation which can be identified witii an oscillation at either of the other stations. At Bridgetown, latitude 13° i' N., the entire range of the barometer for these twelve months was 0.23 inch. Two or three of the barometric oscillations at this station can probably be identified with oscillations at some of the other stations. The track of storm No. 9 can apparently be traced back to Bridgetown on the 10th of August, 1878. At Fort de France, latitude 14° 40' N., the entire range of the barometer for these twelve months was 0.42 inch, and six or seven of the barometric oscillations at this station can probably be identified with oscillations at some of the other stations.
Besides the areas of low barometer enumerated in Table IV there are but few others during this period which can be traced with confidence from one station to another. In 1876 the number of stations of observation in the tropical regions was small, and the storm of Septendier 15-18 is the only one which can be satisfactorily traced from these observations.
In 1877 the center of storm No. 8 passed at a considerable distance from all of the reporting stations, and is only obscurely indicated by the i)ublished observations. On the 26th of August a small but well-marked barometric depression occurred almost simultaneously at all of the stations from Fort de France to Havana. On the 17th and 18th of October there was a noticeable fall of the barometer, which apparently advanced from San Juan de Porto Rico to Havana.
- In 1878, from September 15 to 16, a small barometric depression traveled from Bridgetown to Santiago de Cuba. From the 2d to the 3d of October a small barometric depression traveled from Fort de France to Nassau. On the 21st of October there was a decided barometric depression at Vera Cruz and Havana, which advanced northerly along the coast of the United States, and was marked by great violence.
In 1879, from the Itith to the 18th of August, a small barometric depression traveled from Bridgetown to San Juan de Porto Rico. This was, perhaps, a continuation of No. 18 of Table IV, . &nd, if so, it shows that this storm veered a little to the north of west, like most of the storms of this region. On the 28th of August a small barometric depression appeared almost simultaneously at all the stations from Navassa to Tlacotalpam, on the coast of Mexico. This depression appar- ently advanced northward, but tlie published observations are not suificient to enable us to trace its cour.se satisfactorily.
This examination has disclosed a few barometric depressions, in addition to those enumerated in Table IV, but their courses wei-e generally towards the north of west. We therefore seem authorized to conclude that nearly all the areas of low barometer which occur within the tropics, and advance westward in the neighborhood of the West India Islands, instead of following the ordinary (;ourse of the trade-winds advance in a direction somewhat north of west.
33. 1 have endeavored to ascertain what was the prevalent direction of the wind which pre- ceded each of these tropical storms, and also the prevalent wind which succeeded the low center, and how these two winds generally com])ared in respect of force. It is impossible to make a satisfactory com])arison from the obser\ations in the International Bulletin, on account of the small number of stations, and because the observations arc reported only once a day. The following tables show the height of the barometer, together with the direction and force of the wind, in the case of four of the low areas enumerated in Table IV, for the stations nearest the center of low pressure. The velocity of the wind in miles per hour is shown by the numbers without parentheses; the numbers in parentheses show the force of the wind estimated on a scale from 1 to 10:
No. 9.— 1878, Aiigust 10-15.
August 10. Angust 11. August 12. August 13. August 14. August 15.
San Jnan ' 30.04 SE. 2.. 29. 98 E. 12...! 30.03SE. 4. J 30.02SE. 8. ...I 30.03 SE.O .... 30.0oSE.2.
Na\'as!'a 29.98SE. 12. 29. 99 NE. 10 . 29. 89 N. 19 . . 29. 92 SE. 29.. . 29. 91 E. 17 .. .. 29. 97 E. 17.
Kingston 30.1ncalm.. 30. 17 calm . . . 30.06calm.. 30. 09 SE. 10.. . 30. 09 SE. 20 . . . 30. 12 calm.
Nassau , 30.04SE.(1). 30.02 NE.(2). 30.03 NE. (2). 29.96 SE. (1) .. 25). 97 SE. (2) . . 30. 05 SE. (2).
Havana 30.00 E.2... 30.02 ESE.4. 29.99 ESE 3. 29. 90 ENE. 4.. 29. 81 E.9 29. 90 SE. 16.
22
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
No. 10.-1878, September 3-8.
|
September 3. |
September 4. September 5. |
September 6. |
September 7. |
September 8. |
|
|
NavaNsa Santiago de Cuba... Kino'ston |
29.93 8. 19 .. 29.9HNE. 7.. 30. 10 calm . |
29. /9N. 20... 29.82 S. 22 .. 29.85N. 6....' 29.68SE.(6). 30. 01 calm . 29. 96 E. 3 . |
29. S9 SE. 20 . . . 29.85SE.(4) .. 30. 08 S. 13 |
29.94 E. 14 .... 29.91 .SE.ti .... 30.10 SE. 18 ... |
29. 93 E. 15. 29.91 calm. 30. 11 calm. |
No. 12.— 1878, September 24-29.
September 24. September 25.
Sun Juan I 29.91 NE. 6.. 29.87SE.il.. 29.95 SE.l..
Navasea ' 29. 95 NW. 12 29. 85 NNE. 18 29.83 E.8...
Santiago deCul>a.. 29.96 N. (1) .j 29.88 NNE. a.i 29.85 NNE. (1)
September 26. Srptembei 27.
September 28.
September 29.
29. 92 SE. 6 . . . . 29. 91 SE. 4 . . . . 29. 88 SE. 4.
29. 82 NW. 12 . . 29. 70 S. 25 29. 7H S. 15.
29.79 N.(l).... 29.71 N\V.(1) . 29.72 SW.(l).
No. 21.— 1879, October 10-15.
San Juan
Navassa
Santiago de Cuba.
King.ston
Nassau
October 10.
Havana 29.98 ENE.IO
29. 97 SE. 4 29. 87 NE. 5 29. 92 N. 7 . 30.11 calm 30.02 NE.(3).
October 11.
29.89SE. 7... 29. H2E. 10.. 29. 86 N. 2 ... . 30.(11 calm .. . 29.97 NE. (1). 29.90E. 6....
|
October 12. |
||
|
29. |
89 SE. |
0.. |
|
29. |
79 SE. |
16 |
|
29. |
79 SE. |
10 |
|
29.99 SE. |
4.. |
|
|
29. |
92 NE |
(2) |
|
29. 86 ENE.8. |
October 13.
29.96SE.0 ... 29.76 E.20 ...
29. 83 SE. 6 . . ,
30. 04 SE. 18 . 29. 91 NE. (3) , 29. 76 E. 12 ...
October 14.
29. 99 SE. 0 . . 29. 92 SE. 15 . 29. 90 SE. 8 . . 30. 11 SE. 6 ... 29. H8 E. (2) . . 29. 64 E.20 ..
October \'a
30. 01 SE. 0. 29. 95 SE. 18. 29. 96 SE. 6. 30. 17 calm. 29.95 SE.(l). 29. 75 SSE. 18.
It will be seen that at several of these statious the fluctuation of the barometer was small; the winds were feeble, and their cyclonic character was indistinctly marked; but at those stations where the tlnctuation of the barometer was greatest, there was a decided change in the direction of the wind about the time of least pressure. In two-thirds of the cases the passage of the low center was immediately preceded by a northerly wind, and in every case (but two) the passage of the low center was immediately followed by a wind from the SE. These two cases occurred in storm No. 12, whose progress was almost exactly toward the north, and the low center was followed by a wind from the south at Navassa and by a wind froiu the SW. at Santiago. In all cases, the SE. wind showed indications of being a steady wind, resulting from causes of a more permanent character than the storms here considered, for it generally continued for several days ; and at certain stations, where the fluctuation of the barometer was sn)all, the wind blew from the SE. daring the entire six days here represented.
34. I have endeavored to determine the average direction of the wind for the three months, August, September, and October (which months include nearly iill the tropical cyclones before enumerated), tor that i)arl of the Atlantic Ocean in which these cyclones have most frequently occurred. Table V is derived from Maury's Pilot Charts of the North Atlantic, and shows the number of times the wind was observed to blow from the diflferetit points of the compass, in each of the five-degree S(juares from latitude 15° to 25° N. and longitude .50 to 75° W. from Greenwich.
The 11th, 22d, and 33d horizontal lines of the table show the sum of the observations of each month for each of the sixteeu wind directions, and the last column of the table shows the average direction of the wind computed from these numbers.
35. Table Vt gives the results of all the observations collected by the U. S. Hydrographic Oflice, including Maury's charts and the charts of the British Meteorological Oflice. The numbers represent the percentage of winds from sixteeu points of the compass for each of the five-degree squares. When the sum of the numbers in any horizontal line is less than 100 the difference represents the cases of calms and variables.
This table makes the average direction of the wind somewhat more northerly than Table V.
CONTRIBUTIONS TO METEOROLOGY.
2.i
According- to Table V, the average direction of tiie wind tor tlie tiiree months here considered is two degrees nortli of east. According to Table VI it is 4.] degrees nt)rtli of east. The average
Table V.—Obnermtions of the wind from Mauri/'n Pilot Churln of the Atlantic Ocean.
ATJGUSX.
|
Latitude. |
Longitude. |
u |
&i |
H |
^ ^ |
f^ |
i |
^ a |
fs |
^ ^ |
Course. |
|||||||
|
• |
!zi |
» |
» |
Ui |
M |
a |
aj |
CQ |
w |
m |
'fi |
^ |
1? |
K |
K |
|||
|
aO° to 25° |
50° to 5,5° |
4 |
0 |
41 |
13 |
18 |
2 |
11 |
1 |
1 |
0 |
2 |
2 |
0 |
0 |
0 |
0 |
|
|
■20--25 |
55-60 |
3 |
2 |
28 |
12 |
21 |
2 |
6 |
1 |
2 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
|
|
■20-25 |
60-65 |
0 |
1 |
9 |
19 |
12 |
15 |
7 |
1 |
1 |
4 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
'J(V25 |
6.5-70 |
U |
0 |
0 |
3 |
(i |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
20-2.5 |
70-75 |
0 |
0 |
3 |
0 |
3 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
1.5-20 |
50-.55 |
0 |
9 |
28 |
14 |
18 |
8 |
2 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
1.5-20 |
5.5-60 |
0 |
0 |
17 |
4 |
3 |
/ |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
15-20 |
60-65 |
0 |
0 |
3 |
1 |
3 |
1 |
0 |
0 |
2 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
1.5-20 |
65-70 |
0 |
0 |
1 |
I |
4 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
15-20 |
70-75 |
0 |
0 |
0 |
0 |
6 |
0 |
0 |
0 |
0 |
0 |
0 |
u |
0 |
0 |
0 |
0 |
N. 73° E. |
|
7 |
12 |
130 |
67 |
94 |
36 |
27 |
3 |
7 |
4 |
3 |
2 |
0 |
0 |
0 |
0 |
SEPTEMBER.
|
20° to 25° |
50° to 55° |
2 |
4 |
22 |
23 |
12 |
6 |
15 |
1 |
1 |
7 |
8 |
2 |
2 |
2 |
0 |
1 |
|
|
20-25 |
55-60 |
2 |
17 |
27 |
11 |
23 |
12 |
34 |
1 |
3 |
2 |
4 |
0 |
1 |
0 |
0 |
0 |
|
|
20-25 |
60-65 |
1 |
1 |
9 |
0 |
4 |
2 |
9 |
0 |
2 |
1 |
3 |
0 |
0 |
0 |
0 |
0 |
|
|
20-25 |
65-70 |
0 |
0 |
0 |
0 |
1 |
0 |
1 |
0 |
4 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
20-25 |
70-75 |
0 |
0 |
0 |
0 |
1 |
0 |
1 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
15-20 |
50-55 |
0 |
0 |
12 |
19 |
2 |
0 |
2 |
0 |
7 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
15-20 |
55-60 |
0 |
0 |
3 |
1 |
' 9 |
4 |
3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
15-20 |
60-65 |
0 |
0 |
3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
15-20 |
65-70 |
0 |
0 |
0 |
0 |
4 |
6 |
2 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
1.5-20 |
70-75 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
East, |
|
5 |
22 |
76 |
54 |
56 |
30 |
67 |
3 |
18 |
10 |
15 |
2 |
3 |
2 |
0 |
1 |
OCTOBEK.
|
20° to 25° |
50° to 55° |
1 |
1 |
14 |
9 |
22 |
16 |
18 |
3 |
6 |
6 |
3 |
0 |
2 |
0 |
1 |
0 |
|
|
20-25 |
55-60 |
6 |
4 |
10 |
4 |
12 |
2 |
27 |
6 |
7 |
1 |
3 |
2 |
1 |
0 |
3 |
0 |
|
|
20-25 |
60-65 |
0 |
0 |
12 |
5 |
6 |
7 |
9 |
1 |
0 |
2 |
9 |
2 |
0 |
1 |
1 |
0 |
|
|
20-25 |
65-70 |
0 |
0 |
1 |
1 |
5 |
7 |
2 |
4 |
0 |
0 |
4 |
0 |
0 |
0 |
0 |
0 |
|
|
20-25 |
70-75 |
0 |
0 |
I |
0 |
7 |
8 |
2 |
0 |
0 |
0 |
0 |
3 |
0 |
0 |
0 |
0 |
|
|
15-20 |
50-55 |
1 |
3 |
18 |
10 |
22 |
12 |
7 |
0 |
2 |
0 |
3 |
0 |
1 |
0 |
0 |
0 |
|
|
15-20 |
55-60 |
1 |
1 |
8 |
17 |
12 |
6 |
13 |
3 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
15-20 |
60-65 |
0 |
o| |
1 |
1 |
1 |
0 |
4 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
15-20 |
65-70 |
0 |
0 |
3 |
0 |
6 |
0 |
12 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
lS-20 |
70-75 |
0 |
0 |
7 |
1 |
4 |
0 58 |
2 |
0 |
0 |
0 |
0 |
0 7 |
0 4 |
0 1 |
0 5 |
0 0 |
S. 79° E. |
|
9 ! |
9 |
75 |
48 |
97 |
96 |
18 |
16 |
9 |
22 |
course of the storms mentioned in Table III, while moving westward, was 26° north of west; that is, they came from a point 26° south of east, which differs 28° from the average course of the wind by Table V, and ditters 'o()° by Table VI. It is clear, then, that the West India cyclones do not follow the average direction of the wind for the region in which they occur. Tables Y and VI, however, show that winds from the SE. and ESB. are very common, and the observations quoted in article 'S.i show that SE. winds very generally succeed a West India cyclone. These facts seem to indicate that the direction of a cyclone's progress is not determined by the direction of the i>reva]eut wind for that season of the year so much as by the direction of the principal wind which prevails at the time of the cyclone.
36. I next undertook an investigation of the cyclones origi?)ating in the region south of the continent of Asia. Table VII contains various particulars respecting those cyclones of this region whose paths have been best determined. It includes all those which were most carefuUv investi-
24
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
gated by He^ll•^ Pidiliugtoii, tojifther with tliost; whicb liiive been siinje investigated by Blautbrd, Elliott, ami otliers. Column 1 gives the number oC reference; eoluum 2 shows the date of com- meiiceiueut, so far as indicated by the published observatious ; coUinm 3 shows the latitude of the storm's center when it first became violent; column 4 shows the average course of the storm while advancing westward ; column 5 shows the velocity of progress in English statute miles per hour
Table VI. — Observations of the wind from the charts of the U. S. Hydrographic Office-
AUGUST.
|
Latitude. |
Lougitiide. |
^ |
iz; J2! |
H a m |
e4 |
c4 to |
an |
OQ |
02 00 |
OD |
i |
^ |
1 Course. 1 |
|||||
|
20° to 25° |
50° to 55° 55-60 60-65 65-70 70-75 50-55 55-60 60-65 65-70 70-75 |
1 I 0 2 2 1 0 1 1 6 |
1 2 ■3 4 0 ■(^ 0 2 2 1 |
45 29 12 16 17 44 33 9 9 17 |
24 21 23 26 17 23 25 28 31 14 |
14 27 22 28 29 18 26 41 25 31 |
6 12 13 6 14 4 13 15 12 12 |
6 4 12 6 t 2 4 11 11 |
4 6 1 |
i 2 1 5 |
.... |
1 |
1 |
N. 78° E. 1 |
||||
|
20-25 |
1 |
|||||||||||||||||
|
20-25 |
3 1 |
1 |
2 |
1 |
||||||||||||||
|
20-25 20-25 15-20 15-20 15-20 15-20 15-20 |
||||||||||||||||||
|
1 |
||||||||||||||||||
|
1 |
||||||||||||||||||
|
1 |
||||||||||||||||||
|
... |
||||||||||||||||||
|
2 2 |
2 1 |
1 |
2 |
1 |
||||||||||||||
|
15 |
23 |
231 |
232 |
261 |
107 |
64 |
18 |
12 |
5 |
5 |
2 |
1 |
0 |
2 |
1 |
SEPTEMBER.
|
20° to 25° 20-25 20-25 20-25 20-25 15-20 15-20 15-20 15-20 15-20 |
50° to 55° 55-60 60-65 65-70 70-75 50-55 55-60 60-65 65-70 70-75 |
0 1 0 1 2 0 5 |
i; 6 3 6 1 1 6 6 2 2 |
19 23 16 22 11 29 21 14 15 21 |
xs 14 12 17 11 29 18 4 11 12 |
10 15 18 16 21 20 36 21 20 26 |
6 8 12 18 6 8 11 12 25 15 121 |
12 18 15 9 15 6 ■5 19 14 6 |
5 1 6 4 8 0 0 1 4 4 |
1 2 5 3 9 5 |
2 1 1 6 5 0 |
2 3 2 0 5 1 |
1 0 1 1 4 1 |
2 ] 1 .. |
! |
N. 8ai° E. |
|
|
1 .... 1 0 10 |
|||||||||||||||||
|
2 |
|||||||||||||||||
|
1 3 2 |
5 1 0 |
5 |
4 |
5 .. |
1 . 1 . 1 |
||||||||||||
|
2 |
|||||||||||||||||
|
i |
14 |
39 |
191 |
146 |
i03 |
119 |
33 |
31 |
21 |
20 |
12 |
11 2 4 |
3 |
OCTOBEB.
|
20° to 25° |
50° to 55° |
5 |
2 |
18 |
15 |
19 |
12 |
12 |
2 |
5 |
3 |
1 |
1 |
1 |
1 |
1 |
||
|
20-25 |
55-60 |
4 |
1 |
17 |
11 |
15 |
7 |
19 |
4 |
4 |
1 |
5 |
1 |
2 |
0 |
2 |
i |
|
|
20-25 |
60-65 |
1 |
3 |
11 |
11 |
15 |
14 |
18 |
2 |
2 |
1 |
o |
2 |
0 |
0 |
2 |
.... |
|
|
20-25 20-25 |
65-70 70-75 |
1 2 |
5 1 |
11 8 |
4 12 |
18 37 |
19 11 |
11 6 |
10 4 |
2 3 |
3 2 |
11 2 |
1 2 |
|||||
|
15-20 |
.50-,55 |
2 |
4 |
28 |
20 |
14 |
8 |
9 |
0 |
2 |
0 |
5 |
0 |
i |
1 |
1 |
||
|
15-20 |
55-60 |
4 |
5 |
13 |
14 |
19 |
11 |
17 |
1 |
1 |
0 |
1 |
0 |
2 |
1 |
0 |
||
|
15-20 |
60-65 |
3 |
« |
11 |
19 |
18 |
9 |
«0 |
4 |
in |
1 |
1 |
||||||
|
15-20 15-20 |
65-70 70-75 |
6 6 |
1 4 |
19 21 |
4 18 |
29 18 |
11 1 |
21 5 |
2 5 |
2 |
East. |
|||||||
|
4 33 |
1 8 |
1 7 |
||||||||||||||||
|
11 |
31 |
3 |
6 |
11 |
||||||||||||||
|
34 |
28 |
157 |
12i |
202 |
103 |
138 |
34 |
wiiile moving westward ; column 6 shows the latitude at which the course of the storm became due north ; column 7 shows the velocity while moving north ; ct)lainn 8 shows the average course of the storm after turning eastward; column 9 shows the hourly velocity of progress while moving eastward ; column 10 shows whether rain was mentioned as accompanying the storm, and whether the rain fall was violent or not; column 11 indicates the name of the jierson by whom the phe- nomena of the storm were investigated, and column 12 shows where the record of the investigation may be found.
37. It will be seen that 52 per cent, of these cases occurred in the months of September October, and November, and 43 per cent, occurred in the months of April, May, and June, leaving
CONTRIBUTIONS TO MI^TKOROLOGY,
25
only 5 per cent, of the cases for the six remaining months of the j-ear. Of tlie West India cyclones previously rei)()rte(l 88 per cent, occurred in the months of August, September, and October, leaving only 12 per cent, for the remaining nine months of the year ; that is, the Asiatic cyclones occur in the spring almost as frequently as in the autumn ; but the West India cyclones are almost exclu- sively contined to the period near the autumnal e(iuinox.
The lowest latitude of any storm i)ath here recorded is 61°, and (here are fourteen cases below latitude 12°. The lowest latitude of pny of the West India cyclones is 10°..'i, and there are only three cases as low as latitude 12°.
Table VII. — Course of cyclones originating near the China Sea, Bay of Bengal, tfcc.
No.
Date of coru- mencenient.
1803,
1810, 1835, 1838, 1839,
1840,
1841, 1842,
1843,
1844, 1845,
1847,
1848, 1850,
1«51,
1852, 1854, 1856, 1858, 1864, 1869,
1870, 1672,
1874,
1876, 1877,
Sept. 21 Sept. 28 j Aug. 5 Apr. 8 I June 3 Sept. 20 Nov. 12 ! Apr. 27 I Sept. 22 i May 15 June 2 Oct. 1 Oct. 22 May 20 Nov. 28 Nov. 9 I Oct. 7 Nov. 29 Apr. 1() Nov. 18 i Oct. 12 I Apr. 23 Nov. 17 ' Mav 2 Oct. 21 Mav 12 Apr. 22 Dec. 7 Apr. 9 Oct. 3 May 13 June .5 Oct. 7 Nov. 4 Apr. 28 June 28 Sept. 19 ' May 3 Oct. 13 Oct. 6 Oct. 27 May 14
16.0°
18.1
20.5
22.6
20. 0
22.0
13.3
11.6
1.5.6
10.0
20.5
17.7
12.0
6.1 11.1 17.1
6.7
7.9
17.0
17.8
12.2 10.6 17.6 15.7 13.2 10.0 14.2 16.0 16. 0 16.4 20. 5 16.5
7.5 20.5 21.0
9.0 16.6 14.4 11.0
9.3
•— ' QO — QJ
.5% o o.
St
&2
W. 15 N. 9. 1 W. 12 S. 7. 3 W. 18 N. 117.0
W. 13 S. W. .52 N. W..a3 N. W. 54 N. W. 83 N. W. 25 N W. 69 N. W. 31 N.
W. W. 38 N. W. 40 N. W. 16 N. W. 19 N. W. 12 N. W. 86 N. W. 49 N. W. 50 N. W. 50 N. W. 70 N. W. 54 N.
3.9 9.5 6.2 9.8 10.0 14.7 4.8 7.5
^.2
a
'> o .
-■5
+J o
it
I '5 -a"
'3 a
O IS
24.3
9.4 6.2
4.8 8.1, 6.0 3.6
W. 24N. 11.7
W. 56 N. W. 44 N. W. 83 N. \V. 34 N. W. 11 N. W. 50 N. W. 21 N.
9.2 i 7.6
4.0 12.5 12.0
.\0
7.1
S. 37 E.
5.0
Rain- fall.
4.6
18.5
iao
5.8
9.'i'
N. .53 E. 5. 0
17.6 20.0
21.3
20.5 24.0
|
w. |
.39 N. |
7.0 |
|
w. |
60 N. |
6.9 |
|
w. |
25 N. |
7.5 |
'23. 0
W. 63 N. 5. 0
22.1 17.6 14.0 1.5.0
10.9 10.1
12.0 14.0 9.5
N. 42 E.
N. 39 E.
'n.39E. N. 29 E. N.25E. N.39E
5.7
9.8
12." i
15.0 17.0 11.0
12. 7 N. 43 E.
8.3
6.0
10.0
7.9
N.40E. N. 16 E. N. 17 E. N. 45 E.
13.7
9.4
H.O
:2o.o
!l0.4
Heavy., Hea vy . ,
Heavy . Hail.... Violent Violent Heavy,. Violent. Violent . Heavy . . Violent. Violent . Violent . Heavy.. Rain . .. Heavy . . Rain . .. Violent. Violent . Raiu . . . Rain . . . Violent. Heavy . . Violent. Rain . . . Rain ... Heavy.. Violent. Violent - Violent. Rain . . . Violent , Violent, Violent, Heavy . . Violent. Violent , Violent, Violent, Heavy . , Violent , Violent.
Investigator.
Where re(^orde(l.
Piddington Piddiugton Redtield....
Floyd
Piddington
Piddington
Piddington
Piddiugton
Piddington
Piddiugtou
Piddiugton.
Piddington.
Piddington.
Piddington.
Piddington.
Piddington.
Piddington.
Piddiugton .
Piddiugtou .
Piddiugton.
Piddiugton.
Piddiugtou,
Piddiugton,
Piddiugton .
Piddiugtou ,
Piddiugtou,
Piddiugton,
Manry
Liebig
Gnstrell
Blauford .. . Blanford .. . Blauford .. . Blanford . . , Blanford .. . Blanford -. Blanford . . . Blanford . . .
WillBon
Elliott
Elliott
Elliott
Jo. Asia. Soc.v. 11. .Jo. Asia. Soc, v. 11. Jo. Science, v. 35. Jo. Asia. Soc, v. 7. Jo. Asia. Soc, v. 8. Jo. Asia. Soc, v. 9. Jo. Asia. Soc, V. 9. Jo. Asia. Soc, v. 9. Jo. Asia. Soc, v. 10. .Jo. Asia. Soc, v. 11. Jo. Asia. Soc, v. 11. Jo. Asia. Soc, v. 12. Jo. Asia. Soc, v. 12. Jo. Asia. Soc, v. 13. Jo. Asia. Soc, v. 14. Jo. Asia. Soc, V. 14. Jo. Asia. Soc, v. 18. Jo. Asia. Soc, v. 14. Jo. Asia. Soc, v, 17. Jo. Asia. Soc, v. 18. Jo. Asia. Soc, v. 18. Jo. Asia. Soc, v. 20. Jo. Asia. Soc.v. 23. Jo. Asia. .Soc, v. 21. Jo. Asia. Soc, V. 23. Jo. .\sia. Soc, V. 24. • Jo. Asia. Soc, v. 27. Sailing Directions, v. 1. Jo. Asia. Soc. , v. 27. Special Report. S|)ecial Report. Special Report. Special Report. Special Report. Special Report. Special Report. Special Report. Special Report. Special Report. Special Report. Special Report. Special Report.
The courses of these storms while moving westward range from 13° south of west ro 86° north of west, the average direction being 38° north of west. In two cases the course was reported to be south of west, and in one case it was exactly west, which result accords very closely with that before found for West India cyclones. The average velocity of progress of these storms while advancing westward was 8.1 En^ish statute miles per hour, which is less than half the average velocity of West India cyclones.
The average latitude of the storm centers, when the course became due north, was 19o.8, ami the latitudes range from 14^ to 24°.3, which is ten degrees more southerly than the latitude before S. Mis. 154 i
26
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
found for the West India cyclones. The average velocity of progress of these storms when ad- vancing northward was 9.3 miles per hour.
The average course of these storms, after turning eastward, was 35° east of north, and their velocity of progress was 9.8 miles, which is scarcely half of tlie velocity found for West India cyclones.
Column 10 shows that rain aecomi)anied every one of these storms, and generally the rain-fall was escessivelj- great. These observations were gi nerally made from vessels on the ocean, and the amount of the rainfall could not be measured, but the rain was generally characterized by the strongest terms which the English language furnishes, such as, very heavy rain — constant heavy rain — ceaseless rain— excessively heavy rain — incessant heavy rain — sheets of rain — deluge of rain — rain poured down in torrents — dense, thick, impenetrable rain — rain with a vengeance — rain and very large hail — rain and sleet — hard sleet — torrents of rain and sleet, &c.
38. When a storm center passed overland where a rain-gauge was observed the measurements showed that the preceding terms were no exaggeration. The following table shows the amount of rainfall in twenty-four hours at certain stations within the limits of the cyclones named in Table VII : '
Table VIII. — Eainfall in trojncal cyclones.
|
Date. |
Place. |
Latitude. |
Longi- tude. |
Rain, inches. |
1 Authority. |
|||
|
1839, |
June |
4 |
Dacca |
23. 7° |
90. 5'-^ |
6.00 |
Piddiugton, 1st Memoir, p. 37. |
i |
|
1842, |
June |
3 |
Calcutta |
22. 5 |
88.3 |
5.17 |
7th Memoir, |). 35. |
|
|
June |
3 |
Kissenuggur . . |
23. 4 |
88.4 |
9.00 |
7th Memoir, p. 42. |
||
|
Oct. |
3 |
Pooree |
19.8 |
85.9 |
5.10 |
9th Memoir, p. 27. |
||
|
1843, |
May |
23 |
Cannanore |
11.9 |
93.2 |
5.95 |
10th Memoir, p. 32 |
|
|
May |
23 |
Madias |
13.1 |
80.3 |
10.50 |
10th Memoir, p. 20 |
||
|
May |
23 |
Hyderabad |
25.3 |
68.4 |
9.00 |
10th Memoir, p. 29 |
||
|
1851, |
May |
5 |
Madras |
13.1 |
80.3 |
11.44 |
21st Memoir, p. IT |
|
|
1864, |
Oct. |
6 |
Contai |
21.8 |
87.8 |
10.00 |
Rep. of Gastrell & Blauford, p. |
82. |
|
Oct. |
6 |
Bograh |
24.8 |
89.4 |
7.10 |
P- |
82. |
|
|
Oct. |
6 |
Goalparah |
26.2 |
90.7 |
60.00 |
P- |
82. |
|
|
Oct. |
6 |
Moisgunj |
23.4 |
88.5 |
7.50 |
P- |
82. |
|
|
1874, |
M,ay |
4 |
Madras |
13.1 |
80.3 |
7.10 |
Wilson's Report, p. 127. |
|
|
Oct. |
15 |
False Point.. .. |
20.3 |
86.8 |
6.30 |
p. 9. |
||
|
Oct. |
15 |
Jellasore |
21.5 |
86.9 |
5.82 |
p. 9. |
1 |
|
|
Oct. |
15 |
Miduapore |
22.4 |
87.2 |
10.27 |
p. 8. |
||
|
Oct. |
16 |
Burdwau |
23.2 |
87.9 |
7.43 |
p. 8. |
||
|
Oct. |
16 |
LalgoUa |
24.5 |
88.3 |
16.30 |
p. 8. |
||
|
Oct. |
16 |
Jungipore |
24.5 |
87.8 |
8.00 |
p. 8. |
||
|
Oct. |
16 |
BoodBood |
23.0 |
88.0 |
8.40 |
p. 8. |
||
|
Oct. |
17 |
Riingpore |
25.9 |
89.3 |
6.97 |
p. 9. |
||
|
1876, |
Oct. |
7 |
Vizagapatam . . |
17.7 |
8.3.4 |
5.60 |
Elliott's Report, p. 48. |
|
|
Oct. |
8 |
Vizagajiatam .. |
17.7 |
■ 83. 4 |
12.60 |
p. 48. |
||
|
Nov. |
1 |
Noakliolly |
22.8 |
91.0 |
5.12 |
p. 153. |
||
|
Nov. |
1 |
Putiiaklially .. |
22.3 |
90.4 |
5.85 |
p. 153. |
||
|
1877, |
May |
18 |
Madras . |
13.1 |
80.3 |
13. 01 |
p. 42. |
|
|
May |
20 |
Gya |
24.6 |
85.1 |
5.06 |
p. 75. |
||
|
May |
20 |
Nowada |
23. 9 |
88.4 |
8.00 |
p. 75. |
||
|
May |
21) |
Aurungabad. .. |
19.9 |
75.3 |
8.68 |
p. 7.5. |
||
|
MaV |
20 |
Rajiuahal |
2.5.0 |
87.7 |
5.20 |
p. 75. |
||
|
May |
20 |
Raignnge |
25.0 |
88.0 |
5.71 |
p. 75. |
||
|
May |
20 |
Jawai |
25.0 |
91.0 |
9.70 |
p. 75. |
||
|
May May |
21 21 |
Barrh |
25.5 25.0 |
95.7 88.2 |
6.43 6.14 |
p. 7/. |
||
|
Chanchal |
||||||||
|
May |
21 |
Ruugpore |
25.9 |
89.3 |
11.16 |
p. 77. |
||
|
May |
21 |
Kiirigrara |
25.0 |
89.0 |
5.70 |
p. 77. |
||
|
May |
21 |
Bogdogra |
25.0 |
89.0 |
12.19 |
p. 77. |
||
|
May |
21 |
Julpigoree |
26.5 |
88.7 |
5.53 |
p. 77. |
||
|
May |
21 |
Boda |
26.0 |
89.0 |
8.52 |
p. 77. |
||
|
May |
21 |
Coocb Behar. .. |
26. 3 |
89.5 |
9.77 |
p. 77. |
||
|
MaV |
21 |
Dhubri |
26.0 |
90.0 |
5.60 |
p. 77. |
||
|
MaV |
21 |
Jawai |
2.5.0 |
91.0 |
14.20 |
p. 77. |
||
From this table we see that these cyclones were accompanied by an amount of j-ain such as seldom occurs even within the tropics, and we seem authorized to conclude that excessive rain
CONTRIBUTIOIfS TO METEOROLOGY. 27
invariably aceonipaiiies tlu' most violent cyclones. This conclnsion accords with that deduced from the investijiation of tiie West India cyclones.
39. I next examined all the nuips of the international observations for additional materials showing the course of storms in Sontherii Asia and the adjacent ocjeans. The following are the most important cases which I have found of storms advancing in a westerly direction:
Table IX. — Asiatic storms advancing westerly.
|
No. |
Date. |
Latitude. Beg. End. |
L'lngilude. Beg. Eud. |
Course. |
Velooitj , miles. |
Subsequent course. |
|
|
1 |
1878, Sept. |
l.'S-19 |
15-30° |
134-125^ |
NNW. |
10.8 |
Moved NE. |
|
2 |
Oft. |
7- •) |
19-19 |
122-110 |
W. |
14.3 |
Unknown. |
|
3 |
Nov. |
17-21 |
12-15 |
95- 82 |
w. |
7.2 |
tlnknitwu. |
|
4 |
Nov. |
29-38 |
12-20 |
97- 81 |
W. ifcNW. |
5.8 |
Unknown. |
|
5 |
1879, Apr. |
17-23 |
1.3-20 |
134-126 |
W. & NW. |
5.4 |
Moved NE. |
|
6 |
Mav |
30-32 |
20-22 |
88- 90. |
W. & N. |
10. 8 |
Moved NE. |
|
7 |
1880, Jufy |
13-19 |
6-21 |
121-106 |
NW. |
8.4 |
Unknown. |
|
8 |
Julv |
25-33 |
15-lH |
132-107 |
W. |
7.8 |
Unknown. |
|
9 |
July |
30-39 |
18-30 |
143-12S |
NW. |
5.6 |
Moved northward. |
|
10 |
Auk- |
25-32 |
13-19' |
125-107 |
WNW. |
7.2 |
Unknown. |
|
11 |
Sept. |
14-19 |
16-17 |
127-106 |
W. |
9.6 |
Unknown. |
|
12 |
Sept. |
l.-^25 |
11-19 |
127-106 |
NW. & W. |
7.0 |
Unknown. |
|
13 |
Sept. |
26-28 |
19-22 |
129-113 |
W. |
17.2 |
Unknown. |
|
14 |
Oct. |
10-17 |
17-18 |
127-1U8 |
W. |
6.3 |
Unknown. ! |
|
15 |
Oct. |
24--28 |
9-;2 |
120-122 |
N. |
7.7 |
Unknown. |
|
16 |
Nov. |
9-14 |
10- 7 |
118-103 |
W. |
7.2 |
Unknown. ' |
|
17 |
188J, May |
22-31 |
9-17 |
12H-111 |
WNW. |
7.5 |
Moved eastward. |
|
Irt |
Jiiue |
26-35 |
10-29 |
126-121 |
NW. ; N. & NE. |
8.3 |
Moved NE. : |
|
19 |
July |
6-11 |
9-20 |
123-lOti |
WNW. |
10.0 |
Unknown. |
|
20 |
July |
10-17 |
H-30 |
12"<-122 |
NNW. |
10.0 |
Moved NE. |
|
21 |
Aug. |
9-16 |
24-24 |
136-109 |
NW. & W. |
10.4 |
Unknown. |
|
22 |
Aug. |
18-24 |
12-2-2 |
127-108 |
WNW. |
8^6 |
Unknown. |
|
23 |
Aug. |
23-30 |
17-30 |
130-124 |
NW. & N. |
8.3 |
Unknown. |
|
24 |
Sept. |
6-10 |
14-28 |
126-112 |
NW. |
8.6 |
Unknown. |
|
25 |
Sept. |
29-40 |
14-22 |
1-J6-I07 |
W. & NW. |
8.6 |
Moved NE. |
|
26 |
Oct. |
12-18 |
16-30 |
126-119 |
NW. |
11.5 |
Moved NE. |
|
27 |
Oct. |
18-30 |
12-30 |
124-106 |
W. & NW. |
6.6 |
Moved NE. |
|
28 |
Nov. |
5-12 |
10- 9 |
125-108 |
W |
9.6 |
Unknown. |
|
29 |
Nov. |
26-29 |
9-14 |
127-108 |
WNW. |
14.3 |
Unknown. |
Ou Plate XII, Fig. 2, these tracks are delineated, and are designated by the same numbers as in the table. The average direction of progress of these storms in the early part of their course was 27^° north of west, and their average rate of progress was 9 miles per hour. This velocity corresponds closely with that deduced from Table VII, but the direction corresponds more nearly with that found for the West India cyclones.
40. I ne.xt endeavored to compare this average direction of storm i)aths with the average direction of the wind in the same region. In- the Bay of Bengal and in the China Sea the average direction of the wind is from the northeast in winter and from the soutliwest in summer. In order to make a satisfactory comparison between the average direction of the wind aud that of the progress of storms we must make a separate comparison for the ditf'erent seasons of the year ; and since the winds of the China Sea differ somewhat from those of the Bay of Bengal, I will restrict the comparison to the China Sea, and omit the storuis numbered 3, 4, and 6, which occr.rred in the Bay of Bengal.
Of the remaining twenty-six storms we perceive that none occurred in the months of De- cember, January, February, and March, and only one occurred in each of the months of April, May, and June. Five occurred in July, four in August, six in Sei)tember, five in October, and three in November. We will therefore restrict the comparison to the five mouths from July to November. The following table is derived from Maury's Pilot Chart of the China Sea, and shows for these months the number of times the wind was observed to blow from the different poiuts of the compass in each of the five degree squares from latitude 10° to latitude 20° N., and longitude 110° to longitude 125° E. from Greenwich.
28
MEMOIRS OF THE NATIONAL ACADEMY OP SCIENCES.
Table X. — Obserrations of the u- hid from Mauryh Pilot Charts of the Pacific Ocean.
JULY.
|
Latitude. |
Lougi tilde. |
P. |
a |
M |
a |
i |
%■ |
05 |
^ |
i |
^ |
Course. |
||||||
|
a |
Z |
z |
w |
W |
w |
03 |
02 |
02 |
OD |
OQ |
^ |
a |
||||||
|
150 to ao= |
110° to 115° |
2 |
0 |
5 |
6 |
7 |
2 |
IH |
29 |
54 |
38 |
26 |
5 |
12 |
4 |
1 |
0 |
|
|
15-20 |
115-120 |
2 |
0 |
7 |
0 |
0 |
0 |
2 |
2 |
2 |
33 |
24 |
13 |
3 |
0 |
3 |
1 |
|
|
15-20 |
120-125 |
0 |
0 |
6 |
3 |
2 |
2 |
4 |
1 |
3 |
1 |
3 |
0 |
1 |
2 |
2 |
0 |
|
|
10-15 |
110-115 |
1 |
0 |
2 |
2 |
6 |
4 |
26 |
14 |
27 |
57 |
61 |
18 |
9 |
6 |
3 |
1 |
|
|
10-15 |
115-120 |
3 |
0 |
3 |
1 |
5 |
4 |
16 |
7 |
13 |
13 |
43 |
7 |
15 |
3 |
7 |
3 |
|
|
10-15 |
120-125 |
0 |
1 |
0 |
0 |
0 |
3 |
7 |
1 |
16 |
7 |
17 |
10 |
5 |
1 |
14 |
1 |
S. 22° W. |
|
8 |
1 |
23 |
12 |
20 |
15 |
73 |
54 |
115 |
149 |
174 |
53 |
45 |
16 |
30 |
6 |
AUGUST.
15° to 20° ! 110° to UB'-
15-20 15-20 10-15 10-15 10-15
11.5-120 120-125 110-115 115-120 120-125
24 6
11
16
27
17
28 12
0 13
4 16
73
38 13
0 23 25
0
46 38 0 135 39 14
99 272 60
9
0
0
17
11
0
37
23
s. 390 W.
SEPTEMBER.
|
15° to 20° |
110° to 115° |
22 |
12 |
31 |
15 |
34 |
9 |
15 |
10 |
18 |
10 |
9 |
2 |
7 |
7 |
3 |
3 |
|
|
15-20 |
115-120 |
10 |
2 |
20 |
4 |
13 |
12 |
25 |
6 |
29 |
1 |
29 |
6 |
12 |
7 |
12 |
20 |
|
|
15-20 |
120-125 |
0 |
0 |
0 |
3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
3 |
0 |
0 |
0 |
|
|
10-15 |
110-115 |
19 |
5 |
9 |
0 |
1 |
0 |
6 |
8 |
40 |
54 |
139 |
39 |
39 |
7 |
23 |
4 |
|
|
10-15 |
115-120 |
6 |
1 |
5 |
4 |
1 |
0 |
8 |
4 |
21 |
13 |
49 |
8 |
15 |
3 |
10 |
3 |
|
|
10-15 |
120-125 |
1 |
1 |
6 |
3 |
0 |
0 |
5 |
2 |
7 |
6 |
4 |
9 |
3 |
1 |
1 |
5 |
S. 39° W. |
|
58 |
21 |
71 |
29 |
49 |
91 |
59 |
30 |
115 |
84 |
230 |
64 |
79 |
25 |
49 |
35 |
OCTOBER.
|
15° to 20° |
110° to 115° |
10 |
18 |
67 |
15 |
33 |
4 |
9 |
4 |
3 |
1 |
2 |
0 |
0 |
(1 |
1 |
1 |
|
|
15-20 |
115-120 |
36 |
16 |
111 |
22 |
35 |
7 |
15 |
7 |
21 |
5 |
7 |
1 |
12 |
6 |
5 |
3 |
|
|
15-20 |
120-12.") |
0 |
0 |
3 |
3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
2 |
0 |
0 |
|
|
10-ir, |
110-115 |
43 |
19 |
74 |
11 |
21 |
11 |
15 |
22 |
23 |
10 |
22 |
6 |
8 |
8 |
24 |
15 |
|
|
10-15 |
lJ.5-120 |
32 |
13 |
34 |
10 |
38 |
14 |
6 |
13 |
14 |
1 |
14 |
7 |
5 |
3 |
13 |
10 |
|
|
10-15 |
120-125 |
6 |
0 66 |
2 |
3 |
4 |
1 |
5 |
2 |
0 |
0 |
1 |
0 14 |
0 25 |
0 19 |
4 47 |
0 29 |
N.-53° E. |
|
127 |
291 |
64 |
131 |
37 |
50 |
.48 |
(>3 |
17 |
46 |
NOVEMBER.
|
15° to 20° |
110° to 115° |
-. 5 |
21 |
44 |
14 |
6 |
2 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
■0 |
2 |
|
|
15-20 |
115 120 |
43 |
24 |
107 |
13 |
14 |
5 |
5 |
5 |
7 |
0 |
0 |
0 |
3 |
0 |
11 |
1 |
|
|
15-20 |
120-125 |
3 |
3 |
5 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
10-15 |
110-115 |
30 |
19 |
103 |
34 |
19 |
5 |
7 |
3 |
1 |
0 |
4 |
0 |
1 |
0 |
8 |
7 |
|
|
10-15 |
115-120 |
31 |
13 |
82 |
26 |
25 |
2 |
3 |
3 |
6 |
0 |
11 |
1 |
3 |
3 |
20 |
5 |
|
|
10-15 |
120-125 |
a |
0 |
3 |
0 |
0 |
3 |
2 |
0 |
0 |
1 |
1 |
0 |
3 |
0 |
0 |
0 |
N. 41° E. |
|
114 |
80 |
344 |
87 |
64 |
17 |
18 |
11 |
14 |
1 |
16 |
1 |
10 |
8 |
39 |
15 |
Tlie average cour.se of the wincLs deduced tYoin tbcse iiuiuber.s i.s, for July, S. 22° W. ; for Aiiguist, S. 390 W.; for September, S. 39° VV.; for October, N. 53° E.; aud for November, N. 41° E. For the first three mouths tbe average directiou of the wiuds is S. 33° W., and for the last two mouths it is N. 47° E. For the first tliree months the average directiou of progress of .storms (as deduced from Table VII, combined with Table IX) is 35° north of west, aud for the last two mouths it is 25^° north of west. That is, a change of 166° in the average direction of the wind
CONTRIBUTIONS TO METEOROLOGY,
29
is accoiiipauied by a change of only 9|o in the average direction of the ])rogTess of storms. Tliis fact clearly indicates that the direction in which storms advance is mainly determined by some other canse than the mean direction of the wind.
41. 1 next endeavored to ascertain wliat was the prevalent direction of the wind wliich ])re- cedcd each of the storms referred to in Table IX, and also the prevalent wind which sncceeded the low center. The observations pnblisiied in the United States International Bulletin include only two stations within the tropics in the neighborhood of the China Sea, via, Manila and Tnguegarao, both of them on the island of Luzon, one of the Philippine Islands (see Plate V), and the observations at the latter station commence witii the year 18SL The following table shows the observations at these two stations for all those storms of 1881 which passed near enough to either of these stations to canse a decided fall of the barometer. The observations include (I) The barometer in English inches reduced to sealevel; (2) the thermometer (Fahrenheit); (3) the rela- tive humidity; (4) the wind's direction; (5) the wind's velocity in miles per h> ur; and (6) the rain- fall, in English inches, during the preceding twenty-four hours :
Table XI. — Obnervations near the time of cyclones.
|
MANILLA. |
TUGUEGARAO. |
||||||||||||
|
Barom. |
Therm. |
Hum. |
Wind. |
Rain. |
Barom. |
Therm. |
Hum. |
Wind. |
Rain. |
||||
|
188 1. |
|||||||||||||
|
Direction. |
Velocity. |
Direction. |
Velocity. |
||||||||||
|
June |
27 |
29. H5 |
82. 6° |
87 |
NNE. |
1.1 |
0.08 |
29.92 |
80.1° |
88 |
ESE. |
0.4 |
0.09 |
|
28 |
.51 |
7H.7 |
100 |
W. |
87.2 |
4.71 |
.84 |
79.2 |
92 |
NE. |
0.0 |
0.25 |
|
|
29 |
.83 |
77.4 |
H2 |
ESE. |
8.8 |
5.48 |
.75 |
79.7 |
84 |
SW. |
4.3 |
0.06 |
|
|
30 |
.>'2 |
78.7 |
77 |
SE. |
2.2 |
2.09 |
.76 |
75.9 |
91 |
s. |
11.5 |
0.39 |
|
|
31 |
.b3 |
82.1 |
81 |
E. |
2.2 |
0.16 |
.82 |
H5.0 |
78 |
s. |
1.3 |
0.04 |
|
|
July |
6 |
.80 |
83.0 |
72 |
SW. |
11.4 |
0.04 |
.81 |
83.2 |
71 |
NNW. |
4.2 |
0.00 |
|
7 |
.7' |
80.5 |
69 |
sw. |
12.1 |
3.39 |
■ .81 |
85. 5 |
73 |
ENE. |
2.0 |
0.04 |
|
|
H |
.73 |
«1.0 |
75 |
ssw. |
11.4 |
1.00 |
.76 |
78.0 |
92 |
NW. |
0.0 |
0.93 |
|
|
9 |
.87 |
79.6 |
65 |
ESE. |
2.2 |
0.87 |
.H7 |
77.8 |
94 |
S. |
9.7 |
0.08 |
|
|
10 |
.91 |
80.6 |
66 |
ENE. |
5.5 |
0.15 |
.97 |
81.5 |
87 |
S. |
1.3 |
0.07 |
|
|
July |
11 |
. "'■"' |
84.1 |
72 |
SW. |
6.6 |
0.00 |
.90 |
80.7 |
78 |
N. |
3.7 |
0.01 |
|
1-i |
.71! |
83.7 |
79 |
w |
10.3 |
0.04 |
.80 |
80.0 |
85 |
NNW. |
4.4 |
0.00 |
|
|
13 |
.1-3 |
M. 1 |
77 |
wsw. |
22.0 |
0.22 |
.54 |
78.8 |
93 |
NNW. |
11.0 |
2.40 |
|
|
14 |
.71 |
82.4 |
85 |
sw. |
17.9 |
0.20 |
.65 |
75.5 |
94 |
SSE. |
8.4 |
1.67 |
|
|
15 |
.81 |
82.4 |
84 |
ssw. |
5.9 |
0.31 |
.79 |
79.4 |
90 |
SW. |
1.3 |
0.16 |
|
|
Aug. |
18 |
.85 |
'•O. 5 |
92 |
NW. |
6.6 |
2.41 |
.87 |
80.2 |
78 |
NNW. |
4.7 |
0.04 |
|
19 |
.50 |
78.8 |
98 |
WSW. |
88.4 |
2.17 |
.51 |
77.0 |
92 |
N. |
14.3 |
0.65 |
|
|
20 |
.76 |
79. 2 |
83 |
SE. |
9.9 |
4.68 |
.75 |
77.3 |
83 |
SSE. |
8.3 |
0.70 |
|
|
21 |
.84 |
83.0 |
82 |
ssw. |
8.4 |
0.00 |
.80 |
83.6 |
84 |
S. |
0.0 |
0.00 |
|
|
Aug. |
24 |
.81 |
83.9 |
78 |
wsw. |
16.5 |
0.00 |
.72 |
82.8 |
73 |
N. |
0.9 |
0.00 |
|
25 |
."4 |
r3.3 |
81 |
wsw. |
17.6 |
0.00 |
.64 |
81.7 |
81 |
SE. |
3.2 |
0.00 |
|
|
2'i |
.87 |
-1.7 |
90 |
sw. |
8.4 |
0 98 |
.76 |
83.8 |
75 |
SW. |
4.7 |
e.oo |
|
|
27 |
.94 |
83.5 |
82 |
sw. |
15.7 |
0.00 |
.87 |
84.4 |
74 |
N. |
4.9 |
0.04 |
|
|
Sept. |
5 |
.80 |
-3.9 |
82 |
sw. |
12.8 |
6.00 |
.81 |
80.0 |
83 |
NNW. |
4.5 |
0.00 |
|
6 |
.68 |
84.4 |
80 |
w. |
20.9 |
0.00 |
.56 |
81.9 |
79 |
NNW. |
2.7 |
0.00 |
|
|
7 |
.77 |
82.3 |
80 |
ssw. |
14.7 |
0.61 |
.69 |
81.0 |
88 |
NW. |
0.7 |
0.05 |
|
|
8 |
.82 |
79.6 |
92 |
ssw. |
4.4 |
0.42 |
.82 |
79.0 |
87 |
SE. |
5.4 |
0.01 |
|
|
9 |
.81 |
79.4 |
94 |
E. |
6.6 |
0.11 |
.82 |
82.1 |
84 |
SW. |
0.2 |
0.04 |
|
|
Oct. |
11 |
.82 |
f4.4 |
77 |
ssw. |
8.8 |
0.00 |
.89 |
78.2 |
87 |
NNW. |
5.1 |
0.00 |
|
12 |
.65 |
82. li |
89 |
sw. |
46.2 |
0.77 |
.30 |
75.2 |
98 |
SE. |
40.7 |
0.76 |
|
|
13 |
.86 |
81.9 |
Ki |
sw. |
4.4 |
0.82 |
.84 |
79.2 |
85 |
S. |
1.7 |
0.03 : |
|
|
Oct. |
17 |
.82 |
82.4 |
79 |
NNE. |
7.7 |
0.00 |
.85 |
77.8 |
91 |
NW. |
3.1 |
0.14 |
|
18 |
.72 |
75.4 |
95 |
NNE. |
0.7 |
0.22 ' |
.72 |
84.2 |
98 |
NNW. |
9.6 |
1.28 |
|
|
19 |
.58 |
80.2 |
81 |
W. |
34.8 |
0.55 |
.v2 |
74.9 |
97 |
NNW. |
50.0 |
2.04 |
|
|
20 |
.6-1 |
79.2 |
83 |
SSW. |
3 .7 |
0.45 |
.55 |
80.0 |
78 |
S. |
16.1 |
0.20 |
|
|
21 |
.^2 |
78.4 |
- 95 |
SSE. |
3.3 |
0.65 |
.82 |
78.9 |
86 |
S. |
7.6 |
0.00 |
30
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
42. We see from this table tliat tluring the months from June to September, at both of these statiou.s, in two thirds of the cases, the cyclone was followed by a wind from some point between ESE. and south, and this wind generally lasted more than twenty four hours. In the remaining cases, the wind which followed the cyclone was from the SSW. or SW., and in these cases the center of the cyclone j)assed on the east side of the given station. In the month of October (when the prevalent wind is from the northeast) each cyclone was followed bj' a wind from some point between south and southwest, and this southerly wind lasted more than twenty-four hours. It aj)pears, then, that in the China Sea cyclones are generally succeeded by a southerly wind of con- siderable duration, even in those months in which the average wind is northerly.
From Mr. Elliott's investigations of cyclones in the Bay of Bengal, particularly the cyclone of October S-19, 1882, it appears that these southerly winds, which prevail on the south side of a cyclone, extend down to the equator as strong winds, accompanied by severe squalls and rain. During a tropical cyclone these southerly winds appear to push forward with greater persistence than the northerly winds, and this seems to be at least a part of the reason for the northerly progress of the cyclone.
These results accord substantially with those found in article 33 for West India cyclones, ami show that the average direction of the progress of cyclones does not coincide with the average direction of the wind for the same season of the year, but corresjionds more nearly to that of the principal wind prevailing at the time of the cyclone. It is not, however, claimed that there is an exact agreement between these two directions.
43. An examination of Plate XI shows that in the middle latitudes of the northern hemisphere there is a remarkable correspondence between the average direction of the progress of storm centers and the average direction of the wind as shown on CoflQii's wind charts. I have endeavored to
^ascertain whether this correspondence is exact, or whether there is a constant difference between these two directions. I first made a comparison of these two directions for tlie Atlantic Ocean.
44. In order to determine the average direction of progress of storm centers across the Atlantic Ocean I measured with a protractor the bearing of the storm tracks delineated on the United States International Charts. These bearings were measured for six points, viz, at the intersection of the storm tracks with the meridians of 10°, 2(1°, 30°, 40°, 50°, and 00° west of Greenwich, and the measurements included the observations of four years, viz, 1878-1881. Table XII shows the average results of these measurements for each month of the year and for each of the six points above mentioned. The latitudes named at the top of the table are the average latitudes corre- sponding to the given directions :
Table XII. — Direction of storm tracls.
|
Lou^itucle60°. , Loujiitutle 50°. Latitude 46.9'-\ Latitiule 48.9°. |
Longitude 40°. Latitude 51.3°. |
Longitude 30°. Latitude 53.9°. |
- Longitude 20°. Latitude .54.9°. |
Longitude 10°. Latitude 55.5°. |
||
|
January February March April May |
N. 66° E. 66 73 63 62 76 72 69 67 67 70 65 |
N. 61° E. 67 69 68 67 63 62 74 72 64 67 66 |
N. 64° E. 60 68 72 68 64 59 74 78 72 62 62 |
N. 74<^ E. 60 65 79 71 67 68 77 75 68 69 67 |
N. 86° E. 74 71 91 76 71 76 72 11 (i8 73 |
N. 96° E. 82 79 97 76 71 80 71 73 72 69 80 |
|
June |
||||||
|
July August September.. .. October November December Year |
||||||
|
N. 68 E. N. 67 E. 1 |
N. 67 E. |
N. 70 E. N. 75 E. |
N. 79 E. |
45. I next endeavored to determine the average direction of the wind for the entire year at several poiiits on the Atlantic Ocean, as near as possible to the points corre^pouding to the pre- ceding measurements. Table XIII is derived from Maury's Pilot Charts of the Atlantic Ocean, and shows the number of wind observations for sixteen points of the compass, for each of the
CONTRIBUTIONS TO METEOROLOGY..
31
live-(U'gree squares near the storm tracks delineated un the international (;harts. The direction of the winds, computed from these numbers, is shown in the last column of the table:
Table XIII. — Wind observations from Maury's charts.
|
Latitude. |
Longitude. |
i |
a |
2: |
w |
«' |
^ |
ri |
CO |
i |
?1 |
Course. |
||||||
|
» |
^ |
K |
» |
W |
M |
(P |
73 |
02 |
& |
02 |
^ |
ps |
^ |
-A |
^ |
|||
|
35° to 40° |
65° to 60° |
145 |
86 |
134 |
44 |
65 |
51 |
55 |
79 |
123 |
96 |
260 |
148 |
230 |
138 |
196 |
75 |
N. 88.3° W. |
|
40-45 |
65-60 |
115 |
67 |
85 |
.59 |
92 |
32 |
82 |
84 |
126 |
102 |
205 |
146 |
18rt |
125 |
93 |
89 |
S. 73.0 W. |
|
:!.^-4ii |
60-,55 |
103 |
75 |
101 |
38 |
69 |
32 |
77 |
78 |
138 |
115 |
258 |
137 |
201 |
88 |
134 |
82 |
S.71.1W. |
|
40-4O |
60-,55 |
104 |
51 |
78 |
28 |
78 |
49 |
86 |
54 |
138 |
121 |
201 |
97 |
207 |
115 |
134 |
92 |
S. 74.3 \V. |
|
;iri-4() |
55-50 |
54 |
81 |
64 |
69 |
39 |
87 |
81 |
146 |
135 |
249 |
1.58 |
173 |
87 |
139 |
60 |
9<i |
S.37.0W. |
|
4U-45 |
55-.50 |
94 |
68 |
90 |
39 |
77 |
56 |
92 |
76 |
131 |
90 |
168 |
101 |
179 |
102 |
154 |
93 |
S.79 4W. |
|
40-45 |
50-45 |
81 |
88 |
60 |
«6 |
51 |
8a |
70 |
126 |
96 |
124 |
98 |
160 |
12n |
123 |
94 |
88 |
S.63.7 W. |
|
45-.50 |
50-45 |
4 |
25 |
1 |
23 |
25 |
21 |
11 |
21 |
26 |
.50 |
27 |
29 |
20 |
17 |
13 |
18 |
S.20.0 W. |
|
40-4.-. |
45-40 |
48 |
50 |
19 |
45 |
32 |
60 |
56 |
84 |
97 |
161 |
108 |
142 |
121 |
165 |
94 |
101 |
S. 1)7.8 W. |
|
15-50 |
45-40 |
12 |
17 |
14 |
41 |
33 |
36 |
22 |
44 |
42 |
66 |
75 |
97 |
55 |
65 |
49 |
44 |
S.58.8W. |
|
40-45 |
40-35 |
43 |
42 |
19 |
49 |
34 |
38 |
54 |
96 |
66 |
107 |
108 |
158 |
121 |
112 |
51 |
56 |
S. 58.7 W. |
|
. 45-50 |
40-35 |
20 |
28 |
25 |
34 |
49 |
47 |
24 |
(>8 |
65 |
88 |
107 |
123 |
104 |
i08 |
58 |
50 |
S.61.0 W. |
|
40-45 |
35-30 |
31 |
50 |
26 |
53 |
31 |
41 |
32 |
59 |
61 |
71 |
63 |
82 |
78 |
78 |
61 |
56 |
S.71.3 W. |
|
45-.')0 |
3.5-;i0 |
43 |
49 |
33 |
38 |
38 |
47 |
28 |
48 |
80 |
116 |
115 |
124 |
114 |
133 |
66 |
64 |
S.71.8 W. |
|
45-50 |
30-i5 |
(ir |
46 |
22 |
33 |
28 |
35 |
24 |
59 |
74 |
128 |
98 |
143 |
130 |
99 |
71 |
83 |
S. 75.8 W. |
|
50-55 |
30-25 |
7 |
2 |
2 |
10 |
1 |
11 |
11 |
9 |
15 |
26 |
41 |
45 |
32 |
13 |
14 |
23 |
S.63.2 W. |
|
45-50 |
25-20 |
52 |
41 |
26 |
48 |
45 |
35 |
30 |
73 |
57 |
98 |
101 |
129 |
135 |
122 |
94 |
79 |
S. 81.1 W. |
|
50-55 |
25-20 |
10 |
9 |
5 |
20 |
8 |
20 |
24 |
47 |
32 |
45 |
25 |
59 |
35 |
34 |
21 |
24 |
S. 42 3 W. |
|
45-50 |
20-15 |
47 |
41 |
33 |
39 |
23 |
35 |
31 |
56 |
50 |
90 |
74 |
138 |
86 |
124 |
83 |
84 |
S. 86.8 W. |
|
50-55 |
20-15 |
11 |
16 |
9 |
22 |
28 |
35 |
38 |
68 |
49 |
51 |
3d |
71 1 54 |
49 |
29 |
18 |
S.30.4 W. |
|
|
45-50 |
1.5-10 |
41 |
57 |
49 |
60 |
26 |
29 |
32 |
40 |
41 |
r9 |
65 |
100 , 87 |
129 |
71 |
85 |
N.78.8 W. |
|
|
50-55 |
15-10 |
35 |
34 |
35 |
54 |
56 |
62 |
61 |
82 |
69 |
79 |
76 |
121 85 |
83 |
49 |
63 |
S. 43.5 W. |
|
|
45-r,o |
10- 5 |
15 |
13 |
19 |
12 |
22 |
22 |
19 |
U |
20 |
22 |
23 |
14 |
20 |
19 |
23 |
18 |
S.45.3W. |
|
50-55 |
10- 5 |
42 |
23 |
28 |
22 |
34 |
19 |
23 |
28 |
44 |
24 |
41 |
33 |
79 |
42 |
31 |
17 |
S. 82.2 W. |
46. I have also determined the average direction of the wind for the same part of the Atlantic Ocean for the months of January, April, July, and October, according to the charts of the U. S. Hydrographic Oflice. Table XIV shows the percentage of the wind directions for five-degree squares, from sixteen points of the coinpas.s, as given by the charts. The last column shows the average directions computed from the sum of the numbers for the four given months :
Table XIV. — Wmd observaiions from the charts of the U. iH. Hydrographic Offlce.
|
Latitude. |
Longitude. |
Mouth. |
W 2 |
a |
a |
a' r/J |
a |
a CO |
fe |
1 |
^ |
&' |
Course. |
||||||
|
5 |
5 |
z 5 |
a 5 |
a |
a |
03 |
OQ |
03 |
CD |
03 |
Z |
z |
|||||||
|
40° to 45° |
65° to 60° |
January. |
5 |
5 |
4 |
5 |
5 |
4 |
11 |
5 |
10 |
6 |
10 |
8 |
|||||
|
April |
15 |
6 |
5 |
5 |
4 |
1 |
5 |
2 |
4 |
3 |
6 |
9 |
6 |
8 |
6 |
10 |
|||
|
July .... |
2 |
1 |
2 |
1 |
3 |
2 |
5 |
5 |
10 |
10 |
11 |
13 |
12 |
5 |
6 |
6 |
|||
|
October . |
12 |
e |
/ |
1 |
4 |
1 |
1 |
2 |
4 |
7 |
7 |
7 |
11 |
10 |
9 |
9 |
|||
|
40-45 |
60-55 |
Sum. January. |
34 |
18 |
19 |
18 |
16 |
9 |
15 |
14 |
23 |
24 |
35 |
34 |
39 |
29 |
31 |
33 |
N. 76.7° W. |
|
2 |
3 |
7 |
3 |
1 |
5 |
0 |
3 |
a |
5 |
11 |
8 |
15 |
10 |
17 |
4 |
||||
|
April |
6 |
5 |
4 |
4 |
4 |
3 |
1 |
2 |
5 |
14 |
10 |
5 |
8 |
(i |
11 |
9 |
1 |
||
|
July .... |
5 |
3 |
4 |
2 |
5 |
3 |
6 |
4 |
10 |
• 8 |
10 |
8 |
13 |
5 |
5 |
5 |
|||
|
October . Sum.. |
7 20 |
2 13 |
2 |
I |
2 |
1 |
2 |
1 |
5 |
4 |
4 |
8 |
11 |
19 |
15 |
13 |
N. 81.9° W. |
||
|
17 |
10 |
12 |
12 |
9 |
10 |
22 |
31 |
35 |
29 |
47 |
40 |
48 |
31 |
||||||
|
40-45 |
55-50 |
January. |
7 |
5 |
4 |
5 |
6 |
5 |
1 |
4 |
5 |
7 |
9 |
6 |
8 |
9 |
9 |
5| |
|
|
April |
8 |
5 |
5 |
1 |
3 |
5 |
4 |
4 |
6 |
5 |
8 |
8 |
9 |
6 |
6 |
11 |
|||
|
July .... |
5 |
3 |
6 |
2 |
4 |
5 |
7 |
6 |
10 |
8 |
8 |
6 |
10 |
6 |
6 |
4 |
|||
|
40-45 |
50-45 |
October . Sam.. January - |
6 26 |
18 |
5 20 |
6 14 |
6 19 |
4 19 |
5 17 |
5 19 |
6 |
5 |
4 |
2 |
9 |
7 |
12 |
9 |
|
|
27 |
25 |
29 |
22 |
36 |
28 |
33 |
29 |
N. 82.9° W. |
|||||||||||
|
11 |
4 |
0 |
7 |
2 |
5 |
6 |
6 |
2 |
9 |
5 |
11 |
5 |
16 |
6 |
5 |
||||
|
April |
5 |
5 |
5 |
4 |
4 |
3 |
6 |
6 |
7 |
6 |
4 |
10 |
5 |
6 |
7 |
14 |
|||
|
July .... |
1 |
5 |
3 |
4 |
5 |
5 |
3 |
10 |
8 |
11 |
7 |
12 |
7 |
5 |
4 |
4 |
|||
|
October . |
7 |
6 |
6 |
1 |
5 |
4 |
5 |
11 |
10 |
4 |
4 |
6 |
8 |
6 |
11 |
6 |
|||
|
Sam.. |
24 |
20 |
14 |
16 |
16 |
17 |
20 |
33 |
27 |
30 |
20 |
39 |
25 |
33 |
28 |
29 |
S. 73.3° W. |
32 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
. Table XIV. — Wind observations from the charts of the U. iS. Hydrographic Office — Contiuued.
|
Latitude. |
Longitude. |
Month. |
>i |
1 0 1 2 |
c4 0 0 2 2 |
n 2 4 5 3 |
0 5 2 11 |
00 5 5 3 5 |
a CO 6 8 2 1 |
a CO CO 5 10 • 7 11 |
CO 6 2 4 5 |
to OS 6 6 16 9 |
5 8 12 11 |
CO 16 h 18 8 |
^ |
^ K ^ |
^ ^ |
S5 |
Course. |
|
45° to 50° |
45° to 40° |
January. April July .... October . Snm.. |
6 4 1 1 |
11 5 6 7 |
11 5 2 9 |
6 21 9 5 |
5 8 8 6 |
S. 60.7° W. |
|||||||||||
|
12 |
4 |
4 |
14 |
18 |
18 |
17 |
33 |
17 |
37 |
36 |
47 |
29 |
27 |
41 |
27 |
||||
|
45-50 |
40-35 |
January. April July .... October . |
1 6 1 4 |
1 2 1 5 |
0 5 1 1 |
2 5 0 2 |
2 3 2 3 |
3 2 4 4 |
1 2 2 4 |
10 4 12 5 |
6 2 9 4 |
9 4 8 27 |
H 16 13 4 |
22 5 15 6 |
12 9 11 9 |
11 5 10 9 |
4 14 6 5 |
2 10 2 5 |
|
|
Sum.. |
12 |
9 |
7 |
9 |
10 |
13 |
9 |
31 |
21 |
48 |
41 |
48 |
41 |
35 |
29 |
19 |
S. 62.6° W. |
||
|
45-50 |
35-30 |
January. April July .... October . |
5 4 3 5 |
8 4 2 7 |
2 4 4 1 |
3 5 3 4 |
2 2 1 5 |
6 11 2 4 |
2 5 4 4 |
4 3 9 4 |
4 5 8 6 |
15 7 4 7 |
8 10 9 11 |
18 7 20 9 |
8 8 10 7 |
10 11 8 12 |
5 4 6 5 |
6 5 5 6 |
|
|
Sum.. |
17 |
21 |
11 |
15 |
10 |
23 |
15 |
20 |
23 |
33 |
38 |
54 |
33 |
41 |
20 |
22 |
8.69.5° W. |
||
|
45-50 |
30-25 |
January. April July .... October . |
11 5 4 |
3 8 3 3 |
3 4 3 3 |
0 4 6 2 |
6 4 2 0 |
3 6 2 1 |
4 2 4 4 |
5 4 12 5 |
5 3 4 5 |
13 10 11 10 |
11 5 10 7 |
11 11 8 10 |
8 9 5 7 |
7 5 5 10 |
6 5 6 12 |
5 4 9 14 |
|
|
Sum.. |
24 |
17 |
13 |
12 |
12 |
12 |
14 |
26 |
17 |
44 |
33 |
40 |
29 |
27 |
29 |
32 |
S. 77.5° W. |
||
|
45-50 |
25-20 |
January. April . .'. . July .... October . |
4 6 1 11 |
~2 5 1 6 |
3 4 0 5 |
5 4 3 1 |
4 10 2 6 |
3 4 3 3 |
12 3 2 2 |
4 5 6 1 |
6 5 5 2 |
5 4 6 3 |
7 3 11 5 |
10 10 17 10 |
11 6 12 11 |
8 10 14 11 |
8 9 7 10 |
5 8 4 12 |
|
|
Sum.. |
22 |
14 |
12 |
13 |
22 |
13 |
19 |
16 |
18 |
18 |
26 |
47 |
40 |
43 |
34 |
29 |
N. 87.4° W. |
||
|
50-.55 |
20-15 |
January. April July .... October . |
~2 6 1 6 |
~0 1 7 |
4 4 1 5 |
4 3 4 8 |
5 6 1 16 |
12 3 2 4 |
6 7 3 9 |
10 7 4 9 |
9 4 5 2 |
3 11 14 4 |
5 10 8 1 |
14 10 18 |
8 7 20 |
6 8 5 •J |
7 6 6 1 |
5 4 2 5 |
|
|
Sum.. |
15 |
12 |
14 |
19 |
28 |
21 |
25 |
30 |
2fi |
32 |
24 |
50 |
38 |
22 |
20 |
16 |
S.37.8° W. |
||
|
50-55 |
15-10 |
January. April Jnly .... October . |
~5 5 6 3 |
5 4 1 0 |
5 4 5 6 |
5 2 5 10 |
5 5 2 17 |
4 0 5 10 |
4 7 2 11 |
5 5 3 2 |
6 11 4 5 |
1? 12 4 |
10 7 6 6 |
15 5 15 7 |
6 8 12 1 |
8 11 5 8 |
5 5 6 5 |
5 5 7 5 |
|
|
Sum.. |
19 |
10 |
20 |
22 |
29 |
19 |
24 |
15 |
26 |
32 |
29 |
42 |
27 |
32 |
21 |
22 |
S. 53.9° W. |
||
|
50-.55 |
10- 5 |
January. April July .... October . |
1 0 0 |
4 11 2 0 |
~0 4 3 14 |
1 3 0 0 |
5 12 ■ 14 0 |
0 0 2 0 |
6 0 6 8 |
11 4 6 6 |
20 4 3 10 |
8 3 9 0 |
8 5 8 19 |
10 4 8 0 |
8 7 6 24 |
4 6 12 0 |
5 12 6 0 |
4 6 10 0 |
|
|
Sum.. |
24 |
17 |
21 |
4 |
31 |
2 |
19 |
27 |
37 |
20 |
40 |
22 |
45 |
22 |
23 |
20 |
S. 63.3° W. |
Some of these directions difler from those of Table XIII more than was expected. The difference is probably to be ascribed to the small number of the observations. Since Table XIV is deduced from the greatest number of observations, I have employ td it in the comparisons exhibited in the following table :
CONTEIBUTIONS TO METEOROLOGY. Table XV — Comparison of storm paths with wind directions.
33
|
Lougi- tude. |
Latitude of storm tracks. |
Direction of storm tracks. |
Latitude of wind directious. |
Dircc^tion of wiinl. |
Dift'ereuce of latitude. |
Wind most uortlierly. |
|
60° 50 40 30 20 10 |
46.9° 48.9 51.3 53.9 54.9 55.5 |
N. 67.0° E |
42. 5° 42.5 47.5 47.5 5U.0 |
N. 79 3° W |
4.4° 6.4 3.8 6.4 4.9 3.0 |
— 33.7° — 21.5 + 5.1 — 1.3 + 16. 3 + 27.6 |
|
N.63.7 E |
S 85 2 W |
|||||
|
N.66.7 E |
S. 61 6 W |
|||||
|
N. 72.2 E |
S.73.5 W S. 65.2 W |
|||||
|
N.81.5 E N.86.2 E |
||||||
|
52.5 |
S. 58.6 W |
Column 1 shows the longitudes for which the comparisons are made; column 2 shows the latitude of the points to which the direction of the storm tracks correspond; column 3 shows the average direction of the storm tracks for the months of Januaiy, April, July, and October; column 4 shows the latitudes corresponding to the wind directions from Table XIV; column 5 shows the direction of the wind for the given latitudes and longitudes, according to the United States Hydrographic charts ; column 6 shows the differences of latitude between the points to which the storm tracks correspond and those to which the wind directions correspond; column 7 shows the dift'ereuce between the average direction of the wind and the average direction of the storm paths for the points of comi)arison.
47. It will be seen that there is an average ditference of nearly five degrees between the latitudes of the points for which the wind directions are given and those to which the storm tracks correspond. I have endeavored to deduce from Table XIII the proper correction of the wind directions for this difference of latitude, but the corrections appear so questionable that I have made no use of them.
We see that for the middle of the Atlantic Ocean, near the parallel of 50°, the average direc- tion of storm paths corresponds verj^ closely with that of the average progress of the wind; but in the western part of the Atlantic the average course of storms is considerably more northerly than that of the wind, while in the eastern part it is more southerly. These results accord very well with those derived from tropical storms, and seem to indicate that in the middle latitudes of the northern hemisphere the direction of progress of storm centers is not identically the same as that of the average wind, but is sensibly aflected by some other cause or causes; and the results derived from observations in the China Sea seem to indicate that one of these causes is the prevalent direction of the wind which follows immediately after a storm.
48. An examination of the maps accompanying the monthly weather review of the United States Signal Service, which exhibit the tracks of storm centers, shows that between the Eocky Mountains and the meridian of 90° Irom Greenwich storms frequently travel towards the south- east. I have made a oareiul examination of the observations from this region, to determine whether the storm tracks of this region conform to the average direction of the winds. Table XVI shows the wind observations for twelve of the Signal Service stations in this region, for the three winter months, for the ten years from 1873 to 1882. Iliave restricted the comparison to the winter mouths, because during this period the winds are stronger and the northerly motion is more decided than during the warmer months of the year. The table shows for each station the sum of the observations for the year comi)ared, and also the resulting course computed from the observations.
49. 1 next measured with a protractor, for each of the twelve stations, the direction of the storm paths as delineated on the monthly maps of the Signal Service for the winter mouths, during a period of ten years, from 1875 to 1884. I have omitted the observations of the two or three preceding years, because the storm tracks of this region are not as well delineated for those years as for the subsequent years. Table XVII shows the average results of these measurements and also the results derived from Table XVI. The directious are all measured from the north point towards the east.
S. Mis. 154 5
34
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
Table XVI. — Wind observations for the winter months.
|
North Platte, Lat. 41° S |
', Long. 100° 45*. |
Omaha, Lat. 41° 16', Long. 95° 56'. |
||||||||||||||||
|
w; |
NW. |
W. |
SW. |
S. |
SE. |
E. |
NE. |
Course. |
N. |
NW. |
W. |
SW. |
S. |
SE. |
E. |
NE. |
Course. |
|
|
1873 1874 1875 |
68 38 58 |
54 55 67 |
13 18 13 |
25 14 16 |
32 63 56 |
13 17 20 |
4 10 10 |
6 11 14 |
||||||||||
|
18 |
61 |
23 |
28 |
35 |
28 |
8 |
32 |
|||||||||||
|
1876 |
15 |
49 |
45 |
39 |
15 |
31 |
6 |
15 |
46 |
74 |
18 |
28 |
52 |
20 |
11 |
6 |
||
|
1877 |
19 |
47 |
110 |
11 |
10 |
15 |
22 |
22 |
62 |
52 |
18 |
31 |
52 |
14 |
10 |
8 |
||
|
1878 |
28 |
98 |
43 |
13 |
22 |
21 |
16 |
23 |
81 |
50 |
10 |
11 |
71 |
21 |
8 |
3 |
||
|
1879 |
27 |
112 |
50 |
9 |
17 |
7 |
19 |
26 |
32 |
87 |
38 |
17 |
37 |
20 |
11 |
15 |
||
|
1880 |
22 |
123 |
33 |
17 |
19 |
28 |
15 |
16 |
37 |
78 |
20 |
30 |
39 |
40 |
11 |
12 |
||
|
1881 |
56 |
67 |
43 |
10 |
34 |
20 |
17 |
18 |
70 |
69 |
9 |
19 |
55 |
23 |
10 |
8 |
||
|
1882 Sum. |
24 |
69 |
69 |
14 |
35 |
19 |
14 |
14 |
N. 59.0°W. |
60 |
39 |
16 |
40 |
72 |
24 |
9 |
8 |
K. 65.3° W. |
|
209 |
626 416 |
141 |
187 |
169 |
117 |
166 |
552 |
625 |
173 |
231 |
529 |
212 |
94 |
91 |
||||
|
Fort Sully, Lat. 44° 39 |
, Long. 100° 40'. |
Saint Paul, Lat. 44° 58', Long. 93° 3'. |
||||||||||||||||
|
1873 |
16 |
59 |
47 |
8 |
4 |
22 |
48 |
14 |
18 |
41 |
43 |
32 |
6 |
30 |
26 |
6 |
1 |
|
|
1874 |
8 |
79 |
11 |
5 |
7 |
45 |
21 |
11 |
14 |
50 |
28 |
35 |
29 |
65 |
33 |
2 |
||
|
1875 |
20 |
100 |
15 |
0 |
9 |
55 |
20 |
9 |
14 |
55 |
54 |
52 |
25 |
31 |
17 |
4 |
||
|
1876 |
40 |
71 |
31 |
5 |
16 |
41 |
38 |
19 |
14 |
69 |
33 |
22 |
18 |
59 |
19 |
18 |
||
|
1877 |
3 |
115 |
20 |
7 |
4 |
57 |
8 |
11 |
33 |
46 |
40 |
50 |
19 |
49 |
9 |
6 |
||
|
1878 1879 1880 1881 1882 Snta. |
N.25.8°W. |
56 21 21 25 15 |
38 83 60 60 40 |
14 41 40 33 45 |
16 45 27 21 43 |
21 14 |
61 43 |
27 8 |
13 6 |
S. 78.0° W. |
||||||||
|
23 i 60 17 46 28 75 |
21 1 4 |
|||||||||||||||||
|
23 12 |
8 7 |
|||||||||||||||||
|
|
||||||||||||||||||
|
87 |
424 |
124 |
25 |
40 |
220 |
135 |
64 |
231 |
542 |
371 |
343 |
200 1 509 |
195 |
74 |
||||
|
Bismarck, Lat, 46° 47' |
Long. 100° 38'. |
Keokuk, Lat. 40° 22', Long. 91° 26'. |
||||||||||||||||
|
1873 1874 1875 |
25 25 41 |
45 49 58 |
51 39 25 |
27 33 39 |
28 37 23 |
12 27 28 |
22 21 23 |
18 21 17 |
||||||||||
|
104 |
38 |
9 |
15 |
19 |
20 |
24 |
28 |
|||||||||||
|
1876 |
25 |
103 |
12. |
9 |
16 |
26 |
32 |
38 |
29 |
64 |
29 |
32 |
42 |
32 |
21 |
9 |
||
|
1877 |
13 |
88 |
7 |
19 |
12 |
34 |
10 |
27 |
56 |
53 |
43 ; 41 |
19 |
8 |
16 |
23 |
|||
|
1878 |
19 |
65 |
32 |
16 |
22 |
48 |
32 |
20 |
47 |
37 |
25 |
35 |
40 |
23 |
17 |
35 |
||
|
1879 |
20 |
79 |
45 |
9 |
14 |
23 |
32 |
14 |
28 |
77 |
55 |
27 |
29 |
18 |
13 |
21 |
||
|
1880 |
42 |
75 |
15 |
16 |
17 |
38 |
36 |
13 |
37 |
55 |
31 |
45 |
37 |
31 |
14 |
14 |
||
|
1881 |
18 |
99 |
21 ; 5 |
4 |
27 |
29 |
14 |
40 |
51 |
42 |
21 |
24 |
28 |
28 |
23 |
|||
|
1«82 Sum. |
3 |
97 1 18 1 7 ! 17 |
31 1 58 |
8 |
N. 17.3° W. |
18 |
47 |
40 1 44 |
43 |
32 21 |
17 |
N. 75.3° W. |
||||||
|
244 |
644 169 |
96 121 |
247 253 |
162 |
346 |
536 |
380 344 |
322 |
239 196 |
198 |
||||||||
|
Yankton, Lat. 42° 54 |
, Long. 97° 28'. |
La Crosse, Lat. 43° 49', Long. 91° 15'. |
||||||||||||||||
|
1873 1874 |
23 50 |
44 44 |
16 19 |
45 31 |
42 65 |
52 22 |
2 7 |
34 29 |
||||||||||
|
15 |
91 |
22 |
39 |
15 |
33 |
18 |
13 |
|||||||||||
|
1875 |
20 |
84 |
29 |
23 |
23 |
26 |
12 |
27 |
51 |
32 |
57 |
33 |
68 |
U |
4 |
10 |
||
|
1876 |
16 |
98 |
16 |
33 |
24 |
28 |
23 |
17 |
27 |
39 |
40 |
28 |
56 |
10 |
45 1 10 |
|||
|
1877 |
21 |
80 |
31 |
44 |
21 |
25 |
14 |
26 |
59 |
21 |
4U |
37 |
75 |
10 |
3 1 6 |
|||
|
1878 |
28 |
74 |
24 |
34 |
22 |
34 |
22 |
18 |
64 |
24 |
16 |
12 |
93 |
10 |
21 21 |
|||
|
1879 |
21 |
108 |
27 |
33 |
19 |
28 |
12 |
16 |
60 |
47 |
44 |
31 |
60 |
4 |
4 16 |
|||
|
1880 |
25 |
74 |
26 |
31 |
16 |
20 |
9 |
10 |
45 |
31 |
26 |
24 |
69 |
12 |
3 12 |
|||
|
1881 |
72 |
17 |
16 18 |
15 |
11 18 |
fiO |
66 |
34 |
31 |
25 |
59 |
19 |
14 8 |
|||||
|
1882 Sum |
23 |
58 |
36 60 |
21 |
21 12 |
9 |
N. 58.4° W. |
27 |
31 |
37 |
20 |
103 |
18 |
3 6 |
S.67.1°W. |
|||
|
241 |
684 |
227 315 176 |
226 140 |
196 |
472 |
347 |
326 |
286 |
690 1 168 1 106 1 152 |
|||||||||
|
Pembina, Lat. 49° 0 |
, Long. 97° 5'. |
Dubuque, Lat. 42° 30', Long. 90° 44'. |
||||||||||||||||
|
1874 |
1 |
111 |
0 |
13 |
2 |
116 |
0 |
10 |
30 |
40 |
17 |
26 |
26 |
14 |
9 |
15 |
||
|
1875 |
0 |
51 |
0 |
13 |
0 |
36 |
0 |
6 |
19 |
42 |
57 |
40 |
27 |
28 |
12 |
12 |
||
|
1876 |
10 |
99 |
25 |
13 |
28 |
.^0 |
8 |
7 |
• |
21 |
55 |
56 |
23 |
45 |
37 |
12 |
10 |
|
|
1877 |
17 |
66 |
33 |
11 |
76 |
26 |
2 |
3 |
22 |
52 |
28 |
25 |
13 |
9 |
3 |
14 |
||
|
1878 |
33 |
01 |
21 |
14 |
63 |
58 |
10 |
2 |
38 |
36 |
10 |
23 |
60 |
14 |
25 |
44 |
||
|
1879 |
22 |
132 |
IS |
4 |
65 |
17 |
o |
0 |
44 |
83 |
27 |
20 |
24 |
15 |
6 |
14 |
||
|
1880 |
26 |
94 |
18 |
3 |
78 |
16 |
8 |
1 |
20 |
49 |
50 |
24 |
41 |
41 |
13 |
14 |
||
|
1881 1882 Sura |
S. 85.7° W. |
26 11 |
57 52 |
40 42 |
20 31 35 76 |
22 22 |
12 |
N.87.3°W. |
||||||||||
|
|
26 7 j 16 |
|||||||||||||||||
|
109 |
614 |
115 |
71 |
312 |
319 |
33 |
29 |
231 |
466 |
327 |
236 333 |
206 |
109 j 151 ) |
|||||
|
Breckinridge, Lat. 46° |
11', Long. 96° 17'. |
Davenport, Lat. 41° 30', Long. 90° 38'. |
||||||||||||||||
|
1873 |
38 |
84 |
28 |
9 |
12 |
84 |
3 |
7 |
14 |
65 |
39 |
50 |
13 |
17 |
7 |
33 |
||
|
1874 |
36 |
55 |
29 |
9 |
13 |
97 |
6 |
2 |
16 |
49 |
51 |
41 |
23 |
16 |
28 |
27 |
||
|
1875 |
19 |
121 |
9 |
18 |
10 |
66 |
1 |
5 |
31 |
45 |
62 |
32 |
20 |
18 |
29 |
13 |
||
|
1876 |
33 |
88 |
31 |
11 |
9 |
67 |
13 |
11 |
7 |
72 |
43 |
46 |
22 |
24 |
34 |
13 |
||
|
1877 |
29 |
66 |
32 |
17 |
7 |
68 |
13 |
3 |
19 |
47 |
37 |
53 |
11 |
7 |
15 |
30 |
||
|
1878 |
74 |
23 |
32 |
12 |
56 |
55 |
6 |
12 |
24 |
30 |
25 |
47 |
28 |
16 |
19 |
47 |
||
|
1879 |
60 |
64 |
60 |
9 |
18 |
42 |
7 |
8 |
20 |
59 |
69 |
42 |
27 |
18 |
22 |
20 |
||
|
1880 |
80 |
43 |
39 |
6 |
50 |
34 |
5 |
3 |
19 |
47 |
38 |
48 |
35 |
18 |
27 |
21 |
||
|
1881 1882 Suiu . |
N.53.S°W. |
17 16 |
56 55 |
53 44 |
26 67 |
19 28 |
17 21 |
33 18 |
32 21 |
N.83.20W. |
||||||||
|
369 |
544 |
260 |
91 175 |
513 |
54 |
51 |
183 |
525 |
451 |
452 |
226 |
172 |
232 |
267 |
CONTRIBUTIONS TO METEOROLOGY. Table XVII. — Comparison of storm paths icith wind directions.
35
|
Station. |
Wind blows towarils — |
Storms move towarils- |
Storms most northerly. |
St.atiou. ■ |
Wind blows towards — |
Storms move towards — |
Storms most northerly. |
|
North Platte Fort Sully Bi.^nlarck Yankton Pembina . |
N. 121. 0° E. l.'->4. 2 162. 7 121.6 85.7 126. 2 |
N. 104. 1° E. 106.7 107. 7 106.3 109.4 10.5.5 |
+16.9'^ +47.5 +55. 0 +15.3 -23. 7 +20.7 |
Omaha Saint Paul Keokuk La Crosse ■.. |
N. 114. 7° E. 78.0 104.7 67.1 • 92.7 96.8 |
N. 100. 8° E. 99.3 88.3 90.5 88.3 87.0 |
+13.9^' —21.3 +16.4 —23. 4 + 4.4 + 9.8 |
|
Dubuque |
|||||||
|
Breckenridge |
Davenport |
50. From this table it is seen that at all of the stations (except Pembina, Saint Paul, and La Cros.se) the average wind of winter blows towards a point somewhat south of cast, and at the more western stations this direction is more than 30° south of east. It will also be seen that at the most western stations the average movement of storm centers is towards a point more than 15° south of east, but at the most eastern stations the direction is a little north of east. Comparing these numbers, we find that at the most western stations the average course of storm centers is from 10° to 20° more northerly than the course of the wind, while at the three stations above mentioned the average course of storm centers is decidedly less northerly than the course of the wind. The main result of this comparison is similar to that derived from observations on the Atlantic Ocean, viz, that there is not a rigorous correspondence between the average direction of the movement of storm centers and the progress of the wind, but that in some regions the average course of storm centers is more northerly than that of the wind, and in some I'egions it is more southerly.
51. It frequently happens that the southward motion of storm centers, which is shown by the preceding table in the valley of the Missouri River, is much more decided, and extends to much lower latitudes. Every year cases occur in which this southward motion extends to the parallel of 30°, and occasionally it extends to the parallel of 25°. Table XVIII shows cases in which storms have advanced towards the southeast as far as the parallel of 28°. The arrangement is similar to that of Table VIII. The first six columns describe each storm as long as its course continued southeasterly ; the seventli column shows the highest pressure prevailing at any place within the limits of the United States on the north side of the low area, and the last column gives some indication of the subsequent course of each storm. The tracks of these storms are all delineated on Plate XIII, and are designated by the same numbers as in the table.
52. We see from this table that the average velocity of these storms while pursuing their course towiirds the southeast was 25 miles per hour, which is somewhat less than the average velocity of storms for the United States. In forming this average I have omitted No. 18, whose path is very imperfectly known. The lowest latitude attained by any of these storms was 23°, and in only four cases did the low center reach the parallel of 25°. In thirteen cases the storm center, after completing its course towards the southeast, changed its course and proceeded towards the north or northeast. In six of the remaining cases the intensity of the storm declined in advancing southward, and they apparently became extinct soon after the dates given in the table. The same was probably true in the four remaining cases, but the observations are not sufficient to establish this with certainty.
The low area, No. 12, was quite peculiar, having pursued a path almost directly ojjposite to that of ordinary storms. During the afternoon of August 20, 1878, there was an area of low pressure (29.75) over West Virginia, being part of a greater depression, whose center was over Newfound- land, and there was a slight tendency to the formation of an independent system of circulating winds. Owing to a slight increase of pressure on the north side the center of this low area was crowded southward, and in the afternoon of August 21 the low area (29.78) was pretty distinctly marked, and showed a feeble system of circulating winds. At 7.35 A. m., August 22, this low cen- ter had been crowded south to latitude 30°, the greatest observed depression being now 29.88. By the evening of August 22 the pressure at the center had increased to 29.95, and after this the low
36
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. Table XVIII. — American storms advwncing southeasterly.
|
No. |
Date. |
Latitude. Beg. End. |
Longitude. Beg. End. |
Course. |
! Velocity. |
B.-irniucter on nortli. |
Sulisequeut conr.se. |
|
1874. |
Miles. |
||||||
|
1 |
Feb. 17.2-18.2 |
33°-270| |
86^- 79° |
SE. |
21.8 |
30. 45 |
Became extinct |
|
a |
Apr. 13. 3-16. 3 187.'i. |
41-20 |
102- 89 |
SE. |
21.1 |
30.36 |
Unlinowu. |
|
3 |
Jan. 14. 3-113. 2 1876. |
44-27 |
106- 91 |
SE. |
27.1 |
30.79 |
Became extinct. |
|
4 |
Feb. 3. 1- 4. 1 |
33-28 |
98- 80 |
SE. |
28.4 |
30. 60 |
Became extinct. |
|
5 |
Mar. 8.3-12.1 |
40-27 |
97- 89 |
SE. |
15.7 |
30.66 |
Became extinct. |
|
6 |
Mav 6. 3- 7. 3 1877. |
33-27 |
100- 93 |
SE. |
25.0 |
30.13 |
Unknown. |
|
7 |
Jan. 4.2- .'5.3 |
45-28 |
100- 90 |
SSE. |
40.4 |
30. 02 |
Nortlieast. |
|
8 |
Mar. 21. 2-24.1 |
42-28 |
100- 94 |
SSE. |
22. 5 |
30. 48 |
Nortlieast. |
|
9 |
Dec. 16 -20 |
44-28 |
126- 96 |
SE. |
10.0 |
30. 15 |
North. |
|
10 |
Dec. 22 -27. 2 1878. |
47-27 |
126-101 |
SE. |
29. 7 |
30.35 |
Northeast. |
|
11 |
Feb. 1. 1- 2. 3 |
33-26 |
96- 84 |
SE. |
18.3 |
30.54 |
Northeast. |
|
12 |
Aug. 20. 2-24. 2 |
38-23 |
83- 81 |
SSE. |
15.1 |
30.14 |
Became extiuct. |
|
13 |
Nov. 16. 2-17. 2 1879. |
28-24 |
102- 93 |
SE. |
24.0 |
30.23 |
Northeast. |
|
14 |
Jan. 6. 3- 7. 3 |
38-27 |
110- 98 |
• SE. |
39. 2 |
30.41 |
Northeast. |
|
15 |
Jan. 8.3-11.1 |
49-27 |
119- 98 |
SE. |
30.4 |
30. 25 |
Northeast. |
|
16 |
May 4. 1- 6. 1 1880. |
34-24 |
101- 96 |
SSE. |
16.1 |
30.40 |
Uuliuown. |
|
17 |
Mar. 7.3-13.1 |
45-28 |
109- 87 |
SE. |
24.9 |
30.83 |
Became extiuct. |
|
18 |
Dec. 27. 1-28. 3 1881. |
45-26 |
126- 92 |
SE. |
57.5? |
30.63 |
Northeast. |
|
19 |
Jan. 13. 3-17. 1 1882. |
50-24 |
111- 97 |
SE. |
28.0 |
30. 65 |
Northeast. |
|
20 |
Apr. 9.1-1.3.2 1883. |
45-27 |
123- 83 |
SE. |
24.9 |
30.54 |
Unknowu. |
|
21 |
Jan. 16. 3-19. 1 1884. |
48-27 |
118- 96 |
SE. |
32.3 |
30.79 |
Northeast. |
|
22 |
Jan. 5. 3- 7. 2 |
45-29 |
120- 89 |
SE. |
45.2 |
30. 62 |
North northeast. |
|
23 |
Mar. 14. 3-l«. 1 |
37-27 |
124- 95 |
ESE. |
22. 2 |
30.42 |
Northeast. |
center could not be distinctly traced. This example appears to illustrate the general character of areas of low pressure, and shows that this progressive movement is not due to a simple drifting of the atmosphere, but rather to a diminution of ]>ressun' on one side of the low area and an in- crease of pressure on the other side. In the present ease there was scarcely any a])preciable diminution of pressure on the south side, and only a slight increase of pressure on tlie nortii side.
The low area, No. 17, near the end of its course, exhibited similar peculiarities, and they were the result of similar causes. On March 12. at 3 p. m., there was a well marked low center (29.76) in the northwest part of Georgia, aud a high center (30.83) existed iu Dakota. At 11 P. M. this high area had advanced eastward, the low center had been crowded southward, and the pressure at the low center was 30.04. The next morning the i)ressure throughout Georgia and Florida had further increased, and the low center was crowded still further towards the southwest.
It will be seen from column 7 of the table that in fill of the cases except four or five there was an area of decidedly high pressure on the north side of the low area, and in several of the cases the influence of this high area was similar to that already noticed iu Nos. 12 aud 17. The low area was crowded southward, and the depression gradually closed up, and became nearly or quite extinct. In some of the remaining cases in which the depression did not close up the high pressure on the north side was apparently the cause which crowded the low area so far to the southward.
53. The low areas enumerated iu the preceding table were generally followed by a strong wind from the north or northwest. This will be seen from the following table, which shows the height of the barometer, with the direction and force of the wind, at five stations in several cases in which the low centers passed nearest to Galveston, in Texas.
CONTRIBUTIONS TO METEOEOLOGY. Table XIX. — Areas of low pressure, Nos. 2, 5, 8, and 20.
37
|
Leave |
nwoiili. |
I'oil- |
iilisiui. |
Shrpveport. |
Galveston. |
Iiiil |
aiiiila. |
||||
|
Barou). |
"Wiud. |
Barom. |
Wiud. |
Barom. |
Wind. |
Barom. |
Wind. |
Barom. |
Wiud. |
||
|
No. |
2.— 1874. |
||||||||||
|
Apr. 1.5. 1 |
30.07 |
N. 10 |
29. 81 |
NE. 12 |
29. 83 |
S. 3 |
29.83 |
SE.9 |
29.83 |
S. 20 |
|
|
15. y |
29. 93 |
NE. 12 |
.72 |
NE. 13 |
.77 |
NE. 14 |
.70 |
S. 12 |
.72 |
S. 22 |
|
|
1 |
15.;! |
29. 97 |
NE. 10 |
.73 |
N. 9 |
.80 |
S.2 |
.75 |
S. 8 |
.76 |
S. 10 |
|
1«. I |
30. 05 |
E. 16 |
.89 |
N. 8 |
.84 |
Calm. |
.71 |
SE. 13 |
.72 |
SE. 12 |
|
|
16.2 |
30.06 |
N. 12 |
.93 |
NW. 13 |
.81 |
NW. 6 |
.64 |
N. 30 |
.76 |
N. 26 |
|
|
It). :^ |
30.16 |
Calm. |
30. 10 |
N. 10 |
.96 |
NW. 8 |
.87 |
NE. 12 |
.85 |
NE. 30 |
|
|
17.1 |
30. 25 |
Calm. |
.20 |
N. 4 |
30. 05 |
NE. 10 |
.94 |
NE. 22 |
30. 05- |
N. 40 |
|
|
N(i. |
5.— 1876. |
||||||||||
|
M;u-. 10.1 |
29. 64 |
N. 8 |
29. 54 |
S. 14 |
29. 82 |
S. 10 |
29.83 |
SE. 4 |
29.81 |
SE. io |
|
|
10. 2 |
.67 |
N\V. 15 |
.46 |
S. 22 |
.79 |
S. 9 |
.78 |
SE. 6 |
.73 |
SE. 18 |
|
|
10. :! |
.90 |
NW. 24 |
.78 |
N. 14 |
.76 |
S. 14 |
.80 |
SE. 8 |
.76 |
S. 22 |
|
|
11.1 |
30.14 |
NW. 16 |
.95 |
N. 19 |
.80 |
SW. 4 |
.78 |
SE. 8 |
.73 |
SE. 18 |
|
|
11.2 |
.18 |
N. 15 |
30.07 |
N. 13 |
.78 |
NE. 4 |
.73 |
S.8 |
.77 |
SW. 10 |
|
|
11. n |
.29 |
N. 16 |
.16 |
N. 6 |
30.04 |
NW'. 7 |
.93 |
NW. 39 |
.94 |
N. 36 |
|
|
1 |
12. 1 |
.44 |
N. 14 |
.45 |
N. 25 |
.23 |
NW.9 |
30. 14 |
N. 30 |
30.19 |
N. 48 |
|
' No. |
8.— 1677. |
||||||||||
|
Mar. 22. :i |
29. 82 |
N. 20 |
29. 66 |
SE. 13 |
29. 96 |
S. 3 |
29. 96 |
SE.6 |
29.93 |
SE.16 |
|
|
23. 1 |
30.00 |
N. 14 |
.73 |
S. 8 |
.97 |
Calm. |
.93 |
, S. 6 |
.90 |
SE.8 |
|
|
23.2 |
.07 |
N. 10 |
.79 |
NW. 17 |
.83 |
S. 8 |
.86 |
SE. 11 |
.84 |
SE. 17 |
|
|
23.3 |
.23 |
N. 17 |
.97 |
N. 16 |
.94 |
S. 11 |
.91 |
SE. 1 |
.83 |
SE.8 |
|
|
24.1 |
.34 |
N. 13 |
30.18 |
N. 16 |
.98 |
NW. 12 |
.88 |
W. 20 |
.99 |
N. 29 |
|
|
24.2 |
.23 |
N. 10 |
.17 |
N. 18 |
30. 06 |
NW. 11 |
30.02 |
NW. 38 |
30.10 |
NW. 34 |
|
|
No. |
20.— 1882. |
||||||||||
|
Apr. 11.1 |
30. 12 |
.E, 13 |
29.88 |
E. 10 |
29.87 |
NE. 8 |
29.80 |
S. 12 |
29.76 |
SE. 11 |
|
|
11.2 |
.04 |
E. 16 |
.81 |
NE. 16 |
.74 |
E. 11 |
.77 |
S. 18 |
.73 |
SW. 30 |
|
|
11.3 |
.08 |
NE. 7 |
.89 |
E. 8 |
.80 |
E. 12 |
.72 |
SW.8 |
.73 |
SE.9 |
|
|
12.1 |
.12 |
E. 6 |
.94 |
NE. 4 |
.80 |
NE. 8 |
.72 |
SE. 12 |
.71 |
SE.9 |
|
|
12.2 |
.09 |
NE. 11 |
.95 |
N. 6 |
.78 |
NE. 13 |
.67 |
S. 16 |
.62 |
SW. 23 |
|
|
12.3 |
.19 |
N. 7 |
30.05 |
N. 14 |
.85 |
N. 8 |
.76 |
N. 16 |
.77 |
N. 28 |
|
|
13.1 |
.19 |
N. 6 |
30. 12 |
N. 6 |
.97 |
N. 12 |
.84 |
N. 18 |
.87 |
NE. 22 |
|
|
13.2 |
.17 |
N. 8 |
.13 |
N. 8 |
30.01 |
N. 9 |
.00 |
NE. 18 |
.92 |
N. 27 |
|
|
13.3 |
.23 |
N. 1 |
.13 |
N. 4 |
.09 |
N. 7 |
99 |
NE. 22 |
30.04 |
N. 36 |
|
|
14.1 |
.26 |
NW. 4 |
.22 |
N. 7 |
.10 |
N. 8 |
30.05 |
N. 24 |
.08 |
N. 39 |
54. It sometimes happens that storms originating within the torrid zone, or within two or three degrees of it, and south of the United States, pursue a course of nearly 1,000 miles almost directly towards the uortli. while others pursue a very direct course towards the northeast. Table XX shows cases in which storms have traveled northward and eastward, and came from a i)oint as far south as latitude 20°. The arrangement of the table is similar to that of Table XVIII. Columns 3 and 4 show the position of the storm ceuter at tlie beginning and end of the northeast- erly motion, as far as is indicated by the observations ; column 5 shows the prevalent direction of the storm's progress; column 6 shows the average velocity of its progress in miles per hour; column 7 shows the lowest pressure reported, and column 8 gives a brief indication of the previous course of the storm. On Plate XIV these tracks are delineated, and are designated by the same numliers as in the table.
38 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
Table XX. — American storms advancing northerly and easterly.
|
\ Lati- |
Longi- |
Lowest |
' |
||||
|
No. |
Date. |
tude. |
tude. |
Course. |
Veloc-j.^arom- |
Previous course. |
|
|
Beg. End. |
Beg. End. |
ity. |
eter. |
1 1 |
|||
|
1872. |
Miles. |
||||||
|
1 |
Nov. 6. 1- 7. 3 |
26°-47° |
95°-35° |
ENE. |
60.4 |
29.71 |
Unknown. |
|
2 |
Nov. 7. 3- 9. 3 |
25 -30 |
95 -78 |
ENE. |
21. 1 i 29. 74 |
Unknown. |
|
|
3 |
Doc. 9.2-13.3 |
26 -47 |
101 -57 |
NE. |
28.6 i 29.80 |
Unknown. |
|
|
4 |
Dec. 23. 2-27. 2 1873. |
25 -44 |
95 -58 |
NE. |
29.8 |
29.17 |
Unknown. |
|
5 |
Feb. 19. 1-22. 1 |
21 -45 |
98 -64 |
NE. |
35.1 |
29.17 |
Unknown. |
|
6 |
May 4. 1-10. 1 |
24 -43 |
98 -81 |
NE. |
15. 8 |
29.57 |
Unknown. |
|
7 |
Sept. 18. 1-20. 1 |
24 -34 |
92 -74 |
NE. |
24.3 |
29.57 |
Unknown. |
|
8 |
Sept. 22. 3-24. 1 |
25 -36 |
86 -72 |
NE. |
28.5 1 29.78 |
Unknown. |
|
|
9 |
Oct. 5. 1- S. 2 |
25 -43 |
87 -62 |
NE. |
32.9 1 29.02 |
Towards NW. |
|
|
10 |
Dec. 24. 2-27. 1 1874. |
24 -43 |
88 -62 |
NE. |
30. 4 29. 37 |
Unknown. |
|
|
11 |
Jan. 5.2- 9.1 |
25 -49 |
87 -68 |
NNE. |
18.0 I 29.42 |
Unknown. |
|
|
12 |
Fel). 7.2-11.1 |
25 -46 |
82 -58 |
NNE. |
25.0 |
28.95 |
Towards NW. |
|
13 |
Apr. 17. 3-24. 1 |
24 -46 |
94 -59 |
N.&NE. |
29.7 |
29.36 |
Unknown. |
|
14 |
Sept. 2.3-10.2 |
22 -50 |
99 -89 |
N. |
21. 5 |
29. 47 |
Unknown. |
|
15 |
Sept. 27. 1-30. 2 |
25 -50 |
87 -66 |
NNE. |
26.0 |
28.94 ' Unknown. |
|
|
16 |
Dec. 18.2-21.1 1875. |
25 .39 |
96 -62 |
NE. |
34.6 |
29. 33 Unknown. |
|
|
17 |
Nov. 6. 1- 7. 3 1876. |
25 -31 |
98 -78 |
ENE. |
32. 9 |
29.82 1 Unknown. |
|
|
18 |
Oct. 19.1-21.1 1877. Sept. 16. 1-21. 3 |
21 -32 |
82 -72 |
NNE.. |
19.5 |
29. 51 |
Not traceable. |
|
19 |
25 -31 |
96 -76 |
ENE. |
10.7 |
29.40 |
Unknown. |
|
|
1878. |
. |
||||||
|
20 |
Jan. 6.1-12.2 |
24 -46 |
100 -56 |
NE. |
26.4 |
28.85 |
Not traceable. |
|
21 |
Feb. 26. 2-28. 1 |
24 -30 |
92 -71 |
ENE. |
31.1 |
29. 71 |
Came from NW. |
|
22 |
Mar. 17. 1-17. 2 |
23 -25 |
85 -78 |
ENE. |
(?) 29.79 |
Not traceable. |
|
|
23 |
Mar. 19. 3-22. 3 |
25 -27 |
95 -78 |
E. |
15.0 29.71 |
Came from W. |
|
|
24 |
July 2.1- 2.3 |
25 -27 |
85 -73 |
ENE. |
22.9 1 29.77 |
Not traceable. |
|
|
25 |
Sept. 24. -33 |
15 -32 |
76 -61 |
N.&NE. |
10. 1 ! 29. 70 |
Not traceable. |
|
|
26 |
Oct. 21.1-24.2 |
20 -38 |
81 -57 |
N.&E. |
27.5 28.83 Not traceable. |
||
|
27 |
Nov. 13.3-20.1 |
22 -44 |
97 -57 |
E.&NE. |
24. 5 1 29. 83 j Not traceable. |
||
|
28 |
Nov. 17.2-21.1 1879. |
24 -47 |
93 -57 |
NE. |
40. 3 29. 47 Came froui NW. |
||
|
29 |
Nov. 19. 1-20. 3 1880. |
23 -49 |
74 -60 |
NNE. |
48.8 |
29.00 1 Not traceable. 1 |
|
|
30 |
Jan. 24. -28. 1 |
21 -36 |
86 -75 |
N. |
14.3 |
29. 68 Not traceable. |
|
|
31 |
Mar. 7. 3- 9. 2 |
26 -32 |
99 -74 |
ENE. |
38. 0 29. 86 ! Not traceable |
||
|
32 |
May 3. 1- 6. 2 |
26 -47 |
93 -59 |
NE. |
23.8 29.79 i Unknown. |
||
|
33 |
Ang. 19 -20 |
20 -27 |
78 -74 |
NNE. |
12. 4 1 29. 86 Towards NW. |
55. We see from this table tbafc stoim.s of tlii.s class occur most frequeutly in the autumn and least frequently in the summer. One of these storms began near latitude 15°, two began near latitude 20°, and seventeen of them began south of latitude 24°. Three of these storms had been traveling towards the northwest, previous to the dates given in the table, and two of them came from the northwest; but in the other cases the barometric depression was too small to allow us to trace their course previous to the dates here given. For most of the cases in the last half of the table this is clearly shown by the international observations, and we may therefore infer it to be true in the other cases. As long as these storms continued south of latitude 30° the barometric depression was generally small, but it increased as the storm advanced northward. In tifteen cases the barometer fell below 29.5 inches, and in four ca.ses itl'ell below 29.0 inches. The average velocity of progress of these storm centers, while a<1vancing northward and eastward, was 26.9 miles per hour. From a comparison of this table with Table HI we perceive that the American storms which originate between the equator and latitude 20° N., generally travel towards a point between north and west, but occasionally they advance almost exactly northward.
56. In order to institute a compaiison between the peculiarities of these storms whicli travel northward and those which travel almost exactly towards the south I have selected those storms which passed near Galveston, Tex., and which pursued paths almost exactly opposite to those shown in Table XVIII. Table XXI exhibits the leading phenomena of these storms, as deter- mined by ^observations at five stations.
CONTRIBUTIONS TO METEOROLOGY.
39
Table XXL — Areas of low pressure, Nos. G, 13, 14, and 27.
|
Iii<li;inola. |
(ialve.'itdii. |
Sbrtn |
eport. |
Fort Gibson. |
Leavenworth. |
|||||
|
Barom. |
Wind. |
Baroui. |
Wiud. |
Barom. |
Wind. |
Barom. |
Wind. |
Barom. |
Wind. |
|
|
1873— No. 6. |
||||||||||
|
May 4. 3 |
29.89 |
E. 34 |
29.91 |
E. 13 |
29.96 |
E. 8 |
30.05 |
E. 2 |
29.98 |
Calm. |
|
■ 5.1 |
.83 |
E. 14 |
.87 |
SE. 12 |
30.00 |
NE. 6 |
.06 |
E. 2 |
30. 00 |
Calm. |
|
5.2 |
.70 |
SW. 17 |
.07 |
SE. 18 |
29.75 |
NE. 13 |
29.96 |
NE. 11 |
29. 87 |
S. 3 |
|
5.3 |
.79 |
E. 10 |
.77 |
NW. 3 |
.73 |
SE. 13 |
.87 |
NE. 12 |
.90 |
E. 2 |
|
6.1 |
.85 |
W.6 |
.78 |
NW. 12 |
.72 |
SW. 11 |
.85 |
E. 4 |
.91 |
Calm. |
|
6.2 |
.82 |
N. 4 |
.76 |
W. 13 |
.70 |
SW. 8 |
.78 |
NE. 7 |
.87 |
SE. 12 |
|
6.3 |
.91 |
N. 5 |
.85 |
NW. 4 |
.76 |
W. 5 |
.83 |
N. 6 |
.78 |
SE. 13 |
|
7.1 |
.96 |
SW. 1. |
.92 |
SW. 4 |
.94 |
W.6 |
.90 |
W. 1 |
.77 |
N5. |
|
1874— No. 13. |
||||||||||
|
Apr. 18. 1 |
29. 85 |
NE. 14. |
29.84 |
E. 7 |
30.05 |
NE. 5 |
30. 14 |
E. 8 |
30.22 |
Calm. |
|
18.2 |
.79 |
N. 15. |
.87 |
SE. 8 |
29.87 |
NE. 8 |
.00 |
SE. 9 |
.10 |
SE.5 |
|
18.3 |
.84 |
N. 22. |
.78 |
SE. 3 |
.82 |
NE. 6 |
29.93 |
NE. 12 |
.09 |
SE. 1 |
|
19.1 |
.91 |
NW. 14 |
.82 |
NW. 20 |
.70 |
SE. 6 |
.67 |
E. 4 |
29.92 |
E. 15 |
|
19.2 |
.89 |
W. 20 |
.81 |
W. 18 |
.70 |
SW. 13 |
.47 |
S. 20 |
.."SO |
E. 24 |
|
19.3 |
.98 |
• W. 4. |
.94 |
SW. 5 |
.92 |
S. 8 |
.46 |
S. 28 |
.39 |
NE. 7 |
|
20.1 |
30.09 |
SW. 7 |
30.03 |
SW. 11 |
.99 |
SW. 7 |
.80 |
W. 20 |
.61 |
NW. 20 |
|
1874— No. 14. |
||||||||||
|
Sept. 5. 1 |
29.85 |
NE. 38 |
29. 89 |
NE. 16 |
29.95 |
E. 4 |
29. 99 |
Calm |
29.98 |
S. 3 |
|
5.2 |
.78 |
E. 48 |
.84 |
E. 17 |
.88 |
E. 4 |
.89 |
NW. 3 |
.85 |
S. 10 |
|
5.3 |
.81 |
SE. 36 |
.89 |
SE. 10 |
.96 |
S. 8 |
.93 |
E. 5 |
.89 |
S. 6 |
|
6.1 |
.87 |
SE. 18 |
.91 |
E. 12 |
.97 |
E. 4 |
30.00 |
SE. 6 |
.97 |
S. 1 |
|
6.2 |
.87 |
SE. 20 |
.89 |
SE. 15 |
.92 |
E. 2 |
29. 92 |
S. 14 |
.86 |
S. 10 |
|
6.3 |
.91 |
SE. 18 |
.95 |
SE. 12 |
.98 |
E. 4 |
..99 |
SE. 6 |
.94 |
S. 16 |
|
7.1 |
.94 |
SE. 12 |
.95 |
SE.8 |
.98 |
Calm. |
30. 03 |
SE.5 |
30.02 |
Calm. |
|
1878— No. 27. |
||||||||||
|
Nov. 14. 1 |
29.94 |
NE. 24 |
29.97 |
SE. 12 |
30.08 |
Calm. |
30.08 |
E. 9 |
30.19 |
E. 4 |
|
14.2 |
.88 |
NE. 15 |
.92 |
E.. 15 |
29.98 |
E. 8 |
29.99 |
E. 6 |
.16 |
SE.4 |
|
14.3 |
.91 |
NW. 10 |
.91 |
NE. 8 |
.96 |
Calm. |
30.05 |
S. 8 |
.09 |
E. 3 |
|
15.1 |
30.01 |
NW. 12 |
.95 |
W. 8 |
.92 |
Calm. |
29.94 |
N. 3 |
.04 |
E. 1 |
|
15.2 |
29.96 |
N. 10 |
.97 |
NW. 11 |
.92 |
W. 1 |
.83 |
W. 8 |
29.89 |
S. 1 |
|
1.5.3 |
.99 |
E. 5 |
.99 |
N. 4 |
.98 |
Calm. |
.90 |
W. 3 |
.91 |
S. 2 |
|
16.1 |
.95 |
SE. 9 |
.98 |
E. 5 |
30.01 |
Calm. |
.98 |
Calm. |
.97 |
N. 4 |
By comparing Table XXI with Table XIX, we perceive that iu the ca.sc of the storms which traveled northward the a^ erage barometric oscillation was only two-thirds of that of the storms which traveled southward ; that the average force of the wiud in the former case was less than two thirds of that in the latter case ; that in the latter case the winds which followed the low center were generally from the north, and that 92 per cent, of them were either from the north, northwest, or northeast, while in the former case the winds were very irregular, but southerly winds were somewhat more frequent than northei'ly winds. We perceive, then, that the progress of the storms which traveled southward conformed closely to that of the winds which succeeded the low center, but that in the case of the storms which traveled northward, although there was some tendency towards the same law, this tendency was not strongly marked, and the winds were generally moderative in force. It seems then probable that some other cause or causes than that of the prevalent wind exerted an api)reciable intiueuce in diverting these areas of low pressure towards the north. Among these causes may be mentioned the influence of neighboring areas of high and low pressure, as will be shown hereafter.
57. Occasionally we And instances in which the storms of the middle latitudes of the United States pursue a course still more abnormal than those shown in Tables XVIII and XX, The Signal Service maps show cases in which the storms of the middle latitudes have pursued for a short time a westerly course. In some of these cases the depression of the barometer was small and there was no well-defined storm center. Sometimes there were two centers of slight depression within a few hundred miles of each other, so that a small change in the force of the winds caused one of the centers to predominate slightly, and thus the center of greatest depression was carried iu an unusual direction. Table XXII shows the most decided cases iu which the centers of low pressure in the middle latitudes of the United States have advanced in a westerly direction. Column 1 gives the reference number; column 2 the date of beginning and end of the westerly
40
MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES.
movement; colninn .3 the duration of the westerly nicvemeut, expressed iu units of eight hours; columns i and 5 the latitude and longitude of the points of beginning and end of the westerly movement; column 6 the prevalent direction of this movement; column 7 its velocity in miles per hour; column 8 the lowest barometer reported during the continuance of this westerly move- ment; and column 9 shows its subsequent course. These abnormal movements ai'e all delineated on Plate XV, and are designated by the same numbers as in the table.
Table XXII. — Areas of low pressure in the United States, advancing westerly.
|
No. |
Date. |
Dura- tion. |
Latitude. Beg. End. |
Lougitude. Beg. End. |
Course. |
Velocity. |
Lowest baro- meter. |
Subsequeut course. |
|
1873. |
Miles. |
|||||||
|
1 |
Oct. 20. 1-21. 3 1874. |
5 |
38°-45° |
75°- 86° |
NW. |
20.7 |
29.26 |
NE. |
|
2 |
May 9. 1- 9. 3 1S76. |
2 |
49 -43 |
98 -103 |
SW. |
37.3 |
29.01 |
NE. |
|
3 |
Jan. 8. 3- St. 1 |
1 |
44 -43 |
84 - 86 |
sw. |
22.2 |
29.45 |
ENE. |
|
4 |
Feb. 25. 3-26. 3 |
3 |
42 -38 |
95 - 97 |
ssw. |
8.5 |
29.40 |
Eastward. |
|
5 |
Jnue 17.3-18.2 |
2 |
44 -47 |
86 - 89 |
NNW. |
12.7 |
29.37 |
Soutberly. |
|
G |
Sept. 17.2-17.3 1877. |
1 |
38 -42 |
77 - 80 |
NNW. |
28.8 |
29. 16 |
E. |
|
7 |
Feb. 21.2-22.1 |
2 |
48 -43 |
89 - 92 |
SSW. |
33.9 |
29.35 |
Eastward. |
|
8 |
Nov. 22.3-24.3 1878. |
6 |
32 -42 |
79 - 84 |
NNW. |
15.7 |
29.63 |
Coalesced. |
|
9 |
Feb. 19.2-20.1 |
2 |
43 -35 |
95 - 98 |
SSW. |
24. 6 |
29.33 |
NE. |
|
10 |
Mar. 10. 1-11. 1 |
3 |
43 -44 |
9(i -102 |
WNW. |
18. 0 |
'29.47 |
Eastward. |
|
11 |
Mar. 23.1-24.1 |
3 |
50 -42 |
574- 72 |
SW. |
36.0 |
29.22 |
ENE. . |
|
12 |
Apr. 28. 2-29. 1 |
2 |
37 -41 |
77 - 80 |
NNW. |
18. 5 |
29. 58 |
Coalesced, |
|
13 |
Juue 22.2-23.1 |
2 |
42 -44 |
76 - 79 |
NNW. |
15.7 |
29. 61 |
ENE. |
|
14 |
Nov. 5. 1- 9. 2 1879. Jnly 12. 1-12. 3 |
13 |
49 -47 |
58 - 68 |
W. by S. |
15.0 |
29.18 |
Coalesced. |
|
15 |
2 |
39 -34 |
73 - 80 |
SW. |
35.5 |
29.57 |
Became extinct;. |
|
|
16 |
Dec. 27.1-27.3 1880. |
2 |
45 -42 |
93 - 98 |
SW. |
25.0 |
29.69 |
ENE. |
|
17 |
Feb. 26.2-27.1 |
2 |
42 -38 |
94 -100 |
SW. |
26.9 |
29. 51 |
ENE. |
|
18 |
Sept. 17.1-17.3 |
2 |
46 -41 |
95 - 98 |
SSW. |
17.2 |
29.61 |
NNE. |
|
19 |
Oct. 28. 1-28. 3 1881. |
2 |
49 -44 |
97 -102 |
SW. |
24.1 |
29.77 |
Coalesced. |
|
20 |
May 18. 2-20. 1 |
5 |
38 -46 |
74 - 78 |
NW. |
17.3 |
29.82 |
Disappearpil. |
|
21 |
Aug. 27.2-30.2 |
9 |
31 -45 |
80 - 95 |
NW. |
1.5.4 |
29. 68 |
Disa])peare(l. |
|
22 |
Sept. 15.2-17.2 |
6 |
38 -50 |
87 - 97 |
NNW. |
21.5 |
29. 43 |
Unknown. ; |
|
23 |
Dec. 12. 2-12. 3 1882. |
1 |
47 -42 |
91 - 93 |
SSW. |
35.5 |
29.69 |
ENE. |
|
24 |
Mar. 25.3-26.1 |
1 |
42i-39 |
93 - 99 |
SW. |
28.7 |
29. 58 |
ENE. |
|
25 |
Apr. 11.3-13.1 |
4 |
45--49 |
62 - 68 |
NW. |
17.0 |
29. 21 |
ENE. |
|
26 |
July 5. 3- 6. 1 1884. |
1 |
42 -45 |
70 - 74 |
NW. |
28.7 |
29. 78 |
NE. |
|
27 |
Mar. 5. 2- 7. 1 |
5 |
35 -29 |
93 - 98 |
SW. |
12.5 |
29.80 |
ENE. |
|
28 |
May 19.3-20.1 |
1 |
44 -39 |
97 -104 |
SW. |
43.1 |
29. 62 |
ENE. |
|
29 |
Juue 10.2-13.1 |
8 |
39 -32 |
80 - 86 |
SSW. |
14.4 |
29. 68 |
Became extinct. |
58. We perceive that these cases are distributed with tolerable uniformity through the diflerent months of the year ; they are not restricted to any particular portion of the United States, aud their average velocity of progress is 23 miles per hour, which is somewhat less than the average velocity of the storms of the United States. If we seek in each case for the probable cause of its abnormal movement we shall be forced to conclude that this cause was not the same iu all cases. Among these causes we notice the following :
I. Sometimes near to an area of low pressure, with its system of circulating winds, we find a second area of low pressure, having also its own system of circulating winds. Between these two low centers the winds are usually feeble, and they sometimes change into a single system of winds circulating about a low area of an elongated form. If the depression continues the area of low pressure usually becomes less elongated and the two low centers coalesce. By this union the western low center is accelerated eastward, and the eastern low center is temporarily diverted towards the west. Table XXII affords several illustrations of this principle.
No. S was at first a small dejiiession near Charleston, S. C, and was advancing slowly north-
CONTRIBUTIONS TO METEOROLOGY-
41
ward, while a greater dei)rcssioii prevailed at the same time in Dakota, and was a<l vancing eastward. Tliese two centers tliiis approaclied eacli other and became partially blended on the 24tli, but did not I'orni a s'rand depression, jjrobably on acconnt of a general low pressnre, which prevailed at that time over a large portion of the United States, and which resulted in feeble gradients.
No. 14 continued its abnormal movements for a7i iinnsually long i)eriod, but the time given in the table embraces two i)eriods of movement towards the west, separated by a period in which its motion was eastward, and its abnormal movements were only in part due to the cause here con- sidered. November t! there was a second area of low pressure in the valley of the Mississippi, and this low center partially controlled the winds to a distance of nearly 1,000 miles on its eastern side. This second low was apparently one of the causes which attracted westward the low ]>re- vailing near the Gulf of Saint Lawrence. This seqond westerly movement of the latter low was apparently due in part to another low area, which prevailed at that time in the neighborhood of Hudson's Bay.
No. 19 was apparently diverted towards the southwest by a second low area, which advanced from California eastward, and which coalesced with the former on the evening of October 28.
No. lil was similar to No. 8, being apparently diverted towards the northwest by a low area l)revailiug in Dakota, and with which it coalesced August 29.
No. 26 was a small low near the Atlantic coast, which was apparently attracted by a greater low prevailing in Minnesota, and with which it coalesced.
II. Sometimes a heavy fall of rain or snow appears to divert a system of circulating winds towards the region of rainfall, and the center of a low area may be thereby carried in an abnormal direction. Table XXII affords several illustrations ofi this principle. No. 1 was a storm of unusual violence, accompanied by very higli winds, and a very unusual fall of rain, and the greatest amount of rain fell on the north or northwest side of the low center. Table XXIII shows the rainfall at twelve stations, as reported at each of the three daily observatioiis for two days. The last column shows the aggregate fall for the entire period of forty eight hours. The center of the low area appeared to be attracted toward the region of greatest rainfall.
Table ^XUI.— Bain/all October 19.2 to 21.1, 1873.
Norfolk
Ljuchbur};
Washiugtou
Cape May
Baltimore
Philadelphia
Pittsburgh
New York
Biitfalo
Rochester
Oswego
Kingston, Canada,
19.2
0.15 . 5.5 .13 .00 2-2 .00 .51 .00 .31 .31 .17 .42
19:3
0. 50 .65
1.3iJ .44 .78 .06 .51 .02 .10 .44 .23 .21
20.1
0.32
.32
1.11
.77
1.78
1.96
.97
.75
.32
1.19
1.42
.85
20.2
0.46 .11 .43 .85 .86 .21 .32 .10 .90 1.38 1.02 .30
20.3
21.1
0.02 .07 .01 i .31 I .05 I ,.55 I .67 ! .03 1.23 i 1.20 I ..57 .35
0.00 .00 .08 .00 .02 .00 .33 .04 .05 .49 .15 .00
Sum.
1.51 1.70 3.08 ■2. 37 3.71 ■2.78 3. 31 0.94 2.91 5.01 3.56 2.13
No. 5 was a storm similar to the preceding, but less violent. Table XXIV shows the rainfall at seven stations during a period of two days. The greatest rainfall was generally on the north- west side of the low center.
Table XXIY.— Bain/all June 16.3 to 18.2, 1876.
16.3
17.1
17.2
Grand Haven 1.03
Milwaukee i .01
La Crosse .13
Alpena .00
Escanaba ; .33
Marquette ; .19
Dnluth .50
0.00 ..38
1.13 .02 .37 .82 .00
1.08 .34 .92 .13 .26 .03 .51
17.3
18.1
0.28 j .12 .15 I .00 1 .39 .90 .44
0.32 .28 .43 .00 .08 .04 .27
18.2
0.18 .03 .00 .00 .20 .02 .00
S. Mis. 154—6
Sum.
8.89 1.16 2.76 0.15 1.63 2.00 1.72
42
MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES.
No. 6 was a storm similar to No. 1, witli equally violent winds, and a somewhat greater fall of rain, and tbe greatest rainfall was on the north and northwest sides of the low center. Table XXV shows the rainfall at ten stations during a period of two days.
Table 'KXY .—Rainfall Septemher 16.2 to 18.1, 1876.
Charlestoii. . . Wilmington .
Norfolk
Washington . Cape May . . . Baltimore . . . Philadelphia New York . . . Pittsburgh . Erie
16.2
0.03 .57 .70 .01 .01 .03 .00
■.00 .00 .00
|
16.3 |
17.1 |
17.2 |
17.3 |
18.1 |
Sum. |
|
0.40 |
2.30 |
0.00 |
0.00 |
0.00 |
2.73 |
|
.24 |
3.16 |
.48 |
.00 |
.00 |
4. 45 |
|
.62 |
.32 |
.66 |
.00 |
.00 |
2. 30 |
|
.10 |
.37 |
2.84 |
.05 |
.00 |
3.37 |
|
.28 |
1. 46 |
.20 |
.02 |
.00 |
1.97 |
|
.09 |
I.IS |
2.42 |
.42 |
.00 |
4.14 |
|
.01 |
1.38 |
1.68 |
.42 |
.00 |
3.49 |
|
.00 |
1.03 |
1.20 |
.40 |
.00 |
2.63 |
|
.10 |
.30 |
1.01 |
2.07 |
1.00 |
4.48 |
|
.00 |
.00 |
1.10 |
1.30 |
2.00 |
4.40 |
No. 11 was an area of low pressure which traveled eastward near the parallel of 50°, and when it had passed a little beyond Quebec was for a few hours diverted towards the southwest. This westward movement of the low center was accompanied by a considerable fall of snow in the neighborhood of Lakes Erie and Ontario. Table XXVI shows the amount of the precipitation (reduced to water) at live stations during a period of twenty-four hours.
Table XXVI. — Fall of snow {reduced to water) March 23.3 to 24.2, 1878.
|
23.3 inch. |
24.1 inch. |
24.2 inch. |
Sum. inch. |
|
|
0.00 .00 .15 .04 .06 |
0.48 .30 .20 75 .23 |
0.14 .05 .58 .17 .06 |
0.62 .35 .93 .96 .35 |
|
|
Erie |
||||
|
Buffalo |
||||
|
Oswego .. |
||||
No. 12. The northerly and westerly movement of this low area on the afternoon of April 28 was accompanied by a considerable rainfall on its northwest side, and there was also on the northwest side a second low area, which was traveling eastward, and which coalesced with the former on the evening of April 29. The latter cause may have promoted the westerly movement of No. 12.
No. 13 was similar to the preceding. The movement of this low center towards the north- west on the afternoon of June 22 was accompanied by considerable rain on the northwest side of the low center, and there was also on the northwest side a second low area which coalesced with the former on the following day.
No. 14. There was a heavy fall of snow in the neighborhood of the Gulf of Saint Lawrence, in connection with this storm, and there are indications that this snow-fall had some influence upon the movements of this low area, but, as I have no observations except those published in the International Bulletin, and as these are given but once a day, the evidence is not entirely satisfactory.
No. 24. The diversion of this low center towards the southwest on the afternoon of March 25 was aijparently the i-esult of a heavy fall of rain in Texas.
III. When two centers of high pressure are situated within a few hundred miles of each other a feeble system of circulating winds frequently springs up between them, and if there is a considerable fall of rain or snow a new center of low pressure is usually formed, and this may occasion abnormal movements in a neighboring area of low pressure, in the manner described in Paragraph I.
No. 20 affords an illustration of this principle. There was a center of low pressure over North Carolina, with a center of high pressure over Newfoundland, and another over Montana. Between
COM TRIE DTIONS TO METEOROLOGY.
43
these two areas of high pies.snic the winds were feebh- and several centers of local disturbance were formed, attended by some rain. The barometer Cell slowly, and the low center over North Carolina was carried northward and .si)mewhat westward.
No. 22 was similar to the preceding, except that the rain-fall was very great, and the low center moved rafjidly northward, and the dei)ression at the center of the low area increased.
The movement of No. 23 towards the southwest, December 12, was apparently due to a similar cause.
No. 25 may probably be ascribed in part to the same cause. There was a center of low press- ure near Nova Scotia, with a high area near Lake Superior, and a second high area over Green- land. At the same time there was a considerable fall of snow on the north and northwest sides of the low center, and by the joint intiuence of these two causes the low center was carried north- ward and westward.
The first movement of No. 14 towards the northwest was ap])arently due to a similar cause.
IV. Sometimes we find an extensive area of low pressure with feeble gradients on its southern side, having northerly winds on its north side and southerly winds on its south side. On the north side the barometer rises and the thermometer falls ; ou the south side the opposite ettects usually take place, but in a less marked degree, and occasionally on the south side the barometer does not fall at all. In either case the center of low pressure is diverted towards the south or southwest, even when no rain-tall, or only a fiill of two or three hundredths of an inch, is reported on that side of the low centei-. This abnormal movement of the low center appears generally to result from the influence of an area of high pressure (or relatively high pressure) prevailing on the north or northeast side, and crowding southward with considerable force. The center of the low area appears to be displaced by the influence of the high area, which tills up the low area ou its northern side, and generally but little change takes place ou its southern side. Table XXII affords several examples of this kind. Table XXVII presents a summary of the leading particu- lars relating to twelve of these low areas. Column 1 gives the number taken from Table XXII j column 2 shows the change of the barometer in twenty-four hours on the northern side of the low center ; column 3 shows the change in the thermometer on the northern side during the same period 5 column 4 gives the barometric gradient on the northern side, showing (in decimals of an inch) the change of pressure for a distance of GO nautical miles ; column 5 shows the i^revalent wind on the north side ; and column G shows the magnitude of the high area prevailing within a few hundred miles on the north side of the low center; columns 7-10 show corresponding particulars for the south side of the low center; column 11 shows whether any rainfall was reported on the south side of the low center ; and column 12 shows the change of pressure.which took place at the low center during the period of the western motion.
Table XXVII. — Changes in areas of low pressure.
|
On the north side. |
Ou the south side. |
||||||||||
|
No. |
Change in 24 hours. |
Barom- eter gradi- ent. |
Prevalent wind. |
High. |
Change in 24 i hours. |
Barom- eter gradi- ent. |
Prevalent wind. |
Rain. |
Change at low center. |
||
|
Barom. |
Therm. |
Barom. |
Therm. |
||||||||
|
2 3 4 7 9 15 16 17 18 27 28 29 |
Inch. -f-0.25 + .19 + .16 -f .57 -f .M + .32 + .20 + .33 + .11 + .20 + .34 + .13 |
o -10 —28 — 8 -29 — 5 — 3 — 2 —17 — 2 — 8 -20 0 |
Inch. 0.08 .10 .14 .08 .08 .05 .07 .16 .06 .05 .03 .03 |
NE. it NW. NE. & NW. N. & NE. N. N. & NE. N. & NE. N. & NE. N. N. & NE. N. & NE. N.& NW. NE. |
Inches. 30.38 30.24 30.90 30. 33 30.00 29. 99 30. 35 30. 69 30. 12 30.41 30.15 30.43 |
Inch. —0.09 — .15 — .18 — .20 — .51 .00 — .33 .00 — .11 — .08 — .18 — .03 |
o 0 +10 + 8 + 6 -f 4 0 +12 + 1 |
Inch. 0.06 .09 .10 .06 .08 .03 .06 .06 .05 .04 .04 .03 |
S. S. & SW. S. S. & SW. s. SW. S. & SE. s. s. s. s. SW. |
Slight Considerable Slight Sliglit Rain lu Texas Slight None None Slight Slight Slight Slight |
Inch. 0.00 + .10 -.20 -f .11 + .07 + .19 — .07 + .13 + .08 + .04 + .13 + .24 |
44 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
lu No. 16 there was a second low area advancing from the northwest, with which No. 16 coa- lesced December 28. No. 17 was similar to the preceding. These two numbers may, tlereiore, perhaps be transferred to Class I.
No. 9 was attended by considerable fall of rain in Texas, and this case may perhaps be trans- ferred to Class II.
No. 4 was attended by an area of high pressure on the east side and a second area of high pressure on the west side of the low center, and between these two high areas the isobars were very much elongate<l towards the southwest. This case may, therefore, perhaps be transferred to Class III.
The eight remaining numbers show a remarkable agreement in their general features. The dej)ression at the center of the low area did not in cither of these cases increase during the con- tinuance of the westerly movement, and generally the low became decidedly more shallow.
No. 10 bears a decided resemblance to the cases in Class IV. There prevailed on March 10 a high area (30.40) on the Atlantic Coast; a second high (30.20) on the Pacific Coast ; and a third high (30.60) near Hudson's Bay. The latter high area pushed downward towards the southeast, and this ai>peared to be the cause which crowded towards the west the low center which existed near the Missouri Eiver. There was some fall of rain and snow, but this alone does not seem to be sufiQcient to account for the abnormal movement of this low center.
59. I next sought for cases in which storms in the middle latitudes of the Atlantic Ocean or Europe have for a day or moi-e pursued a westerly course. For this purpose I have carefully consulted Hoflmeyer's daily weather charts from December, 1873, to November, 1876; also the daily charts of the Danish Meteorological Institute and the Deutsche Seewarte from December, 1880, to August, 1881 ; also tlie monthly maps of storm tracks published by the Deutsche See- warte from 1876 to 1884, and the monthly maps of storm tracks according to the international observations from November, 1877, to April, 1882. Table XXYI II shows the most decided cases of these westerly movements. These abnormal movements are represented on Plate XVI, and are designated by the same numbers as in the table.
60. We perceive from this table that these abnormal movements occur in all mouths of the year, but are most frequent in spring. We also perceive that movements towards the northwest are more than twice as fre(]uent as those towards the southwest, whereas in the United States southerly movements are most common. The average velocity of progress of storm centers during their westerly movement is 15.5 miles per hour, which accords very closely with the average velocity of all storm centers for Euroi)e.
If we carefully examine each case in the preceding table we shall find examples of three, if not all, of the classes already described for the United States. In nearly every case we find a fall of rain or snow in the region toward wbicli the low center advanced, and in most of the cases the rainfall was unusually great. In the latter statement are included Nos. 0, 9, 15, 16, 17, 18, 19, 20, 22, 30, 34, 37. and 41. This list does not include cases in which the low center was over the Atlantic Ocean, since in these cases the amount of rainfall is unknown. It may be inferred from this comparison that a fall of I'ain or snow is one of the most important causes which determine the abnormal movements of areas of low pressure.
In a large number of the cases in Table XXVIII the low center appeared to be attracted towards a second low center which was at no great distance, and in several cases the two low centers subsequently coalesced. Nos. 1, 2, 3, 4, 5, 7, 8, 9, 11, 12, 13, 14, 18, 19, 20, 23, 24, 26, 28, 29, 30, 31, 34, 35, 37, 40, and 41 exhibit this attractive influence of a second low center, and in Nos. 1, 2, 5, 8, 11, IS, 23, 28, 29, 30, 34, 35, 40, and 41 the two low centers coalesced. The mutual influence of two low centers would thus seem to be even more efdcieut than that of rainfall, but these two causes generally concur ; and the correspondence between the two lists of numbers here given would i)robably be more complete if the observations had I'urnished a full report of the rain- fall in the neigliborhood of each low center.
The number of cases in which the low center advanced between two areas of high pressuie, not very remote from each other, or in a direction lying between two such areas and apparently under their influence, is very great. Nos. 1, 2, 3, 4, 6, 7, 10, 11, 14, 10, 17, 18, 19, 21, 23, 27, 29, 36,
CONTEIBUTIONS TO METEOROLOGY.
45
Table XXVIII. — IStorms advancing westerly over Eurojte and the Atlantic Ocean.
|
No. |
Date. |
Latitude. Beg. End. |
Longitude. Beg. End. |
Course. |
Velocity. |
Lowest barometer. |
Subsequent course. |
|
1875. |
o |
o |
Miles. |
||||
|
1 |
Mar. 14-U; |
50 -46 |
3.5-4U W. |
SW. |
9.2 |
730""" |
Coalesci'd. |
|
2 |
Dee. 17-19 1870. Apr. 19-20 |
64 -64 |
29-43 W. |
W. |
10.5 |
720 |
Ea.sterly. |
|
3 |
52 -56 |
3-5 W. |
NNW. |
13.1 |
735 |
Northeast. |
|
|
4 |
.June 19-20 |
.57i-60J |
23i-27 W. |
NW. |
10. 9 |
730 |
Sulidividcd. |
|
5 |
June 22-23 |
57i-59 |
26-33* W. |
WNW. |
14.1 |
740 |
Disappeareil. |
|
6 |
Sept. 9-12 |
55 -60 |
21-7' E. |
WNW. |
9.6 |
735 |
Siil>di\id('d. |
|
7 |
Sept. 22-23 |
54i-56 |
26il-30 W. |
NW. |
8.8 |
740 |
Sulidivideil. |
|
8 |
Oct. 20-21 |
56f-C4 |
34i-49 W. |
NW. |
28.8 |
720 |
Eastwax'd. |
|
9 |
Dec. 21-23 1877. Apr. 4- 8 |
53 -56 |
1-8 W. |
WNW. |
8.6 |
729 |
Southerly. |
|
10 |
56 -50 |
9-13 W. |
SSW. |
5.0 |
733 |
East northeast. |
|
|
11 |
May 1- 7 |
45 -65 |
48-16 E. |
NW. |
13.8 |
745 |
Disappeared. |
|
1-2 |
.July 15-16 |
54 -54 |
2-4i W. |
W. |
4.2 |
737 |
Northe,a.st. |
|
U |
Aug. 9-10 1878. Mar. 31-32 |
54 -59i |
0-2 W. |
NNW. |
14.9 |
745 |
Coalesced. |
|
14 |
59*-58J |
10 E.-O |
W. |
14.8 |
729 |
Eastward. |
|
|
15 |
Mav 30-32 |
60 -59i |
27A-17i E. |
w. |
12.1 |
741 |
Northeast. |
|
Ifi |
Nov. 4- 6 |
54 -59 |
25-19 E. |
NW. ■ |
10.1 |
737 |
Northeast. |
|
17 |
Nov. 11-13 |
59 -50 |
6-1 E. |
SSW. |
15.1 |
733 |
Eastward. |
|
18 |
Nov. 1 4-1,) |
44 -54 |
13-4 E. |
NNW. |
17.6 |
734 |
South. |
|
19 ' Dec. 10-11 ' 1 1879. 20 I Feb. aO-21 |
.52 -gCi |
25-23 E. |
NNW. |
13. 5 |
739 |
Noitheast. |
|
|
53 -54 |
32-11* E. |
W. |
35. 0 |
735 |
Northeast. |
||
|
21 Mav 7-12 |
62i-65 |
29i E.-'7 W. |
W. |
18.4 |
738 |
Coalesced. |
|
|
22 |
May 27-28 |
50 -48 |
6 E.-4 W. |
w. |
18.8 |
747 |
Northeast. |
|
23 |
May 31-32 |
60 -60 |
9-4 E. |
w. |
7.2 |
742 |
Divided. |
|
24 |
Sept. 7- 8 1880. |
55 -58 |
9-14 W. |
NW. |
12.2 |
735 |
Northeast. |
|
25 |
July 21-22 |
58 -64 |
62-50 E. |
NW. |
24.4 |
7.39 |
Eastward. |
|
26 |
Oct. 3- 4 1881. |
60 -63 |
28-23 E. |
NW. |
10.9 |
735 |
Eastward. |
|
27 |
Jan. 12-14 |
60 -71 |
42-36 E. |
NNW. |
16.2 |
746 |
Unknown. |
|
28 |
Feb. 26-27 |
48i-46i |
.34-44i W. |
wsw. |
18.6 |
745 |
Northward. |
|
29 |
Mar. 3- 4 |
48 -49 |
24i-26 VV. |
NW. |
5.0 |
735 |
Northward. |
|
• 30 Auu;. 17-18 18-2. 31 , Mar. 30-34 |
59i-63 |
30^-22 E. |
NW. |
1.5. 8 |
737 |
Uncertain. |
|
|
60 -50 |
5E.-20 W. |
sw. |
17.2 |
742 |
Coalesced. |
||
|
32 Mav 24-26 |
58 -50 |
5-20 W. |
SW. |
17.5 |
738 |
Northward. |
|
|
33 1 July 8- 9 |
57 -57 |
6-11 W. |
W. |
7.8 |
740 |
Nortlieasl. |
|
|
34 ' July 10-12 |
58 -62 |
19-17 E. |
N. |
6.5 |
735 |
Northeast. |
|
|
3.5 Nov. 21-23 |
58 -60 |
16 E.-IO W. |
VV. |
19.5 |
738 |
Northeast. |
|
|
1 1883. |
|||||||
|
.S6 Jan. 6- 7 |
49 -55 |
45-40 E. |
NNW. |
19.4 |
749 |
Northeast. |
|
|
37 ' Mar. 8- 9 |
46 -40 |
23-3 E. |
WSW. |
42.0 |
748 |
Northeast. |
|
|
.■?8 Mar. 14-18 |
57 -55 |
40 E.-6 W. |
W. |
19.3 |
742 |
Uncertain-. |
|
|
39 |
Mar. 21-23 |
45i-41 |
10-19 W. |
"wsw. |
12.9 |
748 |
Northeast. |
|
40 |
Mar. 25-26 |
65 -56 |
22-9 E. |
SW. |
33. 6 |
725 |
Northeast. |
|
41 |
Apr. 24-25 |
50 -.55 |
6 E.-3 W. |
NW. |
22.0 |
748 |
Coalesced. |
and 41 are of this class. It will be noticed that in three cases the same number occurs in three of the preceding lists, antl in twenty cases the same number occurs in two of these lists.
61. It may be objected that if I assign two or three causes for the same phenomenon the I)robability is that I have failed to discover the true cause. To this objection it may be answered, that the three causes here assigned are all intimately related to each other, and maj- all concur in the same phenomenon, or in different stages of the same pheuomenou. It will be shown hereafter that the surface winds blow outward Irom au area of high pressure, and circulate around the center from left to right, as shown in the outer portions of Plate XIV, Fig. 2. Now sui)pose that two areas of high pressure are situated at a distance from each other not much greater than the sum of their radii, and that the air between them is quiet, and the i)ressure does not ditfer much from 760'"™ or .30 inches. These two areas of high i)ressure exert au influence to set the air between them in motion, in such a manner as to circulate from right to left about a center. The inward motion which attends this circulation cannot exist unless a portion of the air within this area ascends above the earth's surface. This air, in ascending, becomes cooled, a portion of its vapor is
46 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
coiideused, aud is i)recii)ltated iu the foini of rain or fsiiow. The heat, liberated in the condeusa- tiou of this va])Or, causes a stronger upward uioveuient of the air, tlie inward movement of the air is accelerated, aud the barometer falls for a reason to be explained hereafter. Thus may be formed an area of low pressure as exhibited in Plate XIV, Fig. 2, within which the winds circulate with great velocity, and there is an abundant precii)itation of rain or snow. If there is a second area of low pressure within a moderate distance these two systems of circulating winds may unite to form a single system of winds, and thus the two low centers may coalesce. Whenever the first case exists (vnz, two areas of high pressure not very remote from eacli other), there generally results a fall of rain, with the development of a new low center, and this low center under favorable circum- stances will coalesce with another low center in its vicinity.
62. There remain five cases not included in either of the preceding lists, viz, Nos. 25, 32, 33, 38, and 39, and each of these cases bears some reseml)lance to Class IV for the United States, Art. 58. In No. 25 the ]>ressure was below 30 inches throughout the whole of Asia aud a large part of Europe, and there were several centers about which there prevailed feeble systems ot circulating winds. On the western side of the low, near the Ural Mountains, the gradients were feeble aud the pressure on that side was behnv 30 inches for a distance of 2,000 miles. Under such circumstances a small force was sufficient to change the position of the point of least i)ressure. If the isobars for this region could be drawn in a reliable manner for each tenth of an inch they would probably indicate more definitely the nature of this force.
No. 32 was similar to the preceding. In no [)art of the northern hemisphere did the pressure rise much above 30 inches, aud iu nearly the whole of Euroi>e and Asia the pressure was below 30 inches.
Iu No. 33 the pressure was also below 30 inches in nearly every part of Eui'ope and Asia. These three cases were quite similar, and the abnormal movement of the low center was probably due to the same cause.
In No. 38 the gradients on the eastern siile were considerable, but on the western side they were slight, and the low center appeared to be crowded westward by an area of high pressure (30.4 to 30.0), which followed it i)ersistently on the northeast side, while the pressure on the southwest side for a great distance was below 30 inches.
No. 39 was similar to the preceding after the morning of the 21st, and iu each of the last two cases an area of high j)ressure seemed to exert a decided influence in crowding tiie low center westwaid. Each of these five cases was attended by some rainfall, but the amount reported in the published observations does uot seem to i)resent an ade(inate cau.-se tor the abnormal movement of the low centers.
C3. The preceding discussion seems to warrant the following conclusions, viz : That the westerly movement of low centers, which is occasionally observed in the middle latitudes of Europe and America, is generally due to one or more of the following causes :
1. The intlnence of one low area upon an adjacent low area, which influence sometimes seems to act as an attractive force.
2. The influence of a considerable fall of rain or snow-, which also acts as an attractive force.
3. The influence exerted by two areas of high pressure, uot very remote from each other, by which means a new movement is imparted to the air included between them, and a new low center is sometime developed.
4. The intiueuce of an area of high (or only moderately high) pressure, on the northeast side of a low area, when the gradients on the southwest side of the low area are slight, iu which case the center of the low area may be crowded towards the southwest.
If these causes are sometimes sufficiently i)owerful to divert the center of a low area westward, it may be presumed that there are many more cases iu which these causes are sufficiently powerful to aflect, iu an appreciable degree, both the direction and velocity of the movement of a low center.
04. The facts which have been stated in the preceding ])ages seem to aft'ord a basis for some general conclusions respecting the movement of storm ai'eas. Many meteorologists have claimed that the progressive movement of storm areas is satisfactorily explained by sa.\1ng that they are carried forwajd by the general movement of the mass of the atmosphere within which they are
CONTEIBUTIONS TO METEOROLOGY. 47
formed; that is, tlioy drift, in a sense similar to that in which waves, eddies, &c., Cormed on the surface of a river, drift with the current. They advance as the water of the river advances, and in the same direction. IJut we liave found tliat the average direction of movement of areas of low barometer does not generally correspond with the average directiou of the wind for the same 'region. This is seen not only in the case of tropical storms l)nt also in storms of the middle latitudes. Near the West India Islands the average direction of storm tracks, wliile the storms are moving westward, ditfcrs about ;50 degrees from the average direction of the wind for the same season of the year. In the Cliina 8ea the average directiou of storm tracks is nearly at right angles with the average directiou of the wind, and the average directiou is nearly the same during those months in wlii(^h the prevalent wind is from the southwest as during those moutlis in which the prevalent wind is from the uortheast. In the western part of the Atlantic Ocean, near latitude 50°, the average directiou of storm paths is about 30° more northeiiy than that of the average wiiul, and in the eastern part of the Atlantic Ocean, near latitude 5.5°, it is almost ;jO° more southerly. In the northwestern part of the United States, between the Rocky Mount- ains and the meridian of 90° from Greenwich, we find places where the average direction of storm tracks is io° more northerly than that of the wind, and other places where it is 20° more southerly than that of the wind.
65. Bnt it uiay be claimed that the progress of storm areas is not determined entirely by the average movement of the atmosphere, but by that movement which is taking jilace at the date of the storm. I have endeavored in the preceding 'pages to investigate this question, and to present the ev-idence for the above hyjiothesis in the most lavorable light, but if we scan the evidence critically we must conclude that it is entirely unsatisfactory. ' If we claim that the progressive movement of a storm area is due to the progressive movement of the general mass of the atmosphere in which it is formed it seems necessary to admit that a njass of the atmosphere of considerably greater extent than the storm area is advancing in the same direction and at the same rate as the storm advauces. In order to decide whether such is the fact we need only consult a well-constructed weather map of sufiBcient dimensions to include not merely a storm area but a considerable margin beyond it. The storm represented on Plate III had an average diameter of 2,500 miles, and during the twenty-four hours succeeding the date of the map it advanced about 350 miles towards the northeast. If the movement of this storm area was due to a general diift of the atmosphere then this drift must have included not merely the area within the isobar 30 inches, but al.so the adjacent areas of high ]iressure which clung persistently to the low area. This map seems to be too limited to furnish the required information in a form which is entirely satisfactory, and it is desirable to have similar maps for several successive days. The Signal Service maps afford abundant materials for the proposed purpose, and Hoft'meyer's maps are still better, since they include a much larger portion of the earth's surface. If we open Hottineyer's Atlas anywhere at random we shall not find the mass of the atmosphere in the rear of a storm moving forward in the same directiou as that iu which the storm advances. Plates VIII and IX accompanying this pami)hlet are thought to be decisive on this point. The storm maps of the United States furnish similar testimony. Plates I and II show that the general movement of the atmosphere in the rear of a storm is not iu the same direction as that in which the storm center advances, and the evidence would be still clearer if the maps included a larger area. A slight examination of the United States weather maps, or of Hotlmeyer's charts, must satisfy any one that the general mass of the atmosphere surrounding a great storm is not advancing in the same directiou as that in which the storm center advances.
66. If we follow the progressive movement of a great storm from day to day by means of maps representing the phenomena at intervals not greater than eight hours we shall find that in front of the storm the air appears to be drawn iu towards the center, by which means the pressure on the front side of the storm is diminished. The air thus drawn in towards the center rises to a considerable elevation above the surface of the earth, and its vapor is condensed. In the rear of the storm the exterior air rushes in and restores the pressure on that side, and as the result of this double process tBe i)oiut of least barometric pressure is carried foiward. This movement of the exterior air in the rear of a storm is not necessarily in the same direction as that iu which the
48
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
storm center advances. In the United States storms almost invariably advance eastward, and generally towards a point a little north of east; but the wind which presses upon the rear generally comes from the north or northwest, which direction is often at right angles, or nearly at right angles, with the direction in which the storm center advances. Plates I and II exhibit this fact, and the same is substantially true of nearly every great storm shown on the Signal" Service maps. Tiiis movement of the air by which the center of least pressure is carried forward bears some analogy to tlie movements which cause the advance of a wave upon the surface of the ocean, and hence we may with propriety say that the progressive movement of a storm area is the movement of a great atmospheric wave.
67. Besides the general considerations here stated there are various special phenomena which indicate that the movement of areas of low pressure cannot be fully explained by the theory of a general drift of the atmosphere. We frequently find two neighboring low areas advancing in directions inclined to each other at an angle of 45°, or even a greater angle. In the United States, while a low center is advancing from Florida along the Atlantic coast, towards the north- east, another low center may be advancing eastward over the region of the Great Lakes, and the two low centers may coalesce somewhere in the neighborhood of Nova Scotia or Newfoundland. It will be seen from Plate X that the storms which proceed from the Gulf of Mexico, and from the neighborhood of the West India Islands, generally advance towards Newfoundland, and the storms which come from the northwestern part of the United States also tend towards the same region. Newfoundland becomes thus a point of convergence of storm tracks, proceeding from regions quite remote from each other. In the vicinity of Newfoundland there exists some influence which ap- pears to act as an attractive force upon storm centers. This influence probably results from the great amount of precipitation near that island, arising from the i)roximity of the warm water of the Gulf Stream to the colder air from the land. Plate XI shows other points towards which storm tracks seem to converge, particularly the Asiatic coast near Japan, and this fact probably results from a cause similar to the one just named. If Plates X and XI exhibited the storm tracks of different regions according to the relative frequency of their occurrence, other points of con- vergence of storm tracks would be exhibited. Along these converging storm paths two storms often travel simultaneously and coalesce in a single storm area. Such a movement appears incon- sistent with the drift theory.
68. For the convenience of those persons who may wish to investigate cases of this kind for themselves I present the following list, which shows some of the most decided cases in which two centers of low pressuie in the United States have coalesced. They are taken from the Signal Service weather maps for the years 1873-18S0. These maps show a considerable number of other cases of like kind, some of which have been omitted because the depression of the barometer was small, and others because the position of the low center was not very sharply defined, or was situated near the margin of the weather map:
Examples in which two centers of low pressure approach each other and coalesce.
|
1873, Mar. 29. 1-29. 2 |
• 1874, Sept. 2.''). 1-25.3 |
1878, Mar. 13. 3-14. 1 |
1879, Oct. 16.1-17.1 |
|
Oct. 4. 3- 5. 1 |
1875, Jau. 22.2-22.3 |
May 2. 1- 2. 2 |
Oct. 28.2-28.3 |
|
Oct. 11.1-11.3 |
Nov. 10.1-10.2 |
June 18.1-18.2 |
Nov. 20.1-20.2 |
|
1874, Apr. 19.2-19.3 |
1876, Mar. 25. 3-26. 1 |
Nov. 22. 1-22. 2 |
1880, Feb. 13. 1-13. 2 |
|
Apr. 2.5. 2-2,'j. 3 |
1877, Dec. 29. 3-30. 1 |
1879, Jan. 1.3- 2.2 |
Mar. 7. 2- 8. 1 |
|
Aug. 30.2-31.1 |
1878, Feb. 14.3-15.1 |
Foil. 4. 1- 4. 2 |
Oct. 29.2-29.3 |
Among these twenty-four cases there are only three in which the paths of the two low centers wei'e not inclined to each other at an angle as great as 45°; in half of the cases the two paths were inclined at an angle considerably greater than 45°; in eight or nine of the cases the angle was nearly as great as !)0O; and in three of the cases the angle was greater than 90°.
69. It sometimes happens that within an area of low pressure, having but a single center, a second low center is developed. The following list shows twenty- four such cases selected from the Signal Service maps for 1873-1880, The maps show a large number of other similar cases; but in
CONTRIBUTIONS TO METEOROLOGY.
49
the cases here cited the depression of the barouieter was generally considerable, and tbe position of the low centers was distinctly indicated :
Cases in which a second tow center is developed within an area of lore pressure.
|
1873, Fel). 18.1-18.2 |
1874, Nov. 23. 1-23. 3 |
1876, Mar. 25.2-25.3 |
1878, Mar. 12. 3-13. 1 |
|
Fel). 20. 1-20. 2 |
1875, Jau. 24.2-24.3 |
Mav 7.1-7.2 |
Nov. 23. 3-24. 1 |
|
Mar. 28. 2-29. 1 |
Jan. 30.3-31.2 |
May 7. 2- 7. 3 |
1879, Mar. 29.1-29.2 |
|
1874, Apr. 25.1-25.2 |
Mav 4. 2- 4. 3 |
1877, Dec. 29.2-29.3 |
1880, Jan. 21.3-22.1 |
|
Aug. 29. 1-29. 2 |
Nov. 3.1- 3.2 |
1878, Jau. 13.2-13.3 |
Feb. 12.2-12.3 |
|
Aug. 30. 1-30. 2 |
1876, Mar. o. 3- 6. 1 |
Jan. 30.2-31.1 |
Apr. 17.1-17.2 |
In a majority of these cases the two low centers appear to have subsequently coalesced; but in several of them the two low centers moved off in directions inclined to each other at an angle of 90° or more, and with unequal velocities.
70. Over the Atlantic Ocean and Europe cases similar to tlie preceding are of much more frequent occurrence than in the United States; the depression of the barometer is generally much greater, and the low areas bave a much greater geographical extent. By consulting Hofl'meyer's weather maps we may easily iind examples in which two low centers move towards each other from nearly oi)posite directions and coalesce ; and we may also find frequent cases in which a great area of low pressure, with but one center, undergoes a change by which two low centers are developed, and these new low centers recede from each other. Sometimes there is a further change by which three or four, or even more, low centers are formed, and these low centers have a progressive movement in difleient directions, and with unequal velocities. On the contrary, within a large area of low pressure showing several low centers, a low center may disappear from simple changes of pressure. In like manner a second low center may disappear, and so on. Plate IX shows five low centers within a single area of low i)ressure. The map for the preceding day showed only three low centers within the same low area, while the map for the following day showed five low centers, but one of them had no connection with either of the five shown on Plate IX. In cases like this the changes in the position and magnitude of the low centers are so rapid that, in comparing two weather maps for successive days, we frequently find it impossible to identify a low center on one of the maps, with its corresponding low center on the other maiJ.
71. Examples may be easily found to illustrate all of these different cases; but for the con- venience of those who may wish to examine such cases without the trouble of searching for them the following lists are given, and the cases are all taken from Hofl'meyer's charts for 1875 :
1. Examples in which tivo centers of low pressure approach each other and coalesce.
|
Jan. |
3- 4 |
Mar. 23-24 |
Mav 11-12 |
Sept. 24-25 |
Oct. |
29-30 |
Nov. 30-31 |
|
8- 9 |
Apr. 3- 4 |
21-22 |
27-28 |
Nov. |
1-2 |
Dec. 4- 5 |
|
|
11-12 |
11-12 |
June 14-15 |
Oct. 8- 9 |
3-4 |
6- 7 |
||
|
Felj. |
25-26 |
20-21 |
July 2- 3 |
9-10 |
5-6 |
13-14 |
|
|
Mar. |
3- 4 |
25-26 |
Aug. 15-16 |
11-12 |
6- 7 |
26-27 |
|
|
10-11 |
Mav 2- 3 |
28-29 |
13-14 |
15-16 |
27-28 |
||
|
12-13 |
6- 7 |
Sept. 18-19 |
21-22 |
27-28 |
2. Examples in rchich, within an area of low pressure, two or three low centers are developed where only
one had existed previously.
|
Jan. |
2- 3 |
Sept. |
8- 9 |
Nov. |
4- 5 |
Nov. |
13-14 |
Dec. |
8- 9 |
|
Apr. |
6- 7 |
23-24 |
8- 9 |
21-22 |
21-22 |
||||
|
June |
21-22 |
Oct. |
14-15 |
11-12 |
26-27 |
28-30 |
|||
|
24-25 |
Nov. |
2- 3 |
12-13 |
Dec. |
5- 6 |
In several of these cases the two low centers appear to have started from the same low center and thence receded from each other. This is particularly true for January 2-3; April 6-7 ; June 24-25; September S-9 ; November 11-12 ; November 13-14 ; December 8-9; and December 21-22. S. Mis. 154 7
50
MEMOIRS OF THE NATIONAL ACADEMY OP SCIENCES.
3. Examines in which, icithin an area of low pressure, a new low center is developed by changes of
pressure occurring icithin the low area.
|
Jan. |
18-19 |
Apr. 2- 3 |
June 5- 6 |
Aug. 25-26 |
Oct. |
10-11 |
|
Mar. |
2- 3 |
4-5 |
16-17 |
26-27 |
25-26 |
|
|
4- 5 |
12-13 |
July 13-14 |
Sept. 20-21 |
Nov. |
7- 8 |
|
|
6- 7 |
May 3- 4 |
21-22 |
25-26 |
9-10 |
||
|
27-28 |
20-21 |
Aug. 13-14 |
Oct. 6- 7 |
Dec. |
22-23 |
4. Examples in which, within an area of loio pressure showing several low centers, one or more of them
disappears byichanges of pressure.
|
Jan. |
5- 6 19-20 |
Feb. |
9-10 10-11 |
Mar. |
1- 2 13-14 |
July |
14-15 22-23 |
Nov. |
11- |
-12 |
|
28-23 |
15-16 |
Apr. |
5- 6 |
Nov. |
10-11 |
It surely will not be claimed that in these cases the movement of the low centers can be ascribed to a simple drifting of the general mass of the atmosphere in which the low areas were formed.
72. If we reject the drift theory it will doubtless be asked how can we explain the fact that in the middle latitudes storms almost invariably advance toward the east, and the opposite move- ment only occurs occasionally, and seldom continues longer than one or two days. This fact seems to result from the prevalent movement of the wind toward the east, but the result is due, not to a general drifting of the mass of the atmosphere within which^thelow area is formed, but to the fact that the pressure on the west side of the low area is more steady and persistent than that on the east side. The characteristic features of a groat storm movement iire a m.otion of the air from all sides spirally inward, together with an upward movement, resulting in the condensation of vapor at various places within the low area. Now if the air pressed in with equal force on all sides of the low center, and if there was an equal precipitation of vapor on all sides, no reason is apparent why the low center should advance at all. It sometimes happens that the pressure on the west side is very small, while there is considerable pressure on the east side, and in such cases the low center moves towards tiie west. Examples of this kind have been given in article 58. viz, Nos. 2, 3, 7, 15, 18, 27, 28, and 29 of Table XXII; and in article 62, viz, Nos. 25, 32, 33, 38, and 39 of Table XXVIIl. But this movement towards the west cannot be long maintained. In the middle lati- tudes the east winds are exceptional and result mainly from disturbances caused by storms. On the contrary the west winds result from general causes, which are permanent in their character and are independent of storms ; and if there were no storms the west winds would rarely be inter- rui)ted. During the prevalence of an east wind the causes which i)roduco west winds are not destroyed, their influence is only temporarily suspended, and they soon return with a force not impaired but rather augmented by their temporary suspension. The pressure on the west side of
Table XXIX. — Rate of progress q/ storm centers in the United States.
|
Jan. |
Feb. |
Mar. |
Apr. |
May. 24.7 |
June. |
July. |
Aug. |
Sept. |
Oct. |
Nov. |
Dec. |
|
|
1872.... |
31.2 |
29.4 |
.34.5 |
34.5 |
21.8 |
24.6 |
18.3 |
22.2 |
20.9 |
23.6 |
28.8 |
|
|
1873.... |
25.8 |
32.7 |
28.1 |
22.3 |
23.5 |
20.8 |
24.6 |
17.8 |
23.1 |
28.1 |
27.9 |
26.7 |
|
1874.... |
23. 0 |
33.9 |
29.8 |
31.4 |
22.2 |
22.4 |
25.9 |
19.9 |
23.1 |
28.5 |
30.3 |
32. 7 |
|
1875.... |
32. 1 |
32.8 |
30.0 |
26.4 |
29. 2 |
31.5 |
25. 3 |
17.1 |
30.5 |
23. 4 |
30.0 |
31.1 |
|
1876.... |
38.1 |
31. 5 |
26. 4 |
23. 6 |
24.7 |
19.3 |
26.4 |
23.2 |
23,8 |
27.7 |
22.6 |
38.3 |
|
1X77.... |
37.7 |
26. 5 |
32.6 |
2.5.2 |
27.3 |
55.2 |
24.2 |
20.0 |
17,4 |
20.2 |
25.5 |
24.7 |
|
1878.... |
26,3 |
27.7 |
24.3 |
22.6 |
17.9 |
18.4 |
21.7 |
26. 8 |
23.9 |
19.6 |
21.2 |
34.0 |
|
1879.... |
36.5 |
33.3 |
35. 1 |
27.8 |
25. 3 |
29.4 |
26.4 |
21.0 |
21.7 |
30.8 |
40.7 |
38.7 |
|
1880.... |
37.6 |
39.6 |
35.8 |
27. 2 |
25.1 |
24.5 |
25.7 |
25.9 |
23.5 |
22.3 |
34.1 |
38.8 |
|
1881.... |
32.3 |
35.4 |
26.8 |
37,1 |
32.6 |
32.8 |
26. 6 |
25.4 |
30.6 |
37. 5 |
30.8 |
33. 6 |
|
1882.... |
42.1 |
41.6 |
34.8 |
29.5 |
21.6 |
26.8 |
19.8 |
19.9 |
23.5 |
27.7 |
27.7 |
30.2 |
|
1883.... |
39.8 |
36.4 |
38.0 |
28.4 |
30.0 |
24.2 |
25.8 |
28.0 |
25.0 |
37.3 |
39.4 |
33.0 |
|
1884.... Mean. |
38.6 |
43.9 |
33,3 |
21.5 |
26.8 |
20.5 |
22.4 |
30.7 |
32.6 |
34.4 |
35.2 |
43.7 |
|
33.8 |
34.2 |
31.5 |
27.5 |
25,5 |
24.4 |
24.6 |
22.6 |
24.7 |
27.6 |
29.9 |
33.4 |
CONTRIBUTIONS TO METEOROLOGY.
51
storm areas is thus a strong and porsistiiiit one, while tliat on tlie east side results from teniiuirary causes ami eannot be loiisj- maintained. It oceasionally happens during a violent storm that the east wiuds are stronger than the west winds. In such a case the low center may be pushed west- ward, but such a result does not necessarily follow, for a large i)art of the air which pushes in on
Table XXX. — Barometric minima advancing at least 1,000 miles in twenty-four hours.
No.
Date.
1872.
Nor. 6.-2
24.2
Dec. 14. 1
19.1
1873.
Jan. 4.:i
26. :5
Fell. l.'i. :i
May 12.2
Nov. 3.3
23.1
24.1
1874.
Jan. 3. 3
Feb. 6.2
19.1
22.1
23.1
Mar. 3.1
18.2
Apr. .'). 1
Sept. 2. 1
Nov. 28. 1
Dec. 2.2
13. 2
16. 1
23. 2
27.2
1875.
Jan. 1.3
1877.
Jan. 1.1
6.1
7.3
15.1
19.1
Mar. 1.2
3.2
6.2
8.2
15.3
18.3
20.2
Oct. 28.1
Nov. 1.1
5.1
' 8.2
First station.
Pembina. . Keokuk .. Onialia -.. liidianola
Mempliis
Lake City .. .
MempLis
Saint Paul...
Duluth
Indiauola
Pittsburgh ..
Inch.
29.45
.62
.67
Sccoiul station.
Portland . Quebec... Montreal
Escanaba ... Louisville . ..
Duluth
Indianola. . .. Rochester . . . . Leavenworth.
Keokuk
Saint Louis. . Saint Paul. ..
Mobile
Marquette . .. Cleveland .. .
Omaha
Marquette .. . Bismarck
Marquette .. .
Saint Marks..
Mobile
ludianola. . .. Fort Gibson..
Bismarck
Memphis,
Indianapolis .
Escanaba
Cincinnati. .. Dodge City. Leavenworth Saint Louis.. Leavenworth, San .\ntonio. Indianapolis . Toledo
U Buftalo.
.74
.80 .59 .44 .49 .73 .48
.31
.82 .52 .89 .581 .29! .63 .71 .89 30.15 29. 44 .83 .51 .49 .,59
.94
3 o
Portland
Halifax
New London . .
Portland
Father Point. . . Pittsburgh .... Halifa.\ 28.82
Inch
29.12
.39
.51
.43
.33 .17
.53 .35 .60
.48
.62 .84 .84 .45 .63 .56 .61 .59
Father Point -
Sydney
Father Point. Rochester . ... Father Point .
Ottawa
Quebec
Ottawa
Father Point .
Quebec
Capi' Rozier. .
Halifax
Ottawa
Halifax
Quebec
Halifax .
28.89! 1,170
Boston
Ne w York
Eastport
Malone
Parry Sound..
Parr.v Sound..
Father Point..
Chatham
16! Father Point..
. 56; Knoxville
.66 Cape Henry...
. 55 Malone
. 56 Rocklilfe
. .58 Erie
.84
.47
Means 29.62
Halifax . Chatham
29.55 .70 .70 .58 .47 .34 .19 .63 .72 .54 .64 .42 ..59 .37! .59!
Miles 1,376 1,214 1,132 1,295
Change of barometer in
twenty-four hours.
c
+0. .36 + .55 + .71 + .32
1,215+ .54 1,404J+ .20 1,055+ .49 1,145+ .45 1,100+ .86 1,270+ .39 1,002- .09
1,000+L07 1,212'+ .39 1,123!+ .46
1,374 + 1, 0581+ 1,114{+ 1, 187 + 1,065
—1.06
— .68
— .29 1.06
.94 —1.04 .95 .24 .31 .80 —1.40
+
1, 175 1,466 1.095 1, 092 1,065 1, 165 1,134
29.35 .15 .37
. 56 .19 .07 .52 .71 28.74 29.64 .87
.11
.50 .57
55 95 74
37[- 38!— 41 19
+ +
+ .91 + .54 — +L 08 + .61 + .79
+ .11
1,126 + 1,048 +
1,872 + 1,270+ 1,080'+ 1, 003 + 1,178+ 1,0.55+ 1,0611+ 1,050 + 1.209;+ 1,047,+ 1,077+ 1, 122'+ l,15l!+ 1,128 +
.67-
. 23 -
. 561-
.89
.23
.30
.66
.61
.91
.84
.27
.50
.67
. .52
.67
.69,
.38 .01 .58 .66 .21 .49 .73 .55 .24 .81 .40 .85 .69
- .37
- .56
-1.11
- .67 -1.18
- .01
- .56 -1.03
- .98
- .15
- .26 -1.38
- .50
- .34
- .52
- .54
- .91
- .83
- .54
29.42
1,167+ .55— .65
Rain in low.
t3
0.15 .02 .02 .36
.36
.19 .27 .04 .00 .24 .38
.03 .16 .06 .24 .21 .16 .09 .12 .03 .17 .03 .11 .06 .03 .11
.23
.28 .31 .04 .23 .05 .24 .08 .09 .28 .08 .06 .13 .05 . as .22 .43
0.16
0.02 .01 .00 .20
.13 .05 .05 .01 .00 .14 .13
.06 .10 .01 .21 .07 .14 .05 .03 .01 .14 .00 .04 .03 .02 .09
.16
.06 .08 .02 .07 .01 .05 .02j .02
Wind in low.
9.49
8.31
12.27
9.89
9.16
7.33
7.73
10.09
12. 28
7. 8i:
14. 15!
16.05 7.90 7.96
7.47
8,341
10. 40;
5. 8O:
9.84!
4.211 15. 66 14.33
9.00 11.39 10.79
9.26
6.23
13.92 13.63
8.4' 10. 42
9.05 12. OC 11.19 14.87
.06'. 20. 10
.03 .00 .03 .63 .11 .05 .11
11.46 11.65J 10.481 11.30 9.48 14.25 17. 22
12.39 12. 81 16.97 10. 33
13. 52 9.22
8.83 10.91 12. 30 11.20 10.98
17.61 7.46 10.66 15.04 21.90 16.66 11.36 11.65 9.00' 15. 331 14.58 11.27, 15. 08,
15. 80 7.88
17.78
14.08 11.62
16. 49,
17. 53, 15. 8rs' 13.79t 13.77 16.59 18.26 19. 93 13.92 12. 70 12.10
9.87 14.44 13. 091
a
30.09 .33 .46 .3'
.30 .92 .11 .02 .42 .12 .29
.57 .22 .17 .72
.82 .30 .13 .17 .42 .62 .35 .57 .73 .42 .55
.54
.73 .42 .40 .46 .30 .04 .36 .37 .43 .51 .19 .11 .41 .25 .,56 .54
O.O61 10.761 13.78 30.39
tbe east side rises from the earth's surface, while the air which pushes in on the west side does not rise at all, or not to an equal extent. Thus the low area is filled up on the west side, and were it not for the continued precipitatiou of vapor the low area would soon become obliterated. In the .subsequent pages additional facts will be presented, showiug the unsatisfactory nature of the drift theory.
52 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
Rate of progress of areas of low pressure.
7,3. Ill order to exhibit the average velocity with which centers of low pressure advance over the United States, I have prepared Table XXIX, which shows, in miles per hour, the average velocity of storm centers for each month during a period of thirteen years, according to the observations of the United States Signal Service.
We se« from this table that the average velocity of progress of storms for the entire year is 28.4 miles ; also that the velocity is greatest in February and least in August, and that the former velocity is 50 per cent, greater than tlie latter. We also see that the velocity varies very much for the same month in different years, the greatest mean velocity for several of the months being nearly double the least mean velocity for the same months.
74. In order to discover, if possible, the cause of these unequal movements, I have selected the most remarkable cases of extremely rapid motion, and also the cases of extremely slow motion, during the period for which the tri-daily observations of the Signal Service have been published, viz, from September, 1872, to January, 1875, inclusive, also for the year 1877, making in all forty- one months of observations. Table XXX shows the cases in which a storm center has advanced at least 1,000 miles in twenty four hours.
Column 1 gives the number of reference; column 2 the date at which the rapid motion commenced, where the figures 1, 2, and 3, attached to the day of the month, denote the first, second, and third of the hours of observation foi- the given day; column 3 shows the station at which the barometer, at the given date, was lowest ; column 4 the height of the barometer at the station named ; column 5 shows the station at which the barometer was lowest twenty-four hours after the date given in column 2; column 6 the height of the barometer at the station named in the preceding column; column 7 shows in miles the movement of the low center during twenty-four hours, as indicated by the isobars, which best represent the Signal Service observations ; column 8 the change in the barometer at the stations named in column 3, during the day here considered; (+ denotes increasing i^ressure, — denotes decreasing pressui-e) ; column 9 the change in the •barometer at the stations named in column 5 during the same day ; column 10 shows the average rain-fall at all the stations within the low area (determined by the isobar 30 inches), on the east side of the low center, for each period of eight hours during the given day. These numbers should therefore be multiplied by three, in order to show the average rainfall for the day in question ; column 11 shows the average rain-fall at all the stations within the low area on the west side of the low center, for each period of eight hours ; column 12 shows the average velocity of the wind (in miles per hour), at the stations within the low area on the east side of the low center; and column 13 shows the average velocity of the wind at the stations within the low area on the west side of the low center. Generally the retreat of the low area eastward was immediately succeeded by an area of high pressure on its western side. Column 14 shows the highest pressure observed at any station within this area of high pressure; and when there was no succeeding area of high pressure, it shows the highest pressuie immediately succeeding the area of low pressure. At the bottom of the table are given the means of the inimbers in ten of the columns.
75. Table XXXI shows the cases in which a storm center has advanced not more than 240 miles in twenty-four hours. The arrangement of this table is similar to that of Table XXX. The Signal Service observations show a considerable number of other cases, which, perhaps, ought to be included in these tables, but which are omitted on account of the uncertainty respecting the exact i)osition of the center of low pressure.
76. The following are some of the results derived from a comparison of these two tables :
1. For the cases in Table XXXI the average pressure at the low center was the same at the close of the given day as at its beginning ; that is, the storms neither increased nor diminished in intensity. For the cases in Table XXX the average pressure at the low center was 0.20 in<-h less at the close of the given day than at its beginning ; that is, the storms increased considerably in intensity during the day in question.
2. The average rate of progress of the storms named in Table XXX was more than seven times as great as that of the storms named in Table XXXI.
3. In the cases named in Table XXXI the barometer fell, on an average, 0.0!) inch in twenty- four hours in front of the storm, and rose 0.09 inch in the rear of the storm. In the cases named iu
CONTRIBUTIONS TO METEOROLOGY.
53
Table XXX the biirouicter iell, ou au average, 0.G5 inch in twenty-four liours in front of the storm, and rose 0.55 inch in the rear of the storm ; that is, during the days named in Table XXX the oscillation of the barometer was nearly seven times as great as during the days named in Table XXXI.
Table XXXI. — Barometric minima advancing not more than 240 miles in twenty-four hours.
|
Change in |
|||||||||||||
|
barometer in |
Raiu in low. |
Wind |
n low. |
||||||||||
|
twenty-four |
|||||||||||||
|
hours. |
|||||||||||||
|
No. |
Date. |
First station. |
© a o m |
Second station. |
1 E o |
i u 2 PL, |
|||||||
|
is -a |
03 |
4^ |
i |
||||||||||
|
1872. |
Inch. |
Inch. |
Miles. |
i |
|||||||||
|
1 |
Sept. |
5.1 |
Omalia |
29. 51 |
Omaha |
29.51 |
156 |
.00 |
.00 |
0.04 |
0.02 |
6.11 |
7.52 |
|
2 |
24.2 |
Duhith |
.31 |
Duluth |
.37 |
72 |
+.06 |
+.06 |
.10 |
.06 |
15.33 |
17.78 |
|
|
3 |
25.1 |
Duluth |
.33 |
Marquette . . . |
.43 |
208 |
+.16 |
+.05 |
.08 |
.01 |
14.65 |
14. 95 |
|
|
187:5. |
|||||||||||||
|
4 Apr. |
12.1 |
Cape May. . . |
.65 |
Boston |
.61 |
238 |
+.14 |
-.34 |
.20 |
.07 |
15. 77 |
15.14 |
|
|
5 |
14.1 |
Omaha |
.46 |
Leavenworth. |
.47 |
97 |
+.12 |
-.03 |
.05 |
.05 |
n.40 |
25.43 |
|
|
6 |
16.2 |
Clevelanil . .. |
.71 |
Chicago |
.58 |
218 |
—.04 |
—.25 |
.06 |
.04 |
10. 13 |
10. 70 |
|
|
7 May |
21.3 |
FortSnllv-.- |
.46 |
Breckenridge. |
.35 |
215 |
+.25 |
—.26 |
.04 |
.04 |
6.80 |
12. 86 |
|
|
8 June |
21.2 |
Fort .Sully... |
.46 |
Fort Sully .... |
.30 |
40 |
—.16 |
—.16 |
.07 |
.02 |
8.23 |
8.55 |
|
|
9 ! July |
15.2 |
Fort .Sully... |
.48 |
Bieckenridge. |
.47 |
240 |
+.12 |
—.17 |
.13 |
.06 |
9.76 |
11.46 |
|
|
10 |
21.2 |
Fort Sully.-. |
.30 |
Fort Sully |
.68 |
88 |
+.38 |
+.30 |
0 |
0 |
12. 79 |
15.11 |
|
|
11 |
Aug. |
13.2 |
Fort Sully... |
.58 |
Yankton |
.66 |
181 |
+.12 |
—.17 |
.08 |
.04 |
8.41 |
10.14 |
|
12 |
Sept. |
2.2 |
Fort Sully... |
.38 |
Omaha |
.44 |
240 |
+.15 |
—.35 |
.08 |
.03 |
7.92 |
11.20 |
|
13 |
10.1 |
Fort Garry . . |
.62 |
Pembina |
.61 |
189 |
.00 |
-.19 |
0 |
0 |
6.73 |
9.75 |
|
|
1874. |
|||||||||||||
|
14 |
Mar. |
9.1 |
Eastport |
.24 |
Eastport |
.03 |
129 |
—.21 |
-.21 |
.14 |
.02 |
5.45 |
20.45 |
|
15 |
16.1 |
Fort Sully... |
.26 |
Fort Garry . . . |
.35 |
240 |
+.27 |
-..35 |
.08 |
.04 |
12.08 |
11.67 |
|
|
16 |
Apr. |
30.1 |
Father Point |
.11 |
Father Point . |
.05 |
90 |
-.06 |
—.06 |
.07 |
.02 |
10.91 |
16.90 |
|
17 |
May |
1.1 |
Father Point |
.05 |
Sydney |
.48 |
184 |
+.51 |
—.06 |
.06 |
.02 |
7.58 |
11.91 |
|
•18 |
9.2 |
Fort Sully... |
.01 |
Breckenridge. |
.29 |
217 |
+.37 |
—.10 |
.12 |
.00 |
14.45 |
14.64 |
|
|
19 |
22. 3 |
Fort Sully. -- |
.57 |
Fort Sully |
.31 |
0 |
—.26 |
—.26 |
.02 |
.01 |
6.50 |
10.50 |
|
|
20 |
26.2 |
Fort Sully... |
.16 |
Fort Sully.... |
.16 |
0 |
.00 |
.00 |
.01 |
.00 |
10.33 |
12.00 |
|
|
21 |
27.2 |
Fort Sully... |
.16 |
FortSullj.-.. |
.27 |
0 |
+.11 |
+.11 |
.02 |
.01 |
10.25 |
14.80 |
|
|
22 |
28.2 |
Fort Sully... |
.27 |
Breckenridge - |
.77 |
218 |
+.64 |
+.23 |
.03 |
.00 |
10. .55 |
11.10 |
|
|
23 |
Juue |
18.1 |
Portland .... |
.50 |
Boston |
.85 |
125 |
+.38 |
+.22 |
.25 |
.02 |
11.87 |
16. 35 |
|
24 |
26.2 |
Fort Sully... |
.33 |
Yankton |
.27 |
180 |
—.04 |
—.38 |
.07 |
.01 |
8.67 |
8.60 |
|
|
25 |
July |
2.2 |
Fort Sully. .. |
.45 |
Fort Sully |
.55 |
0 |
+.10 |
+.10 |
.04 |
.00 |
8.82 |
13. 13 |
|
26 |
17.3 |
Fort Sully... |
.65 |
Fort Garry - . . |
.59 |
217 |
+.0f |
—.12 |
.00 |
.00 |
8.34 |
9.67 |
|
|
.27 |
Aug. |
5.2 |
Leavenworth |
.63 |
Leavenworth. |
.73 |
1.51 |
+.10 |
+.10 |
.03 |
.02 |
5.26 |
7.50 |
|
28 |
9.3 |
Fort Sully. .. |
.54 |
Yankton |
.37 |
179 |
—.04 |
—.31 |
.04 |
.01 |
5.25 |
9.87 |
|
|
29 |
1 a |
27.1 |
Oraaha |
.61 |
Oraaha |
..54 |
111 |
-.07 |
—.07 |
.12 |
.01 |
9.00 |
10.80 |
|
30 |
18/ /. Feb. 13.1 |
Saint John . . |
.44 |
Port Hastings |
.59 |
211 |
+.03 |
+.05 |
.14 |
.09 |
14.37 |
20.61 |
|
|
31 |
17.2 |
Chatham |
.16 |
Chatham |
.22 |
73 |
+.06 |
+.06 |
.30 |
.10 |
15. 67 |
18. 12 |
|
|
32 |
Mar. |
27.2 |
Baruegat |
.22 |
Boston |
.09 |
237 |
+.21 |
—.24 |
.13 |
.12 |
11.14 |
18.05 |
|
33 |
30.2 |
Fort Sully... |
.47 |
Yankton |
.14 |
164 |
-.28 |
-..52 |
.11 |
.06 |
11.63 |
17.14 |
|
|
34 |
Apr. |
5.3 |
Eastport |
.45 |
Eastport |
.49 |
150 |
+.04 |
+.04 |
.27 |
.02 |
13.93 |
13.48 |
|
35 |
16.2 |
North Platte |
.18 |
Oraaha |
.28 |
240 |
+.10 |
—.25 |
15 |
.11 |
9.54 |
14.50 |
|
|
36 |
17.3 |
Omaha |
.44 |
Leavenworth. |
.11 |
159 |
-.06 |
—.36 |
.08 |
.01 |
10.27 |
20.24 |
|
|
37 |
May |
18.3 |
Fort Sully... |
.55 |
Bismarck |
.30 |
126 |
-.11 |
—.33 |
.11 |
.01 |
11.84 |
13.75 |
|
38 |
20.2 |
La Crosse . . . |
.36 |
Saint Paul. .. |
.45 |
240 |
+.15 |
+.06 |
.14 |
.06 |
8.18 |
14.31 |
|
|
39 |
29.2 |
Bismarck |
.10 |
Bismarck |
28.79 |
0 |
—.31 |
—.31 |
.00 |
.01 |
14.75 |
15.75 |
|
|
40 |
30.2 |
Bismarck |
28. 79 |
Bismarck |
.97 |
80 |
+.18 |
+.18 |
.18 |
.04 |
12. 90 |
13. 33 |
|
|
41 |
.Tune |
22. 2 |
Bismarck |
29. 29 |
Bismarck |
29. 17 |
0 |
—.12 |
-.12 |
.12 |
.03 |
10.88 |
14.66 |
|
42 |
July |
26. 2 |
Fort Sully... |
.24 |
Bismarck |
.49 |
240 |
+.41 |
+.18 |
.15 |
.07 |
8.11 |
10.36 |
|
43 |
29.3 |
Bismarck |
.43 |
Bismarck |
.48 |
180 |
+.05 |
+.05 |
.02 |
.04 |
11.37 |
9.83 |
|
|
44 |
Aug. |
4.2 |
Bismarck |
.44 |
Fort Sully .... |
.55 |
184 |
+.22 |
+.01 |
.01 |
.02 |
8.35 |
9.14 |
|
45 |
Sept. |
10.2 |
Bismarck |
.33 |
Bismarck |
.30 |
183 |
—.03 |
—.03 |
.03 |
.00 |
7.93 |
9.71 |
|
46 |
13.1 |
Bismarck |
.34 |
Bismarck |
.43 |
187 |
+.09 |
+.09 |
.02 |
.04 |
9.39 |
14.31 |
|
|
47 |
19.2 |
Mobile |
.49 |
Saint Marks.. |
.67 |
168 |
+.25 |
0 |
.51 |
.07 |
15. .54 |
11.. 52 |
|
|
48 |
20.3 |
Bismarck |
.53 |
Fort Sully.... |
.35 |
232 |
—.11 |
—.28 |
.00 |
.00 |
11. 06 |
13.60 |
|
|
49 |
28.2 |
Bismarck |
.38 |
Fort Sully |
.29 |
240 |
—.01 |
—.44 |
.01 |
.00 |
9.83 |
12. 27 |
|
|
50 |
Oct. |
2.2 |
Mobile |
.52 |
Saiut Marks.. |
.43 |
240 |
+.11 |
—.13 |
.30 |
.03 |
14.02 |
16.82 |
|
51 |
24.2 |
Bismarck |
.52 |
Bismarck |
.31 |
192 |
-.21 |
—.21 |
.07 |
.00 |
9.00 |
8.66 |
|
|
52 |
25.2 |
Bismarck Mean |
.31 |
Bismarck |
.50 |
140 |
+.19 |
+.19 |
.04 |
.01 |
6.57 |
8.26 |
|
|
29.;38 |
29.39 |
156 |
+.09 |
-.09 |
.09 |
.03 |
10. 30 |
13. 24 |
|||||
54 MEMOIRS OP THE NATIONAL ACADEMY OF SCIENCES.
4. During the days named in Table XXXI the average daily raiu-fall for tlie entire low area was 0.27 inch on the east side of the low center and 0.09 inch on the west side. During the days named in Table XXX the average daily rain-fall for the entire low area was 0.48 inch on the east side of the low center and 0.18 inch on the west side. In each case the rainfall on the east side of the low center was about three times as great as on the west side, and for the storms in Table
XXX the average rain-fall was about double that for the storms in Table XXXI.
5. For the storms in Table XXX the average velocity of the wind was 3.02 miles per hour greater on the west side of the low center than it was on the east side. For the storms in Table
XXXI the average velocity of the wind was 2.94 miles per hour greater on the west than on the east side. For the storms in Table XXX the average velocity of the wind was a half mile per hour greater than for the storms in Table XXXI.
77. We conclude from these results that the velocity of the wind, within an area of low pressure, has very little influence upon the rate of progress of the low center. Moreover, the rain- fall within the low area cannot be the sole cause, and probably is not the principal cause, of the very rai)id ])rogress which the center of low pressure sometimes exhibits, for in sixteen of the cases in Table XXX the rainfall was less than the average rainfall for the cases in Table XXXI, In No. 9 of Table XXX no rainfall w.as reported at any station within the low area either on the east or west side during the twenty-four hours named, and in Nos. 2, 3, 12, 22, 24, and 30 the amount of rain-fall was quite insigniflcant. On the other hand, in seven cases of Table XXXI the rain-fall was greater than the average rain-fall in Table XXX, and in No. 47 the rain-fall on the east side of the low center was greater than in any storm named in Table XXX.
The facts which the two tables exhibit most strikingly in contrast are that iu the cases of rajiid progress the storms generally were increasing in intensity, and the extent of the oscillatiou of the barometer iu twenty-four hours was almost exactly proportional to the rate of juogress of the storm center.
78. In order to discover the causes which were most influential in accelerating the movements in Table XXX, and retarding the movements in Table XXXI, I have carefully examined each case, and have found the following results :
In twenty of the cases in Table XXX the movement of the low center appeared to be accele- rated by the influence of a low area on its east or northeast side, viz, iu Nos. 3, 6, 8, 9, 13, 18, 19, 20, 24, 25, 27, 28, 30, 32, 33, 34, 35, 37, 38, and 41. There are also four other cases which appar- ently ought to be included in the same class, but the Signal Service observations do not cover snflicieut territory to furnish decisive information on this point. These cases are Nos. 1, 17, 39, and 40.
In twenty-two of the cases in Table XXX the low center advanced between two neighboring areas of high barometer, and its movement was apparently accelerated thereby, viz, in Nos. 2, 3, 4, 5, 6, 9, 12, 14, 15, 16, 17, 20, 21, 22, 23, 24, 31, 35, 36, 37, 42, and 43. It is probable that No. 26 should be included in the same class, and perhaps two or three other cases.
There are only eight cases not included in either of the i)receding lists, viz, Nos. 1, 7, 10, 11, 26, 29, 39, and 40, and seven of the cases are included in both lists. There is little doubt that Nos. 1, 39, and 40 should be included in the first list, but the low center passed so near the northern boundary of the United States that the evidence is not entirely satisfactory. There are only four cases which do not api)arently belong to one of the preceding classes, viz, Nos. 7, 10, 11, and 29, and iu these cases the amount of rainfall on the east side of the low center was unusually great, viz, an average rain-fall of 0.81 inch, 0.72 inch, 1.14 inch, and 0.93 inch, iu 24 hours, for the entire area within wh ch the barometer was below 30 inches. These are amoirg the greatest rainfalls which have occurred iu the United States since the SigUiil Service observations commenced. Greater rainfalls have occurred within districts of limited extent, but few cases have occurred which showed so large an average rain-fall for the entire extent of the low area.
In several of the cases in Table XXX the isobars were very much elongated in the direction towards which the low center advanced, so that a small change of pressure was sufficient to carry the low center forward with unusual rapidity. Nos. 4, 7, 10, 14, 17, 21, 23, 30, 34, 36, 37, 40, and 42 were of this kind, and if the stations of observation had been sutficiently extended to show in each instance the complete form of the isobars it is probable that more cases of the same kind
CONTRIBUTIONS TO METEOROLOGY. 55
would have been fouud. In No. 17 the form of the isobars was quite siuuUir to those shown on Plate II.
From tlie last colninn in Table XXX we see that a considerable number of these storms were immediately succeeded by au area of high pressure of unusual nuiyuitude. In thirfeen of the cases the pressure exceeded 30.50 inches; in thirty-two of the cases the pressure was as great as 30.25 inches ; but in six of the cases it was as low as 30.12 inches. These facts seem to indicate that an area of high i)ressure, immediately succeeding an area of low pressure, is favorable to the rajjid progress of the latter, but a very high pressure is not essential to riii)id progress.
79. We perceive that about four fifths of the storms included in Table XXXI occurred between the jMississippi River and the Rocky Mountains, and they occurred most frequently in the neighborhood of Fort Sully and Bismarck. This region, therefore, appears to be especially favorable to the slow movement of areas of low pressure. A careful examination of the Signal Service mai)S shows that in the cases which occurred in the region above mentioned a pressure below 30 inches extended to a considerable distance westward, generally as far as the Pacific Ocean, and the low center did not make much progress eastward until an area of increased pressure, coming from the west or northwest, began to be felt on the east side of the Rocky Mountains. Nos. 1, 2, 3, 7, 9, 12, 13, 15, 18, 19, 24, 25, 26, 27, 28, 29, 33, 35, 36, 37, 38, 42, 44, 45, 46, 49, 51, and 52 were apparently examples of this kind.
In Nos. 5 and 11 there was an area of moderately high pressure prevailing at the time over the Eocky ISIountains, but this high area remained sensibly stationary during the day in question. As soon as the high center began to advance eastward the low center advanced also, and at about the same rate.
In se\eral instances the low areas appeared to have been filled up by a slowly increasing pi-essure on the north side, until the depression was so inconsiderable that it could not be satisfactorily traced. Nos. 8, 10, 20, 21, 22, 39, 40, 41, 43, and 48 were apparently of this kind.
In some of the cases the low center vibrated to and fro within the limits of a few hundred miles for two, three, or four days. At length an increasing pressure on the northwest side either drove the low center eastward or filled up the low area so that it could no longer be satisfactorily followed. Nos. 20, 35, 37, 41, 45, 46, and 51 were of this kind.
Apparently the reason why these areas of low pressure lingered so long in the neighborhood of Fort Sully and Bismarck was the absence of a sufficient pressure on the west side, and the Eocky Mountains api)areutly formed the barrier, which ju'evented the air from flowing in freely on the western side.
SO. The amount of rain which accompanied these low areas was extremely small, and it is surprising that the winds within them acquired so great velocity. The average amount of rainfall in eight hours for the forty eases which occurred in the northwestern part of the United States was 0.06 inch on the east side of the low center and 0.02 inch on the west side. A part of this rain fell near the borders of the low area, where the pressure was but little less than 30 inches, and it probably had but little intiueuce upon the movement of the low center. In the twenty-two cases which occurred nearest to Fort Sully there were only nine in which a drop of rain fell at that station during the days in question, and much of the time the sky was reported as either clear or fair.
81. It seems probable that the direct heat of the sun, acting ui)on the dry surface of the barren plains, between the meridian of 97° and the Eocky Mountains, supplied a large part of the moving force which maintained the velocity of the winds. Of the forty cases which the table enumerates for the northwestern ])art of the United States two occurred near the end of March, three occurred in A{)ril, ten in May, three in June, six in July, five in August, nine in September, and two in October. During five months, including the colder part of the year, no case occurred, and at. the time of nearly all the cases here enumerated the heat was unusually great. Table XXXII shows for three successive days the maximum temperatures observed at Fort Sully at the time of the twenty-two cases which occurred nearest to that station. Column 1 shows the number of the case as recorded in Table XXXI; column 2 shows the maximum tem- perature two days before the date in the table; column 3 shows the maximum temperature one day before the given date, and column 4 shows the maximum temperature on the given day.
56
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
Table XXXII. — Maximum temperatures observed at Fort Sully.
|
No. |
2 days |
1 day |
Given |
1 \No. |
2 days |
1 day |
Given |
No. |
2 days |
1 day |
Given |
No. |
2 days |
1 day |
Given |
|
before. |
before. |
day. |
before. |
before. |
day. |
before. |
before. |
day. |
before. |
before. |
day. |
||||
|
o |
o |
o |
o |
c |
o |
o |
o |
o |
o |
o |
o |
||||
|
7 |
66 |
69 |
73 |
15 |
.57 |
64 |
60 |
24 |
99 |
100 |
100 |
42 |
94 |
89 |
97 |
|
8 |
92 |
103 |
105 |
18 |
90 |
96 |
82 |
25 |
80 |
90 |
80 |
44 |
95 |
94 |
93 |
|
9 |
H5 |
91 |
108 |
19 |
• 78 |
82 |
91 |
26 |
86 |
93 |
94 |
48 |
79 |
83 |
90 |
|
10 |
89 |
101 |
106 |
20 |
77 |
93 |
101 |
28 |
94 |
92 |
96 |
49 |
84 |
71 |
87 |
|
11 |
84 |
91 |
107 |
SI |
93 |
101 |
99 |
33 |
40 |
50 |
50 |
||||
|
12 |
83 |
92 |
95 |
22 |
101 |
99 |
96 |
37 |
76 |
73 |
74 |
||||
We see that in eight of these cases the theruionieter rose to 100° aud upwards; in thirteen of the cases the thermometer rose as high as 95°; aud in seventeen cases it rose as high as 90°. Of the five cases in which the thermometer did not rise as high as 90° two occurred in March, two in May, and one in September. In three of these cases there was a considerable fall of rain at Fort Sully, and in the two remaining cases the temperature was above the average for that season of the year.
82. Besides the forty cases already examined Table XXXI contains twelve others, of which nine occurred near the northeastern portion of the United States ; two occurred near the Gulf of Mexico; and one near Lake Erie. In all of these cases the most noticeable feature was a nearly stationary condition of the barometer throughout an extended region on the western side, reaching as far as the Rocky Mountains, and sometimes to the Pacific Ocean. In each case there was a second area of low pressure, at a distance generally of about 1,500 miles on the western side^ which made very slow progress eastward ; and in each of the cases (except Nos. 47 and 50) there was an area of high, or moderately high, pressure, generally situated between the two low areas, which high area was also nearly stationary for one or more days, or moved slowly towards the south without disturbing the low area on its eastern side. In the case of No. 14 this high area made no considerable progress for four days, and in Nos. 16 and 17 the high area remained nearly stationary for six days. These facts seem to indicate that the slow movement of these twelve low areas was not principally due to any local cause; it was not wholly due (probably it was not mainly due) to any thing occurring within the limits of the given low area; but a like stationary condition extended to a distance of several thousand miles on the western side, and must, therefore, have been the result of causes which had a very wide extent, perhaps com- prehending a large portion of the northern hemisphere, and possibly portions of the southern hemisphere. We also perceive that the causes which deternnned the slow movement of these twelve low areas are in many respects similar to the causes which operated in the forty cases which occurred in the northwestern portion of the United States.
83. In order to study the movement of areas of low pressure under the greatest possible variety of circuu)stances, I have endeavored to obtain information from European observations. In the Uebersicht der Witterung for 1881, publi-shed by the Deutsche Seewarte, is given a table showing the mean velocity of movement of the barometric minima for the five years 1876-'80, as deduced from the monthly charts of storm tracks. The following table shows the average results deduced from the observations of these five years :
Table XXXIII. — Rate of progress of storm centers in Europe.
January . February March . . .
April
May
June .. .. July
Myriam.in
twenty-four
hours
67.3 69.4 67.6 62.6 56.9 60.9 54.9
|
Miles per hour. |
Miles in U. S. |
Ratio. |
|
17.4 |
33.8 |
1.94 |
|
18.0 |
34.2 |
1.90 |
|
17.5 |
31.5 |
1.80 |
|
16.2 |
27.5 |
1.70 |, |
|
14.7 |
25.5 |
L73 1 |
|
15.8 |
24.4 |
L54 ! |
|
14.2 |
24.6 |
L73,| |
August ... September October . . . November December.
Year...
Myriam. in j Miles twenty-four per hours. hour.
I Miles in U. S.
54.1 66.7 73.2 72.0 69.3
14.0 17.3 19.0 18.6 17.9
64.6
16.7
22.6 24.7 27.6 29.9 33.4
28.4
Ratio.
1.61 1.43 1.45 1.60 1.87
1.70
CONTRIBUTFONS TO METEOROLOGY.
57
(^oluiim 2 sliow.s tlio vi'ldclty of inovtMiuMit for v.ivh inoiitli, expn'ssed in myriiimoters for tweiityfonr iioiirs ; coluimi .'J sliows the veUndty tvKl)ressi'(l in English miles [wv hour; coliiinii -4 sbows the velocity of moveinent of .storm centers for tlic United States, and column 5 shows the ratio of the iinmliers in columns 3 niul 4.
We see that in tlie United States the average velocity of movement for the entire year is abont two-thirds greater tiian it is in Enrojje. This ratio is greatest in winter, when it amounts to 1.9, and least in the autumn, when it amounts to 1.5. So large a ditt'erence between the mean ratio of progress of storm centers in the United States and Europe must he the result of a permanent cause of great energy. A conii>arison of the cases of most rapid movement in Europe with the cases of extremely slow movement may afford some clue to the nature of this cause.
S4. The most satisfactory materials I have found u|)on which to base such a comparison are the daily weather charts, publislied by the Danish Government for three years, from December, 1873, to November, 1876, and by the Danish Governmenr in connection with the Deutsche See- warte, from December, 1880, to August, 1881. Table XXXIV contains the most decided cases of rapid motion that 1 have been able to tind from a comparison of these charts. They are cases in which the depression of the barometer was considerable, and generally there was no second low center in the vicinity. The charts show a great number of other cases in which the movement of low centers apparently was equally rapid ; but in some of them the exact position of the low
Table XXXIV. — Atlantic and European storms advancing at least 750 miles in twenty-four hours.
|
Change of l)a- |
si |
||||||||||
|
First date. |
Second date |
Prog- |
romcter in 24 hours. |
a i o |
|||||||
|
No. |
Date. |
ress. |
K |
||||||||
|
Lati- tude. |
Longitude. |
Barom- eter. |
Lati- tude. |
Longitude. |
Barom- eter. |
First station. |
Second station. |
||||
|
1873. |
o |
o |
mm. |
o |
o |
mm. |
MiUa. |
mm. |
mm. |
vim. |
|
|
1 |
Dec. 16-17 1874. |
61.3 |
1.1 W. |
715 |
60.9 |
26.2 E. |
715 |
966 |
+37 |
—29 |
770 |
|
2 |
Feb. 5- 6 |
66.7 |
20. 9 E. |
734 |
59.0 |
37.2 E. |
733 |
759 |
-f-24 |
—22 |
775 |
|
3 |
13-14 |
68.7 |
IL 8 E. |
737 |
63.7 |
37. 9 E. |
730 |
780 |
+14 |
—20 |
765 |
|
4 |
Sept. 18-19 |
60.3 |
2. 4 W. |
738 |
64.3 |
20.7 E. |
743 |
793 |
+14 |
—12 |
765 |
|
5 |
Nov. 1- 2 |
6H. 1 |
28.4 E. |
724 |
64.0 |
55.0 E. |
724 |
828 |
-f28 |
—20 |
770 |
|
6 |
19-20 1875. |
40.9 |
42.7 W. |
730 |
62.2 |
55.7 W. |
731 |
1566 |
+28 |
—24 |
765 |
|
7 |
Feb. 21-22 |
47.5 |
65.5 W. |
730 |
60.1 |
59. 7 W. |
735 |
897 |
-1-35 |
—26 |
775 |
|
8 |
26-27 |
46.3 |
64. 0 W. |
726 |
56.2 |
53.7 W. |
728 |
807 |
-f26 |
—15 |
765 |
|
9 |
28-29 |
45.1 |
61'. 5 W. |
730 |
60.4 |
52.5 W. |
732 |
1097 |
+34 |
— 7 |
775 |
|
10 |
Mar. 1- 2 |
60.4 |
52.5 W. |
732 |
73.3 |
45. 0 W. |
734 |
925 |
+14 |
—21 |
775 |
|
11 Oct. 4- 5 |
59.6 |
29.9 W. |
735 |
65.3 |
6.5 W. |
725 |
862 |
-1-20 |
-21 |
775 |
|
|
1876. |
|||||||||||
|
12 Jan. 11-12 |
49.8 |
60.4 W. |
735 |
60.8 |
53. 4 W. |
732 |
800 |
+12 |
—24 |
775 |
|
|
13 20-.il |
48.0 |
6.5.6 W. |
731 |
59.2 |
49. 1 W. |
715 |
1021 |
-(-26 |
—35 |
775 |
|
|
14 |
27-28 |
63.8 |
3.!. 9 W. |
724 |
49.2 |
34.2 W. |
716 |
1007 |
+15 |
—34 |
770 |
|
15 |
28-29 |
49.2 |
34.2 W. |
716 |
61.8 |
32. 6 W. |
720 |
869 |
-f-32 |
—18 |
770 |
|
16 |
Apr. 5- 6 |
69.3 |
1.1 W. |
730 |
66.3 |
39.5 E. |
736 |
1111 |
-1-22 |
—17 |
770 |
|
17 |
11-12 |
h-. 2 |
8.6 E. |
723 |
63.4 |
27. 2 E. |
727 |
766 |
4-24 |
—18 |
775 |
|
18 |
July 21-22 |
60.5 |
54. 3 W. |
732 |
75.8 |
53.3 W. |
731 |
1056 |
-1-18 |
—23 |
770 |
|
19 |
22-23 |
75.8 |
53. 3 W. |
731 |
71.8 |
19. 6 W. |
734 |
787 |
+13 |
—18 |
765 |
|
20 |
Oct. 12-13 1880. |
60.7 |
2.4 E. |
721 |
69.7 |
32.5 G. |
726 |
1069 |
-f35 |
—17 |
7&5 |
|
21 |
Dec. 14-15 |
56.0 |
14.0 E. |
737 |
50.8 |
34.5 E. |
730 |
883 |
+20 |
—19 |
770 |
|
22 |
30-31 lyyi. Jan. 16-17 |
47.5 |
61. 0 W. |
727 |
64.0 |
54.5 W. |
707 |
1145 |
+26 |
—28 |
770 |
|
23 |
36.4 |
27. 5 W. |
737 |
43.3 |
11. 1 W. |
740 |
980 |
-f22 |
—17 |
765 |
|
|
24 |
17-18 |
45.3 |
35.7 E. |
743 |
55.8 |
47. 7 E. |
736 |
883 |
-1-26 |
—22 |
770 |
|
25 |
20-21 |
52.-'2 |
14.2 E. |
738 |
50.0 |
39.4 E. |
733 |
1063 |
-1-24 |
—26 |
765 |
|
26 |
21-22 |
50.0 |
39.4 E. |
733 |
59.4 |
61.1 E. |
731 |
105(; |
+17 |
—25 |
765 |
|
27 |
Feb. lH-14 |
45.6 |
68. 8 W. |
735 |
60.0 |
51. 0 W. |
731 |
1203 |
-1-23 |
—15 |
775 |
|
28 |
Apr. 26-27 |
45.5 |
46.9 W. |
738 |
58.5 |
43. 9 W. |
746 |
904 |
-F24 |
— 8 |
775 |
|
29 |
May 16-17 Means.. |
56.4 |
1.3 E. |
737 |
66.9 |
16.1 E. |
737 |
862 |
+21 |
—18 |
770 |
|
731.0 |
729.5 |
956 |
+23.2 |
—20.6 |
770 |
||||||
S. Mis. 154-
58 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
center is not clearly iudicated, tiiid in other cases the change in the form of the isobars in twenty- four hours was so great as to leave some doubt respecting the identity of the low areas. With regard to tlie rapid movement of the twenty -nine cases included in the table it is thought there can be no difference of opinion.
Column 1 gives the number of reference ; column 2, the dates of the two maps compared ; columns 3 and 4 show the latitude and longitude of the low center at the first of the two dates ; column 5 shows the estimated heiglit of the barometer in millimeters at the center of the low area. This estimated pressure is generally two or three millimeters less than that of the lowest isobar drawn on the map. Columns C and 7 show the latitude and longitude of the center of the low area at the second of the two dates, and coluiuu 8 shows the estimated jtressure at the center; column 9 shows the i)rogress of the low center in tweutyfour hours expressed in English miles; column 10 shows the rise of the barometer at the first-named point during the twenty four hours succeeding the first dates, and column 11 shows the fall of the barometer at the second-named point during the twenty-four hours preceding the last named date. Generally the low area was immediately succeeded by an area of pressure above 760"'". Column 12 shows the highest isobar in this area. The highest pressure was probably a few millimeters greater than the highest isobar. At the bottom of the table are given the average values of the numbers in six of the columns.
83. We see from this table that the depression at the center of the low areas increased slightly during the given twenty-four hours, showing a slight increase in the inteusity of the storms. The average rise of the barometer at the first station during the succeeding twenty-four hours was 23.2""", or 0.91 inch, and the average fall of the barometer at the second station during the same time was 20.6""", or 0.81 inch. These changes are nearly one-half greater than those shown in Table XXX for American storms.
If now we examine each of these cases singly we shall find that in about half of them, viz, Nos. 4, 9, 11, 12, 13, 15, 16, 17, 22, 23, 24, 25, 26, and 27, there was a second low center nearly in the direction towards which the first low was moving, and this may be supposed to have accelerated the movement of the first low center. The same was probably true in several cases not distinctly indicated by the charts, and in all of the cases the point reached by the low center at the end of twenty-four hours (if not previously the center of a system of circulating winds) was at least a point where tlie pressure was less than 760""", and the barometric gradient was very feeble. No. 14 may perhaps be claimed as an exception to this remark, but if we had a chart for the evening of January 27 it might perhaps appear that the low area prevailing in the middle of the Atlantic Ocean on the morning of January 28 is to be connected with the low area prevailing south of Hudson's Bay on the morning of January 27.
In more than a third of the cases, viz, Nos. 6, 7, 9, 10, 12, 15, 16, 17, 23, 25, and 26, the low center advanced between two neighboring areas of hij^h barometer, and its movement may have been thereby accelerated. The same was probably true in some cases not indicated by the maps, since the low areas enumerated in the table were geu<M-!illy near the northern limit of the charts. It uuist, however, be admittetl that in many of the e:ises the charts do not show two such areas of high barometer. In all of the cases the charts show a fall of rain or snow on the front side of the low center, but I have not been able to make any satisfactory estimate of its amount. As the low center moved forward it was succeeded h\ a i)ressure above 760""", as is shown by column 12 of the table. The average of the highest isobars, following the low centers, was 770"™, and the average pressure at the center of the high areas was about 772"""', or 30.39 inches, the same as found in Table XXX.
86. Table XXXV shows the most distinctly marked cases in which a storm center, over the Atlantic Ocean or Euroi)e, has advanced not more than 200 miles in twenty-four hours. The arrangement of this table is similar to that of Table XXXIV.
We see from this table that during the twenty-foui' hours here compared the depression at the center of the low area in some cases increased, and in other cases decreased, but generally the change did not exceed two or three millimetei's. On an average of the fifty cases the depression at the center was slightly diminished. In forty of the cases there was a slight increase of pressure at the first staUou during the twenty-four hours here considered, auc| iu thirty-two of
CONTRIBUTIONS TO METEOROLOGY.
59
the cases tbere was a slight decrease of pressure at the second station. In nine of the cases there was a diminution of pressure at the first station, but during the same time there was a greater diminution of pressure at the second station, sliowing tiiat the storm was increasing somewiiat in intensity. In twelve of the cases there was a sliglit increase of pressure at the second station, but during the same time there was an equal or greater iucieasc at the first station, showing that the intensity of the storm was decreasing.
Table XXXV
-Atlantic and European xtornis advancing not more than 200 miles in twenty four
hours.
|
Change of ba- |
|||||||||||
|
First date. |
Second date |
rometer |
in twen- |
||||||||
|
ty-four hours. 1 |
|||||||||||
|
No. |
Date. |
Prog- ress |
|||||||||
|
Lati- tude. |
Longitude. |
Barom- eter. |
Lati- tude. |
Longitude. |
Barom- eter. |
First station. |
Second station. |
||||
|
1874. |
c |
o |
mm. |
o |
o |
mm. |
Miles. |
mm. |
mm. |
||
|
1 |
Mar. 24-25 |
58.6 |
47.4 W. |
731 |
59.6 |
49.1 W. |
721 |
97 |
— 8 |
—13 |
|
|
2 |
Mav 29-30 |
60.7 |
52.2 W. |
736 |
59.4 |
47.3 W. |
737 |
193 |
+ -^ |
- 4 |
|
|
3 |
June 1- 2 |
56.4 |
50.6 E. |
742 |
.57. 6 |
52. 9 E. |
740 |
124 |
+ 1 |
— 5 |
|
|
4 |
Julv 11-12 |
52.3 |
52. 4 E. |
746 |
51.5 |
.52. 0 E. |
742 |
69 |
- 1 |
— 5 |
|
|
5 |
An;;. 11-12 |
56.7 |
1.1 W. |
742 |
57.5 |
0.3 W. |
743 |
55 |
+ 2 |
— 1 |
|
|
6 |
8.-i)t. ."i- 6 |
64.3 |
11.9 E. |
742 |
63.9 |
16.6 E. |
740 |
152 |
-f 1 |
— 3 |
|
|
7 |
Oct. 2- 3 |
."i?. 7 |
9. 5 W. |
719 |
59.4 |
5. 1 W. |
719 |
193 |
+ 10 |
— 9 |
|
|
8 |
9-10 |
66.2 |
24.8 W. |
723 |
63.8 |
26.2 W. |
723 |
166 |
+ 9 |
— li |
|
|
9 |
Nov. 11-12 |
63.3 |
31.7 E. |
722 |
63.1 |
34.9 E. |
736 |
103 |
+15 |
+11 |
|
|
10 |
25-26 |
61.4 |
24.9 W. |
734 |
62.3 |
26. 9 W. |
735 |
97 |
+ 3 |
— 1 |
|
|
11 |
Dec. 12-13 |
51.9 |
1.1 E. |
729 |
51.2 |
5. 6 E. |
735 |
200 |
+13 |
0 |
|
|
12 |
16-17 |
40.5 |
53.3 W. |
741 |
41.4 |
53. 5 W. |
736 |
62 |
— 3 |
— 8 |
|
|
13 |
30-31 1875. |
58.5 |
50.0 W. |
722 |
59.4 |
51.2 W. |
716 |
69 |
— 5 |
— 6 |
|
|
14 |
Jan. 7- 8 |
51.8 |
32.7 W. |
718 |
49.8 |
30.1 W. |
715 |
186 |
+ 5 |
—10 |
|
|
15 |
9-10 |
53.4 |
27.4 W. |
725 |
51.6 |
27.7 W. |
725 |
124 |
+ 3 |
— 4 |
|
|
16 |
Mar. 13-14 |
49.0 |
38.4 W. |
730 |
50.2 |
37. 2 W. |
734 |
90 |
+ 8 |
0 |
|
|
17 |
Apr. 17-18 |
45.5 |
26.9 W. |
736 |
46.5 |
27. 5 W. |
740 |
83 |
+ 5 |
+ 1 |
|
|
18 |
May 20-21 |
60.2 |
30.4 W. |
720 |
58.2 |
27.5 W. |
720 |
179 |
+ 5 |
—10 |
|
|
19 |
22-23 |
62.5 |
23.4 W. |
724 |
64.7 |
25.2 W. |
737 |
166 |
+Ui |
+ 8 |
|
|
ao |
23-24 |
64.7 |
25. 2 W. |
737 |
63.6 |
20.0 W. |
742 |
179 |
+ 9 |
+ 1 |
|
|
21 |
Aug. 29-80 |
hl.l |
51.7 W. |
740 |
.59.5 |
5.5.0 W. |
740 |
159 |
+ 5 |
— 5 |
|
|
22 |
30-31 |
.59.5 |
55.0 W. |
740 |
60.0 |
51.5 W. |
738 |
62 |
0 |
— 7 |
|
|
23 |
Sept. 20-21 |
72.8 |
30.6 E. |
726 |
71.3 |
32.5 E. |
721 |
117 |
+ 4 |
— 9 |
|
|
24 |
22-23 |
45.5 |
28.6 W. |
730 |
44.8 |
25. 2 W. |
735 |
179 |
+11 |
- 4 |
|
|
25 |
28-29 |
61.0 |
52.7 W. |
736 |
60.0 |
.55. 5 W. |
737 |
114 |
+ 4 |
— 2 |
|
|
26 |
Oct. 18-19 |
60.3 |
54.6 W. |
741 |
61.5 |
55.3 W. |
732 |
83 |
- 6 |
—11 |
|
|
27 |
Dec. 17-18 |
64.3 |
29.6 AV. |
718 |
63.0 |
30. 3 W. |
721 |
97 |
+ 6 |
+ 1 |
|
|
28 |
30-31 1876. |
65.6 |
2H.9 W. |
729 |
67.0 |
24.2 W. |
727 |
166 |
+ 1 |
— 4 |
|
|
29 |
Jan. 21-22 |
59.2 |
49.1 W. |
715 |
61.0 |
51.2 W. |
711 |
131 |
+ 2 |
- 9 |
|
|
30 |
Feb. 1- 2 |
64.2 |
27. 5 W. |
716 |
64.5 |
23. 2 W. |
719 |
131 |
+ 9 |
— 2 |
|
|
31 |
.5- 6 |
61.2 |
50.2 W. |
739 |
63. 8 |
51.1 W. |
722 |
183 |
— 10 |
-23 |
|
|
32 |
Mar. 9-1 n |
r)9. 4 |
2. 3 W. |
710 |
58.6 |
1.0 W. |
7ie |
69 |
+ 4 |
— 2 |
|
|
33 |
May 1- 2 |
43.9 |
66.1 W. |
741 |
44.9 |
63.4 W. |
743 |
159 |
+ 6 |
— 4 |
|
|
34 |
June 14-15 |
58.3 |
18.1 W. |
729 |
59. 5 |
14.7 W. |
731 |
152 |
+11 |
— 7 |
|
|
35 |
18-19 |
.57.4 |
27.6 W. |
736 |
57.6 |
23. 4 W. |
725 |
159 |
— 3 |
—19 |
|
|
36 |
July 1- 2 |
64.1 |
24. 6 W. |
731 |
65.9 |
19. 5 W. |
735 |
200 |
+ 9 |
0 |
|
|
37 |
23-24 |
71.8 |
19.6 W. |
7:55 |
70.1 |
19. 8 "W. |
735 |
117 |
+ 3 |
— 1 |
|
|
38 |
Sept. 11-12 |
59. 4 |
8.9 E. |
735 |
59.6 |
7.0 E. |
740 |
62 |
+ 8 |
+ 3 |
|
|
39 |
22-23 |
54.4 |
26.7 W. |
735 |
56.0 |
29.7 W. |
737 |
159 |
+ 7 |
— 2 |
|
|
40 |
Oct. 8- 9 |
57.4 |
50.6 W. |
724 |
58.3 |
49. 5 W. |
718 |
65 |
— 4 |
—12 |
|
|
41 |
12-13 |
55.9 |
49.6 W. |
715 |
57.3 |
49. 3 W. |
720 |
97 |
+10 . |
0 |
|
|
42 |
Nov. 12-13 |
48.0 |
19. 6 W. |
728 |
47.3 |
18. 5 W. |
722 |
69 |
— 2 |
—12 |
|
|
1880. |
12.5 E. |
737 |
67.0 |
12. 0 E. |
739 |
48 |
+ 3 |
0 |
|||
|
43 |
Dec. 21-22 |
66.3 |
|||||||||
|
1881. |
37.5 W. |
715 |
46.6 |
37. 5 W. |
727 |
7 |
+12 |
+12 |
|||
|
44 |
Jan. 5- 6 |
46.7 |
^ |
||||||||
|
45 |
6- 7 |
46.6 |
37.5 W. |
727 |
46.9 |
36.9 W. |
735 |
48 |
+10 |
+ 7 |
|
|
46 |
lb-19 |
49.0 |
2. 0 W. |
733 |
49.5 |
1.6 W. |
737 |
34 |
+ 5 |
+ 4 |
|
|
47 |
Mar. 16-17 |
66.3 |
24. 4 W. |
733 |
64.4 |
22.5 W. |
744 |
131 |
+15 |
+ 4 |
|
|
48 |
27-28 |
47.0 |
59.7 W. |
728 |
47.0 |
.59.7 W. |
730 |
0 |
+ 2 |
+ 2 |
|
|
49 |
Apr. 20-21 |
.58.4 |
18.8 E. |
730 |
58.5 |
18.5 E. |
736 |
11 |
+ 6 |
+ 6 |
|
|
50 |
May 18-19 |
56.3 |
12. 6 W. |
737 |
56.3 |
10.5 W. |
738 |
76 |
+ 3 |
0 |
|
|
730.1 |
730.8 |
113 |
+ 4.5 |
— 3.4 |
|||||||
60
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
87. The cases enumerated iu this table are all comprehended between latitude 40° and lati- tude 72°, and between longitude 66° W. and 52° E., but they are by no means uniformly distrib- uted over tliis area. Eleven cases occurred near the southern extremity ot Greenland, viz, Nos. 1, 2, 13, 21, 22, 25, 26, 29, 31, 40, and 41. Nine cases occurred near the western coast of Iceland, viz, Nos. 8, 10, 1 0, 20, 27, 28, 30, 36, and 37. These cases seem to indicate distinctly the influence of local causes. Both of these localities are remarkable for a larger rainfall than is generally found in the same latitude, and it seems probable that this rainfall exerted an influence to hold the low center for twenty-four hours in a nearly fixed position. A similar remark applies to Nos. 5, 7, and 32, near Scotland; to Nos. 6 and 43, on the coast of Norway; to No. 33, near Nova Scotia; and No. 48, near Newfoundland. In all of these cases (twenty-seven in number) it seems probable that local causes exerted an appreciable influence on the movement of the low center, and there are a few other cases in which there is room to suspect the influence of local causes.
88. There remains, however, a large number of cases situated in the middle of the Atlantic Ocean which we cannot ascribe to anj local influence, and therefore it may be presumed that in the cases above specified local influence was not the sole cause of the slow movement of the low centers.
It seems impossible to avoid the conclusion that the extremely slow progress of storm centers which we sometimes observe, and the extremely rapid progress which we find at other times, are mainly due to variations in that general movement of the atmosphere which is shown in the average system of atmospheric circulation. It has already been stated that there are permanent causes in operation, which, in the middle latitudes, give rise to an average wind from west to east. The operation of these causes is temporarily suspended by the action of great storms, which give rise to easterly winds, but the permanent causes which influence the winds are not changed by the action of storms, however violent. By temxjorary obstruction the permanent causes acquire increased energy. Hence it results that the general" system of circulation of the winds, although pretty uniform when we compare the average direction of one year with another, appears very irregular when we comjjare one day with another. Sometimes over large portions of the earth's surface the movement of the winds from west to east goes on with destructive violence ; some- times, over extended districts, the movement is reversed, and the prevalent wind is from east to west; while at other times the advance from west to east is almost entirely suspended, or proceeds in the average direction with inconsiderable velocity. According to this view the general system of atmospheric circulation (consisting of the trade winds of the equatorial regions and the prevalent westerly winds of the middle latitudes) is the primary cause which determines both the direction and velocity of the movement of storm centers; but for each individual storm the determining cause is not so much the average system of atmospheric circulation as the general movement of the atmosphere which is going on at the time and in the vicinity of that particular storm. The iufluence of this general movement is moreover materially modified by a variety of causes, such as the amou/it of rainfall and the position of the rain-areas with reference to the center of the storm, the magnitude and position of the neighboring ai"eas of high and low pressure, the distribution of temperature, local influences, &c.
8!). The preceding investigation has shown that the causes which produce unusually rapid movements or unusually slow movements of storm centers in Europe are similar to the causes which produce like results iu the United States, but it does not explain wby the average movement of storm centers in the United States is so much greater than it is in Europe. In the hope of obtaining some light on this question I have determined the average velocity of storm centers over the Atlantic Ocean by a comparison of the monthly charts of storm tracks i)ublished with the International Bulletin for a period ot four years from 1870 to 1882. The following table shows in miles per hour the average rate of progress for each month of the year :
The average velocity for the entire year is 18 miles per hour.
CONTRIBUTIONS TO METEOROLOGY. 61
90. If now wp compare the preceding results with those hei'etofore found for the West India cyclones, while pursuing a westerly course, and for the cyclones of the liay of Bengal and China Sea, for the same part of their course, we shall liave a view of the movement of storm areas under a great variety of conditions. The average results for these five districts for the entire year are as follows :
Miles per hour.
For tlie United States 28. 4
Middle latitudes of the Atlantic Ocean 18. 0
Europe 1(1. 7
Neigbborbood of the West Indies 14. 7
Bay of Bengal and China Sea 8.^^
The velocity here given for the West India cyclones is the mean of all the determinations in Tables III and IV, and the velocity given for the Bay of Bengal and China Sea is the mean of all the determinations in Tables VII and IX.
Thus we see that the average rate of [)rogress of storm centers over the Atlantic Ocean is about the same as over Europe and is double the rate of progress for the China Sea, and the rate of progress for the United States is more than three times the rate for the China Sea. These results are derived from so large a number of observations that they must be accepted as substantially correct, and the.y demand a clear explanation.
91. 1 have endeavored to determine how far these difl'erences may result from a ditference in the mean velocity of the wind for these several districts. For thi.s purpose I determined the average velocity of the wind for that portion of the United States within which the storm centers are most frequently iouud, viz, that portion north of the parallel of 40° and east of the meridian of lOOo from Greenwich. A slight examination of the observations sliows that at stations near the Atlantic Ocean or near one of the Great Lakes the velocity of the wind is greater than at stations in the interior of the country. I have therefore divided the observations into two groups, one including the stations near the ocean or one of the Great Lakes, and called coast stations, the other group including the remaining stations, which are called inland stations. Table XXXVI shows for each month of the year the average monthly movement of the wind in miles for these two classes of stations, according to the Annual Report of the Chief Signal Officer for 1883.
Column 2 shows tor each station the number of years of observation, and at the bottom of each group of stations is given the mean hourly velocity of the wind for that group. In the succeeding line is given the mean between the velocities of the two groups; the next line shows for each month the rate of jirogress of stoiiii centers as given in Table XXIX, and the last line shows the ratio of the velocity of storm centers to the mean velocity of the wind.
We see that this ratio is not the same for all months, but for that month in which the rivte of progress of storms is greatest the ratio is sensibly the same as for that month in which the rate is the least. This coincidence seems to indicate that the rate of progress of storms is in some degree dependent upon the mean velocity of the wind, but the considerable inequalities in the value of the ratio show that the rate of progress of storms cannot depend solely on the average velocity of the wind.
92. I next determined, as well as I was able with the means at my command, the average velocity of the wind for that part of Europe within which storm centers are most frecpieiitly found, viz, between the parallels of 50° and 6(1°. Table XXXVII shows the results which I have obtained, the velocities being expressed in meters per .second, and the observations are divided into two groups, as in Table XXXVl.
Column 4 shows the number of years of observations from which the velocities are derived. At the bottom of each group of stations is given the mean of the observations for that group- The succeeding line shows the average between the results for the separate groups; the next line shows the mean velocities expressed in miles per hour; the next line shows the average rate of progress of .storm centers, as given in Table XXXIII; and the last line shows the ratio of the numbers in the two preceding lines. These ratios are quite different froui those found for the United States, and the corres]tondence between the rate of storm movements and the movements of the wind is not as distinctly marked. Nevertheless some degree of corresi)ondence can be detected, and it is noticeable that the change in the wind's mean velocity for the different mouths
62
MEMOIES OP THE NATIONAL ACADEMY OP SCIENCES.
Table XXXVI. — Mean monthly movement of the tcind for the United States.
COAST STATIONS.
Years.
Alpena
Block Island
Boston
Buffalo
Chicago
Cleveland
Diiluth
Eastport
Erie
Escanaba
Grand Haven
Marquette
Milwaukee
New Haven
Newport
New York
Oswego
Port Huron
Portland
Roebester
Sandusky
Sandy Hook
Tbatclier's Island
Toledo
Wood's Holl
Hourly
10
2
12
12
12
12
12
10
10
12
12
12
12
10
7
12
12
8
12
12
.5
9
7
12
10
Jan.
6706 13181 7225 7961 6646 8011 4740 9227 8922 7198 8535 6863 8601 5760 8316 7496 7797 7501 5560 8095 9759 10705 12773 7073 9.:,54
Feb.
6809
11236
7212
7006 6219 6956 5119 8608 8047 6924 8266 6041 8206 5634 7473 7506 7199 7472 5607 7347 9716 9875 12046 6187 9258
10.98
11. 33
Mar.
7747 13169 8342 7565 7406 8035 5740 9503 8670 8101 9196 6946 9522 7130 8167 8645 7682 8130 6721 8424 10999 12375 12783 7306 10228
Apr.
11.76
6689 11207 7283 6233 6812 6712 6142 7425 8043 7482 8502 5986 8383 6602 7162 7251 6397 7732 6426 7476 10223 10418 10197 6647 8715
10.67
May.
6072 10694 6454 .5580 6393 6125 4910 6281 6533 6759 7828 5323 7698 5492 6037 6463 5481 7268 .5778 6940 9414 8891 9086 6604 7422
9.22
June.
5737
8807 5522 50,57 5549 5712 4437 4995 613S 6260 6499 4867 6719 4628 5121 5813 4537 6075 4931 5971 8()69 1-351 7437 5667 6525
8.34
July.
5493 7821 5377 5183 5256 5404 4805 4700 5391 6219 6236 5097 6220 4444 5053 5740 4584 5720 4841 5593 7652 7835 7061 .5015 6512
7.70
Aug.
5171 6939 5166 4647 5201 5103 4859 4424 5188 5776 ■5930 5124 6.'.84 4317 4754 5538 4269 5348 4250 5102 7615 8206 6817 4842 6i.91
7.42
Sept.
6031 10364
5886 5711 5668 6349 5383 5506 6390 6797 7113 6203 7240 4914 5546 0418 5248 6144 4843 6H6:i 8440 9744 84l3 52S9 6222
8.98
Oct.
6653 10955 6501 6646 6325 7378 5826 7096 7762 7739 8785 6892 8316 5425 7041 6884 6324 7095 5476 6008 9624 10842 9809 6244 8002
Nov.
9.96
6833 12351 725(i 7534 6177 8040 5197 8735 9004 6894 8624 6574 8528 5876 7973 7465 7432 7352 595t; 7118 1030(i 11821 11528 (1546 I 9788
Dec.
11.16
7042 12740 7340 8798 6469 8121 5140 8793 9596 7196 8894 7083 9017 5846 8535 7659 7890 7810 5810 7901 10126 12565 12492 6992 10417
11.30
INLAND STATIONS.
Albany
Breckenridgo
Burlington
Clianipaign
Davenport
Des Moines
Detroit
DuIuKjue
Huron, Dak
Keokuk
La Crosse
Madison
Moorliead
New London
Ouuiba
Pittsburgh
Saint Paul
Saint Vincent . .. Siiringfield, Mass. Willianisport
Hourly . Mean hourly.
Storms
Ratio
9 11 12
2 12
4
19 10
2 11
9
4
2 12 12 12 12
2 10
1
6029 9.323 6069
8368 (;2li6 4.527 5890 3609 88-J9 (i069 4986 7487 7677 5708 6893 5073 5945 7338 3812 5135
.5816 8782 4996 8160 60U1 5094 .5718 3849 7679 5770 ,5229 8179 7822 5928 6465 4603 5673 7872 3874 3764
8.40 9. 69 33. 8 3.5
8.94 10. 13 34.2
3.4
6776
10715 6003
12266 7712 6168 6703 5030
11300 7160 6281 9141
10215 6912 8178 56.52 7042 8359 4789 5071
10. 18
10.97
31.5
2.9
|
6310 |
.5274 |
|
9924 |
10036 |
|
5.537 |
4999 |
|
9580 |
8796 |
|
7518 |
6732 |
|
583] |
4820 |
|
6119 |
5(i74 |
|
5095 |
4484 |
|
10010 |
8966 |
|
7291 |
6664 |
|
6153 |
5733 |
|
8053 |
7230 |
|
8432 |
8930 |
|
6276 |
5338 |
|
7840 |
7134 |
|
4834 |
4068 |
|
6845 |
7174 |
|
7.571 |
7712 |
|
4605 |
4043 |
|
4245 |
3489 |
|
9.59 |
8. 55 |
|
10.13 |
8.88 |
|
27.5 |
25.5 |
|
2.7 |
2.9 |
4265 8388 4434 8219 ?545 4540 4927 3918 6646 5490 5171 6184 7165 4417 6098 4059 6250 6186 3485 3495
7.56 7.95 24.4 .3.1
|
3793 |
3316 |
|
7571 |
7314 |
|
42r.5 |
3918 |
|
6831 |
6282 |
|
4885 |
4715 |
|
3576 |
33^8 |
|
4676 |
4408 |
|
3186 |
3132 |
|
8146 |
7249 |
|
4501 |
4649 |
|
4620 |
4498 |
|
5501 |
5686 |
|
8646 |
7713 |
|
42.59 |
4043 |
|
5450 |
5363 |
|
3773 |
3281 |
|
.5401 |
5488 |
|
6864 |
5747 |
|
3071 |
2709 |
|
3095 |
2422 |
6.87 7.28 24.6 3.4
6.40 6.91 22.6 3.3
3643
7862 4801 7476 .5504 4117 ; 4821 i 3341 7615 i 5380 I 5030 i 6402 j 7423 4500 5821 ; 36.52 I 5950 6171 3103 I 2447 I
4454
9050
5366 I
7398 1
.5987 1
4406
5662
3985
7702 1
5846
5806
7575
7784
5330
6552 ;
4086 I
6711
7477
3483
2036
6.96 : 7.84
7. 97 8. 90 24.7 '.^7.6
3. 1 3. 1
|
5223 |
5565 |
|
8655 |
8880 |
|
6176 |
6246 |
|
8392 |
920» |
|
6202 |
6146 |
|
4767 |
4776 |
|
5773 |
6134 |
|
3819 |
3552 |
|
8052 |
7147 |
|
5967 |
5764 |
|
5334 |
5035 |
|
7765 |
7670 |
|
8298 |
8314 |
|
5846 |
5594 |
|
7084 |
6.551 |
|
4737 |
5174 |
|
6062 |
.5753 |
|
7859 |
7281 |
|
3812 |
3834 |
|
2645 |
5025 |
|
8.50 |
8.20 |
|
9.83 |
9. 75 |
|
29. 9 |
33.4 |
|
3.0 |
3.4 |
of the year ia Europe is ouly about half as great as in the United States. The inequalities in the value of the ratio for the different months are considerable, and indicate thQ operation of some other cau.se than the mean velocity of the wind.
93. I next determined, as well as I was able with the means at my command, the average velocity of the wind in the neighborhood of the Bay of Bengal and China Sea. Table XXXVIII shows the results which I have obtained, the observations being all derived from the Report on the Meteorology of India for 1882, with the exception of Manilla, which is derived from the international ob.servations. I hiive employed only stations south of latitude 20°, an.d I have rejected all stations having an elevation greater than 3,000 feet.
CONTRIBUTIONS TO METEOROLOGY.
63
Tahle XXXVII. — Mean velocity of the wind in Northern Europe.
COAST STATIONS.
Grconwiili Boiklitiiii Wilhi'liii8li:ivoii Kelt II Haiiiliiirj;
Kiel
Wustrow Swiiipiniiudo Neut'alir Wassvr Libaii *. Meiui'l
Mean
|
Apr. |
May. |
June. |
|
5. n |
5.10 |
5. 32 |
|
i.m |
4.54 |
4.50 |
|
.'•>. 54 |
.5. 18 |
4.98 |
|
7.. 50 |
0.79 |
6. 25 |
|
.'■). 59 |
5.22 |
4.98 |
|
5. :«> |
4.83 |
4.79 |
|
5.81 |
6.08 |
5. ,55' |
|
5.9ff .5.6« |
5.(13 |
|
|
.x42l 4.9. |
4.21 |
|
|
4.31 |
4.33 |
3. 53 |
July.
5.27 4. 30 5. 19 16 94
5.35 4.43
6.20 6.25 6.08 5.49
,16
5.30
5.10
4.581
6. 4. 5. 18 5. ()3
6.14 4.35 3.68 5. 72
.5.18
4.9.51 5.15
Aug.
5.10 4.42
5. .58 6.48
5. 30 5.26
6. 01 6. 23 4.89 3.84 5. 69 5.45
5.35
Sept.
4.78
4.30
4.81
6. 04
4.95
4.84
5.19
5. 83
4.79
3.7:
6. 35
5.03
5.06
Oct.
5.50 4.68 6.06 7.53 5. 95 5. 64 6.31 6.87 5. 66 4.50 6.57 6.24
5.96
Nov.
4.78 5. 12 6.77 8.47 6. 291 6. 65 1 7.14; 8. 38' 6. 28' 4. 72 7.00. 5.851
Dec
7.60 5. 26 5.79 7. 90
5. 42
6. 13 5.92 7.23 5. 82 4.46 6.13 6.41
6. 45 6. 17
INLAND STATIONS.
Oxford . . . . Ebersdorf Upsjila ... Cracow ... AVarscb.'ui
Wilua ' 54
Pinsk
Dorpat
Starv) Bve
St. Petersburg..
Kiew -
Nowgorod
Moskau
Ka.sau
Meau
General mean . . Mill's pti hour.
Stonus
Katie
46
0
52
4
13
41
7
23
31
56
27
31
50
47
1 16 W.
16 0 E.
17 38
19 58 21 2
20 18 26 6 26 43 30 16 30 16
30 30
31 18 37 33 49 8
5.65 4.51 4. 13 1.92 4.60 1.74 4.83 3.27 4.45 4.18 3.46 4.16 4.19 2.86
3.85
5.02
5.44 5.07 4.03 2.61 4.75 1.87 4.94 3.51 4.61 4.46 3.84 4.71 4.36 2.87
4.08
5.16
5.47 4.11 3.97 2.61 4.82 2.14 5.32 3.41 .5.43 4.40 4.34 4.80 4.43 3.12
4.17
5. 12
4.80 4.17 3.91 2. 36j 4.14! 1.79, 4.54 3.25 3.81 .3.88 3.36 3.65 3.93 2.80
4.25
4. 22 4.10 2. 25 4.00! 2.24, 3.91 3. 15l
4.10; 3.75| 3.121 3.94 3.39
3.60
4. .54
3.50
4.40
4.21
2.82 3.79 1.04 3. 24 1.71 3.34 2.90 3. 6() 3. 70 2.88 3.72 3.44 2.17
3.09
11. 2311. .'■4 11. 45 10. 15 9.84
17.4 1.5
18.0 1.6
17.5 1.5
16.2 1.6
14.7 1.5
4.02 8.99 15.8 1.8
4.05 2.74 3.21 1.94 3.41
2. 00 3.24 2.53 3.41
3. 36 2.95 3.11 3.00 1.87
2.92
4.03 9.01
4.24 2. 79, 3. 10: 1.31 3.28 1.55 3.24 2.56 3.42 3.40 3.00 2.90 3.52 1.84
2.87
4.11 9.19
4.351
3.20| 3. 22! 1.61 3.64 1.57| 3. 531 2.65! 3.33 3.84 2.94 2.96 3.56 2.08
3.03
4.23 4.17: 3. 76
2. 31 4.28 l.Sli 4.09
3. 09i 3.77 4.09 3.24 3.48 4.18 2.75
3. .52
4.66 4.82 3.81
2. 25 4.91 1.82, 4.441 3.25 4.62 4. 53 3. 2.'- 4.29 4.29
3. 12
3.86
4.05; 4.741 .5.15 9. 06 10. (10 1 1. 52
14.2 ,14.0 17.3 19.0 1.6 1 1.5 1.9 1.8
18.6 1.6
4.97 4.88 3.59 2. 28 4. HO 1.67 5.21 3.01 4. .59 4.10 3. 91 3.58 4.46 2. 99
3.86
.5.01 11.21 17.9
1.6
Column 4 shows the height of the statious in English feet, and eolnnin .5 shows the number of years of observaiioii employed. Tlie numbers given for each mouth represeut the meau daily movement of the wind in English miles. At the bottom of each group of stations is giv^en the mean of the numbers in each column of that grouj) ; the tbllo^v^ing line gives the average of the numbers in the two groups; tlie next line shows the velocity of the wind expressed in miles per hour ; the next line shows the average rate of progress of the cyclones recorded in Tables VII and IX for each month in which more than one cyclone was observed, and the last line shows the ratio of the numbers in the two jtreceding lines.
Here we find no correspondence between the average rate of progress of storm centers for the different months of the year and the average velocity of the wind, the rate of progress of storms being no greater for the four months in which the wind was s rongest than for the four months in which the wind was feeblest. The iueipiality in the values of the ratio for the difterent months is quite noticeable, but this may be partly due to the small number of the observations.
94. I next endeavored to determine the mean velocity of the wind in the neighborhood of the West India Islands, but found very Uiw ol)servations suited to this purpose. Tal)Ie XXXIX shows all the materials I have been able to obtuin. The numbers for the first four stations are derived from the Signal Service ob.servations, the numbers for the last two stations are derived from the international observations, and the numbers for Havana are derived partly from the international observations and partly from observations at the observatory of St, Beleu,
64
MEMOIRS OF THE NATIONAL AOADEMT OF SCIENCES.
Table XXXVill. — Mean daily movement of the winds in Southern Asia.
COAST STATIOIfS.
|
Lat. |
Long. |
Elev. |
Years. Jan. |
Feb. |
Mar. |
Apr. |
May |
June. |
July. |
Aug. |
Sept. |
Oct. |
Nov. |
Dec. |
||
|
Bonil)a,y Vizagajiatam .. Madias Mangalore Ncgapatam Jaffna .. Trincomalt-e .. . Batticaloa Colombo Hambautofa . .. Galle.... Moulmcin Diamond Island. Mer<;ui Port Blair Nancowry Manilla '. Mean .. |
O ' 18 54 17 42 13 5 12 52 10 4(; 9 40 8 33 7 43 6 56 6 7 6 1 16 29 15 52 12 11 11 41 8 0 14 35 |
O ' 72 49 83 22 1-0 17 74 54 79 53 79 56 81 15 81 44 79 52 81 7 HO 14 97 4(1 94 19 98 38 92 2 93 46 120 56 |
37 31 22 52 15 9 175 26 40 40 40 94 41 96 61 81 54 |
13 11 13 3 12 12 12 12 13 12 10 3 4 5 7 9 1 |
245 44 149 91 136 75 231 235 180 244 56 58 157 50 173 227 89 |
■ 253 51 123 90 97 73 190 206 135 237 54 58 179 .52 122 205 101 |
278 76 154 89 93 96 168 161 113 183 64 71 192 50 112 150 129 |
271 96 193 92 127 155 221 151 126 181 89 74 173 55 132 121 79 |
244 94 226 106 184 277 334 137 188 271 185 61 161 59 186 1,50 117 |
396 94 218 89 199 322 469 135 233 282 236 72 203 56 258 263 199 |
458 101 204 78 185 293 444 143 203 291 194 83 211 53 289 273 223 |
390 76 175 73 1.52 284 372 134 194 288 201 64 180 47 244 251 266 |
285 56 1.56 58 134 275 362 123 195 282 205 64 164 40 236 240 173 |
231 50 122 69 99 175 253 126 167 218 179 41 163 36 163 149 137 |
236 61 164 "77 135 72 159 142 126 155 83 .57 199 41 175 129 95 |
234 53 182 95 170 81 202 174 177 205 68 58 168 44 168 168 95 137 |
|
1 |
144 |
131 |
128 |
137 |
172 |
219 |
219 |
199 |
179 |
139 |
126 |
|||||
rULAND STATIONS.
Chanda .
Sironcha
Poena
Sholapnr
Secunderabad .
Belgaum
Bellary
Bangalore
Salem
Coimbatore
Trichinopoly. .
Madura
Kaudy
Thyetmio
Touiiti'boo
Eanfioou
Bassciu
19 56
18 51
18 28 17 41
17 27 15 52
15 9 12 59 11 39 11 0 10 50
9 55
7 18
19 22
18 57
16 46 16 4
Mean
Gi^iicral mean . Miles per hour
Storms
Ratio
79 19
80 0
74 10
75 56 78 33 74 42
76 .57
77 38
78 12
77 0
78 44 78 10 80 40
95 12
96 24 96 12 94 50
652
401
1849
1590
1787
2550
1455
2981
940
1348
275
448
1696
134
169
41
35
12
7
3
4
6
6
10
12
10
13
12
13
12
4
4
48
48
125
1.54
97
92
82
79
137
79
123
131
75
62
48
6 1 1P4 4 , 57
91 117
4.87
|
65 |
76 |
91 |
|
70 |
85 |
112 |
|
165 |
198 |
241 |
|
150 |
161 |
173 |
|
86 |
117 |
126 |
|
84 |
102 |
101 |
|
98 |
113 |
128 |
|
75 |
77 |
74 |
|
150 |
146 |
129 |
|
80 |
82 |
88 |
|
105 |
99 |
105 |
|
123 |
101 |
87 |
|
77 |
48 |
34 |
|
120 |
141 |
202 |
|
49 |
75 |
96 |
|
10 |
125 |
145 |
|
86 |
107 |
116 |
|
115 |
147 |
|
121 |
112 |
|
334 |
405 |
|
237 |
269 |
|
165 |
309 |
|
167 |
ia5 |
|
200 |
243 |
120 115 133 155 91 54 199 103 122 101
99 I 109 I 120 149 115 118 128 I 160
4.79
4.91 5.34 :(;.67 ...|7..54 J8.54 ...ll.4 L3
189 135 196 251 124
82 208 118 132
98
187 105 310 260 327 186 276 192 127 207 264 113
74 164 114 137
89
188
203
8.46
5.62
0.7
184
201
8.37
8.36
1.0
121
84 338 197 238 174 254 1(59 110 184 202
91
69 1.52
99 123
84
1,58 178 7.42 10.3 1.4
88
71
278
198
156
146
217
150
96
165
169
85
63
120
(i7
98
83
54
69
135
139
84 94 103 87 69 87 96 72 44 89 'ol
!-0
60
132 , 83
155 I 111 6.46 4.63 9.77 9.26
1. 5 \2. 0
41
66
132
158 77
100 78 82 87 65
109 99 43 82 45
103 65
84
105
4.37
7.38
1.7
38 50
140
142 71
101 75 84
110 76
126
122 55 95 t)4
122 55
90
113
4.71
Table XXXIX. — Mean velocity of the wind near the W''st India Islands,
Pinita Rassa
Rio Grande City.
Brownsville
Key West
Havana
Saint Thomas . .. Kiuiistoii
Mean Storms ... Ratio .. . .
Lat.
26 26 25
24 23
18 17
Lena
10 45 26 49 28 .56 47
Years,
12 8 7
12 3 1 2
Jan,
Feb.
15 10.
94 1 7. 80 7. 7910. 31 (J. 04 1 6. 84 3. I
Mar.
Apr.
8012. 84! 7. (ili 7. 1811. 84! 6. 68l 3. (i7 3.
7. 12, 7. 66
06 12. 20 69 9.34 93 8.49 28 10. 62 81 7.25 34 3.22 76 4.47
7.55, 7.94
May. June
10.51 8. 9.94 10.
7.29 7.
9.59 7.
.5.41 ,5.
.5.44 ().
4.09 6.
.47
7.46
July.
Aug.
8.16 10. 67
6. 78J 7. 51; 4.92J 6. U6i 6. 11 1
7.171
8.26 7.32 4.90 7. 39 4.77 4.49 3.42
5.79
14.44
2. 49
Sept.
Oct.
Nov.
8.7211. 6.84| 6. 4.371 5. 8. 30 11. .5.51' 6. 4.07; 3. 4.05, 3.
0610. 171 6. 00 7. 9211. 04 7. 16 2. 52 2.
Dec.
10.31
6.08 6.75 11.39 6. 7li 4.84 3.17
CONTRIBUTIONS TO METEOROLOGY.
65
Colmini 4 shows tlie number of years of observations employed, and the velocities are expressed in miles per hour. The line marked mean siiows for each moiitii the average of tlie numbers for the sever;il stations; the next liue shows the rate of progress of storm centers as derived from Tables III and IV for the mouths August, September, and October. These are the oujy months for which the tal)les iurnish more than a single observation, with the exception of June, for which month there are three observations. In determining tlie average rate of progress of storm centers I have rejected the velocity given for No. 4 of Table III, because it dift'ers widely from all other velocities recorded in the two tables, and because it was derived from insufficient data. The last line of the table shows the ratio of the numbers in the two preceding lines.
its. I next endeavored to determine the mean velocity of the wind for that part of the Atlantic Ocean in the neighborhood of the usual tracks of storm centers, and have adopted the results contained in No. 3 of the Mittheilungen aus der Norddeutsche Seewarte, as exhibited in the pamjihlet No. 5 (non-official), published by the British meteorological committee. The first line of the following table presents a summary of these results for the four seasons of the year, the force of the wind being estimated in units of Beaufort's scale (1-12).
|
Winter. |
Spring. |
Summer. |
Autumn. |
|
|
Beaufort'8 mirabers |
5.9 33.0 18.4 0.56 |
5.5 30.8 18.6 0.60 |
4.5 25.5 16.5 0.65 |
5.3 29.7 18.6 0.63 |
|
Mi 1*^8 per hour .......... .... .. |
||||
|
Ealio |
||||
The second line shows the velocities denoted by Beaufort's numbers reduced to miles per hour according to the table prepared by the British meteorological committee ; the third line shows the average rate of progress of storms according to article 89, and the fourth line shows the ratio of the numbers in the two i>receding lines.
96. If we group together the results now obtained we shall have the following summary for the average rate of progress of storm centers, the average velocity of the winds, and the ratio of these two velocities.
|
Storms. |
Winds. |
Ratio. |
|
|
Tlnited States |
28.4 18.0 16.7 13.7 8.4 |
9.5 29.8 10.3 6.2 6.5 |
3.0 0.6 1.6 2.2 1.3 |
|
North Atlantifi Ocean . |
|||
|
Wt'st Indies ...... .. . - |
|||
|
Southern Asia ....... .. ......... ....... |
|||
This table appears at first view to present a discouraging medley of anomalies, but some of the anomalies may appear less formidable after a careful examination. It seems highly probable that the slow progress of storm areas in Southern Asia is partly due to the small velocity of the winds of that region. It is not obvious why storms should travel more rapidly near the West India Islands than in the China Sea. It is possible that this anomaly may disappear when the mean velocity of the wind has been determined by a more extensive series of observations.
It seems to be established that over the North Atlantic Ocean the mean velocity of the wind is considerably greater than the rate of progress of storms. This inequality is strikinglj- exhibited in numerous cases. Over this ocean we frequently find an area of low pressure 2,000 miles or more in diameter, with a pressure of about 28 inches at the center, attended by winds blowing with hurricane violence (see Nos. 14, 29, 32, 41, and 44 of Table XXXV), while from day to day the center of the low area makes little or no progress eastward, showing that the movement of the atmosphere which corresponds to the average system of circulation is almost entirely interrupted over this ocean.
The most noticeable anomaly shown in the preceding table is, however, presented by the United States, where the mean velocity of the wind is only one-third as great as over the Atlantic S. Mis. 154 9
66 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
Ocean, but storms travel with nearly double velocity. This anomaly may be partly explained if we admit that the progress of storms is determined, not by the wind which prevails in close contact with the earth's surface, bnt by that which prevails at an elevation of several hundred feet, where the velocity is probably much greater than at the' earth's surface. The same anomaly, however, is found when we compare the storms of the United States with those of Europe. In Northern Europe the surface winds have a velocity greater than those of the United States, and we may infer that the same is true for elevations of 1,000 or 2,000 feet above the surface, yet storms in Europe advance with but little more than half the velocity of those in the United States. There must then be a powerful cause which accelerates the movement of storm areas in the United States, and which does not operate in Europe or over the Atlantic Ocean ; and apparently the same cause does not operate in Southern Asia or in the West Indies, at least in an equal degree. This cause (or one of these causes) is probably the precipitation in the form of rain or snow which usually takes place on the east side of a storm area, greatly in excess of that on the west side, by which means the progress of the storm center is greatly accelerated. This is a question which will be carefully examined hereafter.
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PLATC V.
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PLATE XI
FOR THE NORTHERA^
^f/W
'SPl
tQVJNTO^
•Ijlius Hii-ii.'i To Pti-«.i I.ilh
NATIONAL ACADEMY OF SCIENCES.
VOL. Ill
TENTH MEMOIR.
ON FLAMSTEED'S STARS "OBSERVED, BUT NOT EXISTING."
67
FLAMSTEED'S STARS OBSERVED, BUT NOT EXISTING."
BEAD NOTEMBEB 11, 1885.
By C. H. F. Peters.
In the "Account of the Rev. John Flamsteed," by Francis Baily, on page 646, is found a list of stars with the above heading, wliich means, as is explained on page 393, stars " of which the ob- servations appear to be accurately recorded, but which still cannot now be found i!i the heavens."
When, with the splendid and exciting discoveries of Sir W. Herschel, there had come life among the fixed stars, and the construction of the heavens began to be a lield for active research as well as for speculation, it was but natural that, whenever in a place given by the Catalogus Britannicus no star was seen, at first thought the star was believed to have become extinguished since Fiamsteed's time. Under this impression, it seems, various astronomers, and among them especially Lalaude, then engaged upon his zone survey, from time to time published long lists of "missing" stars. Already Bode, however, curtailed tiiese considerably, and the number of such stars gradually has been diminished, thanks to the labors especially of Miss Caroline Herschel, systematically indexing and comparing with the British Catalogue all the observations contained in the second volume of the Historia Cce'estis Britan?iica; — then of Argelander and of Baily, so that the latter finally leaves only 22 stars to be accounted for. It might seem fruitless to attem]>t a revision of positions that have passed through the hands of such able critics and been dismissed by them as inexplicable, especially as Baily made a very thorough inspection of Fiamsteed's original manuscript entries, preserved at the Eoyal Observatory, Greenwich. Nevertheless, as the dis- appearance from the skies of so many stars in comparatively so short an interval of time is rather improbable, it seems desirable that these cases be scrutinized somewhat more thoroughly than perhai)s it was feasible for Baily, who, having taken in hand the revision of the catalogue in its entirety, could not well devote so much time to a few particular stars. The resources, besides, for 'the sake of identification, are much more complete now than they were at the time of Baily's pub- lication, dating back fifty years. Flamsteed did not observe stars fainter than the eighth magni- tude.* Hence all of his stars between the pole and 02° north polar distance, if not belonging to the classes of variable and temporary stars, we must expect to tiud iu the "Durchmusteruug." Con-
* In the British Catalogue the uiagnirnde 8 Is fouml assigned to 24 stars. According to modern catalogues all of them are brighter, with the exception of the following 3, viz:
B. FI. 1-J23 in the Bonn Dm. 8°> . 3 1280 8 .2
1613 8 .0
Besides there are 23 stars without having any magnitude assigned to them in the British Catalogue. Of these, according to modern observers, the following 5 are smaller than eighth magnitude :
B. Fl. 792 in the Dm. 8"° . 2 1418 8 .1
while the remaining 18 are estimated brighter.
|
1422 |
8 |
.2 |
|
3256 |
8 |
.2 |
|
3257 |
8 |
.2 |
70 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
cerning the positions of the more southern stars that come under consideration in the following discussion, I have consulted the skies directly.
It is well to premise here, that of the 23 stars that Baily left unidentified, Flamsteed gave to 3 the magnitude of 5, to 1 the magnitude of 5.J, to 9 the magnitude of 6, to 1 the magnitude of 6J, to 3 the magnitude of 7, and of 5 (2 of which belong to the group of Prcesepe) the magnitudes are not recorded.
Fortunately, what discrepancies Baily detected in the manuscripts are communicated in the copious notes to the new edition of the British Catalogue, so that for the stars in question we may take the figures as they are given for time and zenit distance in Volume TI of the Historia Ccelestis for the actually recorded ones, without any apprehension of errors of print.
For none of these stars is there more than one observation, and the record of it may involve a mistake, either in noting the clock time, or in circle reading, or in hearing and writing by the amanuensis. For the reading of the circle "j^er lineas diagonales^^ a check is given by that "per strias cochleae." This, however, may not always hold good, as, for example, there are indications that sometimes (perhaps when the stars came in quick succession, or for some other reason) only the fraction was read off or put down for the screw, and the whole number of revolutions afterwards filled in from the corresponding reading of the division.
When, by some hypothesis of a mistake, we try to bring about an agreement with a star known by modern determinations, the question naturally presents itself. What difference are we allowed to admit"? or, in other words, since the modern observations in this comparison may be assumed as perfectly accurate, what is the probable error of a position in Flamsteed's Catalogue "? For ob- taining approximately an idea of this, may serve the dift'erences from Bradley, which Baily has added in his edition. By taking from twenty pages (about every fifth page) the mean of these differences, without regard to sign, excluding, however, the stars of high northern declination, also avoiding those with a known considerable proper motion and those which clearly appear to be affected with some gross accidental mistake, I find 44" in right ascension and 17" in declination. By another count, viz., by taking the means of differences for all the sixth-magnitude stars that were observed only once (about 400 in number), I find 50" and 18", respectively. Disregarding as small what the comparison with Bradley may have added, these figures give an approximate measui'e of the mean uncertainty of a position in the British Catalogue. Considerably much smaller is the pure mean observation error of Flamsteed, which Argelander has computed, viz., ± 10".4 in right ascension and ± 7".8 in declination.* These values are independent of the situation of the Quadrant, while the others are affected, besides, by the imperfection of the elements Flamsteed used in his computations. The contrast is a proof how greatly the usefulness of the Catalogus Bri- tannicus could be increased by a re-reduction of the original observations.
Proceeding now to the examination of each of the 22 stars in particular, it seemed necessary to communicate the discussion with some detail, in order to leave as little doubt as the subject in each case permits. Every one accustomed to observe is aware of the facility of committing mis- takes, however careful he may believe he has been. The assumption, therefore, of some other- wise plausiiile error of Flamsteed which leads to a modern star-place is to be held much more reasonable than the vague acquiescence in a supposed disappearance of the star. In that sense I think I have succeeded in finding for every case at least a probable explanation.
1) B. Fl. 314.
This star in the British Catalogue is called 28 Arietis, and its position given thus :
6 mag 330 33' 20"; +18° 23' 40"
which reduced to 1800 would be
3504/44//. +180 59' 3"
* Argelander (De oljservatiouibus astron. a Flamsteedio institutis dissertatio. Regioiuont., 1^22) finds the probable error of a poiatiug in right asooasiou J; 0'.3i():5, or of the right ascension itself, being the result of the ditferentiatioa from a so-called "deteruilning star, " J- 0=.32G3 -/a = ± Os.4614 = ± 6".U, of the zoait distaace or decliuatioa J; 5". 20. Hence follow the main errors as given ia the text.
ON FLAMSTEEU'S STAVES "OBSERVED, BUT NOT EXISTING."
71
where there is no star to be seen now. But Pi. 2''. 9S, 26 Arietis (Dm. +190.3G5 . 6™. 4) differs about 15' in right ascension. lu fact, we have
26 Arietis for ISOO : 34° 51' 44"; +18° 57' 36" Precession to icOO —1 31 22 —30 28
Proper motion in llQy (Miidl. Br.) —7 +5
26 Arietis for 1690 : 33 20 15; +18 27 13^
26 Arietis —Fl. 314 -13 5; -1 27
By reading, therefore, in the Historia Ccelestis Britannica, 1692, December 10, the time of transit, S'' 18™ 58» instead of S^ 19™ 58% we come upon tliis star, and the star denominated 28 Arietis has originated from a mistalce of 1™. Already Miss Herschel had made this conjecture, and Baily had hardly any reason not to accept it.
2)
B. Fl. 639.
The absence in the skies of the star, which in the British Catalogue is reported thus:
100 Tauri G'^'s 700 2' 0"; 15° 50' 5"
seems to have puzzled much the older astronomers, and Bode, assuming the observation to be unmistakable [Astronomisches Jahrbueh, 1788, p. 175), takes pains to show (ib., 1817, p. 249) that it could not have been any one of the four asteroids that were then known. In the Historia Ccelestis, II, p. 389, stand the following observations:
|
1700. |
Clock time. |
Zenit diet. linesB diago- nales. |
Striae cochleae. |
Corrected zenit distance. |
|
|
Jan. 1 ]) Index error.. |
h. ra. B. 8 58 9 9 11 59 9 20 5 9 21 55 |
0 1 II 35 44 45 36 11 20 35 45 25 36 2 50 36 39:: 50 |
810. 21 820. 20 810. 48 817. 06 831. 13 |
0 / // 35 36 5 36 2 40 35 36 45 35 54 10 36 31 10 |
aTauri, Palilicium. |
|
—8 40 |
|||||
Baily found this in accordance with the MS., except that at the third star (which is exactly the questionable one) "the zenith distance is marked as doubtful in the original MS. entry." (The sign of uncertainty ( :: ) attached to the last star perhaps was placed two lines too low in the print?) The other stars are identified by means of a Tauri. Eeducing the times of transit for rate of clock to 9'' 20", the third and fourth columns of the next table are obtained.
|
B. Fl. |
Name. |
Reduction to sidereal in- terval. |
T=clocl£time reduced for rate. |
Striffi cocblese in arc. |
Difference. |
|
581 611 639 642 652 |
87 a Tanri 96 Tanri (lOU)? Tauri 101 Tauri 11 Oriouis |
a. —3.6 -1.3 0.0 4-0.3 |
h. m. 8. 8 58 5 9 11 58 9 20 5 9 21 55 |
0 1 II 35 45 6 36 11 27 35 45 11 • 36 3 9 36 40 17 |
—21 - 7[-24] 4-14 — 19[— 15] -27 |
In the same table are added, in column 6, the striw eoehleoe readings converted into arc, and in column 7 the differences of these with the readings jjer lineas diagojiales, which sliow at least that both indications are in pretty good harmony with each other. With greater regularity, however,
72
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
proceed the figures iu this coIuniD if we adopt the corrections presently to be spoken of, and which leave the differences added in brackets.
For the known stars modern determinations furnish the following positions, referred to the equinox of 1700 :
|
Name. |
No. and raapni- tudeof Durchm. |
a |
6 |
|
|
87 a Tanri |
o +16. 629 15. 687 15.713 15. 732 |
m. 1.1 6.5 7.0 5.3 |
h. m. 8. 4 18 45 |
o / /' -4-15 .52 2 |
|
96T;mri |
4 32 37 15 20 25 1 |
|||
|
101 Taiiri |
4 42 33 4 47 27 |
15 25 30 14 .56 44 |
||
|
11 Orionis |
||||
The difference a — T should be constant. Further, the observed zenit distance {per lineas cUagonales, wbich Flamsleed always uses, in preference to that per sfrias cochlea') should result when subtracting the declination from 51° 30' 38", which is the sum of 51° 26' 38" + 8' 40"— 40'' (latitude of Greeuwich + index error — refraction). We get —
|
Name. |
a-T |
Computed zenit dist. |
Comp. — obs. zenit dist. |
The same, with assnmed correction. |
|
87a:Tauri 96Taiiri |
h. m. s. —4 39 20 4 39 21 4 39 22 |
o / // 35 44 36 36 16 13 |
/ // — 9 -4- 4 53 |
// — 9 — 7 + 18 + 4 |
|
101 Taiiii |
36 11 8 I- -i- a 18 |
|||
|
36 39 54 |
+ 4 |
|||
|
Mean |
||||
|
—4 39 21 |
+ 1 |
The large errors remaining here, column 4, in the declinations of 96 and 101 Tauri have been pointed out already by Baily (iu Notes to No. 611 and No. 642 of British Catalogue), without the attempt of a conjecture as to their origin, the MS. entry showing no trace of mistake. I venture to suggest lor the correct zenit distance record :
96 Tauri 36° IC 20" 822.20 instead of 36° 11' 20" 820.20 101 Tauri 36° 10' 50" 820.06 instead of 36° 2' 50" 817.06.
This rests upon the hypothesis, that of the strice cochleoe first were written only the fractions, and the whole revolutions supplemented later so as to correspond with the respectively 5' and 8' erroneous Unecc dlagonales. At least in the case of 96 Tauri the changes proposed are highly probable. Converted into arc the screw readings are then
822.20=36° 16' 44" and 820.06=36° 11' 5",
leaving the differences from the Unece dlagonales of — 24" and — 15" respectively (the values in brackets in the table above), in better agreement with the two other stars, and also, as seen from the last table, iu good harmony with the computed zenit distances.
Now, as to the disputed star, it must be between 96 and 101 Tauri. Here the following stars are the only ones of sufticient brightness for i)ossible objects of Hamsteed's observations:
|
Nnniber aiHl mag- nitude of Dm. |
Piazzi. |
Right ascension (1700). |
Declination (1700). |
||
|
o +16. 607 16. 608 16. 672 |
m. 7.5 7.0 5.6 |
h. 4.228 4. 231 4.246 |
m. 8 8 6.7 |
° ' " h. m. s. 69 25 48 = 4 37 43 69 31 32 = 4 38 6 70 1 18 = 4 40 5 |
o / /' +15 51 34 16 5 47 16 38 34 |
ON FLAMSTEED'S STARS " DRSERVEDi BUT NOT EXISTING."
73
The last star is Br. 680, wliercfore its i)osition was taken from Miidler's Bradley, while the others are from I'iazzi's Catalogue. If we add to the rigjht ascensions the constant 4'' 39™ 2P, and snbtraet the declinations from 51° 30' 38", we shonld get the clock time of transit and the aj)- parent zenit distance {per Uncas diagonales) that would have been observed by Flamsteed, viz:
|
T |
Z. |
Differences. |
||
|
Pi. 4''228 .. |
li. m. s. 9 17 4 9 17 27 9 19 26 |
0 1 II 35 45 4 35 30 51 34 58 4 |
m. 8. —3 1 —2 38 — 39 |
/ // — 21 —14 34 —47 21 |
|
Pi. 4'' 231 . . |
||||
|
Br. 686 |
||||
|
Flamsteecl's record is |
||||
|
9 20 5 |
35 45 25 |
The zenit distance, within the probable error, is that of Piazzi 228, and by the assumption of an error of 3™ in the time we can make also the right ascension agree with that star. This seems to be, indeed, the most ])lansible explanation. There remains, however, one difficulty that speaks against this identification. Flamsteed noted the star he observed, of Cth magnitude, while Pi.azzi 228, is according to the Dm. 7"'. 5, and according to Piazzi and Bessel (Wj 4'' 1048) even only 8™. There is here in the neighborhood the bright star Br. 080, which must have been in the field almost together with the spurious star, Flamsteed's telescope having a field of about 1^°. It would be singular, indeed, if Flamsteed should not have observed this star at all. But by two plausil)le changes the record can be reconciled with it.
First, as to the time of transit. Suppose the observer (Flamsteed) called out " twenty-five," meaning 2.") seconds, but the amanuensis wrote 20™ 5^, not inquiring, of course, further for the minute, which was 19. Hence, out of 9^ 19'° 25« became 9'^ 20™ 5". The zenit distance can be cor- rected by the assum])tiou of 34° 55' instead of 35° 45', a mistake in writing that is easily made and of which there are other examples in Flamsteed's manuscripts. Moreover, this observation was hastened by the next star following soon after. It remains to be seen how the check reading ^jer strias cochleae would have been. Leaving the fraction the same, but changing (upon the same ground as stated before iu discussing the data for 90 and 101 Tauri) the number of entire revolu- tions, if we replace 810.48 by 791.48, the difference between the two modes of reading comes nearer to that derived from the other stars. For we Iiave —
|
Zenit distance per line as di- agonales. |
Zenit distance per strias cochlere. |
Difference (lineae diagonales — str. ) |
|
|
The record as it stands .. The record as corrected . . |
o / " 35 45 25 34 55 25 |
c / '/ 810.48=35 45 11 791. 48=34 55 39 |
+14 —14 |
while the mean difference from the other stars (s. last column in second table above) is— IS" [or— 22" respectively].
The final position for 1700.0, thus corrected, becomes:
|
Eiglit ascension. |
Declination. |
|
|
Fl. observed Br. 686 eompnted . . Difference .... |
h. ni. 8. o ' " 4 40 4 =70 1 0 4 40 5.2=70 1 18 |
o ' " -fl6 41 13 ■fl6 38 34 |
|
__ -LIS |
— 2 39 |
|
The error still remaining in declination appears rather large ; but it will be remembered that Baily found in the manuscript the sign of uncertainty attached to the zenit distance. S. Mis, 154 10
74
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
3)
B. Fl. 756 (5^").
As there is no oi magnitude star in the position of the one, whicli in the British Catalogue is called 27 Camelopardalis, Argelander thought the observation of it, made on 1690, January 22, might be only a repetition of 24 Gmnelopardalis, still in the field.
The observations as they stand in the Historia Ccelestis, II, page 286, are shown in the first five colniHus of the following table. The other columns give the names of the stars, the arcs cor- responding to the readings _2Jer strias cochlea', and the differences of these with the readings 2>er lineas diagonales.
|
Clock time. |
Zenit (1 i 8- tauce per lineas diagouales. |
Zonit d i s- tauce per strias cochleie. |
Zenit d i s- tauce corrected. |
Name. |
S trite cocUlea arc. |
y ill |
Linete diag- ouales— Striaj coch- ■ leai. |
|
|
ll. 111. s. |
o / // |
o / // |
o / |
II |
// |
|||
|
S 23 7 |
bor. |
4 47 50 |
108. 05 |
4 53 50 |
24 Camelop. |
4 47 |
52 |
— 2 |
|
bov. |
3 .'-> 20 |
69. 93 |
3 11 20 |
25 Camelop. |
3 5 |
32 |
— 12 |
|
|
2(i 41 |
bor. |
4 21 3.''. |
98. 83 |
4 27 35 |
26 Camelop. |
4 21 |
55 |
— 20 |
|
bor. |
4 4S 10 |
108. 90 |
4 54 10 |
(X) |
4 48 |
32 |
— 22 |
|
|
30 29 |
bor. |
.'■> 11 . 5 |
117.58 |
5 17 5 |
29 Cameloi>. |
5 11 |
30 |
— 25 |
|
33 40 |
bor. |
8 10 55 |
185. 4G |
8 16 55 |
31 Cauielop. |
8 11 |
5 |
— 10 |
Index error -^-()' 0.
The field of Flamsteed's telescope being 80', the star 24 Camelopardalis would have left the field
40'
y^ sec. S = 4"' 49' after transiting (supposing the transit wire to have been pretty near the center),
that is at S'' 27'" 50" clock time. As the questioned star {x) was observed after 8'' 26'" 41% when 26 Camelorxirdalis transited, Argelander's hypothesis seems not impossible. Still, of the 1'" 15" that 24 GamelopardaUs remained yet in the field, a ])art was certainly taken up by tiie readings for 26 Camelopardalis, so that the former must have been quite near the edge already when observed. That here is not the remark ^'posttraiisitum" which Flanisteed probably never has omitti d in such cases, seems to indicate rather a star in transitu. Of stars in right ascension between 26 and 29 Camelopardalis, and nearly uiiou the parallel of 24 Camelopardalis, the Uurchmusterung has the following :
|
o |
m. |
L. m. 8. |
0 ' |
|
|
Dm. |
+ 50. 1060 |
9.0 |
5 34 54 |
-f5G 27.0 |
|
Dm. |
1063 |
9.5 |
37 9 |
31.5 |
|
Dm. |
1064 |
9.5 |
37 50 |
31.0 |
altogether too faint for Flamsteed's telescoi^e ; but they, especially the two latter stars, should be watched as to variability. We must confess, however, that shifting the hypothesis from an " extinct" to a variable star, is but a very unsatisfactory exiiedient. I am rather inclined to sup- pose that ill some way, now unaccountable, the zenit distance was recorded erroneously. Only about 20' or 22' farther north is 28 Camelopardalis (Dm. -f 56o.l()5i). 0"'.6), which in 1696 pre- ceded 20 Camelopardalis in right ascension by 5% hence tiaiisited near tlie limit assigned for the time, which itself was not recorded.
4J
B. Fl. 864 (5'^).
The observation of this star stands (Historia Ccelestis, II, p. 411) between r; Geminontm and 5 Monocerotis, thus:
1701,Feb.2.
h. ni. 8. 8 12 56
16
Gemiuorum ?;
Mouocerotis post trausitum m
o ' /'
29 4 0
58 2 0
.57 49 20
658. 82 1307. 42 1310. 70
28 56 40 57 52 40 57 40 0
Index error — 9' 20"
ON FLAMSTEED'S STARS "OBSERVED, BUT NOT EXISTING." 75
Already Bail.y leinaiki'd that tlieiv- is a ilitterenco of 131' Ix'twecn the. reading 'per linean (liaf)0)i(ihfi kxml thai per .sirias cochlea'. Indeed 1;>()7.42 converted into are. make 57° 41' 2". The corrections proi)osed by Ar.n'elan<ler are very i)lansible, viz: 58° 7' 0" for the liiicw didf/onalct and l,'J17.4li = 58° 7' -1" for the sfrifc cochlav, since from the other stars here observed follows the ditlereuce {lincw (lintionalcs — stria; cochlvw) =—29". The deeliiiation in the BritiKli Cutahxjuc then onjilit to be corrected by — r»', and the star is easily recognized as LL. 11805, which was also twice observe*! by Bessel.
We have W. (!'' 112, for 1825: (i'' ;3™ 20^73 = 90° 50' 11" ; - (P ;!l' 7"..'5 Keduction to 1G90 - 1 38 24 +0.8
W. 1 1 2 for 1090 890 uTil'-" - 6° 316
Brit. Cat. 804 (corrected f^ by -5') 89 — G 30 40
Dift'erence — 26"
5) B. FI. 913(6i"')-
There can be no doubt but that the star, which in the British Catalogue passes under the name of 21 Oeminoriim, is identical with the preceding star or 20 Geminorum. and originated from an error of 1'" iu the time. Historia Gcelestis, II, p. 294, 7'' 26'" 50" ought to be corrected into Th 25™ 50^
20 Oeminoriim is a double star, now about 19" asunder, and the sequens is called by Piazzi
and others 21 Geminorum, which, therefore, is different from what in the British Catalogue was
called so. The components are, according to Piazzi, respectively 8th and 7th magnitude, but
together they made to Ileis the impression of a 6.7 magnitude star. Fhun-iteed's telescope hardly
could separate them, especially if they were at, his time still nearer together, as the proper motions
in Miidler's Bradley seem to indicate, lieducing Br. 955 and 956 from the last-meutioueil catalogue.
to 1690, we find
Br. 955: 93° 33' 15.02"; +17° 56' 59".9l
Br. 950: 33 16.34 57 19 .03
or the middle, 93° 33 15.7 + 17° 57 9.5
The British Catalogue has .... No. 912 : 93 32 30 + 17 57 15
No. 913 : 93 48 30 17 57 40
and it is clear that the former right ascension is the correct one, and the latter must be diminished by 15'.
6) B. Fl. 1007 (7").
In the note to this star, which was observed by Flamsteed 1095, March 8, at 7'" 1™ 51", Haily says: "I cannot find any star that will correspond with the position here given. In my list of Flamsteed's inedited stars, I have suggested that it might be Piazzi VI, 346 ; but on reconsidering and re-examining the subject, I am not now of that opinion." The star, however, exists still iu its place, where Flamsteed observed it, and is VVj 7'' 66 = Dm. + 17° 1498 (7'"). We have
W2 1^ 66, for 1825 : 7'' 1"' 40^01 = 105° 25' 0.2" ; + 17° 15' 31".3
Reduction to 1690 ■■.- 1 57 13.6 ; + 11 15 .1
W. 60 for 1690 103 27 47 ; +17 26 46
British Catalogue 1007 is 103 27 5 ; + 17 26 30 _
W. - Fl + 42" + 16"-
Argelander makes (A. N. No. 226, p. 162) a curious mistake. He says (ad. No. 148) : " Stimmt vollkommen niit Piazzi VI, 346, wenn man die Durchgangszeit liest 7'' I'" 31" statt 7'' 1™ 5P." The position of Piazzi 6"^ 346 is
for 1800 : 104° 57' 47".2 ; + 15° 38' 57".0 Reduction to 16'JO: -1 34 25. 0; +9 0.2
Piazzi 34t3 reduced to 1690 : 103° 23 22 ; + 15° 47 57
76
MEMOIRS OP THE NATIONAL ACADEMY OF SCIENCES.
The place of the British Catalogue 1007, when corrected by — 20» or — 5' in right ascension, as Argelander proposes, is
103° 22' 5"; +17° 26' 30" Difiereuce (Pi.— Fl.] +i' IT"; - lo~38^3''.
lutheHistoria Coelestis, II, p. 250, the observed zenit distance for B. Fl. 1007 is given asoio o' 45" ^ for the star immediately following, which is 51 Geminorum,'iiP 50' 20" (this should be, rather, 34° 55' 20", if corrected according to the reading ^cr strias cochleev, which here is right). The star No. 1007 was therefore north of 51 Oeminonim by 49' 35", which is so neaily half of the difference between Pi. 340 and Flamsteed's star that, through applying it with a wrong sign, as it seems, Ar- gelauder was misled to the identification with Pi. 346.
7 and 8)
B. Fl. 1198 (6°') and 1199 (G"').
These stars are but very imperfectly observed (see Historia Ccelestis, II, p. 287, 1096, January 23); the times were not recorded and the zeuit distances read off only approximately j[>er /t«eas diagonales. They transited
between B. Fl. 1232=7 Ursaj maj.=Dm. + 61o 1070 (7, 5"') : S"" 31°' 5^; +61° 25',6 and B. Fl. 1235=0 Ursa} maj.=Dm.+65o 073(6,0"'): 8" ll-" S'*; +65° 9',0.
There are in the Durchmusterung zone for +49° between these right ascensions no other stars of sufficieut brightness for possibly being seen in Flamsteed's telescope than the following, viz:
Dm. 1758 (S"'3), 1759 (0"'8), 1766 (7'"5), 1768 (8'"5), 1771 (8'"4), 1772 (7"9), 1776 (8-"2).
Only the two brightest ones of them agree with the condition imposed by the zenit distances as far as recorded. Eeduced to 1696 they are:
Dm. +490.1759 (=LL. 17058-9=:Pi. 8''.13]) : 8'' 21''' 40=; + 49° r.i' 8 Dm. +49 .1706 (=LL. 17138 =Pi. 8.141) : 8 24 3 ; + 40 56,3,
which give the apparent zenit distances, south 1° 40', while Flamsteed's readings were mist. 1° 30',
and south 1 38, and aust. 1 35.
These two stars, therefore, well satisfy the roughly taken observations. Argelander had come to the same conclusion, from which Baily, however, dissents, without giving anything better in its place.
9 and 10)
B. Fl. 1205 and 1212.
The stars in and around Prwscpe, contained iu the British Catalogue, with the right ascen- sions converted from arc into time, are shown iu the fii'st five columns of the following table:
|
No. |
Fl. |
Mag. |
Brit, Cat. 1G90. |
Dm. No. and mag. |
1690 computed. |
Coiiip. — Fl. |
||||
|
L. m. 8. |
0 / II |
0 |
m. |
h. m. 8. |
0 / if |
s. |
/ /V |
|||
|
1193 |
337 |
6i |
8 14 45 |
+21 27 25 |
+20. 2109 |
5.6 |
8 14 42.3 |
+21 27 22 |
— 3 |
- 0 3 |
|
lig.'S |
35 |
7 |
17 26 |
20 37 15 |
.2118 |
7.6 |
17 25.8 |
20 37 12 |
0 |
— 0 3 |
|
1196 |
. |
7 |
17 .55 |
20 0 0 |
.2123 |
8.2 |
17 51.8 |
20 48 14 |
— 3 |
— |
|
1205 |
— |
20 47 |
20 18 50 |
19. 2053 |
7.2 |
19 .56. 4 |
20 18 54 |
—51 |
+ 04 |
|
|
1211 |
38 |
8 |
21 51 |
20 49 45 |
20. 2149 |
7.0 |
21 49. 5 |
•.;0 50 6 |
— 2 |
+ 0 21 |
|
1212 |
/ |
— |
22 2 |
20 46 10 |
. 2150 |
7.3 |
21 58.4 |
20 35 54 |
— 4 |
-10 16 |
|
1213 |
39 |
6 |
22 14 |
21 4 30 |
.2158 |
6.7 |
22 11.8 |
21 3 59 |
— 2 |
— 0 31 |
|
1214 |
40 |
6 |
22 19 |
21 1 .50 |
.2159 |
6.8 |
22 17. 2 |
21 1 48 |
— 2 |
- 0 2 |
|
1216 |
_ |
— |
22 31 |
21 0 0 |
.2166 |
7.1 |
22 28. 7 |
20 43 48* |
— 2 |
— |
|
1217 |
4l£ |
7 |
22 40 |
20 36 20 |
.2171 |
7.2 |
22 36. 0 |
20 36 22 |
— 4 |
+ 02 |
|
1218 |
42 |
n |
22 51 |
20 46 45 |
. . 2172 |
7.2 |
22 50. 8 |
20 46 53 |
0 |
+ 08 |
|
1219 |
• • |
23 1 |
20 38 45 |
.2175 |
7.7 |
23 4.9 |
20 38 38 |
+ 4 |
— 0 7 |
ON FLAMSTEED'S STAES " OBSERVED, BUT NOT EXISTING."
77
The next eoluiniis sbowfbe places of the same stars lioiii modern catalosni's, rcdnced to KiiX); the last two coliinuis, the ilirtVrences with the Ihitisli Catalogue. The maj;nitiuU's are IVoin the Diuehuiusternng and liom I'lof. A. Hall's monofiiapli ni)on this cluster.
If we correct the right ascension of FL 1205 by —:11s, that is, if we assume witli Arijelander, that on 109S, March 10, the time of transit was 8'' 27'" Jt3" instead of 8'' 28'" 'M", the af,n-eement of the ])ositiou of this star with the modern determinations is perfect. Argelander's -i-iyo.2053 is LL. 16939-41, Pi. 8M12, etc.
As to Fl. 1212, the right ascension of which is quite correct, Baily afBrms from the MSS. that owing to the quick succession of the star's transiting there was, on lOOO, ;\[arcii 18, some con- fusion in the entry of the zeuit distances, so that opposite to this star very probably belonged the reading 30o 58' 45" instead of 30° 43' 5". The star Dm. +20O.2150 is No. 05 of Professor ITall's list of the stars of Prasepe. We ought to hesitate tbe less to accept the proposed corrections, as Flamsteed's list thus is complete of the brighter stars of Prwsepe, but only by including these two. There is no reason at all, therefore, to suspect here the disappearance of a star.
11)
B. Fl. 1220.
There were observed by Flamsteed on 1703, March 11, six stars north of the zenit, which, in the Historia Ccelestis, II, p. 457, stand thus : we denote them, for the sake of reference, besides by the numbers of the British Catalogue, also by letters:
|
B. Fl. |
Clock time transit. |
Zcnit dis- tauce per liiieas |
Per strias cochleie. |
Zeuit dis- tauce |
StriiE cocli- |
Lilies di.ago- nales-strin) |
||
|
diiigonales. |
corrected. |
• |
coclileaj. |
|||||
|
b. m. s. |
o / // |
o / " |
o |
/ // |
' " |
|||
|
a |
1190 |
8 19 38 |
9 22 20 |
210. 36 |
9 3i 30 |
9 |
17 13 |
+5 7 |
|
* |
laio |
26 55 |
16 5 50 |
364. 86 |
16 16 0 |
16 |
5 45 |
+0 5 |
|
0 |
1-J20 |
28 34 |
4 22 45 |
99.34 |
4 32 55 |
4 |
23 16 |
—0 31 |
|
d |
1284 |
52 52 |
11 12 10 |
253. 72 |
11 22 20 |
11 |
12 25 |
-0 15 |
|
e |
1287 |
54 30 |
10 57 40 |
246. 23 |
11 7 ,50 |
10 |
.57 52 |
—0 12 |
|
f |
1325 |
9 12 19 |
19 26 20 |
440. 77 |
19 36 30 |
19 |
26 35 |
—0 15 |
Index error + 10' 10".
The conversion of the reading per strias coclilece into arc shows, by the last two additional columns, that the zenit distance jpcr lineas diagonales of the first star was read off too great by 5'. The stars are easily recognized to be identical with the following:
|
Number and magni- tude Durchm. |
Reduced to 1703. |
Authority. |
||||||||
|
o |
m. |
h. |
m. |
8. |
0 |
/ |
II |
|||
|
a |
+60. 1148 |
6.8 |
8 |
14 |
37 |
+60 |
55 |
52 |
LL. 16805, 0. Argejander 9124, and by Argel observations at Abo meridian circle. |
luder's |
|
b |
67. 560 |
6.0 |
8 |
21 |
20 |
67 |
44 |
46 |
Fed. LL. 1371-2, Piazzi 8". 137, 0. Argelauder9262. I |
|
|
c |
55. 1297 |
7.5 |
8 |
30 |
36 |
56 |
1 |
30 |
LL. 17350, 0. Argelander 9357. |
|
|
d |
62. 1054—5 |
7.6 |
8 |
48 |
42 |
62 |
51 |
7 |
LL. 17990—1, 0. Argelander 9644 and 7. |
|
|
e |
62. 1058 |
5.0 |
8 |
f,0 |
28 |
62 |
36 |
33 |
16 c Urss majoris (from Madler's Bradlev). |
|
|
f |
70. 565 |
5.2 |
9 |
7 |
25 |
71 |
5 |
50 |
24 d UrsiE majoris (from Miidler's BradU^y). |
In order, however, to insure a good agreement the obsei'ved clock times of the lirst three stars need some coirection. For the star c, which is the star put into question by Baily, we adopt Argelander's very acute suggestion, that the time probably was 8^ 34°" 28% instead of S"" 28" 34», Stars a and 6 were written down 1" too late, which, at least for 6 is readily conceded, the seconds being 55. For more complete evidence the times thus corrected and reduced for rate of the clock to some middle epoch are compared with the computed right ascensions for 1703 in the following
78
]MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
table. The same table contains also the computed zenit distances, obtained by subtracting from
the de(!linations the latitude {<f=51°2ii' 3S"), the index error {i—W 10"), and the refractions, so that the3' are comparable directly with the readings 2>er llneas diarjonales. The stars are arranged here in the order of their zeuit distances or declinations, which makes apparent a regularly pro- gressing effect of the Quadrant's deviation upon the times of transit:
|
Reduced for |
t, observed time reduced. |
Computed |
Zenit dist. |
||||||
|
star. |
time. |
rate from |
a— |
-t |
S—ip-i |
Rofr. |
north zenit |
(comp— |
|
|
distance. |
obs.) |
||||||||
|
h. 111. 8. |
8. |
li. m. 8. |
111. |
a. |
0/1/ |
// |
o // / |
// |
|
|
c |
8 34 28 |
0 |
8 34 28 |
-3 |
52 |
4 22 42 |
— 3 |
4 22 39 |
— 6 |
|
a |
8 18 38 |
—2 |
8 18 36 |
3 |
59 |
9 17 4 |
7 |
9 16 57 |
—23 |
|
e |
8 54 30 |
+4 |
8 54 34 |
4 |
6 |
10 57 45 |
11 |
10 57 34 |
— 6 |
|
d |
8 52 52 |
+4 |
8 .52 58 |
4 |
14 |
11 12 19 |
12 |
11 12 7 |
— 3 |
|
6 |
8 25 55 |
—1 |
8 25 54 |
4 |
34 |
16 5 58 |
17 |
16 5 41 |
— 9 |
|
/ |
9 12 19 |
+7 |
9 12 26 |
5 |
1 |
19 27 2 |
20 |
19 26 42 |
+22 |
From this it is clear that the star Fl. 1220 (letter c) fits so well to the other stars as to ex- clude also in this case the hypothesis of the disappearance of a star.
12)
B. Fl. 1232 (6").
In the note to this star Baily explains, from the inspection of the J\ISS., how Flamstiied, baviug failed to record the time of transit at the Quadrant, tried to supply the right ascension for the catalogue by an observation with the Sextant, but in so doing he took in its stead 5 Ursw majoris. The right ascension in Flamsteed's British Gatalogue-^127o id' 30"— is therefore quite wrong, and much too large. Baily says further: "I cannot find any star in any catalogue that will correspond with the zenith distance observed by Flamsteed, and I therefore consider that the star does not exist." If we take from Argelander's north zones the place of Dm. + 01° 1070 (7"'. 5), which is also Fed. LL. 13G1, and reduce it to 1G90, we find
0. Argelander's 9191 : 124° W 31" Flamsteed's British Catalogue has (127 46 30
; -)-61o 59' 1" \; +61 50 0
The star indeed transited, as from the record of the observation on 1090, January 23, is required, soon after 4 i Ursw majoris, and before the two imperfectly observed stars, which have been con- sidered above under the head of 7) and 8). We are now enabled to till up the gaj) between 3 and 6 Ursie majoris in the column of clock time, on page 287 of the Histoiia Ccelestis, II, as follows :
|
B. Fl. |
Star. |
Clock time. |
|
1185 1186 1232 1198 1199 1235 |
3 Ursie majoris 4 TT Ursio majoris 7 (=O.Arg.9191) Pi 8'' 131 |
h. m. 8. 11 13 34 [14 .56] [19 32] [23 28] [25 51] 31 51 |
|
Pi. 8M41 ........ |
||
|
6 Urs» majoris |
which confirms the justness of the identification of stars B. Fl. 1232, 1198, and 1199.
13) B. Fl. 1486 (5"').
This star, which in the British Catalogue passes under the name of 28 Sextantis, was observed 1702, February 28, at lO'' 48"' 3G», and Baily found in the original manuscript entry that the 4 (in 48™) had been originally a 5. There can be no doubt that the time should be corrected by
ON FLAAISTEED'S STARS "OBSERVED, BUT NOT EXISTING." 79
+2'", or tbat instead of 48'" should be read 50™, and that it is an observation of 29 Sextantu, iden- tical with Pi. W'.Sa (in Tiazzi's catalogue erroneously called 28 Sextanfis).
Piazzi 10''.S6 for 1800 ]54o 49' 43"; — 1° 43' 10"
Reduction to 1690 — 1 23 58 +33 G
Piazzi 8G for 1G90 153° 25' 45"; —1° 10' 4"
British Catalogue 1486 152 52 15; —1 10 25
Difference +33' 30"; +21"
29 Sextantis, or B. Fl. 1491, is 153° 23 45; -1° 10' 30
which differs from B. Fl. 148G with the correction of +2™, only 1' 30" in right ascension and 5" in declination.
14) B. Fl. 1647 (7'").
Argelander (A. N. No. 227, page 171) says :— "ist eine bis jetzt noch nicht bekannte Beobachtung des Uranus. Aus einer geuaueu Reduction folgt die Position 1714, Dec. 14., 17*' 54™ 57' M. Z. Gr. 11'' 29'" 1''.94; + 4° 11' C".5, selir schou niit den iibrigen Flanisteed'schen Beobachtungen dieses Planeteu iibereinstimmend."
Baily, on the contrary, in the note to this star, remarks: "I cannot find any star that will correspond with this observation. ]\Ir. Argelander thinks that it may be Uranus, whose position on that day, at 17" 54-" -57' mean time at Greenwich, was 11" 29"' I'.Ol (=172o 15' 29") and D= +4° 11' 6". 5; but the great difference in the declination is against this supposition."
For the time of observation concluded by Argelander 1 have computed from the solar tables of Hansen and Olufsen :
The sun's apparent trop. longitude © =262° 59' 23".9 The sun's apparent trop. latitude o'=+0''.27 The sun's radius vector log. R = 9.9928995
Also the obliquity of the ecliptic f = 23° 28' 29".2 And the nutation in longitude — + 14".5G.
For the same instant, but diminished by 2" 11'" 34% the time required by the light to travel from Uranus (for which the distance was taken from a preliminary computation), 1 derived from Newcomb's Tables :
The longitude of Uranus in reference to the mean equinox 168° 9' 22".67
to which added the nutation in longitude found from the solar tables + 14.56
gives the true or apparent lotigitude of Uranus X = IGS 9 37.23
Further the latitude of Uranus /? = + 0 46' 6".44
and the radius vector of Uranus log. r = 1.2620674,
With these data we obtain:
The apparent right ascension of Uranus a = 172° 15' 47".5 The apparent declination of Uranns (J = + 4 11 5 .9
Distance from the earth log. z/ = 1.2G07247, and the small correction for parallax, to be added to computed declination, will be = — 0".36.
Hence the final comparison stands thus:
Tabular computed place 11" 29-" 3M7; + 4° 11' 5".5
Observed (Argelander's reduction) 11 29 1 .94; +4 11 6 .5
Difference (C-O) ' +r.23 ^-HO
Argelander's assertion of this being an observalion of Uranus ("very finely agreeing with the other observations of this planet by Flamsteed") is therefore completely vindicated. Perhaps misled by Baily, no notice has been taken of this observation in the recent tables of Ui'anus.
80
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
15)
B. Fl. 1686.
Flainsteed compared, on three days in April, 1708, the planet Jnpiter with 3 stars of Virgo, as seen in the Historia Cce.lestis, II, p. 518, thus:
Jupiter
5 Virgiiiis
i- (i.e., 10) Virginis
April 2.
Time. Zenit dist.
h. in. 8.
10 8 48 16 52 26 33 30 51
47 16 50
46 11 10
47 56 50 47 34 40
April 5.
Time. Zenit dist.
h. m. 8. o ' "
9 56 23 47 10 20
10 5 27 46 10 50
15 9 19 27
47 55 40 47 34 40
April 6.
Time. Zenit dist.
L. m. s. 9 50 16
10 1 38 11 23 14 17
o ' 1/
47 8 20
46 10 50
47 55 50 47 34 40
It is quite niauifest that the last star observed on April 6 was the same as that observed on the other da.vs, viz: Pi. 12i'.lfi, No. 1C88 of the British Catalogue. Already Aliss Hersehel noted this, but that the clock time was put down 1™ 24* too early, and should read 10'' 15™ 41' instead of 10'' 14"' 17\ Baily's inspection of the MS. showed the print in conformity with the original. How the mistake may have originated it is quite useless now to speculate about; but it seems not less unreasonable to suspect here the observation of a star now lost.
16) B. Fl. 1910 (6").
There is no star of the sixth magnitude in the place entered in the British Catalogue under the name of 91 Virginis, and which comes from an observation made on May 13, 1703.
We compute from Miidler's Bradley for 1703 the right ascensions and apparent zenit dis- tances of:
|
a |
S |
<p—S |
Eefr. |
App. Z. |
|
|
84 0 Virg. 92 Virg. 93 r Virg. |
° ' " li. m. s. 202 2 24=13 28 10 205 20 29=13 41 22 206 38 22=13 46 33 |
O / 11 +5 3 22 +2 31 16 +3 0 5 |
o / " 46 25 16 48 57 22 48 28 33 |
/ // —1 1 —1 6 —1 5 |
o / // 46 24 15 48 56 16 48 27 28 |
On page 401 of the Historia Ccelestis, II, are reported the following observations, in agreement, as Baily assures us, with the MS. transcript, the original entry being lost:
|
Clock time. |
Zenit distance corrected. |
Redac- tion for rate. |
T |
a-T |
|
|
° Virg. . [Stan] . rVirg. . |
li. m. 8. 9 29 52 41 10 48 12 |
o / // 46 24 10 48 56 30 48 27 45 |
8. 0 -f2 +3 |
b. m. 8. ■ 9 29 52 41 12 48 15 |
L. m. 8. +3 58 18 60 10 58 18 |
Here the zenit distance of star x agrees with that of 92 Virginis.
Reducing the clock time for sidereal rate, as in the 4th column, and subtracting the resulting Tfrom the respective light ascensions of the pre 'odiiig table, the column a — Tis formed. The variance shown here would disa[)pear by assuming a correction in the recorded time of +1"" 52= (or of l"" 50», or, perhaps, roundly 2™), and the star therefore very likely was 92 Virginis. No fur- ther conjecture regarding the origin of the error can be made, since, as said, the book with the original entry for this time is lost.
ON FLAMSTEED'S STARS "OBSERVED, BUT NOT EXISTING."
81
17)
B. Fl. 1922 (6™).
This star, observed on May 13, 1704, can hardly be any other than 10 Booiis, which is near the place. Flamsteed observed on two consecutive days a sequentse of stars in Bootis, bej^inniiig on May 13 with the questioned star [.cj, and on May 14 with lU Bootia. The observations ot these are, in the Historia Coelestis II, pages 477 and 478, reported thus:
|
Date. |
Name. |
Clock time. |
Zenit diBt. per lineas diagouales. |
Zeuit (list, per strias cocblfie. |
|
1704, Mav 13.. May 14.. |
10 Bootis . . |
h. m. a. 9 43 28 9 38 12 |
o / /. 27 53 0 28 28 50 |
631.92 r= 27 53 22 iu arc] 645. 57 [=28 29 27 in aroj |
From 11 stars, the transits of which were taken on both days, the rate of the clock in a sidereal day = — 4™ 48% so that, according to the observ^ation of May 14, 10 Bootis would have tran- sited on May 13 at 9'' 42'" {Y clock time. The book with the original entrie.s for these years nu- fortnnately does not exist ; Baily found only the copies. To reconcile both days' observations, I imagine the entry of May 13 originally may have stood thus:
9 43 28 27 35
92
which was copied in the way as written above, the whole number of the strixB cochlece being filled in to correspond with the linece dUigonales. But the figures should have been distributed, and the stride cochlece supplemented rather, as follows :
9" 43-" 0' I 26° 27' 35" | 644.92 [= 28° 27' 44" in arc].
The substitution here of 35 for 53 is necessary, since the division was read off only to 5". Of such interchange of two figures Flamsteed was not quite free, as we see from other examples. The error in the clock time of 1" likewise is nothing extraordinary, and the identity of the star fa;] with 10 Bootis thus becomes complete.
Argelander's hypothesis that Flamsteed observed a star north of the zenith, which would lead to the star Fed. LL. 2349 {5i"), is contradicted by the fact that the declination +79° 12' would bring it far beyond the limit of the constellation Bootes, where it is distinctly stated that it was. The parallelism of the two series of May 13 and 14 also speaks against the surmise that the word bor., which is neither in the print nor in the manuscript, as Baily assures us, had been omitted only by forgetfulness.
18)
B. Fl. 2120 (— ).
In the Historia Coelestis, II, p. 116, are the observations:
|
Date. |
Name. |
Zenit dist. Clock time. ] per linens ; diagouales. |
Zenit dist. per strias cochleiB. |
Striie eochlesB con- verted into arc. |
|
1691, June 4 .. |
a CoronsB.. |
h. m. 8. o ' " 5 52 45 1 23 29 20 53 56 23 43 20 |
.^32. 06 537. 42 |
O ' // 23 29 :« 23 43 44 |
where the adjoined column .shows the agreement between the two readings of zenit distance.
There exists no large star so near to a Goronw, as already Burckhardt pointed out (Zach's Mon. Corr. 26, p. 579). The difference in time from a Corome, as Argelander remarks, equals exactly the difference in right ascension of 6 Goronw from the same star; and als') the zenit distance biings us quite upon this star, if we diminish by 100 the strice cochlece reading, or for 532.0(j read 432.00, which converted into arc is =19° 4' 52" S, Mis. 154 11
We cannot hesitate in taking this
82 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
for the solutiou. For the difference ffCoronce — aCoronm for the epoch of 1690 is indeed /ia= — !■" 10» aud Jc?=+4°39'.
Baily found in the original MS. entry the statement that "Mr. Clowes alone made the obser- vation." In the short interval of 1" 11= between the transits of the two stars, Mr. Clowes had scarcely the time, with writing and noting the clock, to make both the readings. Probably he contented himself with the striw cochlece reading, but in the haste made a mistake of 100 units. Modeled from the wrong figure. .532.06, arose afterwards, it seems, the strange zenit distance in the column j^er tineas diagonales.
19) B. Fl. 2335 (5").
In the Catalogus Britanuicus, in the third volume of the Historia Ccelestis, on page 53, the 55th star of Hercules is united with the 54th by a circumflex, with a figure for the magnitude common to both. This, together with what Baily (in the note to No. 2335) says of the MSS., shows that Flamsteed considered them as one aud the same star. The single observation, of the zeuit distance only, on April 8, 1703, is probably nothing but a repeated measure of the preceding zenit distance, which is of 54 Herculis. The number 55 Herculis, therefore, must be stricken out in the catalogue; it cannot be counted in the class of "observed and disappeared" stars.
20). B. Fl. 2441 (6").
The star, that in the British Catalogue passes under the name of 65 Ophiuchi. could not be found by Piazzi; and Airy, who, at Baily's request, looked out for it, had no better success. In the observation of 1691, May 6. probably a mistake was made in both the co-ordinates. If we correct the clock time by +1'" (perhaps better still by +1'" 10^) aud the zenit distance by — 50', i. e., if Historia Coelestis, II, page 112, for 14'' lO"' 58% we read 14" 11"' 58^ (or perhaps 14'' 12'" 8=) aud for 69° 24' 30" . . . . 68° 34' 30", the place is in perfect harmony with G Sagittarii. Indeed, by determining the constants from 15 other stars observed on that day, I find when applying the proposed corrections,
the observed place, reduced to 1690.0: 17" 43'" 14= (or 24');— 17° 5' 52", while 6 Sagittarii, as derived from Miidler's Bradley, is for the same epoch: 17'' 43"" 24«; —17° 5' 58".
The only difliculty remaining is to find an explanation for the figures of the column per strias cochlea, which would have to be altered into 1554.62 about. But the agreement resulting from the very simple and unstrained changes projjosed is so close, and on the whole the siuirious place so near to the corrected one, that about the identity with 6 Sagittarii there can scarcely be a doubt. The number 65 Ophiuchi, therefore, must be erased from the Catalogue.
21) B. Fl. 3150 (T-").
Flamsteed's star 80 Aquarii has often been observed in more recent times. In the catalogues it is : LL. 45022, Pi. 22''.279, W. 22''.1133, E. 10795, Lam. 4695, Glasgow 6039. All these indi- cate no pronounced proper motion, aud give
the position for 1690.0: 22" 45"' 27^8; —6° 21' 58" No. 3150 of the Brit. Cat. is : 22" 44"' 30«; —6° 22' 35" so that it is clear the star exists, but Flamsteed's time of transit was 1"' in error, and the Cat- alogue right ascension must be increased by +15'.
The name 80 Aquarii should be reinstated in modern catalogues, lor ex. to Heis. No. 99. I do not find that the star has been reobserved at Greenwich sintje Flauisteed's time.
22) B. Fl. 3213 (6").
There is no trace of actual observations for the position of 3 Cassiopew, which seems to have originated, as we understand from Baily's examination of tlie MSS., in Flamsteed's computations of No. 3224. Hence we have no reason to suspect here a " disappeared" star.
ON FLAMSTEED'S STAES "OBSERVED, BUT NOT EXISTING."
83
Tbe conclusions arrived at in the foregoing discussions are recapitulated in the following tabular form:
|
No. B. Fl. |
Name in British Catalogue. |
Result of investigation. |
|
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 |
314 639 756 864 913 1007 1198 1199 1205 1212 1220 1232 1486 1647 16S6 1910 1922 2120 2335 2441 3150 3213 |
28 Ariotls |
26 Arietie. Bradley 686. 28 Caiuelopardalis (or a variable t). LL. 11805. 20 Gemiuorum. W, 7". 66 (Dm. + 170.1498). LL. 17058-9 = Pi. 8M31. LL. 17138 = Pi. 8M41. LL. 16739-41, etc. (Dm. + iy°.2053). ProEsepe, Hall No. 65 (Dm. +20O.2150). LL. 17350 = O.Arg. 9357. 0. Arg. 9191 (Dm. + 61°.1070). 29 Sextantis. Uranus! B. Fl. 1688 = Pi. 12''.16. 92 Virginia. 10 Bootia. 6 Coronte borealis. 54 Herculis. 6 Sagittarii. 80 Aquarii. Obs. ? substituted in computation of No. 3224. |
|
100 Tauri |
|||
|
27 Camelopardi Monocerotis 21 Gemiuorum Gemiuorum UrsaB majoris Ursas majoria Cancri |
|||
|
Cancri Ursae majoris 7 Urs» majoris 28 Sextautia |
|||
|
Virgiuis 91 Virgiuis Bootia CoroDie bor 55 Herculis 65 Opbiuchi 80 Aquarii ......... |
|||
|
3 Cassiopeae |
Although the evidence of identity could not be made equally strong for all of the twenty-two cases left unsolved by Baily, nevertheless it is manifest that no reason exists to suppose any of the stars seen by Elamsteed to have been lost, or become extinct in the nearly two hundred years since elapsed. All the stars in the British Catalogue have now been accounted for, as well as the positions permit.
In concluding I may be allowed a remark, suggested while occupied with examining Flam- steed's observations. The astronomical world has not yet done justice to the sacrificing zeal, the , industry, the honest work of the first Astronomer Eoyal. The star catalogue is still in the same crude state as it came from the hands of the author. Baily has done much in rectifying errors of computation, discarding wrong positions, rectifying others; but still, the British Catalogue of Baily is yet the old Catdlogm Britannicus, the product of an age when the methods of reduction were in their infancy, the elements for the same imperfect, aberration and nutation even not yet discovered. The catalogue does not represent the observations with equivalent accuracy. Already Baily urged strongly a new reduction. "I do not despair," he says, "of its being accomplished at some future time, since those observations have much intrinsic value." But, since these words were uttered, over half a century has elapsed again, and however carefully the 70 volumes of Flamsteed's MSS. may be preserved at Greenwich, with time the paper must molder and the writing become more and more illegible. Baily, Argelander, and Krueger have done valuable preparatory work for a reduction. Has England no young astronomer ambitious to undertake the task?
NATIONAL ACADEMY OF SCIENCES.
VOL. III.
ELEVENTH MEMOIR
CORRIGENDA IN VARIOUS STAR CATALOGUES.
85
CORRIGENDA IN VARIOUS STAR CATALOGUES.
By C. H. E. Peters. head notember 12, 1885.
The frequent use of star catalogues for various purposes (planetary and cometary comparisons, zone observations, charts, &c.) lias led to the occasional detection of errors in them, which are here collected. Their publication may bu useful and save much trouble sometimes to other ob- servers, especially to those who, like the writer, have not at their disposition a meridian circle for verifying a position needed, but must rely upon tlie correctness of the positions i)nblished.
I have excluded here the lists for the Harvard zones, which have been published elsewhere (Annals of the Astronomical Observatory of Harvard College, Vol. XIII, pages 188-208), those for the Washington zones, which were communicated in MS. to Professor Holden, now engaged upon cataloguing the zones, and those for Lament's publications, which at the present are under- going a revision and reordination by the astronomers of the Munich observatory.
To discard the errors from catalogue positions has not only a practical utility, but is a step towards a more and more truthful representation of the skies. Therefore we see an Argelan- der, perhaps the best informed in our as:e of the starry heavens, revising step for step the "Histoire celeste," correcting Baily's catalogue of the same, then examining with equal endurance Bessel's zones, &c. Following the example of this master critic, I have, for the lists here presented, not been content with the simple fact of an error, but mostly turned to the original observations, when accessible, in oi'der to discover the source of error.
These contributions, from the way in which they originated, as stated, make of course no claim of completeness. Most of the errors indicated, however, will be found hitherto unknown. The corrections proposed are, I believe, wholly reliable; where not quite certain, ^.proh., or the sign of a query, has been adjoined.
I. — Corrigenda in Oeltzen's Catalogue of Argelander^s Southern Zones.
No.
70 135
774
790 869
972
1589
1773 1872 2007
2571 2761 2769
2858
Col.
a a S
S a
a 6 6
For 38'.99 read 48'.99 (or perhaps 49'.99j.
10».20 read 0».20.
25' read 23' (error of Cat., Z. 336.13 rifjbtj.
18' read 19'.
36«.74 "read 56».48 (-error iu Z. 266.16 in the reduction to middle wire).
19° read 18'^ (error in Cat., Z. 331 64 right).
23«.38 read 13».38 (Z. 313.30 wire 3 right, while wire 2 too large by 10", wiiich error was retained in re- ducing to the middle wire.)
36™ read 37™ (misprint in Z. 322.10).
23054' read 24-4'.
33°33'50".5 read 23043'54".l (-error of print of 10° iu Cat., and besides error of 10' in circle reading in Z. 313.67).
36' read 34'.
55' read 54'.
43'38".l read 53'40".4 (error of 10' in Micr. Z. 325 95).
12«.28 read 15".86 (-wire 4 iu Z. 350.7 was right).
|
No. |
Col. |
|
1 3084 |
S |
|
1 3120 |
S |
|
3123 |
S |
|
3492 |
S |
|
3819 |
a |
|
4091 |
S |
|
4202 |
S |
|
4402 |
S |
|
4435 |
a |
|
4885 |
a |
|
5022 |
S |
|
.5532 |
S |
|
6020 |
a |
|
6260 |
S |
|
6357 |
a 1 |
For 36' read 37'.
3'48".2read4'B".2.
80' read 20' (misprint;.
54' read 53'.
20".31 read 30".31.
23'13".0 read 33'15".3 (-error in Z.
274.45). 59' read 50' (prob. misprint ; Z. cor- rect). 19' read 16' (-Z. 323 105 is correct). 28'.50 read 39i>.03 (one wire interval, as suspected already by Argelander hiuisell). Perhaps too great by 19».7 (or the inter- val belween wires 3 and 4). The cor- recticiu would bring agreement with Lamout 65. For 11' read 12' (prob.). 37' read 38'.
45".86 read !J5^86, by correcting an error couiiiiitted iu reduciug Z. 2-2.26 to middle wire. Wash. Mur. Z. 216 gives still 10" more. 27' read 26'. 4°" read 5™ (misprint).
87
88 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
I. — Gorrigenda in Oeltzen's GataJogtw of Argclander's Southern Zones — Continued.
|
No. |
Col. |
No. |
|||
|
6377 |
a. |
For 33'.41 read 32«.41. |
14720 |
S |
For 8'40".6 read 9'10".6, about. |
|
6580 |
a |
Wash. Z. Mnr. lul.2 and Mer. C. 145 69 attree to iiiaUe the AR. 2' greater (-rislitly reihiced from Z. 2W2.49). |
14803 |
a |
Needs a correction of about — 10". Per- haps Z. 212.2 was observed wiie 7, not 6, which would make the AK. U-'..59 in- |
|
6964 |
a |
For 15^44 V>ad 27 ".04 (-ia Z. 282.66 for |
stead of 26«.05. |
||
|
wire 7 read wire 6). |
14807 |
a |
For S:,'" read :il>'". |
||
|
7011 |
a |
39'.32 rnad 29".32. |
14846 |
a |
37"" read 38"". |
|
72(54 |
S |
17°53'39".6 rea.l 18°3'40".8 (-error |
14862 |
S |
29' read 28'. |
|
of 10' sn.spected already bv Argel- |
14863 |
a |
38"" read 39™. |
||
|
an. er in note to Z. 278.118). |
14907 |
a |
16".34 read 26s.34 (error in Z. ; the |
||
|
7301 |
S |
23° read 2J° (niispriut; in Z. right). |
star = No. 14911). |
||
|
7496 |
S |
2-^° read W3° (luispriut; iu Z. rtgbt). |
14921 |
a |
26«.01 read 36».01 (the star = No. |
|
7535 |
a |
44'" read 45" |
14927). |
||
|
8J49 |
d |
19° read 29° (misprint). |
15003 |
s |
38° read 28° (misprint). |
|
8697 |
a |
27™ 1*. 1)2 read v:6'"51'.27 (error of one |
15043 |
a |
52».93read 53».93 (prob.). |
|
•wire interval in Z. 368.48). |
15082 |
S |
24'. 51 ".7 read 34'53".2 (error of col. 7 |
||
|
8754 |
d |
40' reail 42'. |
iu Z. 20.1.104). |
||
|
9303 |
a |
57™ read ;j8™ (error in Zone, .alike the foil.). |
15149 |
8 |
45' read 44' ( — also obs. in Bonn B., VI). |
|
9306 |
a |
57™ read 58'". |
15150 |
a |
54"' read .'5'" (— errorof 1"' in Z. 297.65. |
|
9307 |
a |
57'" re;id 58'". |
Thestaris idt-ntieal with No. 15166). |
||
|
9823 |
S |
9' read 8' (error in Z. 363.37). |
15259 |
S |
No star exists in that position. By cor- |
|
98-J7 |
a |
36».21 read 26».21. |
recting in Z. 205.69 the niierosc. reading |
||
|
loiia |
6 |
15' read 16'. |
bv+50', the declination of the Cat. will |
||
|
10220 |
a |
48'" read 47'" (error iu Z. 361.27). |
result 15°42'10".4 instead of 16°32'15".7. |
||
|
10280 |
d |
2' read 3' (?). |
The star therefore identical wilh No. |
||
|
10298 |
S |
15'14".l reail 5'11".9. |
1,5260. |
||
|
10583 |
6 |
25' read 24'. |
15266 |
S |
In Z. 207.132 is an error of 1°. The Cat. |
|
10594 |
d |
3U' read 31'. |
declination for 18°50'0".9 read 17°49' |
||
|
1080& |
a |
29''.93 read 28».93 (?-coinp. Bonn B. |
53" 4. |
||
|
VI). |
15292 |
S |
For 3' read 2'. |
||
|
11026 |
S |
Is 20" farther north than LL. andLanioiit. |
15489 |
d |
13'13".5 read 3'8".0. |
|
11193 |
a |
for 34'. 45:: read 44'.45 (Wash. Z.). |
15768 |
a |
2«31 read 43s.38 (—wire was 3, as Arg. |
|
11259 |
a |
285.78 re.ad 58».78 (error of Cat. ; Z. riglit). |
suspected in the note to the star Z. 213.40). |
||
|
11319 |
a |
13'" read 14'" (also Z. 401.39 to be oorr. |
1.5865 |
a |
34"" read 3.5™. |
|
by + 1'"). |
15944 |
S |
3".3 read 13".3 (prob., though rightly |
||
|
11433 |
S |
24°43'36".2 read 2.5°43'49".8 (error of |
reduced from Z ). |
||
|
1" in Zone). |
15989 |
S |
33'23".9 read 23'21".6 (Y. 6937, and |
||
|
11491 |
d |
10' rea'l 12'. |
Tacchini 638). |
||
|
11621 |
a |
42».40 read 52«.34 (in Z. 376.15 wire 6, not 7). |
16218 |
S |
32'46".8 read 42'49".l (obs. also by Arg. in Bonn B., VI). |
|
11674 |
S |
5'2".3 r(^ad 15'4".2. |
16242 |
a |
Arg., iu note to Z. 383.48, says: -'lO'?" |
|
11919 |
S |
M' read 13'. |
But according to Was . Z. Mnr. 173.33, |
||
|
1202.3 |
S |
16°47'is".t read 17°47'2.5".6 (error of 1° in Z. 367.127). |
and Mer. Cir. 97.114, the AR. needs rather a correction of about — 40'. |
||
|
12029 |
S |
16°42'(i".8 H'ad 17°42'14".2 (error of 1° in Z. 367.126). |
16287 |
a |
For 33" 93 read 23».56 (in Z. 392.23 prob- ably wire 3, and not wire 2). |
|
12066 |
S |
59' read 58'. |
1633-2 |
S |
30' read 29' (confirmed bv Bonn B.,VI). |
|
12429 |
d |
29° read 24° (error typ.). |
16431 |
S |
19°l:'.'44".l read 20°13'52".5 (Arg., |
|
12594 |
S |
28' read 27'. |
Bonn B., VI). |
||
|
1264b |
S |
28'29".6 read 38'33".6 (error in Z. 383.4). |
16585 |
— |
Found no star iu tliis place. Au 8.9™ star is about 4'.;0" farther north and 7".5 |
|
127.52 |
S |
51' read .52' (ob^. in Bonn B., VI). |
less iu AR. |
||
|
12758 |
6 |
57' read 58'. |
16668 |
d |
For 48' read 38' prob. (Bonn B., VI). |
|
12909 |
a |
22™read23'"(errorofCat. ; Z. riglit). |
Iii9l6 |
S |
37' read 38'.' |
|
12998 |
a |
Is about 30" too small (VV. 13''.509, and Ham. Coll. Z.). |
16934 |
s |
14' read 4' (— as Argelander already suspiM-ted in note tc) Z. 213.102). |
|
13269 |
a |
For 27M9 read 17».19 (the star occurs 3 |
16913 |
s |
.5' read 6' (Ham. Coll. Z.). |
|
times iu Wash. Z.). |
16955 |
a |
25™ read 24"" (unstake iu red. to mid- |
||
|
13402 |
S |
50' read 51' (error iu last colnnin of Z. |
dle wire). |
||
|
206 30). |
16982 |
— |
Found no star iu this place, though often |
||
|
13652 |
S |
37'.5-.d".0 read 27'53".0. |
looked for. The stars pn'ce<ling and fol- |
||
|
13747 |
S |
34' lead 35'. |
lowing it in Z 393 are correct. |
||
|
13774 |
6 |
49'37".l read 39'35".6 (the star occurs also in Bonn B., VI). |
17064 |
a |
For 3^"'1'.84 read 31°'51».91 (— the differ- ence of 1 wire in Z. 300.126, thus |
|
14295 |
S |
29' read 39'. |
agreeing with observatiou iu Bonn B., |
||
|
14291) |
S |
28' read 38'. |
VI). |
||
|
14362 |
a |
+20'=? Y. 6257 and Wash. Z. Mur. 167 10 agree. |
17075 |
a |
39«.40 nad 29'.09 (prob. error of 1 wire dist.). |
|
144H0 |
S |
For 6' read .5' (i-rror alre.idy in Z.). |
17087 |
a |
To be corr. by +5'.56, which makes the |
|
14616 |
S |
39' read 3S' (star is duplex). |
star identical with No. 17093. Argel. |
||
|
1462i |
s |
18°0' read 17°5»'. |
snsiiects theerror iu his note to Z. 393.81. |
||
|
147U3 |
d |
57° read 17° (Miis]irint). |
17090 |
6 |
29". 5 rea<i 9". 5 (error of redunion). |
|
14707 |
d |
39' read 38' ( — also obs. in Bonn B., VI). |
17231 |
a |
3il™44=.0.Sread4u™4»."J5(— iu Z 222.34. the wire was 3, not 4). |
CORRIGENDA IN VARIOUS STAR CATALOGUES. 89
I. — Corrigenda in Oeltzeii'ii Cataiogue of Argelander^s Southern Zones — Contiuued.
No.
19371
19416 19652
19910
youo7
20009 20201
20260
20368
20542
20555 2U61T
20688
20727 20810
20978
Col.
|
17236 17309 17404 17523 17607 |
<>: 6 S 8 s |
|
17746 17790 |
s a |
|
18155 1«279 18288 |
d S S |
|
18429 |
S |
|
18774 19058 |
S S |
|
19109 19370 |
S a |
d
a
a
a
S a
Is about 8' too great.
For 26° read 27° (misprint; Z. rigbt).
f>W read 45' (Bonn 15. VI eoirect).
41' read 42' (obs. in lioiin 15. VI).
42'21".9 read 32'16". 7 (error of reduc- tion in Z. 223.41).
24°6'25".8 read 23°56'23".5.
45^.80 n ad ■13».86 ( — error of reduc- tion to middle wire iu Z. 217.80).
37' read 38'.
53'3S".9 read 43'37".0.
17°44'4".4 read 16O43'57".0 (= LL. 34124. In tbe position of tbe Cat. no star is to be seen. There is an error of 1° in Z. 391.166).
49'47".5 read 39'46".3 (also obs. in Bonn B. VI).
54' read 55'.
38'37".3 read 28'35".l (—error of re- duction Z. 220.179).
.57' read 27' (error of Cat. ; Z. correct)-
10'>J6''.3y read 9"'45».30 (in Z. 308.133 the wire should be 7, not 5).
6'.94 read 12'.94 (error i)erliaps from writing tbe time 10».0 for 16».0 in Z. 240.13).
51' read 52' (Lamont, and Bonn B. VI).
34'20".0 read 44'21".6 (Wash. Z., and Bonn B. VI).
37' read 36'.
42' read 44'.
41'23".8 read 31'22".0.
38».63 read58».63 (in Z. 244.42 the wire
should be 4, not 5).
To be corrected by — 10"; the preceding
number is right, as shown by LL.
and Lam. observations.
An observation made at Berlin, A. N. No.
1637, has tbe AR. smaller by lO''. For 41".42 read 31'.42 (— error of Cat. ; Z. right).
20° read 29° (misprint).
26™ read 27™ (— error of Cat. ; in Z. right. The star thus appears to be identical with 20632).
84' read 35' (—error of col. 7 in Z. 311.82). This star was not found in the sky. Needs a correction of -f 10'*, or perhaps of +9°. 82, the time interval be- tween wires 2 and 3 in Z. 249.82. For 24'. 44 read 228.44 (—error of Cat.; Z. right).
|
No. |
Col. |
|
20990 |
a |
|
211125 |
a |
|
21036 |
a |
|
21041 |
a |
|
21075 |
a |
|
21214 |
S |
|
21252 |
a |
|
21371 |
S |
|
21403 |
S |
|
21434 |
a |
|
21436 |
a |
|
21436 |
S |
|
21439 |
S |
|
21660 |
a |
|
21727 |
8 |
|
21808 |
a |
|
21909 |
a |
|
22158 |
a |
|
22162 |
8 |
|
22172 |
a |
|
22212 |
a |
|
22217 |
a |
|
22220 |
a |
|
22224 |
a |
|
22291 |
8 |
|
22420 |
a |
|
22430 |
a |
|
22502 |
8 |
|
22577 |
S |
|
22716 |
a |
|
22794 |
8 |
|
22889 |
8 |
|
23063 |
S |
|
23141 |
a |
|
23165 |
8 |
|
23193 |
8 |
|
23230 |
a |
|
23247 |
a |
Is about 4» too small ; also in Zone. For 51» read 52= (error in Z. 247.95).
52= read 53= (error in Z. 247.97).
52"'43" read 53"'33= (error in Z. 247.96).
24=.83 read 34=.83 (error of Cat.; Z. right).
5' read 53' (misprint).
26=.86 read 27».68.
20° read 30" (misprint).
20°4y'51".7 read 19°49'42".6. There is no star in the uncorrected posi- tion, and the Z. 255.23 is 1° in error.
22"> read 21°'.
22'" read 21'".
56' read 51'.
4' read 5' ( — error of Cat. ; Z. right).
40"' read 41"' (error in Z. 245.63).
21' read 20' (error of Cat. ; Z. right).
59».43 read 17».63 (iu Z. 234.96 the wire should be 5, not 3, which makes 41".80 difference).
48».36 read 3d».07 (corrected by inter- val of wires 5 and 6 in Z. 254.95, to agree with Y. and Lam.).
12=.23 read 33".09 (error in reduction to middle wire in Z. 257.32).
44'46".8 read 54'47".9 (Ham. Coll. Z.).
29=.27 read 39".27 (error of Cat. ; Z. right).
24'" read 25™ (error in Z. 265.29).
24'" read 25™ (error iu Z. 265..30).
25™ read 26™ (error in Z. 265.31).
25™ read 26™ (error in Z. 265.32).
48'54".7 read 38'50".6.
40™ read 41'" (error iu Z. 250.18).
41'" read 42"' (error in Z. 2,50.19).
45' read 47' (error in Cat. ; Z. right).
51° read 15° (misprint).
30'.34 read 20".34.
19'50".5 read 59'55".2 ( — error arising from a misprint in col. 7 of Z. 253.63).
14°37'54".3 read 15°38'0".0 (iu col. 7 of Z. 250.68 there is a misprint of 1°).
2.3° read 24° (misprint iu Cat.).
49™ read 50™.
43'2".6 read 53'5".5.
27'6".5 read 37'9".4.
29'.51 read 39=.72 (error in reduction to middle wire Z. 269.34).
59'" read 60™ (error of Z. 250.100 ; also the AR. of 107 and 108 of the same zone, and hence No. 1 and No. 16 of the Cat.o ught to beiucreased by 1'").
Among errors of smaller .amount, not rare is that of 1" in AR., which is more difficult to be found out. It would be desirable that iu future no zone work be undertaken without the use of a chronograph, as the i)rincipal source of this error lies iu miscounting the tloek-beat. Many of tlie doubtful cases have been cleared up by Argelauder him self, by a reobservation, in the • Bonn B.,' Vol. VI. A few others are here appended.
Errors of about 1= in right ascension.
|
No. |
No. |
||
|
14087 |
For 38".33 read 39».33 prob. (LL. and Lam.). |
17822 |
For 49.35 read 48.35 (error of Cat. ; Z. correct). |
|
• 14858 |
54.25 read .55.25 (3 obs. Ham. I oil. Z.). |
19055 |
18.19 re.id 19.19 (Lamont and Wash. Z.). |
|
16116 |
Between 1= and 2" too small ; tbe star was ob- |
19413 |
59.29 read 60.29. |
|
served at Berliu, A. N. No. 1637. |
20606 |
13.73 read 12.73 (error of Cat. ; Z. right). |
|
|
16899 |
For 8.54 read 9.54 (olis. Ham. Coll.). |
21012 |
3.18 read 4.1f( (the star is 20 Capricorni). |
|
16971 |
59.28 read 60.2» (Wash. Z. aud Ham. Coll. |
21079 |
50.88 read 51.88 (the star is i] Capricorn). |
|
Z.). |
21939 |
53.65 read 52.65 (R. 9859 and Ham. Coll. |
|
|
17325 |
35.59 read 34.59 (Wash. Z. and Ham. Coll. z.). |
Z.). |
S. Mis. 154-
-12
90 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
II. — Corrigenda in the catalogues of volume VI of the Bonn observations.
|
Page. |
Star. |
Col. |
Page. |
Star. |
Col. 5 |
||
|
4 |
— 1°.2534 |
a |
For 19'.91 read 20'.91. |
91 |
+1.5°. 2185 |
For 44' read 42' (?). |
|
|
10 |
— 0°.2611 |
a |
For 36«.51 read 37=.51 (the num- ber is uot2610.) |
94 |
16°. 394 |
— |
Never seen, though often looked |
|
for. As it is also in Durchm., |
|||||||
|
13 |
+ 0°.448 |
S |
For 38' read 40'(prob.). |
it may be a variable. A star |
|||
|
16 |
0°. 2749 |
a |
Perhaps 10" too small (conip. Harvard Z 4 and 5, No. 71. ) |
was observed, however, in -|-3»and +10' 0". |
|||
|
20 |
1°. 282 |
S |
For2.V read 24' (Ham. Coll. Z ) |
99 |
17°. 1818 |
a |
For 10"' 5(is.65 read 11™ 2».65 |
|
32 |
3°. 43 |
a |
For 31". -52 read 32".82 (prob.). |
( — the Zones of Vienna and |
|||
|
32 |
3°. 215 |
a |
For 25'" read 24"'. |
Ham. Coll. agreeing.) |
|||
|
50 |
6°. 23.59 |
a |
For 9'.22 read 10".22 (prob.). |
102 |
lii'\ 1043 |
a |
In the2il observation read 18'. 66 |
|
50 |
6°. 2372 |
a |
For 48».74 read 47''.74 (prob.). |
(—is W. 5".1664-.5.) |
|||
|
50 |
6°. 2408 |
S |
For 57' read 59'. |
105 109 |
19°. 438 20°. 483» |
> a |
(.For 34''.39 read 33'.39 (W. 2'> |
|
55 |
7°. 2455 |
a |
Seems from l" to 2^ too small. |
} 1210 is in agreement with |
|||
|
55 |
7°. 2492 |
S |
Is about 20" too far uorth. |
i Ham. Coll. Z.) |
|||
|
. 61 |
8°. 2556 |
a |
For 2H=.50 read29^50 (prob.). |
108 |
19°. 4699 |
d |
For 15". 1 read 5".l. |
|
65 |
+ 9°. 120 |
a |
For 51».82 read 21".82. |
115 |
21°. 1390 |
a |
For 30" read 40°'. |
|
67 |
9°. 2244 |
a |
For 13".57 read 3'..')7 (in Dm. is |
125 |
23°. 1542 |
6 |
For 42' read 52'. |
|
the same mistake.) |
130 |
24°. 694 |
S |
For 3' read 1'. |
|||
|
70 |
10°. 2228 |
|
Ar<;el:uulersays iu the note that |
131 |
24°. 1985 |
a |
For 45M6 read 46».I6(?) |
|
this star is double. I hare |
131 |
24°. 1989 |
a |
For .'i7».2y read 58».29 (?). |
|||
|
never seen it so, though often |
333 |
22i'^9'"23«.70 |
11 |
For 23».70 read 24=. 70. |
|||
|
looked for it. |
342 |
St-. 116 |
a |
For 40'" read 49"' (mi.sprint.) |
|||
|
83 |
13°. 2272 |
a |
For 26"' read 24"'. The star is |
353 |
13 .55 |
a |
For 57^29 reatl b8'.29. |
|
Sclij. 3860. The number is not |
363 |
20 .49 |
S |
For 31° 0' read 30° 58'. |
|||
|
2274. |
364 |
21 .46 |
S |
For 17' read 20' (star is ;' Capri- |
|||
|
83 |
13°. 2285 |
a |
For 3i.».20 read 31».20. |
corni . ) |
|||
|
87 |
14°. 2231 |
a |
For 13^64 read 12».64 (prob.). |
364 |
21 .52 |
a |
For 47' read 48' (star is S Ca- |
|
87 |
14°. 2326 |
S |
For 50' read 40', in the last line. |
pricorui.) |
|||
|
91 |
15°. 488 |
S |
For 37' read 36'. |
364 |
22 . 6 |
a |
For 2;M.73 has LL. 43296 : 30«.62; |
|
91 |
15°. 532 |
S |
About 15" too great (2 obs. Ham. Coll.). |
Lam. 841: 30'.99 ; K. 9915: 29».55; Wash. Z. Mur. 203.19 : |
|||
|
91 |
15°. 2175 |
a |
For 35^09 read 36^09 (prob.). |
28».74. |
III. — Corrigenda in Weisse^s Catalogue of BesseVs Zones between —15° and +15° of declination. Note. — The following list contains only the correetious found additional to the many errors known before.
|
Star. |
Col. |
Star. |
Col. |
||
|
0i'.47 |
S |
For 38' read 37'. |
769 |
S |
For 49' read 50'. |
|
417 |
a |
Is from 1» to 2" too great. |
842 |
d |
2° read 1°. |
|
995 |
a |
Is more tban 1= too small. |
847 |
6 |
+ read — (is = LL. 22502). |
|
1^. 132 |
a |
For 4ti'.33 read 49».33 (about). |
885 , |
a |
Is from 5" to 6» too large. |
|
141 |
S |
7' read 27'. |
901 |
a |
For 51'" read 50^. |
|
210 |
a |
10M0read9M0. |
943 |
a |
Seems about 15' too large. |
|
218 |
a |
38'.5I read 39^51. |
V2K 109 |
d |
For 32' read 33'. |
|
270 |
S |
18' read 16'. |
124 |
a |
13".i'0read 12».00. |
|
452 |
a |
Is rather more than 1' too small. |
153 |
a |
.56'.21 read 55'.21 (T perhaps prop. |
|
21'. 22 |
a |
For24'.87read34''.87. |
motion). |
||
|
142 |
S |
37' read 39'. |
184 |
8 |
58' read 57'. |
|
224 |
a |
11».83 read 17".83 (about). |
232 |
a |
Is, perhaps, 1' too small. |
|
4''. 613 |
a |
50^09 read 59».09. |
414 |
a |
Is from 1' to 2" too small. |
|
dK 478 |
a |
48M6read46'.16. |
438 |
8 |
For 16' read 15'. |
|
lO"-. 176 |
6 |
40' read 39'. |
516 |
a |
Is about 2' too small. |
|
364 |
S |
8' read 10'. |
551 |
a |
Is3» too great. |
|
381 |
S |
43' read 42'. |
567 |
8 |
For3U' read 32' (probably). |
|
412 |
S |
Is about 50" too large. |
709 |
a |
Ought to be I's.. aller. |
|
438 |
a |
Precession ought to be 3". 172. |
799 |
a |
For 29".90 read 39'.90. |
|
438 |
S |
For 13' read 12'. |
813 |
8 |
32' read 33'. |
|
705 |
a |
15«.64read25«.64. |
939 |
a |
Should be 1' smaller. |
|
735 |
S |
+ read — . |
13". 242 |
8 |
For 15° read 14°. |
|
889 |
a |
31«.12read30".12(?). |
444 |
a |
Seems to be 1' too large. |
|
908 |
a |
41'.33 read 40«.33 (?). |
595 |
8 |
Requires a correction of about — 30". |
|
927 |
S |
4° read 3°. |
838 |
a |
Is 1' too large (?). |
|
1023 |
a |
Is 1" too great. |
931 |
a |
Probably is to be corrected so that the |
|
11''. 273 |
6 |
For 22' read 32'. |
star becomes identical with 942. |
||
|
555 |
8 |
— read -)-. |
U\i9 |
8 |
For 45' read 46'. |
|
560 |
a |
44«.76 read 34«.76. |
224 |
8 |
32' read 33'. |
|
647 |
a |
Seems to be 1" too small. |
296 |
8 |
11° read 10°. |
|
667 |
a |
Is rather more tban 1" too large. |
3.59 |
8 |
17' read 19'. |
|
687 |
S |
For 51' read 50'. |
15". 355 |
a |
Is 1' too great. |
CORRIGENDA m VARIOUS STAR CATALOGUES. III. — Corrigenda in Weisse's Catalogue of BesseVs Zones, &c. — Continued.
91
|
star. |
Col. |
Star. 1 |
Col. |
||
|
15i>. 704 |
a |
For 10M7 read 14M7. |
2SIK 438 |
a |
For 575.48 read 47". 48. |
|
16^ 312 |
a |
15" read 16'". |
562 |
S |
-f read — . |
|
S-iS |
S |
27' read 29'. |
704 |
— |
No st.ir seen in this position. |
|
18". 959 |
a |
37» read 47'. |
7.52 |
S |
For 3' read 4'. |
|
20". 2:! |
a |
20" 0'" road 19" 59" (star identical |
902 |
S |
52' read 49'. |
|
with 19".i:>38). |
1076 |
— |
There is no star in this position. A |
||
|
41 |
a |
1" read 0"' (star identical with 19). |
correction in right-ascension of — 19' |
||
|
1134 |
a |
Is about 'M too sreut. |
would lead njion 1068, one in declina- |
||
|
1157 |
a |
For 50" 95 read 60".95; precession, 3". 342. |
tion of -f 10' upon a star 9 magnitude |
||
|
14ei9 |
a |
53^.78 read 55».78. |
observed in Ham. Coll. Zones. |
||
|
1498 |
a |
22^57 read 12»..57. |
1074 |
a |
For 9».43 read 19«.43. |
|
21". 366 |
6 |
22' read 32'. i |
1214 |
S |
30' read 31' (f). |
|
656 |
s |
42' read 45'. | |
1240 |
a |
2».71 read 1».71. |
|
665 |
Isnotin tlie skies; Ijut by correcting tLe| |
1241 |
S |
31' read 32' (?) .1= = Lam. 4015. |
|
|
right-ascension bv — 2.5" the star will. |
23". 713 |
a |
21«.56 read 22».56. |
||
|
be in the same position as 656 ( — the |
718 |
a |
33'" read 34"'. |
||
|
latter corrected in declination as stated |
723 |
a |
3^29 read 4».29. |
||
|
here before). |
834 |
a |
39'" read Sb'" (same star as 808). |
||
|
813 |
S |
For 59' read 57'. |
837 |
a |
39'" read 3H™ (same star as 811). |
|
1150 |
a |
37'.84 read 27^84 (??) |
905 |
d |
35' read 36'. |
|
22". 22e |
— |
No star found in this position, nor any |
958 |
S |
40' read 41'. |
|
plausible correction. |
964 |
S |
11' read 12'. |
||
|
272 |
a |
For 12i>' read 13™ (star identical with 295). |
1099 |
a |
Is 1* too great. |
|
313 |
S |
9' read 11'. |
1154 |
d |
For 9' read 7'. |
Furthermore, for the stars 11". 848, 849, 850, 855, 858, the precession in right-ascension ought to be 3' instead of 2', and for the stars 11". 723 and 724 the precession in declination ought to be 19".
IV. — Corrigenda in Weisse's Catalogue of BesseVs Zones between +15° and 45° of declination.
|
Star. |
Col. |
- |
Star. |
Col. |
|
|
1". 1153 |
tx |
Is 1« too great. |
8". 210 |
S |
For 18' road 8'. |
|
3". 417 |
a |
For29».44 read 19^.44. |
1122 |
a |
For41M0re,ad21M0. |
|
1106 |
S |
59' read 58'. |
9". 833 |
a |
40"" read 41"^. |
|
4". 731 |
S |
50' read 55'. |
12". 587 |
a |
5«.8:i read 15».83. |
|
5". 12G6 |
— |
There is no star in the position given, |
16". 970 |
a |
0^65 read lOs.65 (same star as 976). |
|
which ought to be corrected either |
17". 307 |
ex |
12».88 read 7'.88. |
||
|
by reading the right-ascension 3.5"" |
lo". 763 |
a |
'.i'.lri read 5". 78 (?) |
||
|
for 36™ or by leading the declination |
19". 52 |
a |
31''.2I read 1«.21. |
||
|
53' for 43'. |
1473 |
a |
44'" road 45"'. |
||
|
1269 |
S |
For 15' read 5'. |
1537 |
d |
Is from 30" to 40" too largo (two obser- |
|
2032 |
s |
10' read 6'. |
vations in Ham. Coll. Zones). |
||
|
6". 265 |
s |
4' read 3'. |
1683 |
a |
For 13".47 read 23».47. |
|
935 |
d |
Is 30" too large (—star = Y. 26-2). |
20". 401 |
a |
42».51 read43».51 (probably). |
|
965 |
a |
For 30" read 29'" (same star as 927aud 929). |
22". 162 |
a |
24''.09read23».09. |
V. — Corrigenda in Biimker's Catalogue of 12000 stars.
|
No.R. |
Col. |
No. R. |
Col. |
||
|
1637 |
a |
1 ! For 36».00 read 38».00. |
3157 |
S |
For 35° read 36° (the star i826 Leouis min. ). |
|
1649 |
a |
Is about 7» too large. |
3219 |
S |
16° 1' read 15° 59' (?). |
|
1714 |
S |
For 17' read 16'. |
3332 |
S |
1.5' read 14'. |
|
1859 |
— |
Does not exist. Decl. for 23° prob. 33^. |
3778 |
d |
24' read 23'. |
|
1897 |
— |
Not seen. Decl. for 23= prob. 33°. |
5332 |
S |
29".5 read 59".5. |
|
1997 |
S |
For 52' read 22'. |
9218 |
S |
15' read 5' (prob., as thus we come |
|
2010 |
a |
42"" read 44"". |
upon a star of 9.10™, while in the |
||
|
2636 |
8 |
: 20= read 10° (prob., and the star 49 '. Cancri). |
Cat. position there is none to be seen). |
||
|
2762 |
S |
1 Somewhat uucortain. |
9248 |
S |
11° read 12°. |
|
3087 |
a |
For 4"" 36' read 5"" 20» (about). |
|||
|
3130 |
— |
Poiiition erroneous; perhaps to be cor- |
9254 |
S |
For 11° read 12°. |
|
; rected by -)-5' in AK. and +3' in Decl. 1 |
9314 |
— |
No star here; correct a: by -|-7' (=No. 9315). |
92
MEMOIRS OF THE NATIONAL ACADEMY OP SCIENCES. V. — Corrigenda in Eumlcer^s Catalogxie 0/ 12000 stars — Continued.
No.E.
9395
9965 10307 10427 10439 10492 10559 11789 11^94 Nacbtrag G the varia
Col.
For 55" read .56" (prob.).
.S8».75 read 48".75 (about).
22'" read 20"' (the star is 58 Aquarii).
44* read 45«.
20= read 21".
24' read 22' (prob.).
— read + (?).
13' read 12'.
29' read 30'. b 59m 41B for ig' ju Oecl. read 17' ; the star is ble R Canis min.
Nachtrag 12'' 13"' 12" prob. is too small in AR. by 1'" 7*, and the star identical with Schj. 4459.
No star was seen in the position of No. 4338 ; but in Hani. Coll. Z. a star was oliserved 4= greater in AR , and 1' 35" farther north, which might be the star of Riim- ker.
Not found are the following stars of this Catalogue, viz: 1399, 3607, 3t;l0, 3698, 9926, 10006, 10072, 10109, 10516, 11933, for which a revision of the original manu- scripts would be desirable.
VI.— Corrigenda in Eumlcer^s Catalogue, new series.
|
No. |
Col. |
|
470 |
a |
|
534 |
S |
|
564 |
S |
|
638 |
a |
|
663 |
S |
|
732 |
|
About 45" too small. For r read 11'.
8" read 7-.
15"" read 16'".
59".4 read 19".4 (3 obs. Ham. CoU. Z.). There is no star in this place.
|
No. |
Col. |
|
834 |
S |
|
1620 |
a |
|
2091 |
S |
|
2633 |
S |
For 34' read 33'.
3^914 read 3*.194 in precession. About 10" too small (LL. 7581 and 2 obs.
Ham. CoU.Z.). For 13^ read 3'=' (star is 33 n'Orionis).
VII. — Corrigenda in Schjellerup^s Catalogue. Note. — Several of the corrigenda contained in the following list may have been indicated before.
|
No. |
Col. |
No. |
Col. |
||
|
568 |
a |
For 54^26 read 55=.26 (?). |
9234 |
S |
For 47' read 48'. |
|
568 |
S |
75" read 45" (misprint). |
9307 |
S |
35".9 read 25".9. |
|
572 |
S |
45' read 43' (?). |
9747 |
a |
Probably to be corrected by — 20", since |
|
805 |
— |
W. 787 read W. 788. |
no star is found in the place of the Cata- |
||
|
3780 |
a |
38«.08 read 39».08. |
logue. |
||
|
4261 |
d |
56' read .55'. |
As synonyms may be inserted the following: |
||
|
4424 |
6' |
9° 0' read 8° 59'. |
3474 |
2 |
LL. 18585. |
|
4588 |
d |
13' read 14'. |
4065 |
3 |
W. .50. |
|
8467 |
(X |
55"" read 56™ (misprint). |
7982 |
3 |
W. 346. |
|
8706 |
a |
23™ 21M5 read 22'" 51M5. |
8833-3 |
3 |
W. 891 (corrected by +1™). |
|
9027 |
a |
54'.82 read 55'.82. |
VIII. — Corrigenda in Bailyh Catalogue of Lalande's Zones.
Note. — The following few mistakes have escaped the scrupulous investigation of Argelander, and are not noted in the extensive list published in Vol. VII of the Bonn Observations.
|
No. |
Col. |
No. |
Col. |
||
|
5229 30685 30784 |
a P.D. P.D. |
For 38"" read 37". 23' read 24'. 39' read 41'. |
35071 45064 45489 |
a P. 1). P.D. |
For 17S.90 read 7=.90. 36' read 31'. 11' read 12'. |
CORRIGENDA IN VARIOUS STAR CATALOaUES.
93
IX. — Corrigenda in YarnalPs Catalogue, second edition (1878).
NdTE. — This catali>i;vio in greater part is dcrivi'd from observations with tlie Transit iiistrnniont for tlio riglit ascensions and vritli the Mnral circle I'cirthe declinations. Very often, however, the ])recaution was neglected to read the second co-ordinate with snfficient apjiroxiniation far identifying the star beyond ijiiestion. Therefore in composing the catalogue not seldom wrong combinations of right ascension and declination were niado, giving rise to spurious stars, which of course are found among the many anonymous of which the catalogue abounds. To sift these, a com- parison with other catalogues was made by me. Professor MiUoserkli recently has published (Attuali della iletcorologia Hallana, Parte III, 1884) a complete investigation of all the anonymous in Yarnall's Catalogue Ihat come within the limits of the DKrclimiislcrKiifj. For tlu'se, therefore, I have suppressed my notes, except where I differ from my distin- guished friend in the conclusions arrived at, or wheie ii more detailed elucidation, by going back to the ll'asliiuiitoii Obserialioiis, seemed necessary for contirniing some of his veiy hajipy conjectures. Below I apjieud a supplemental list of YarnalTs anonym(Dis, the positions of which I found secured liy other catalogues.
|
Cat. No. |
Col. |
Cat. No. |
Col. |
||
|
119 |
— |
The declination should be south {nnt north, as seen from Wash. Obs., IrIM), and is that of LL. :!10=Dm.— 0'^.:i7. But the |
2133 |
S |
For 32' 47".4 read 29' 53". 1 (—error iu Wash. Obs., 1870). The star hence iden- tical with Y. 2134. |
|
right ascension belongs to another star. |
2139 |
a |
The reduction to mean equinox in Wash. |
||
|
tIz. Dm.-|-(1'\29, which is found also in |
Obs., 1862, p. 8, is erroneous, and the |
||||
|
the Harvard Zones. |
star identical with Y. 2i:!5. |
||||
|
150' |
— |
The declination belongs to Y. 1.59: the |
2275' |
— |
Has in 1st edition the numlier 2270. |
|
right ascension is that of W.j.0''.3()9, of |
2311 |
a |
For28.'n read 29'" (—as seen in Wash. Obs., |
||
|
which the ileclination, however, was not |
1869, p. 2(i0). |
||||
|
observed at Washington. |
2362' |
a |
40^35 reail 38«.35 (—error in Wash. |
||
|
1 |
The magnitudes as well as the declina- |
Obs., 1877, p. 10.5, No. 2). |
|||
|
198 |
I |
tions of these two stars should be inter- |
2373 |
a |
2^.885 read 2'=.285 in precession. |
|
199 |
} |
changed, the preceding star being the |
2594 |
= ! |
Both magnitudes and right ascension of |
|
J |
nortbern and smaller one. |
2595 |
these two stars seem to be interchanged. |
||
|
329 |
a |
For 3;i"' read 34™ ( — the same mistake also in Weisse's catalogue, W.O''. ^>72). |
2704 |
There is no star in that position. But changing the ajiproximately noted dec- |
|
|
341 |
— |
There is no star in this place; there must be some mistake in the transit in 18«5, |
lination from +23° 49' into 24° 1', the star is W;. 6''. 1080. |
||
|
from which the right ascension is rightly |
2779 |
6 |
For 44". 1 read 12". 8. Although the 2 ob- |
||
|
reduced. |
servations with the Mural Circle agree. |
||||
|
378 |
a |
For39"'-26».l'3 read 40"' 27M4 (—error in Wash Obs., IStio, p. 114, No. .35). The star is identical with Y. 388. |
the declination must be about 30" far- ther north. Probably at both times an error of 1 revolution =31". 34 was com- |
||
|
590 |
a |
For 1'" read 0'". It is the right ascension |
mitted. |
||
|
of Dni.+3 .KU ; but the declination be- |
2796 |
S |
Belongs still to Y. 2798; the approximate |
||
|
longs to another star, viz. R;.538. |
right ascension erroneous. |
||||
|
664 |
S |
The reduction of the declination from |
2798 |
S |
For47'read46'(— as seen from Wash. Obs.). |
|
Wash. 01,1s., 1871, App. II. p. (il, is erro- |
2876 |
S |
11' read 12'. |
||
|
neous. It should be — 1° 10' 58".t), and |
2886 |
— |
Is identical with No. 28-i9 (also 0. Arg. |
||
|
belongs still to Y. 1108 (43 Ceti) ; the dec- |
6317). |
||||
|
lination of Y. 664 has not been observed |
2952 |
s |
For 13' 56".4 read 14'13".7. In Wash. Obs. |
||
|
at Washington. |
1870, pag. 125, No. 19 is put south, |
||||
|
848 |
Is to be canceled, origin.aling from the comliination of several errors in the Wash. Obs., 1^61 (pag. 163, 1st star, and I'ag. 224, No. 47). When these are corrected, the right ascension for 1.-60 comes 1'' 42"' 48«.2.5, which is thar of Y. |
and hence also thereduction to mean equinox made erroneous. Yarnall has corrected the sign of the declina- tion, but left the reduction un- changed. The star appears now to be identical with No. 29.53. |
|||
|
854, and the declination +13° 39' 9".9, |
3.572 |
s |
57' read .55'. |
||
|
which is that of Y. 852. |
3718 |
a |
42"' read 43"'. |
||
|
937 ! a |
For 55'" read uO"" ( — error in Wash. Obs., |
3729 |
— |
Is No. 3734 in 1st edition. |
|
|
1«68, p. 369). |
3730 |
— |
3729 in l.st edition. |
||
|
966 |
S |
Iserroneous. Of the twoobservations one |
3731 |
— |
3730 in 1st edition. |
|
was made in 1874, and gives -|-3.S° 58' |
3732 |
— |
3731 iu 1st edition. |
||
|
59".6. agreeing with W.:.l".1468. Of the |
3733 |
— |
3732 in 1st edition. |
||
|
other, made in 1852, the originals have |
3734 |
. — |
3733 iu 1st edition. |
||
|
never been pubiislnd. |
3787 |
a |
For .50'" 50^87 read 51"" 0".87 (-error in |
||
|
1342 |
a |
For 4"" read 5'" ( — error in Wash. Obs., 1871, Ajip. II. p. 1(>). The star is also Arg. +8°.474. |
Wash. 0b.s., 1862, p. 31, No. 13), so that this right ascension belongs still to No. 3792. The declination. |
||
|
1776 |
Does nor exist. The declination probably was wrongly noted north, and should be south. This makes the right ascension change to 3ss.24, ami hence the star |
however, is prob*ldv that of Arg. +23°. 2024, of wjiicli" the right as- cension was not observed at Wa.sh- ington. |
|||
|
identical with Y. 1777. |
3964 |
S |
— read + (misiirint). |
||
|
1894' |
— |
Has in the 1st edition the number 1896. |
4111> |
S |
The approx. declination should be +18° 5' |
|
2098 |
a |
Mean year : for 31.6 read 63.1 ( — error car- ried over from l.st edition). Also the |
{s. Wash. Obs., 1877), and the star is identical with Arg. -f 18°. 2278. |
||
|
" number of obs." ]irob. should be 1 in- |
4114 |
— |
There is no star here. The right ascen- |
||
|
stead of 2, — this one observation being |
sion for 44"> should be 45'" probably, and |
||||
|
made on Feb. 2, 1863, the result of which |
the Circle reading was either 5' or 10' |
||||
|
shows exactly the same figures as the |
wrong, so that the star is identical either |
||||
|
right ascension in Catalogue. |
with Y. 4117 or with Y. 4118. |
94
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
IX. — Corrigenda in YarnalVs Catalogue, second edition (1«78) — Coutinued.
Cat. No.
4177 42S5
4598 4598 4693
4879
Col.
5269
|
5459 |
— |
|
5831 |
d |
|
5831 6347 |
a S |
|
6538 683-2 |
8 S |
|
6999 7016 |
a S |
|
7022 |
S |
|
7027 |
a |
|
7252 7355 |
7356
7.582 7965
8047
8486 S490 8665
S a
S a
S S a
For 32' read 31'.
20^.74 read 18».74 (—error in Wash.
OL>s.,ls6!), p. 269). + read — .
3». 158 read 2^986 iu precession. Right ascension and declination are of two
different stars. a and 5 belonj; to two different stars, and are wrongly conihined. The right as cension is that of Lam. 1181, the declina- tion proliahly that of a star that was ob- served also by Wash. Eqnatorial, A. N., No. >573. In Ham. Coll. Zones were ob- served :
111- 32" 38»: —5° 14' 21" (Lam. 1181) 33 1 20 3 (Wash.Equ.)
33 18 19 48
There seems to be no good authority for calling this star Far. It is 6.7 magui- tnde. For g Virginis read 49 Yirg. (s. Argelau- der in Bonn Obs., VI], )). 41M). 25° read 23° (as it is in Wash. Obs.,
1849). 2«.749 read 2'. 777 in precession. 42' read 38' (s. Wash. Obs., 1848). The
star is R. u070. 23' read 21'.
48' read 47' (s. Wash. Obs., 1871, App. II, p. 78). The slar is 29 li Herculis. 3'.716 read 2".71ii in precession. 58' .')'J".9 read 5'.!' 31". 5. The correction of 1 rev. =31". 6 is demanded by 5 observations in the Wash. Zones. Is over 5' too far south. The star is O. Arg. 16153. Prob. 30= too great, and the star is identical with No. 7021. For 2".571 read :i«.571 in precession.
46«.83 read M'.^'S. The right ascen- sion 4tj».83 probably was O. Arg. 170>-'8, tlie declination of which was not oliserved at the Mnral Circle. Belongs to the preceding slar, and is here to be canceled. The right ascension of O. Arg. 17094 was not observed. For 6". 8 read 16". 8 ( — error of Cat.; Wash. Obs. correct). 26' read 27' (s Wash. Obs., 1845, p. 267; by oversight the star is omitted in the special catalogneon p. 273). 38' read 37' (—right in' Wash Obs.). There is no star to be seen in ihis place. The right ascension agrees with 0. -Arg. 19016, the declination (to about 20") with O.-Arg. 19^)00-2. For 8' read 10'. 6' read 9'.
8«.36 read 9'.36 (LL., O.-Arg., Lam. agree).
Cat. No.
8670" 8768 8868'
9067 9218
Col.
a Mag.
9382 —
9521
9633
9666 ; a
9678
9970
10304 10340
10342
10495' 10577
Seems to be identical with 8670'". For — read -(- (misprint). aaud 5 are wrongly combined; the right ascension is that of R. 82rt8=0.-Arg. 2047.'., the declination that of R. 8291 = O.-Arg. 20493. For 40™ read 41" prob., and the star = Y. 9078.
8.0 should be* rather 4.0 — error car- ried over from the ist edition. No star seen in this place. By assuming in Wa>h. Obs., 186-, p. 298, K'o. 38, the micrometer reading 32 rev. instead of 39 rev., the declination would result — 23° 49' 11". 1, and the star become identical with No. 93^1. In the Wash. Obs., Id46, p. 439, No. 520, are two errors: for 3l3™ 46«.f'3 and iiO' 40".69 ought to be read 33'" 46'. 83 and 50' 14". 69. This makes the position for 181)0: 21" 34" 11M4; + 38° 52' 55".9; which is therefore another ob.serv.Ttion of Y. 9481. This right ascension belongs .still to 7/ Piseis Aust. ; that of Lac. 89n9 has not been observed at Washington. For 34M^4 read 37^84 (perhaps typo- graphical error). 5,sm ivatl .">7'" — error of n duction from Wash. Oi>s., 1809, where, on p. 289, the right ascensiou is given cor- rectly. The star is identical with Y. 9. .69. 22' read 21'. The error exists already iu Wa.sh. Obs., 1871, App. II., p. 96; hut the originals for 1855 are not publisbed. 15"> rea<l W'" (s. Wash. Obs., 1875). 13' 56". 7 read 9' 6".0 — error origi- nated from erroneous refruclioii in Wash. Obs., 18i'.9, p. 221, No. 44 ; for 5' U".8 read 0' 31". 0. The star is identical with No. 10339. Is still an other observation of ihe star just menliont;d. In Wash. Obs., 1846, p. 18, No. 12, the instrumental correction is erroneously computed ; for +U^8i it should be — 1''.35. Then the mean of the 2 oliservations made in 1846 gives tlie liglit a.scension of Y. 10339: 4:i".14 (2) instead of 42».93(1). Tlie declina- tion (Wash. Obs , 18.i9,p. 218, No. 53) is probably iu error by 1 revolution :=31".2, and should be 5".l instead of 36". 3. For 14' read 1' (misprint). The star is Dm. +117°. 1562. Is not O.-Arg. 23156, but 23141 (corrected by -f 1'").
COEEIGENDA IN YAEIOUS STAR CATALOGUES.
95
Here follows a list of "Auouj-mous " identified in other catalogues. Arg. VI means the 6th volume of the Boun Observations ; Lamont's number refers in each case to the particular catalogue for the corresponding declination.
|
No. |
No. |
No. |
||||
|
Yar- |
Catalogue. |
Yar- |
Catalogue. |
Yar- |
Catalogue. |
|
|
nall. |
nall. |
uall. |
||||
|
745 |
Arg. VI. 1''.37. |
6532 |
Lam. 1911. |
8624- |
Lam. 426. |
|
|
914 |
Lam. 291. |
6552 |
Arg. VI. 15.75. |
8677' |
0. Arg. 20215 (corr.). |
|
|
928 |
LaCailleGOO. |
6555 |
LL. 2Hyi3. |
8688 |
Lani. 1097. |
|
|
945 |
Arg. VI. 1.92. |
6696 |
Arg. VI. 16.6. |
8700 |
Lam. 1102. |
|
|
1107 |
Arjt. VI. 2.37. |
(5937 |
O.-Arg. 159.*l (corr.+10'j. |
870.S' |
Lam. 3120. |
|
|
1313 |
O.-Ai's. 2UU7 (5 coiT.). |
6953' |
O.-Arg. 16019. |
8718 |
Lam. 3126. |
|
|
1480 |
Arg. VI. 3.57. |
6962 |
Arg. VI. 16.61. |
8725 |
Lam. 3130. |
|
|
1695 |
Arg VI. 3.yti. |
6964 |
O.-Arg. 161135. |
8735 |
Lam. 1118. |
|
|
1738 |
Arg. VI. 3.113. |
6964' |
0. Arg. 16037-8. |
H753 |
Lam. 477. |
|
|
1888 |
Arg. VI. 4.53. |
6976' |
O.-Arg. 16062. |
8761 |
Lam. 479. |
|
|
1970 |
Arg. VI. 4.99. |
(i980' |
O.-Arg. 16067. |
8828 |
Lam. 502. |
|
|
2U00 |
Arg. VI. 4.108. |
7013 |
O.-Arg. 11.133-4. |
8849 |
Lam. 515. |
|
|
2115 |
Aig. VI. 4.142. |
7064 |
Arg. VI. 16.92. |
8855 |
Lam. 517. |
|
|
2193 |
0.-\rg. 3742. |
7198 |
Arg. VI. 17.31. |
8868 |
O.-Arg. 20508. |
|
|
2202 |
Arg. VI. 5.14. |
7199 |
Arg. VI. 17.33. |
8900 |
Lam. 1205. |
|
|
2225 |
O.-Arg. 3846 (prob.). |
7201 |
Arg. VI. 17.36. |
8922 |
Lam. 7632. |
|
|
2297 |
Lam. 59. v |
7317 |
Arg. VI. 17.68. |
8930 |
Lam. 7645. |
|
|
2464 |
Lam. ItiO. |
7421' |
O.-Arg. 17242. |
9020 |
Lam. 595. |
|
|
2571 |
Arg. VI. ().20. |
7428' |
O.-Arg. 17260. |
9040 |
Lam. 3374. |
|
|
2572 |
Arg. VI. 6.2 . |
7429' |
O.-Arg. 17262. |
9043 |
Lam. 317. |
|
|
2573 |
Arg. VI. (i.22. |
7470 |
Arg. VI. 17.102. |
9051 |
Lam. 318. |
|
|
2635- |
O.-Arg. 5144. |
75f<9 |
Arg. VL 17.118. |
9099' |
O.-Arg. 20902. |
|
|
2672 |
Arg. VI. 6.102. |
76O0 |
Arg. VI. 17.122. |
9130 |
Lam. 639. |
|
|
2716 |
Lam. 3.57. |
7694 |
Arg. VI. 18.16. |
9134' |
O.-Arg. 20966. |
|
|
27a5 |
Lam. 393. |
7713 |
Lam. 535. |
9149 |
Lam. 7930. |
|
|
2790 |
Arg. VI. 6.171. |
7? 19 |
Lam. 29. |
9152 |
Lam. 3452. |
|
|
2809 |
Arg. VI. 6.1 4. |
7777 |
Lam. 58. |
91.57 |
Lam. 340 (corr.-f-lO'). |
|
|
2927 |
O.-Arg. 6484-5. |
781.5" |
Lam. 44 (corr. — 1*). |
9174 |
LL. 40;,99. |
|
|
2943' |
O.-Arg. 6.536. |
7H78 |
Arg. VI. 18.97. |
9228 |
Lam. 362. |
|
|
3045 |
Arg. VI. 7.22. |
7906 |
Lam. 60. |
9246' |
LL. 41021. |
|
|
3180 |
O.-Arg. 7449. |
7915 |
Lam. 63. |
9260 |
Lam. 3546. |
|
|
3255 |
O.-Aru. 7740-1. |
7919 |
LL. 34650. |
9261' |
LL. 41100. |
|
|
3432 |
Arg. VI. f.Ki. |
7719' |
LL. 34661-3. |
9294 |
Lam. 702. |
|
|
3434 |
Arg. VI. 8.66. |
8035 |
L;im. 7.'.0. |
9322 |
Lam. 714. |
|
|
3451 |
La Caille 3374. |
8051 |
Lam. 2951 (?). |
9334 |
Gniiimlir. 3445. |
|
|
3456 |
O.-Arg. 8697. |
8154' |
\V. 18''. 1293. |
9363 |
Lam. 727. |
|
|
3476 |
Arg. VI. 8.81. |
8090 |
Lam 3003. |
9380 |
O -Arg. 21434 (corr.— 1™). |
|
|
3652 |
Lam. 460. |
8091 |
Lam. 3007. |
93H1 |
O.-Arg. 21436 (corr.— 1'"). |
|
|
3H67' |
O.-Arg. 8870 (prob.). |
8114 |
O.-Arg. 19058. |
9399' |
O.-Arg. 21447. |
|
|
4092' |
w. yi-.gio. |
8122 |
Lam. 797. |
9401 |
Lam. 740. |
|
|
4297 |
Lam. 8ri9. |
8157 |
Lam. 2688. |
9404' |
O.-Arg. 21466. |
|
|
4357 |
Lam. hg4. |
8169 |
Lam. 3077. |
9417 |
Lam. 4317. |
|
|
4448 |
Lam. 775. |
f^l74 |
Lam. 3083. |
9429 |
Lam. 1426. |
|
|
4543 |
Schj. 3972. |
8178 |
Lam. 3091. |
9439 |
Lam. 4328. |
|
|
4566 |
Laiii. 3134. |
8184 |
Lam. 109. |
9518 |
Lam. 37.52. |
|
|
4822 |
Lam. 3373. |
8248 |
Lam. 875. |
9529 |
Lam. 1464. |
|
|
4838 |
Lam. 1163. |
8309 |
O.-Arg. 19.551. |
9542 |
Lam. 8544. |
|
|
5034 |
Lam. 1096. |
8344 |
Arg. VI. 19..57. |
9549 |
Lam. 8.551. |
|
|
5035 |
Lam. 1097. |
8362 |
Lam. 150. |
9556 |
Lam. 8,563. |
|
|
5104' |
O.-Arg. 12021-2. |
8372 |
O.-Arg. 19735. |
9558 |
R. Nachtrag 132. |
|
|
5333' |
O.-Arg. 12425. |
8406 |
Lam. 161 (corr.— 10»). |
9567 |
Lam. 1472. |
|
|
5403 |
w. lyi-.^sg. |
8408' |
LL. 37162. |
9675 |
O.-Arg. 21870. |
|
|
5G07 |
Arg. VI. l^>^ 48. |
8417' |
LL. 37207. |
9735 |
R. 9003. |
|
|
5860 |
O.-Arg. 13447-8. |
842li |
LL 37236. |
9809' |
W. 22^295. |
|
|
5948' |
LL. 20307. |
8434 |
Lara. 358. |
9848 |
Arg. VI. 20..54. |
|
|
5984 |
Lam. 1702. |
8439 |
Lam. 169. |
9850 |
Arg. VI. 20.55. |
|
|
6024' |
O.-Aig. 13758. |
8441 |
LL. 37290. |
9907 |
O.-Arg. 22220 (corr.-|-l°>). |
|
|
6179 |
Arg. VI. 14.107. |
8470 |
Arg. VI. 19.79. |
9928 |
Lam. 3931. |
|
|
6204 |
O.-Arg. 14v!.^0. |
8493 |
Lam. 176. |
9948 |
Lam. 514. |
|
|
6257 |
O.-Arg. 14362 (? eorr.+20«). |
8511 |
Lam. 3012. |
9993 |
Sclij. 9302. |
|
|
6373 |
Arg. VI. 15.32. |
8.524' |
LL. 37701. |
10036 |
Lam. 4662. |
|
|
6377 |
0. Arg. 14614. |
8538 |
Lam. 401. |
10129 |
LL. 2.5028 (?). |
|
|
6481 |
Arg VI. 15..53. |
8.574 |
Lam. 411. |
10622 |
O.-Arg. 23208. |
|
|
6502 |
Arg. VI. 15.63. |
8585 |
Lam. 1046. |
96 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
X. — Corrigenda in the Olasgoic Catalogue of 6415 stars.
|
No. |
Col. |
|
|
1640 3289 4051 |
N. P. D. a a |
For 5". 94 read 59".48 (misprint). 52™ read 5:i">. The star is rightly identified with W. 897; it is also Schj. 468.1, and Dm. -|- 10". 2496; so that there remains uoduu lit about I he correction. This changes also the pre- cessions a little. 20'" read 19™. This, together with the correction of north polar distance indicated in the eriala on page Ixvii, makes the star identical with No. 4U44, which is LL. 29924, W. 802, and Dm. + 8°. 3194. There is no star in the uncorrected place. |
In the precessions some mistakes, besides those pointed out in the Errata, have been detected.
|
No. |
Read precession in right ascension. |
No. |
Read precession iii north jiolar distance. |
|
|
708 |
2" |
9930 • |
934 |
10". 621 |
|
982 |
2 |
. 9729 |
2375 |
14 .548 |
|
1274 |
2 |
.9627 |
2577 |
16 .786 |
|
1947 |
3 |
.5306 |
3143 |
20 .023 |
|
3289 |
3 |
.0166 (for correction in position). |
3289 |
19 .516 |
|
3300 |
3 |
. 0207 |
3484 |
17 .669 |
|
4067 |
3 |
. 0237 |
3485 |
17 .667 |
|
4258 |
2 |
.8177 |
4694 |
5 . 106 |
|
4261 |
■2 |
.7817 |
5390 |
14 .651 |
|
4262 |
3 |
. 1)202 |
5439 |
15 . 107 |
|
4363 |
2 |
. 4641 |
||
|
4476 |
3 |
. 2680 |
For No. .39.% the ".secula r variation of precession "should |
|
|
4558 |
2 |
. 8996 |
be read + 0". 0142 iush-;id of + 3".4796 (indicated |
|
|
4953 |
2 |
. 8345 |
by Anwers). |
|
|
5079 |
2 |
.8158 |
||
|
5169 |
2 |
. 3320 |
||
|
5522 |
3 |
1923 (for correction in north pol.ar distance). |
||
|
5912 |
3 |
.1072 |
||
|
6095 |
2 |
.9744 |
'Kl.— Corrigenda in the catalogues of the tiro volumes of '■^ Ohservations at Santiago de Chile " j)ub-
lished by Moesta.
A. lu Volume I (Observations 1853-'55).
|
No. |
Col. |
No. |
Col. |
|||
|
24 |
5 |
For 119° 51' 28". 30 read 122° 51' 30".74. |
655 |
S |
For 34' read 44'. |
|
|
24 |
a |
30«.3rf read 30».31. |
675 |
S |
3' read 2'. |
|
|
32 |
(5 |
59' read 58'. |
682 |
a |
0S.20 read 1^20. |
|
|
51 |
d |
24' read 14'. |
743 |
d |
132° read 133°. |
|
|
60 |
d |
9".21 re.id 19".21. |
762 |
d |
23' read 30' (i.* Lac. 7202). |
|
|
95 |
S |
46' read 47'. |
774 |
a |
51'" read 50'". |
|
|
151 |
S |
46' read 45'. |
788 |
S |
.58'35".0reail.^9'll".0. |
|
|
152 |
S |
40' read 39'. |
813 |
d |
31' read 41'. |
|
|
209 |
6 |
4:!' read 53' (the star is W. 3^233). |
849 |
d |
,54' read 33'. |
|
|
211 |
6 |
37' read 38'. |
850 |
6 |
7' 43".86 read 8' 39".97. |
|
|
219 |
B |
44' read 34'. |
888 |
Name |
Lac. 8778 read 8777. |
|
|
260 |
d |
39' rea<l 4 1'. |
926 |
5 |
120° 17' 7".37 read 114° 22' 4 |
".42. |
|
316 |
a |
3y».60 read 9'.60. |
926 |
a |
21M7 read21«.28. |
|
|
341 |
S |
70° 0' 2".20 read 68° 55' 1".94. |
989 |
a |
43».56 read 41».4l. |
|
|
341 |
a |
33«.24 read 32^43 (the star is W. 5'= |
992 |
a |
46«.34 read 47M9. |
|
|
.1344-5). |
994 |
S |
32' read 22'. |
|||
|
470 |
S |
36' 26".85 read 35' 2".98. |
■ 995 |
a |
53M2 read 20».31. |
|
|
618 |
a |
59'" read 58'". |
CORRIGENDA IN VARIOUS STAR CATxVLOGUES.
97
XI. — Corrigenda in the catalogues of the two rohtmesj &c, — Coutinued.
B. In Volume II (Observatidiis 16r)fi-T)0).
|
No. |
Col. |
No. 1066 |
Col. |
||
|
236 |
a |
Preu., for 2«.fi31 read :!'.514. |
5 |
For 37' read 38'. |
|
|
236 |
a |
For 33"'5d".62 read 34"'2Mo (the star is LL. |
1087 |
a |
4(;n. 448 read 47"' 4". |
|
6786). |
1248 |
S |
51' read 41' (prob.). |
||
|
263 |
a |
Free, for 2'.378 read S'.'JTl. |
1249 |
S |
52' read 32'. |
|
263 |
a |
For 41«.70 read 41*.:{7. |
2022 |
8 |
116° read 140°. |
|
386 |
S |
57' read .'•>8'. |
2102 |
S |
101° read 100° (is = LL. 41921). |
|
425 |
S |
30' read 29'. |
V2109 |
a |
29™ read 28"' Htlie star Is W. 21'> 101° read 100° S -662). |
|
546 |
d |
118° read 138°. |
>2109 |
d |
|
|
800 |
a |
37».87 read 32^87. |
2257 |
S |
95° read 96° (is = LL. 45340). |
|
805 |
a |
28».17read29".17. |
XII. — Corrigenda hi the catalogues of the Geneva Observations from 1842-'49.
|
Tear. |
Page. |
Star. |
Col. |
For— |
Yeai-, |
Page. |
Star. |
Col. |
For— |
|
1''42 |
69 |
39 Andromeda'. . |
S |
41° read 40°. |
1844 |
87 |
A' Tauri |
or |
41' read 3^ |
|
77 |
24 ni Scorpii |
a |
28» read 26«. |
90 |
Pi. 8^48 |
8 |
irread9'. |
||
|
77 |
42 0Opblucbi... |
a |
22S.67 read 7».G7. |
1846 |
91 |
W. 14M158 |
a |
.50'.73 read 47^73. |
|
|
78 |
Piazzi282.... |
Name |
282 read :i01. |
1847 |
69 |
Anon. 81' 27"' ... |
8 |
15' read 14'. |
|
|
78 |
Piazzi282.... |
a |
39M0 read 34'.10. |
72 |
W. 14". 687 |
a |
9». 119 read 11».09. |
||
|
1843 |
82 |
42 Leonis |
5 |
16° read 15°. |
75 |
An. 10"46"°49».. |
a |
46"' read 45'". |
|
|
84 |
(1585)Viri;iuis |
S |
18' read 17'. |
1848 |
97 |
Anon. lOii 11" . . |
8 |
22° read 21°. |
|
|
84 |
3 Serpentis |
6 |
32' read 31'. |
97 |
W. 10''.620 |
a |
43'" read 34'". |
||
|
85 |
6 Serpentis |
8 |
7' read 17' |
108 |
LL. 43294 |
a |
•^l».63read 22^63. |
||
|
. 85 |
10 Serpentis |
a |
2» reail 42". |
100 |
LL. 43297 .... |
a |
27».98 read 28".98. |
||
|
87 |
Pi. nh.S/G ... |
8 |
19° read 9°. |
1849 |
111 |
Pi. 13".294 |
8 |
.'>7' read 51'. |
|
|
90 |
Anon. 201' 18'"- |
S |
22' read 21'. |
119 |
Pi. 21".173 |
a |
21«.40 read 22».71. |
||
|
91-2 |
Pi. 21>'.173... |
S |
48' read 47'. |
■ |
Sup2)lement to Corrigenda in YarnaWs Catalogue.
|
No. |
Col. |
No. |
Col. |
||
|
2033 |
aprec. |
For 3«.010 read 3«.310. |
6654 |
a prec. |
For 2,531 read 3,.'',31. |
|
2209 |
8 |
+ read — . |
7036 |
a prec. |
3,713 read 2,713. |
|
4200 |
anrec. |
2.237 read 3,237. |
7562 |
a: prec. |
+2.501 read — 2,.501. |
|
4678 |
5 |
+ read — . |
76119 |
a prec. |
3,064 read 4,064. |
|
4694 |
a prec . |
3,37& read 3,578. |
8622 |
8 |
+ read — . |
|
5091 ' |
a prec . |
2w,44 read 2,844. |
9442 |
8 |
+ read — . |
|
5526 |
5 |
+ read — . , |
9550 |
8 |
+ read — . |
|
6451 |
a prec - |
3.148 read 2,148. ' |
9705 |
S |
+ rea.i — . |
|
6510 |
a prec. |
3,787 read 2,787. |
9751 |
ornrec. |
Read 3,417. |
|
6516 |
a prec. |
3,050 read 2,0.-.0. |
6651 |
Name |
For Anon, lead \V. l.-,".llli9. |
|
6563 |
a prec . |
+ 3,561 read — 3,561. |
Additions to be inserted :
O. Arg (Soutb Cat.) 21966: ais 3" too small (also in Z. 256.87).
W. 1>'.445 : 5 is 2' too great (t).
Wj. 5^.1275 : a is 6' too great.
Scbj. 5464 : nrprecession for 3'.271 read 3i'.261.
Y. il21 : 8 for 44' read 43' (see Wash. Ol.s., 1862, ]>. 317. and 1869, p. 424).
Y. 8851 : a for 4^.67 read 3».67 (Is correct in the Wash. Obs.).
Y. 9338: a precession, for 2'',496 read 3».496 (error carried over from let edition).
S. Mis. 154 13
NATIONAI^ ACADEMY OF SCIENCES.
VOL. III.
TWELFTH MEMOIR.
RATIO OF METER TO YARD
99
RATIO OF METER TO YARD.
By C. B. CoMSTOCK.
READ APRIL 21, 1885.
Before the close of the work of the Lake Survey, a steel meter then designated R 187G, was sent to the Bureau International des Poids et Mesures, at Sevres, France, for comparisons with the standards of that Bureau. It has recently been returned with values for its length and for its coelficient of dilatation. As it had previously been compared in the Lake Survey office with the Clarke yard A, a yard which had been carefully compared by Colonel Clarke with the standard yard Yjs of the Ordnance Survey, the comparisons give a value for the ratio between the yard and meter.
The value for that ratio which for some years was supposed most exact, is given by Colonel Clarke in his comparisons of standards of length, and was derived from comparisons with several closely agreeing toises, dependent for their length on the toise of Peru. As the meter was legally defined to be 443.296 lines of the toiseof Peru, Colonel Clarke, from this definition, found the meter ecjual to 1.09362311 yards, or .39.370432 English inches.
The meter of the archives was intended to satisfy this definition, but when adoi)ted as a standard the ideal meter became the length at 0° V of the bar of platinum called the meter of archives, and no longer depended on the toise for its length.
In recent years it has been known that the ratio obtained by Colonel Clarke needed correc- tion, and as a value for it, which cannot be lai-gely in error, can be obtained from the Lake Survey comparisons already mentioned, I have thought the result might be of interest to the Academy. The details have been communicated to the Chief of Engineers and will probably soon be pub lished.
The compaiisons made in the Lake Survey office of tlie Clarke yard A with the metre K 1876, and by Colonel Clarke with the Ordnance Survey standard Yss, may be found in the Report on the Primary Triangulation of the United States Lake Survey. From those comparisons and from the value of Y55 in terms of the English prototype yard ISo. 1, there results :
E 1876=l.y 09388063 at 57.092 F.
The errors which enter this value are those in the value of Y55 in terms of the English i)roto- type yard No. 1; those in the value of Clarke yard A in terms of Y55; and those in the value of Meter R 1876 in terms of Clarke yard A. As to the probable error in the value of Y55, given by Colonel Clarke as 0.y9999996 at 62° F. little is known, and Colonel Clarke's "Comparisons of Stand- ards of Length" does not indicate that Yr,5 has been compared with the prototype No. 1 since 18.'i3. At the time of its construction the value given by Mr. Sheepshanks for Y55 at 62° P. was 1.^00000043, differing about one millionth of a yard from the value given above by Colonel Clarke, which value results from intercomparisons by him of five standards under the assumption that the mean length of these standards had, in 1864, the same relation to the yard as that found by Mr. Sheepshanks in 18.53. Moreover, there is a possibility that the prototype No. 1 has changed length by a small (juantity.
The value of Clarke yard A in terms of Y55 is known with accuracy, probably to within less
101
102 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
than a millionth part. The value of R 1876 in terms of Clarke yard A was very carefully deter- mined. But the comparison of aline meter with an end measure yard is one involving many oper- ations, and of great delicacy. While the computed probable error in the value of R 1876 in terms of Clarke yanl A at 57° 93 F. was less than s-o-o^oTo pai't, the real error may be considerably greater.
Considering these sources of error or uncertainty, it would not be safe to assign a probable error to the vahie of R 1876, given above, less than from joifoiro to sWooo P'^i't of its length.
The value of R 1876 in terms of the English yard having now been given, its value in terms of the meter, will next be considered.
The Buieau International des Poids et Mesures in their comparisons of R 1876 have designated it as U. S. (Repsold,) and give for its length at 0° C.
U. 8.0=1000097^.81.
and for its coeflflcieut of dilatation between about 0° and 36° C. a, =0.000010563 ±0.000000011. The details of the work may be found in Tome III, Travaux et Meinoires Bureau International des Poids et Mesures.
This value of U. S. (Rei)sold) results from its comparisons with a meter of the International Bureau known as type II. The value of type II has been determined by the International Bureau in terms of another platinumiridium meter designated as I,, with the highest accuracy.
L, has been directly compared with the metre des archives and the committee in adopting provisorily as a unit of length Ij— 6"=l meter at 0° C. state that this value can only be changed by some tenths of a micron when the prototype meter is finally adopted.
As the probable error in tlie difference of U. S. (Repsold,) and type II is but a few tenths of a micron, that of type II and I2 less than one-tenth, and that of I2, with reference to the proto- type yet to be adopted, oidy some tenths of a micron, it will l)e seen that the value of U. S. (Rep- sold) = R 187G, given above, is i)robably not in error by one micron.
From the value of U. S. (Repsold) at 0° C. and from its mean coefficient of dilatation given by the International Bureau, its length at 57° 92 F. is U. S. (Rei)sold) = l ■".0002499. Comparing this with its value at the same temperature in terms of the English yard previously given, there results :
?^L^^= 1.093607, or ineter=39'°.3699 yard
In the Primary Triangulation of the Lake Survey a value for U. S. (Repsold) is given, furnished me by Professor Foerster of the Standards Bureau at Berlin. Tlie value is R 1876 = 1'". 00008618 at 0" C. a value ll.'*6 less than the one now given by the International Bureau. The value given by Professor Foerster depended on the value of the meter type I of the Interna- tional Bureau, for which he used the value at 0° C, type I = l™.0000676. This was doubtless the best value then known to the International Bureau, and was derived from indirect com|)arisous with the mfetrii des archives. Tome III, Travaux et Memoires, now gives —
Tyi)e I„=l"'.00007604 at 0° C
a value Si'A greater than the preceding one, and accounting for the larger part of the change in the value of U. S. (Repsold).
Nothing could show more clearly the importance of the work the International Bureau is now doin^; than the fact that the value of one of their princii)al meters, supposed known in 1880 within l** or 2** hns since had its value increased by the t2o"ooo part.
This increase in the value of type I, resulting from recent direct comparisons of L with the meter of the archives corres])on(Is to a similar diminution in the length of the ideal meter. But the change from Colonel Clarke's value of the meter in terms of the yard, to the value found above, corres[)onds to a reduction in the length of the meter of about 70^50^ part, and the recent change of 12^00 '" tlie value of type I accounts for but little over one-half of this 70000-
It .seems probable that a considerable part of the discrepancy must be due to errors in the values heretofore used of the ratio at diifereut temperatures of the meter of the archives to the toise of Peru and its derivatives.
NATIONAL ACADEMY OF SCIENCES.
VOL. III.
THIRTEENTH MEMOIR
ON COMPOSITE PHOTOGRAPHY AS APPIJEI) TO CRANIOLOGY; AND ON MEASURING THE CUBIC CAPACITY OF SKULLS.
103
ON COMPOSITE PHOTOGRAPHY AS APPLIED TO CRANIOLOGY,
By J. S. BILLINGS;
AND ON MEASURING THE CUBIC CAPACITY OF SKULLS,
By WASHINGTON MATTHEWS.
READ APRIL 22, 1885.
At the last annual ineetiug of the National Academy, we presented, through the courtesy of Major Powell, a preliminary communication upon the application of the method of composite l)hotography to the study of craniology.
Experiments in this direction have been continued at the Army Medical Museum during the past year, and we have arrived at what seems to be a fairly satisfactory method for centering succes- sive skulls in a series, in order that the images of each may be properly superimposed in the camera. This might be done in a great variety of ways; but the one u])on which we have settled, the details of which have been worked out by Dr. Matthews, is as follows :
The camera stand and "patent k^ver adjustment-gallery stand," for the object are leveled with a spirit level and the tops of both stands are adjusted at exactly the same height. Two flue black lines, one horizontal and one vertical, are drawn from margin to margin on the ground glass focusing plate, intersecting in the exact center. On the object stand are placed two frames on which intersecting threads are stretched, exactly parallel with the lines in the camera plate, so that they may be covered by the latter when focused. Besides these cross lines there is a verti- cal thread, stretched on a separate frame, lying in the same plane as the other vertical threads and the vertical line on the camera plate. The craniopbore is placed on the object stand behind the first or anterior frame at such a distance that the facial bones of the longest skulls will not interfere with the cross threads. The second or middle frame — that which bears a vertical thread only — is 22 centimeters behind the first frame and is, of course, behind the craniopbore. The third or posterior frame — a vertical board with a central opening 16 centimeters square — stands 50 cen- timeters behind the first frame; to its top attached by one margin, is a screen of black velvet, which IS raised while the skull is adjusted and dropped while the exposure is made. The posterior frame is fixed in its vertical position; the other two frames are attached to the stand by hinges, and are lowered during the exposure. A giaduated rule is placed by the side of the craniopbore and is photographed with the skull so that scale of each picture may at any time be ascertained.
After making sure that the threads are properly adjusted to correspond with the lines on the ground glass ])late, the sensitized [ilate is inserted, the cap put over the camera and the plate cover withdrawn. A skull is put on the craniopbore and adjusted, the first and second fi-araes are lowered, the velvet screen let oown, the cap removed and a fractional or partial exi)osure is made, the time being regulated by the metronome. The cap is then placed over the lens, another skull is adjusted on the craniopbore and another fractional exposure made, and so on until all the skulls of the selected series have been photographed on one plate which is not removed from the camera until the last exposure is complete. The focal distance is the same for each skull.
Tlie plane and points by which the skulls of the later series have been adjusted are the Ger- mau horizontal plane, the subnasal point, the supra-auricular point, and the maximum occipital point. For the front, the rear, and the side views we adjust the German horizontal plane to cor- respond with the plane of the horizontal threads, while the subnasal and maximum occipital points (or the supra-auricular points as the case may be) are brought into the plane of the vertical threads. In preparing for the front view we take sight on the horizontal plane and the subnasal point from the front — i. e. the side next the camera — and on the occipital point from behind through
105
S. Mis. 154 14
106 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
the oi^eiiiug in tbe third frame. In preparing for the rear view we take sight on the horizontal plane and subnasal point from behind, and on the maximum occipital point from before. With the side view the facial portion of the skull is turned toward the left. We take sight on the horizontal jjlane from a position to the left of the center; on the left supra auricular point from before, and on the right supra-auricular point from beliind. With the described apparatus views of the base and vertex have not yet been attempted, but it is believed that lateral frames with the usual cross-threads nuist be added to secure good views of these asi)ects of the skull.
The duration of each fractional exposure depends on many conditions; the sensitiveness of the plate, the refractive power of the lens, the orifice of the diaj)hragni, the degree of light, the color of the skull, and the number of skulls in each series. In a series of five skulls, other things being equal, each fractional exposure will be twice as long as in a series of ten. In photographs, 19 et seq., we used " Carbutt's Keystone dry plates," a Dallmeyer triplet, 4i-inch lens, a diaphragm with 14 inch aperture, and an exposure of from 10 to 20 seconds for each skull.
Different method-j of determining the adjustment of the skulls have been tried: First. Two sets of cross threads have been used, and the operator taking sight only from the front, with his head placed immediately in front of the lens. Second. Two sets of cross lines employed, the operator looking throiigii the camera only, the plate necessarily removed from the camera before each exposure. Third. Two sets of lines as before; an accessory camera used at the side; the front vertical thread aligned on the more distant margin of the anterior nasal orifice. Fourth. Two sets of lines used; a sketch of the first skull drawn on a cross-lined gelatine film, and each subsequent skull made to conform as nearly as possible to this sketch. Fifth. The plan already described at length and at present adopted by us, in which there are four sets of lines — one ou the ground-glass plate — and which the operator views not only from the front, but from behind, through the opening in the posterior frame, in order to secure a proper alignment of the maximum occipital point in the front view, and of the subnasal point and the horizontal plane in the rear view.
The apparatus used, which is illustrated in the plates, is rudely improvised from material at hand. The frames were not made on purpose, but were such as we had in the museum for other uses. A more convenient apparatus is to be constructed, but the general principles of the one now in use will be preserved.
Our craniophore, however well it may be adapted for the purpose for which it was originally intended, is not well suited for adjusting skulls in photography. The modification of this, recom- mended by Ranke figured in "Archiv fiir Anthropologic, 1S83," would undoubtedly do better, but a still more suitable craniophore can, we believe, be devised, and we propose to have such an instrument constructed.
Two sets of composite photographs of crania are shown herewith, viz : One set including six male Sandwich Islanders' skulls, and one set including six male Arapahoe Indian skulls. There are six photograjihs in each set, and all are exactly half the size of the original objects.
The value of this method of composite photograi)hy, as applied to crauiological studies, de- pends, to a very considerable extent, upon the adoption of some uniform standard of size for the preparation of such i)hotographs, in order that the series of specimeus in different uuiseums and collections may be directly compared. It appears to me that the most convenient scale for such photographs is to make them of one-half their natural size — that is, so that the inch divisions on the graduated rule, which is always photograjihed with each set, shall measure exactly one-half inch in the photograpli.
These composite photographs must be studied in connection with the measurements of the crania represented in them. The method is simply a rapid and convenient means of obtaining a graphic representation of a series of irregular objects, a jdccure whicli should indicate not only the mean size and shape of these objects, but also, to a certain extent, the maxima and minima of their variations. I think it is much better to make the photograi)hs directly from the skulls them- selves, than to construct them from separate photographic i)rints of each skull ; which appears to be the method pursued by Dr. Thomson, of Edinburgh, in the specimens given by liim in the "Journal of Anatomy and Physiology," London, 1885, Volume XIX, Ft. II, page 230.
It is well known to ethnologists that the distinctions of race are much more marked in the physiognomy of the living subject than in the differences shown by dried crania ; and that the
*'<».
?i.m-«.
• ' I .
4 ^
\^^ *c* - * ^, ¥ .'^ ^'W: '*i'':f ""^^
TEMOmS OF THE }=(A'r
ihini II,: !t from i , 'r V tin ll::r ••
OIJ i.
aiici vertex i, i utteiuj
cmss-thread* ..^ ..-. ... lo secure
The dur.itiou of each fractional e. the ])late, t!j<' refractive power of the lcui^, lii. (•(>!. ij '>!' i' knU, and the number of skulls in ■ nil, each fractional exposure will be tv
- ' " Garbntt's KeJ^ I , ! tare, and an exp'
.rept niethodis of determining the atljustin,eat of the skulls ha \ ids havf; beeu used, and the oi ' ' •
iliately in front of the k'n>i . ug through thecameraonly, th I'd. Two soth »f lii,' :^^ued on the more C ii sketch of the first skull drawn o o' form as nearly as possible '■ 111, sent adopted by us, in whi' which the operator views not only from ti posterior frtyme, in order to secure a pro| view, and of the subna«al point and thi The apparatus used, which is ilhis ;iaud. The frames were not made on ,^t., .
SOIENOES.
UH' llUi'I/DlllUI [MiUU'
ore. With the side
nt oil the horizontal
■ ' from before, aiid
; 'W8 of tlie-base
with the usual
iliveuess of
■f light, the
ilici' things
';4raphs,
. apliragm
et.s
thooamera befoj'e each exposure.
' ' ' 1 thread
■; used;
;ch subsequent skull made 'c
- ' ■■' -^ ' .- -" -^'dat
nd
opeuiug in the
4 ii.u iioint in the front
: ihe plat&s, IS raueiy unprovised from material at ■ . . but were such as we had in the museum for other uses. A more convenient apparatus is to be constructeil, but the general principles of the one uow in use will be jireserved.
Our crauiophore, however well it may be adapti ,1 .^,. , .... ^ ..,.^ ., ,.r which it was originally intended, is not well suited for adjusting skulls in photography. The modification of this, recom- iiieiided by Ranke figured in "Archiv fUr Anthropc' • do be'
.1 still more suitable craniophf"" '■<'" ^^^ ''u-'',.\,. i ii^i <>.
iiistniment constructed.
Two sets of ( iiug SIX
II. .I"' Sandwich 1^ . Thcr,
six photographs in eai il objeci
Hie value of ■ ■ ^j-Qji^^jg^ j^,.
peii'* .. tv) n very I' ■ _ ■, . ; . size for the
pre; '*t' such photographs, in order that the series of spfeciuvons in different museums and
ly be direct'y compai. ' o me that the most convenient scale for such
is to make them of ; val size — that i^
1 rule, which is always photographed with each ac
; hat the inch divisions on leasuro exactly one-half
:ih.
Lima i\
ami con
d pursued b 'imy and i'b \vn to ethm he living su
ji'^o'-ojxraphs must be studied in r-fv i'he method is .simply
• regular objeci*, it ■ ':
t»nt also, to a !■
to make the pljotogrn , '■ "'''"Vraphic printis ■>. ■ urgh, ill the spe
.irements of the
,eans of obtaining a
.:i' ; u' indicate not only the
tlie maxima and mininvi of
-tcalls th(?m-
. . ,. iL Li appears to
iiven by him in the
:ige230.
..i.\. ...^ u... .. more marked in the
hown by dried crania; and that the
1^ . j^ .. * ^ :^ » fi^.
ARRANGEMENT FOR TAI^NG COMPOSITE PHOTOGRAPHS OF SKULLS.
PHOTOGRAPH NO 1 Shows elevaung table, craiuophore.a-oss lines. aiidnieasure.blackvel\''eLl3ackgi'oimd raisedivlule skull ia bemg placed inposit-ion. Front and middle sets of lines, set, on hinged frames, are lowered before tJielensisuncoveredSkuUnoLaccuraLely adjustjpd
Julius Hieniit-" l-itli
ARRANGEMENT FOR TAKING COMPOSITE PHOTOGRAPHS OF SKULLS.
PHOTOGRAPH NO. 2. Same as Nwl , nearer view, skull accuralely adjusted ior ;photo^raphiii^.
ARRMGEMENT FOR TAKING COMPOSITE PHOTO GR.APHS OF ^KT^TT
PHOTOGRAPH NO.;: Sum.. rtS Xo 1 . Skull i-.-iin)v<-,l
APPARATUS FOR TAKING COMPOSITE PHOTOGRAPHS OF SKULLS.
PHOTOGRAPH NO. 4 Shows cvcrvtlijiig rt-ady U> makp tlu^ exposTirG. The anterior and middle frames are lnw(!r<?(l , ut\cl the velvel screen has been di'oypi'd
luJsHicniColirh.
SIX ADULT MALE SANDWICH ISLAND SKULLS N0S425 444 442. 445, 438 a 286. .
No 16 A Dr3' plate. Exposure, eigliL seconds.
.MilmsTficr-KO-Lill.
SIX ADULT MALE SANDWICH ISLAND. SKULLS N°s 425, 444. 442. 445. 438 8 286
\t) 10 H Coruliljons same as No. 16 A.
JuluiSPicniiCn Lull
SIX ADULT MALE SANDWICH ISLAND SKULLS. ]v[os425, 444. 442, 445. 438 8 286,
No. 16. C Conditions same as No IG A.
SIX ADULT MALE SANDViTCH ISLAND SKULLS NO'S 425, 444, 442, 445. 438 a 286.
Xo 16 D Norma vertically based oiv alveolo condyleaiv plane. Conditions same as No IG A
SIX ADULT MALE SANDWICH ISLAND SKULLS N<'"425, 444, 44^. 445, 438 8 286,
Nil !(i I. i'vutUuous siinif us No. IG A
■TuImsliien^lCoLilh
SIX ADULT MALE SANDWICH ISLAND SKULLS N°s425, 444, 442. 445. 438 a 286
No 16. F. Norma veriicalas based on German lionzontal plane. Conditions same as N0-I6A,
SIX ADULT MALE ARAPAHOE INDIAN SKULLS N°=J2, 667, 774,892,1760,1832.
No. 17 A Dry pl:ite.Exposare, eij!;lit secoruls
SIX ADULT MALE AKAPAHOE INDIAN SKULLS . N°s 12, 667, 774,892, 1760, 1832.
No.l7 B Conditions sanae as No 17 A
SIX ADULT MALE ARAPAHOE INDIAN SKULLS ii"^i2, 667, 774,892,1760,1832
No.17 C. Coiidilionis same as No 17 A
Jnilu.sn.tl.ilCoLill.
SIX ADULT MALE ARAPAHOE INDL^N SKULLS N°=]2, 667, 774,892,1760,1832.
N'o 17 D Norraa verticalis based on alveoio-condylean plane Conditions same as JIo 17. A
Iiusllicll.'ifril.iti,
SIX ADULT MALE AP^PAHOE INDIAN SKULLS N°=12, 667, 774,892,1760,1832.
No.l7E. Conditions same as No, 17 A
ON COMPOSITE PHOTOGRAPHY AS APPLIED TO CRANlOLOCrY. 107
boues of the face with the rehitions which they bear to those of the calvarium, give more valuable race indications than do the calvaiia alone. While something has been done iu the study of the internal eonlij;nration of the cranial c:ivity, and more esi)ecial]y of the various fossae and projec- tions at its base, with reference to their differences in various races, this field of inciuiry is as yet coMijiaratively unworked. It seems very desirable to follow out this special line of investigation in connection with the large and valuable collection of crania of American races which now exists in the Army Medical Jluseum and in the National MnseuTn. To do this, however, it is necessary that sections should be made of the skulls, and before making such sections it is desirable that all measurements and especially the measurements of cubic capacity of these crania, should be made according to the best and most approved methods, and the results carefully recorded.
From the results of some preliminary experiments upon the methodsmost iu use for measuring the cubic capacity of crania, 1 became much dissatisfied with their accuracy, and accordingly requested Dr. Washington Matthews, my assistant at the Museum, to undertake a series of exper- iments for the purpose of obtaining, if possible, some more accur.ate aud reliable method of ascer- taining the cubic capacity. I think that he has succeeded, to a very great extent, iu devising a perl'ected method which accomplishes this result, and I have the honor to present to the Academy, by jtermission of the Surgeon-General, a full report, prepared by Dr. Matthews at my request, embodying the results of his observations and experiments.
Surgeon General's Office, Army Medical Museum,
Washmgton, D. C, April 14, 1835.
Sir: I have the honor to report, as directed, ou the experiments which have recently been made iu the Army Medical Museum to test the practicability of finding the cubic capacity of the cranial cavity by means of water. I will review briefly the general reasons which led us to perform these experiments.
The labors of anthropologists have been largely directed to perfecting methods iu which solid particles are used, but the laws regulating the fall and subsidence of granular substances are imperfectly understood and every change of condition and manipulation produces a change in the space occupied by them. True, Broca has formulated certain laws which govern the flow, distri- bution, and subsidence of solid particles, or, as Dr. Topinard calls them, granular bodies. But these laws are of limited application, " all bodies do not obey them with equal regularity," and, notwithstanding the accurate rules he lay.? down to govern our procedures in handling these bodies, it seems almost impossible for any two persons, by merely reading his instructions to arrive at the same results ; for Dr. Paul Topinard, the famous disciple of Broca, in his latest great work, says : " Published documents on the capacity of the skull can only be used with extreme caution. As a general rule only the results obtained by the same hand or by the immediate disciples of the same authority should be compared."* The laws of granulistic physics have been but recently studied, have been studied by few men, and are still imperfectly known. This is not the case with hydro- statics and hydraulics ; there are no sciences more widely or well understood, none which have louger formed a subject for study to our race. If, therefore, water could be used as a medium for cubing skulls, the perfect knowledge we possess of the laws which govern its motions would be of of vast advantage to us.
This is no new idea. A careful search, made in all the papers ou the subject that we could obtain, showed that experiments had been made iu this direction but without satisfactory results. Skulls had been rendered waterproof but at such a great expense of time and labor that when the best results were obtained, the skulls were available only for standards, by means of which to study or regulate measurements by other methods. As the conclusions of those who had pre- viously experimented with water are epitomized by Dr. Topinard in his work already referred to, I cannot do better than quote his words, which are as follows:, "The most simple and most direct procedure is that of water. All the exterior orifices except the occipital foramen are closed with wax, the cavity is filled with water, and to do it well, with distilled water at 4 degrees if the abso- lute weight is to be determined, aud at 14 degrees temperature, at which measuring glasses are
* El^meuts d'Antliropologie G^n^rale par le Dr. Paul TopiD.ard. Paris, 1855, p. 609.
108 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
graduated, if tbe volume is to be determined ; the water is emptied into a measuriug-glass of 3,000 cubic centimeters and you read; there is tbe difficulty, tbe water wetting tbe sides of tbe glass rises on it, and one can be mistaken to tbe extent of five cubic centimeters. Another cause of error, which is more important, is in tbe water wetting tlie walls of the skull itself, soaking and penetrating through the internal free orifices as far as the vacuoles and sinuses. If this water remained in tbe walls it would only be a half evil ; but when the skull is drained a part comes out of the sinuses and vacuoles a)id is unduly measured with what comes out of the cavity proper.
''Instead of directly seeking the volume we can proceed by weight. We weigh the skull full, then the skull empty; the difference is the weight of tbe water; but comprised in it is tliat which the vacuoles and sinuses contain. There is only one means of reme<lyiug this cause of error, it is to saw the skull, to cover it internally with au impermeable coat and to join the two halves. This (;an succeed; but in spite of the care exercised in the preparation one cannot guarantee that Ihe water will not again infiltrate the walls uni)erceived. If instead of measuring tlie water as it comes out of the skull it is measured as it goes in, the same causes of error persist."'*
Elsewhere he speaks of the use of those sawed and carefully varnished skulls as terms of comparison ; but even in this capacity he condemns them.t
A careful consideration of all the literature attainable on tbe subject of water-measurements led us to conclude that the experimenters had been too easily discouraged, had not sufficiently contended with the difficulties which the problem presented, and that we still had a good field for investigation.
In seeking for a substance with which to coat the skull and render it water-tight, the merits of fresh putty, to be removed before it hardened, were suggesteil, and it was first a]»i)lied on the 30th of last June. At first it gave by no means perfect results; yet it seemed to promise so much that we determined to persevere in its use. It appeared from the beginning that our chief diffi- culties were lack of dexterity in applying the putty and the hygroscopic nature of the osseous tissue. A number of experiments were performed, the causes of error noted and means devised to remedj' them. It is needless to recount all our mistakes and the various stages in the growth of the system. I will, therefore, proceed at once to describe our present methods and appliances, and, with these fully explained, the merits and demerits of the system can be more easily under- stood.
The following are the necessary implements and materials :
1. Scales and weights. •
2. An ether spray-apparatus of the pattern known as the reversible spray-apparatus with revolving spray-tube.
3. A bottle of shellac varnish, made by adding one part by measure of dry gum to nine parts of strong alcohol.
4. A roll of Seabury and Johnson's India rubber adhesive plaster.
5. A quantity of putty ; at least'teu pounds should be kept in store. C, 7, .S. Simi)le cerate, lard and linseed oil.
9. A bread-board and rolling-pin with which to work the putty.
10. A covered jar containing water in which to preserve the putty when it is not in use.
11. A reservoir of water provided with India rubber tubing and stop-cock. The reservoir now in use in our laboratory has a capacity of about 16 liters, is elevated 1| meters, has a tube - meters long and of 13 millimeters caliber, and a stop-cock of 5 millimeters caliber; but these are not essential details.
12. An ordinary tin half gallon measure, half-covered, and provided with a s]K)ut 3 centim- eters in diameter.
13. A wide shallow pan ])rovided with a lip, for receiving the water from the skull and trans- ferring it to the measuring glass. The pan we use is 36 centimeters wide and 8 centimeters deep.
14. A metronome, set to count seconds.
15. A measuring glass graduated for 2,000 cubic centimeters, such as that adopted by Pro fessor Eanke, of Munich.
•TOPINAUD, ioc.cit., page 592. t Id., ioc, ci«., pages 597,598.
ON COMPOSITE PHOTOGRAPHY AS APPLIED TO CEANIOLOGY. 109
IG. A wiper, consisting of a sponjje tied to a stout rod, to dry tiie nieiisuring glass after each measurement.
17. An insufflator.
18. A quantity of lycopodiuui in a convenient box or bottle; or a mixture of lycopodiuin and charcoal.
19. 20, 21, 22. Implemeuts for removing putty, from foss;e and foramina. We use dressing forceps, tenaculum, scoop, and nail-brush.
23. Thermometer. Procedure.
1. For this and all other methods of cubature of cranial cavities it is well to wash them out carefully first. In making measurements with granular bodies the value of cleanliness may have been overlooked and its absence may have proved an iun)ortant source of error. lu measuring with water it has been observed that much dirt comes from some skulls. One complaint made against methods where shot is used, is that they are dirty. This complaint would cease if the skulls were washed.
2. Before being washed or measured the skull should be weighed aud the weight recorded. After washing it should be left for some weeks to dry, until it again weighs exactly the same as before it was wet. This is to assure against increase in cul)ic capacity from absorption of moisture.
3. Spray the inside of the skull uniformly and completely with the shellac varnish by means of the reversible ether spray apparatus, taking care that the anterior and middle fossae are not neglectetl, as they cannot be seen so well as other parts. Use exactly 10 cubic centimeters of the varnish; this ainouut has been found sufficient to give the skull a complete coating; if more than this amount is used at one time it is apt to pour out through the sutures. This quantity, too, will leave exactly one ceutimeter of gum in the skull to be considered when we come to the cubing. It will not, however, alter the results if another measure of 10 centimeters of varnish is used after the first coat dries, care being taken to add one ceutimeter to the measurement for the additional gum put in the skull. The ])endant portion of the skull should be often changed while the spray- ing goes on, lest the varnish accumulate in one spot and flow out on the external table through some open suture. The largest skulls may be well varnished by this means in about three min- utes. It will be found a great saving of time to spray a large number at one sitting, as all the apparatus used iu this work must be thoroughly washed with alcohol before being laid aside. When the sprayiug is complete the skull should be allowed to remain, before measuring, long enough for the alcohol to evaporate aud the varnish to harden ; for this, in our experiments, at least twenty-four hours in a warm room has been given, but it is probable that a much shorter time would suffice.
4. The skull is examined, and if any artificial holes are found in its parietes, they are covered with pieces of suitable size of the Jndia-rubber adhesive plaster. The sijhenoidal fissure and the entire apex of the orbital cavity is also closed with a piece of this plaster, about au inch square, well forced into place.
5. Before the piece of plaster is put on the sphenoidal fissure, a piece of putty, sufficient to fill it and no more, is pressed into the optic foramen. The orbits are then entirely filled with putty. The carotid canal is next filled from its external opening, aud the putty is pressed until it appears or is telt at the inner opening of the canal, or until no more will enter. The operator puts his index finger iu at the foramen uuignum, aud places the tip, iu turu, in contact with the internal orifice of each foramen of the base; "he holds it there and presses a piece of putty into the foramen until he feels the putty comiug iu contact with his inserted finger; by this means he knows that the foramen is filled, ami yet that the true cranial cavity is not encroached on. The condyloid foramina aud the internal meatus are filled from within. He may put a piece of plaster over the meatus instead of the putty. Next the nares are tilled completely with the putty, and it is important that the substance should be well forced up to the base of the cribriform plate of the ethmoid. Next the sphenopalatine and temporal fossiB are filled, the putty being well pressed into all parts. If the squamous suture or other sutures are open, a little may be pressed into them, care being taken that none is forced into the cerebral cavity proper. The base of the cranium from the foramen magnum to the alveolar process is next liberally covered with putty applied with
110 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
barely sufiQcient pressure, except ou the palate, to make it stick ; if too miicli pressure is applied it will force iuto the crauial cavity the material ia the foramiua at the base of the skull, which has previously beeu applied with such great care. Next roll out on the breadboard, with the rolling- pin, a sheet of the putty of a size sufiBcieut to cover the vertex of the skull. It should be of uniform thickness — not less than an inch throughout. Now the skull is laid on the table, base downwards — and this position is important — the cap of putty is placed on the vertex, pressed closely on and worked around until it completely covers the cranium, leaving only the superior alveolne, parts, perhaps, of the zygomatic arches, and the margin of the foramen magnum exposed to view. The completed, the skull is ready to be filled.
6. In the mean time, or before you begin operations, you have the half-gallon measure filled to within about 3 centimeters of the top. Tbe skull is now held in the hands of an assistant, base upwards, in such a manner that the plane of the foramen magnum .shall dip forward at an angle of 45 degrees or more with the horizon. This is necessary in order that, as tbe water rises in the skull, air may not be imprisoned in the middle cerebral fossae. I have seen an error of 10 centim- eters result from a neglect of this precaution. Now take in the left hand the tin vessel of water and have the stop-cock either in, or convenient to, the right hand. Empty the water from the vessel iuto the skull through the foramen magnum as rapidly as you can, without sjnlling, until the skull is nearly full. Then rai)idly lay down the tin measure, open your stop cock and com- plete the tilling of the skull, taking good care that you fill it at once rapidly and exactly. Much depends on the care with which the last few drops are added. As the assistant sees the water rising to the edge of the foramen magnum, he will gradually elevate the anterior portion of the skull until the plane of the occipital foramen is horizontal, and when the stop-cock is opened he will bring the skull close to the edge of the pan so that the process of emptying may begin the instant the filling is done.
7. The moment you consider the cranium properly filled, close the stop cock and notify your assistant, who should instantly begin to pour out the water; this is best done by holding the skull in such a manner, occiput depressed, that during a greater i)art of the time the air may enter freely as the water runs out. I might convey an idea of the approved method by saying that the occipital region is held fixed and the superior alveolar region made gradually to describe an arc of 180 degrees, until at the end of tbe operation tbe base of the skull is downward. Once more the anterior portion is elevated so as to allow any accumulation in the anterior and middle fossie at the base to come back to the foramen magnum, and again depressed and rocked a little to each side to empty tbe posterior fossne. This completes the task of emptying. Not a drop of the subsequent drainage from the skull, no matter how abundant it may be, sbimld be taken into account. The filling and emptying of the skull should be done as rapidly as is consistent with l)roper care. Upon this celerity depends as much as on anything else the correctness of tbe results. A person who has gained a little experience can till a skull of 1,400 cubic centimeters accurately in 45 seconds and empty it in 15 seconds; both operations together should not occupy more than one minute. We have filled in 30 and emptied in 12 seconds, but for emptying we would recommend that just 15 seconds be always consumed.
8. Next comes tbe cubature: First wipe out the measuring-glass carefully, in case it is moist from a previous measuring, and then em]>ty the water from the pan carefully into the glass; every drop that can drain out being allowed to fall. Tbe measure is then placed on a carefully leveled table. A small quantity of lycopodium is put in the insufflator and blown on the surface of tbe water. This makes the true general surface of the water easily discernible and prevents us from mistaking for it the edge of the water which has been raised by capillary attraction on the surface of the glass. Then read oft' the number indicated and add one centimeter for the dry shellac in the skull.
9. Now take all the putty carefully from tbe skull, have tbe latter well cleaned and put it away in a dry, warm apartment for a week or more until it is as dry as it was before the measure- ment was begun ; this is determined by again weighing it, then you measure it once more to verify your former experiment.
Some further comments on the appliances and proceedings must now be given, which could not be introduced before without sacrifice of clearness.
The varnish has beeu only recently employed. The propriety of using it was early thought
ON COMrOSITE PHOTOGRAPHY AS APPLIED TO CRANIOLOGT. 1 1 1
of, but no good means of applying^ it siifrgcsted itself until the reversible ether spray apparatus came under our notice; since then we ha\e had time to experiment on only 10 skulls. Table II shows the result of these experiments. As far as they go they appear to mark a decided improve- ment in the process. But the imj)roveuient is probably not so great as the figures seem to indicate, for the measurements on the varnished skulls are our latest, and we have observed that our dex- terity in pursuing our own method is daily increased by ])ractice. The varnish does not entirely prevent the absorption of water by the skull, but it probably so retards the absorption and return of the water as to nearly eliminate the errors arising from these causes. Excellent results have been obtained without the use of the varnish — a maximum variation of 10 cubic centimeters, a mean of 5.20 cubic centimeters. (See Table 1.) The application of varnish is a means that requires more experiment ; perhaps the use of a difl'erent gum would be better, and perhaps it would be of advantage to use a larger amount, but in the majority of skulls this could not be done at one sitting. Furthermore it would be necessary to allow for a larger amount of solid gum in the skull when we come to measure.
The putty should be of firm consistency and as dry as may be compatible with due plasticity. If, in some dry skulls, it does not adhere well, the external table may be oiled a little. One slight trouble with the use of putty is this: In pressing it into and extracting it from the nasal fossffi it is impossible to keei) from injuring the turbinated bones where they are present. In the majorit}' of the skulls of our collection the turbinated bones are already so injured that it is unnecessary to exercise any care of them; but the advisability of preserving them in some cases has not been lost sight of, and a means has been devised to keep them intact when desire<l. This is to till the nares with a semisolid oleaginous substance that can be forced well uj) into the nasal fossae without breaking the bones. Simple cerate will do well in warm weather and lard in cold weather. This filling should be used only in the nasal fosste proper, and the coating of putty should comiiletely conceal and sustain it on the outside. It is removed by passing a stream of hot water through the nose; and, if motives of economy prevail, the unguent can be skimmed ofl" the water, preferably after the latter has cooled. A large skull will require all of the ten pounds of putty to cover it, smaller skulls proportionally less. To put on the putty properly and expeditiously requires some practice, particularly in tilling the foramina at the base. It would be well for the beginner to apply it first for a few times to the base of the sawed skull, looking only at the outside until he thinks his task is completed ; then let him inspect the inside of the fragment and see what sort of work he has made of it. Again he may proceed, looking Irom time to time at the inside to see how he is doing each i^art of the work. It is stated in the instructions that the skull must be placed base downwards when the cap of putty is put on the vertex; this may seem unnecessary, but experiment has shown it to be essential. If you place the skull vertex downwards on the sheet of putty and attempt to draw the latter up around the skull you will not make it stick closely one time in ten. The close adherence ot the putty to the skull is of course of prime importance. If, when the skull is full, you observe a single drop leaking anywhere through or around the putty, your work is a failure, stop it at once, clean off the skull and put it away to dry for another day.
The bread-board and rolling-pin are those ordinarily used by pastry cooks. They are best if made of hard wood. They should be thoroughly oiled in the beginning and the oiling should be renewed from time to time. They should be well scraped with a blunt wooden instrument when the day's work is done. We have found that these implements in wood answer well enough, but perhai)S it would be better to have a roller and slab of glass, china, or stone.
It is, as before intimated, important that the skull should be filled very rapidly as well as very accurately. Our present arraugeuieuts of tin vessel, reservoir, tube, and stopcock are designed to attain these ends, but better means may perhaps be easily devised. To fill the skull entirely through our small stopcock takes too much time, hence the use of a tin vessel with a wide orifice to put in the greater part of the water ; but when j'ou come to the last few drops at the brim of the foramen magnum, it has been found that they can be added more accurately and conveniently through the orifice of the small stop-cock fed from a reservoir not too high, for a strong pressure jnakes the water unmanageable.
The Bauke measiiriug-glass, as we received it, was not emootU aud level op the bottom, and
112 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
this had to be remedied, as must be done in all cases. Of course it is essential that the axis of the glass cylinder should be perfectly perpendicular ; so not only should the bottom of the stand be made quite even, but the stand on which the glass is placed to be read should be carefully leveled.
Different substances have been tried to define the surface of the water. Any dry impalpable powder of low specific gravity may do ; many such powders would, no doubt, answer as well as lycopodiuiii. Lampblack gives a beautiful and accurate line of demarkation, but it does not work well in the insufflator and is a dirty thing to handle. Charcoal tends to sink. A mixture of two parts of lycopodium and one of charcoal floats well and gives a more distinct line than lycopodiuiu alone.
As it is stated that the measuring-glass of Ranke is graduated with water at 14 degrees cen- tigrade, we have adopted this as the temperature of the water we use. But it is important that not only should the water, when taken from the reservoir, be of this temperature, but that the skull and all the vessels used should be of the same temperature. Indeed, it is well if the general tem- perature of the ai>artment in which the measurements are taken does not vary much from this standard. If water is taken from a vessel at 14 degrees, poured into a colder skull, thence through a colder atmosphere into a colder pan, and thence into a colder glass, it will not be at the standard temperature when you come to read, and will register too low. The reverse will be the case if the temperature of the vessels and surrounding atmosphere are higher than 14 degrees. If the tem- perature of the room has been maintained for some hours at 14 degrees, tbere is little doubt that the skull and all the vessels will be at the right temperature ; but if the heat has been increased or diminished but a short time before you begin work, water of the proi)er temperature must be put m the vessel before the measuring begius ; but of course the skull cannot be thus regulated.
It will be seen in Tables I and II that the second measurement was taken in many cases within a week of the first, as it was found that in this time the skulls were reduced by evaporation to their former weight. It seems they had ample time to contract, for we record only one case (21, Table I) where the second measurement was greater than the first. Nevertheless, siuce Broca maintains* that the contraction of a drying skull is not always in direct ratio to the loss of weight, it would perhaps be well to allow a longer time for drying than we have done, in an apartment maintained at a low temperature. Care must be taken, however, that the weight, aiul therefore the capacity, are not reiluced below the original standard.
The cutu-e work of applying the putty and measuring the skull need not ()ccu[)y more than 15 minutes. The time necessary for gauging and cubature of the skull after the putty is applied need not exceed 3 minutes. The task of cleaning the skull may be deferred for some hours and left to an unskilled assistant. Two persons have with us been employed ia doing the work of filling, one to pour in the water while the other held tiie skull, but I think means might be devised by which, if necessary, one person could do the work.
We will now consider the merits, diflftculties, and disadvantages of this method and see how it compares with others.
Dr. Topinard says, in the passage quoted above, that one of the prime difficulties is that the water gets into the sinuses and vacuoles of the skull and returns when the skull is drained (6goutt6) ; this is true, and if the skulls were drained in our system we would never arrive at comparable or uniform results. As for the larger foramina, we fill them with putty. The sutures, the sinuses, and the osseous tissue take up much water, some of which they part with in a few seconds or minutes, some of which remains for hours and days, and is finally only carried away by evapora- tion. Now, that which soaks into the bony substance remains there until lost by evaporation ; that which reaches the closed sinuses, which I believe to be very little during the few seconds the skull is tilling, does not get time to return in emptying, and that which enters the sutures is held there some time by capillary attraction and departs slowly. Again, it is the sutures and sinuses at the base of the skulls which are the most extensive and the most bibulous, and these, at the close of the operation for emptying, are held in such a position that they cannot part with their water before the cranial cavity is emptied. Observations taken on sawed skulls and on skulls having the external tables of the frontal and sphenoidal sinuses broken, seem to- corroborate these
•Etudes sur les propridtds hygroiu^triquea des craues, cousid^r^es dans leurs rapports avec la cranometrie, Revue d'Anthropologie, Paris, 1874, iii, pp. 385 to 444.
ON COMPOSITE PHOTOGRAPHY AS APPLIED TO CKANIOLOGY. 113
statements. During the few seconds taken to empty the skull it is hardly possible that some water does not return from the sagittal, coronal, and squamous sutures to the cerebral cavity, but I am satistied that it is an almost inappreciable amount.
Does all the water which properly belongs to the cranial cavity drain out in fifteen seconds ? I am certain it does not. If you fill Professor Eanke's bronze skull with water exactly according to our directions, and empty it in fifteen seconds exactly according to our directions, you will find that about 6 cubic centimeters are still retained. It cannot be maintained that the natural skull, even wheu well varnished, will do better than this. If it ever becomes desirable in craniometry that the true and exact cubic capacity of the skull must be ascertained, this quantity, or some other quantity to be determined by experiment and computation, may be added to the amount in the glass; but this small amount may perhaps be disregarded so long as science demands only "com- parable values, collected under the same conditions and effecting among them afiQnities conformable to reality."*
Another objection brought forward by Dr. Topinard, and already quoted, is that " the water wetting the sides of the glass rises on it, and one can be mistaken to the extent of 5 cubic centi- meters." This would truly be a grave source of error if it were not so easily removed. Many plans for remedying this difiiculty have been thought of, and the one we have recommended of scattering some light powder on the surface of the water will, we hope, give satisfaction to all who may try our method.
One of the most important obstacles in our way to success in the early stages of our investiga- tions— an obstacle not brought forward in this connection by Dr. Topinard — was this : The water soaking into the walls of the skulls almost invariably causes them to expand and rapidly increases their cubic capacity. Table III will illustrate this. But it will be seen that in twenty-one skulls re-measured within five minutes, fourteen did not expand appreciably in that short time ; two increased 5 cubic centimeters, three 10 cubic centimeters, and two 15 cubic centimeters, which was the maximum. These were unvarnished. Among nine varnished skulls tried, the expansion never exceeded 5 cubic centimeters in five minutes, and reached this only in three cases. There- fore, I think we are j ustified in concluding that in forty-five seconds, the time allowed by our method for filling a skull, the expansion from moisture is inconsiderable ; and it is siiecifled in our instructions that before the next comparable measurement is made the skull shall be reduced by drying to its former weight, and presumably to its former capacity.
The amount of water which a skull will hold in its meshes is much greater than one would suppose who had not made special investigations into the subject. Some idea may be gained of the hygroscopic capacity of the skull by consulting Table IV; but this subject has received such extensive treatment at the hands of Mr. Broca, in his paper already referred to, that it need not be further considered here.
One advantage of our method I conceive to be the elimination of much of the personal equa- tion, which is such a disturbing factor in all other methods. There is little, if anything, left for muscular exertion to alter. With our most imi^ortant operations the unchangeable element of time takes the place of the fickle element of vital force. In the most popular of all systems, that of Broca, the muscular action is chiefly limited to one part of the operation, that of ramming or thrusting. But hear what Dr. Topinard has to say of the personal effort in this case: "The same person * * * does not thrust the same, morning and evening, before and after meals, in think- ing of his business or in giving his entire attention to what he does, in conversing, or in smoking for stronger reasons, two persons at a distance from one another, who have not given an example to one another, of different ages, one of sixty, the other perhaps young, one convinced of the at- tention he must pay to the operation, the other having read the description and imagining that it is very simple."
For uniformity of results I think the figures shown in the accompanying tables (I and II, par- ticularly the latter) have never been excelled by any method, and in considering these it must be remembered, in favor of the system under which they were obtained, that it is new and seems still capable of much improvement.
• Topinard, op. cit., p., 591. S. Mis. 154 15
114 MEMOIRS OP THE NATIONAL ACADEMY OF SCIENCES.
We canuot claim rapidity as one of the advantages of the method we describe ; it occupies more time, we fear, than any of the ways in which solid particles are employed ; but time and trouble on the one hand should not be weighed too heavily against exactness and uniformity on the other if it can be shown that this method possesses both of these advantages. If it eliminates the muscular effort, it does not eliminate the personal equation in other respects, for it requires for its proper performance a scrupulous care and a perfect patience.
One of the most desirable objects to be attained by any system of measurement of the cranial cavity is a comparability of the figures given by different persons in different parts of the world, who have not had the advantage of studying under one master or taking personal instructions in one particular laboratory. When this end is reached our data for generalization will be vastly increased. The advocates of the various methods where solid particles are used do not claim that they secure such universal comparability. Dr. Topinard says : " One must have seen the method practiced that he wishes to follow. One cannot indicate in writing the force that must be put in a tap of the hand or in a blow of the rammer. The forty-eight knocks that Mr. Ranke performs on the platform, with his great measuring glass full, are difficult to repeat with the same effect.* • • * It is not, however, certain that it [the method of Broca] is everywhere well understood and rigorously practiced, and I, for my part, would not dare to unite in one list the figures obtained here and there in its name. Amongst the authors in which I have full confidence in this connec- tion I will quote M. Mantigazza, M. Schmidt, M. Ranke, M. de Torok, M. Merejkowski, and all persons in general who have passed through the Broca laboratory."^ May we claim for the method we describe any higher degree of comprehensibility ? May we hope that craniologists through- out the world can, by the mere perusal of our description, follow our method exactly in all its de- tails and arrive at the same results ? We can only offer conjectures, into which the elements of hope and egotism must enter too largely to render them of any value. We cannot answer these questions until some other students are found who will take the pains to give our method a trial. Very respectfully, your obedient servant,
W. MATTHEWS, Assistant Surgeon, U. 8. A. Surgeon John S. Billings, U. S. A.,
Curator Army Medical Museum.
* Op. oit., p. 599.
t Op. dt., p. (jy. The italics are our own.
ON COMPOSITE PHOTOGRAPHY AS APPLIED TO GKANI0L0(;Y.
115
Table I. — Showing meaaurements, in cubic centimeters, of twenty-five skulln not varnished.
|
1 Si ^ |
Date of first measurement. |
£ 3 at -^ a 0 a 0 -a 3 a |
Date of second measurement. |
imum differ- ence. |
Condition of skull. |
||
|
0 0 |
; |
||||||
|
1 |
83 ! 1390 |
January 28 |
1335 |
February 4 |
5 |
Porous; weatherworn. |
|
|
2 |
84 1425 |
January 27 ' 1420 |
February 4 |
5 |
Very light and porous. |
||
|
1 3 |
87 1300 |
January 29 1300 |
February 4 |
0 |
Sutures open ; hole measuring 2 by J inches ; porous. |
||
|
4 |
93 1300 |
January 29 1300 |
February 5 |
0 ' Porous and weatherworn ; hole ^ inch in diameter. |
|||
|
5 |
199 1400 |
February 13 1390 |
March 14 |
10 Very light; roofs of orbits broken. |
|||
|
6 |
200 1300 |
January 26 1295 |
February 13 |
5 Several holes, measuring about 5 square inches in all. |
|||
|
■ 7 |
292 1485 |
February 3 1475 |
February 11 |
10 Solid and heavy. |
|||
|
8 |
359 1450 |
January 30 |
1445 |
February 10 |
5 Porous and weatherworn ; several holes. |
||
|
9 |
362 1275 |
January 27 |
1270 |
February 5 |
5 1 Porous; weatherworn; sutures open, and several suiall j holes. 5 Sutures much open ; light and porous; weatherworn ; |
||
|
10 |
363 , 1360 |
January 30 |
1355 |
February 10 |
|||
|
several holes. |
|||||||
|
11 |
364 |
1335 |
January 30 |
1330 |
February 10 |
5 1 Very porous; holes; weatherworn; light; sutures open. |
|
|
12 |
369 |
1230 |
February 3 |
1230 |
February 10 |
0 Very porous ; eroded ; fissured ; several holes aggregat- ing about 5 square inches. |
|
|
13 |
372 |
1135 |
February 2 |
1125 |
February 9 |
10 Very porous and weatherworn ; several perforations. ! |
|
|
14 |
373 |
1455 |
February 2 |
1455 |
February 9 |
0 Porous ; sutures open ; many perforations. |
|
|
15 |
374 |
1295 |
February 3 |
1290 |
February 9 |
5 Very porous. |
|
|
16 |
375 |
1305 |
February 2 |
1305 |
February 11 |
0 Very porous ; sutures open ; four small perforations. |
|
|
17 |
394 |
1275 |
February 2 |
1270 |
February 11 |
5 |
|
|
18 |
481 |
1455 |
January 22 |
1445 |
February 5 |
10 |
Squamous; sutures open. |
|
19 |
482 |
1410 |
January 22 |
1405 |
BYbruary 12 |
5 |
Light. |
|
20 |
1516 |
1160 |
January 19 |
1155 |
February 6 |
5 |
Squamous ; sutures open. |
|
21 |
1517 |
1550 |
January 19 |
1560 |
February 6 |
10 |
Good and solid. |
|
22 |
1804 |
1575 |
February 3 |
1570 |
February 1 |
5 |
Fine and solid. |
|
23 |
1914 |
1285 |
February 9 |
1280 |
March 14 |
5 |
Good, but light. |
|
24 |
1915 |
1450 |
January 26 |
1440 |
February 12 |
10 |
Roof of orbits broken ; very light skull. . - |
|
25 |
2034 |
1200 |
January 22 |
1195 |
February 12 |
5 |
Sutures open. |
Table II.
-Showing measurements in cubic centimeters of ten varnished sliuUs, compared with measurements of the same
unvarnished.
|
I |
.2 0 |
Unvarnished. Table 1.) |
(See |
Varnished. |
||||
|
i |
2 |
£ 2 |
£ 3 |
|||||
|
1 |
a |
a |
C3 . -d a |
a £ |
li a |
ag -d B |
Dates of measure- ment. |
|
|
I |
§ |
g |
a § |
^ |
2 |
a S |
i§ |
|
|
S |
fe . |
£ |
Q |
£ |
^ |
« |
||
|
1 |
199 |
1400 |
1390 |
10 |
1400 |
1400 |
0 |
March 26, April 2 |
|
2 |
359 |
1450 |
1445 |
5 |
1450 |
1450 |
0 |
March 23, April 3 |
|
3 |
362 |
1275 |
1270 |
5 |
1270 |
1265 |
5 |
March 26, April 2 |
|
4 |
373 |
1455 |
1455 |
0 |
1450 |
1450 |
0 |
March 24, April 2 |
|
5 |
375 |
1305 |
1305 |
0 |
1300 |
1300 |
0 |
March 24, April 3 |
|
6 |
481 |
1455 |
1455 |
0 |
1445 |
1445 |
0 |
March 24, April 2 |
|
7 |
1516 |
1160 |
1155 |
5 |
1160 |
1160 |
0 |
March 23, April 3 |
|
8 |
1914 |
1285 |
1280 |
5 |
1285 |
1285 |
0 |
March 27, April 3 |
|
9 |
1915 |
1450 |
1440 |
10 |
1440 |
1435 |
5 |
Marcli 21, April 2 |
|
10 |
2034 |
1200 |
1195 |
5 |
1190 |
1190 |
' |
March 26, April 2 |
Sum of differences, 45.10.
Average variation in nnvarnished skulls, 4.5.
Average variation in varnished skulls, 1,
116
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
Table III. — Shojoing increase of cubic capacity, in cubic centimeters, from absorption of water.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
a .
go 3 ^
83
84
87
93
199
200
292
359
362
363
364
369
372
373
374
375
394
481
482
1516
1517
1804
1914
1915
2034
|
i |
|
|
fl |
0 |
|
c3 . |
ce . |
|
»+= |
|
|
sg |
ag |
|
a |
"2 a |
|
4S |
|
|
\^ |
GQ |
|
1390 |
1390 |
|
1425 |
1440 |
|
1300 |
1300 |
|
1300 |
1310 |
|
1400 |
(') |
|
1300 |
1300 |
|
1485 |
1485 |
|
1450 |
1450 |
|
1275 |
1275 |
|
1360 |
1360 |
|
1335 |
1345 |
|
1230 |
1245 |
|
1135 |
1140 |
|
1455 |
1455 |
|
1295 |
1295 |
|
1305 |
1310 |
|
1275 |
1275 |
|
1455 |
1455 |
|
1410 |
1410 |
|
1160 |
1175 |
|
1550 |
1610 |
|
1.575 |
1585 |
|
1285 |
(*) |
|
1450 |
1450 |
|
1200 |
1200 |
o
§a
m S m
.9 S H
5 minutes . 5 do 5 do 5 do
5 minutes . 5 do 5 do 5 do
do
do
do
do
do
do
do
do
do
do
24 hours . 24 do 5 minutes .
5 minutes . 5 do
a 3
JS
B
a
1445 10 minutes . i330 : io minutes .
1315 24 hours.
1305
1250
1470 1415
1610
1470 1215
24 hours.
10 minutes
48 hours
10 minutes
a ^^ •a a
3
tn CI
S H
1475
1315
1425
48 hours.
24 hours. 48 do .
24 hours..
24 hours.
48 hours.
5 ° a'-S
i- 3 r- a
0 50
0 30
15
0
0
30
0
10
20
5
0
0
5
0
15
15
15
60
10
20 15
0
15
0
10
0 0 0 0 0 10 15 5 0 0 5 0 0 0
10
* Not tried.
Table IV. — Showing amount of water held in the walls of the skull after measuring.
|
1 1 i a |
2 . <2 'c |
.-S 60 |
||
|
a |
^l- |
■S.5 |
© |
|
|
ss |
^ ^ |
a |
||
|
1 : S |
Weigh meas |
-Si |
1 s |
|
|
Grams. |
Gi-ams. |
Grams. |
||
|
83 |
561 |
656 |
95 |
' |
|
87 |
420 |
470 |
50 |
Weighed a lew minutes |
|
93 |
482 |
591 |
109 |
J- after measuring, before drain- |
|
481 |
548 |
660 |
112 |
age was complete. |
|
1517 |
1067 |
1211 |
144 |
J |
|
a 3 3 a| 1 |
Weight before measuring. |
Weight after measuring. |
o o 3 (3 |
|
|
Grams. |
Grams. |
Grams. |
||
|
84 |
523 |
561 |
38 |
'\ |
|
199 |
505 |
538 |
33 |
Weighed several hours |
|
362 |
452 |
481 |
29 |
> after measuring, when drain- |
|
373 |
553 |
596 |
43 |
age was complete. |
|
375 |
402 |
456 |
54 |
J |
«.«■
..*' .1»'.«
I r I
?,^
rr
!i
lie
^
MEMOiKS OF THE 1
Tmslk Iir. — H'hominff iiierea-f »'-'»«^H.■ -M^ptrnty, in
So • 2
c
9 o S ^
•VLliiiVlX Ui' faUiilJiSOES.
/! ofiitnter.
a. 2
.2 -a
|
1 |
.-.J |
ioL'U |
1390 |
5 |
niiiiuU. |
|
o |
rA |
1425 |
1440 |
5 |
do |
|
;j |
87 |
1300 |
1300 |
5 |
do |
|
■) |
ys |
1300 |
1310 |
5 |
do |
|
--, |
199 |
1400 |
1300 |
||
|
li |
200 |
1300 |
5 minntes |
||
|
292 |
1485 |
1485 |
5 |
do . |
|
|
^^ |
359 |
1450 |
1450 |
5 |
do |
|
9 |
362 |
1275 |
1275 |
5 |
do |
|
10 |
363 |
1360 |
:-(>. |
-" |
' |
|
11 |
304 |
1335 |
v: |
||
|
)-2 |
369 |
1230 |
li'.. |
||
|
13 |
372 |
1135 |
1140 |
5 |
do |
|
14 |
373 |
1455 |
1455 |
5 |
do |
|
15 |
374 |
1295 |
12ii5 |
5 |
do |
|
16 |
375 |
1305 |
1310 |
5 |
do |
|
17 |
394 |
1275 |
?■' ■ |
f |
1 , |
|
18 |
481 |
1455 |
1 |
||
|
19 |
483 |
1410 |
|||
|
20 |
1516 |
1160 |
) |
||
|
:J1 |
1517 |
1550 |
; |
||
|
22 |
1804 |
1575 |
15.'>;> |
O |
ml.: |
|
23 |
1914 |
1285 |
(*) |
-- . . |
|
|
24 |
IJlo |
1450 |
1450 |
5 |
miui.Mr |
|
25 |
2034 |
1200 |
1200 |
6 |
do |
lijiS
TaBLI! IV.-
-(S'/iowiji^ amount ■>/ mater held in ilie vuills of '
ic, :,lciitl after vieaturina.
a
3
a
ic5
m
|
33 |
.'jCI |
|
|
87 |
4-20 |
|
|
93 |
48-:! |
|
|
4S1 |
r.-!-' |
1)1-111 |
|
.* 1 7 |
. ir:" |
■ n |
few minntes . before drain-
Grams.
r.\
S-^
' hours 11 drain-
's coiup:
'VV> •. '
• • • I
f .»*#■'
f'^^^/^^^
.^ 1r P
ASCERTAINING CAPACITY OF CRANIAL CAVITY BY MEANS OF WATER
PHOTOGRAPH NO I. Filling the Skull l^^ParL The skull covered wiLh putty aud placed with the frontal poition depressed is held in the hand of an assistant .while the operator nearly fiUs the skull as rapidly as possible from a half gallon measure provided with a spout held in the left hand
ASCERTAINING CAPACITY OF CPANIAL CAVITY BYMEANS OF WATER
PHOTOGRAJ^H SO. 2. Killing the SkuU. ^'-^Part ITw skuUplaced with theha.se in ii tinnzoiila) position isheld nithe hands of ari assistant wlule the operator fills accurately 1o the edge of the foramen Tnagimni. ftrjm a reservou- tlut)u^ n smnll siop-cocl^ , Before this is done the sloill Lslirou^hl. close; tii ihcpamvhich is to recpi%-p llus^vaio' sotliat no tune niiiybo Irjst in einptjTn^ .
Julius ijien A:<.aLiih
ASCERTAINING CAPACITY OF CRANIAL CAVITY BY MEANS OF WATER
PHOTOGKAI'H NO. .'.J, Emptying Sltoll,!?^ Position. "Das pirtiu-e also sliowy aumidjuit. reiiioviii!^ pui.ty from. skoU ,
ASCERTAINING CAPACITY OF CPANIAL CAVITY BY MEANS OF WATER
PHOTOGRAPH NO 4 Emplvnig Skull , 2'>'' PosjUoii
ASCERTAINING CAPACITY OF CRANIAL CAVITY BY MEANS OF WATER
PHOTOUKAPH NO fv Usui^ insufllatoi- charged. -vviU\ djy puwdei- to dttiiie tlie sui'f'ace of tJw water. In tltis arid ottier pu:Uu't'a are seen various appliances: scales, weights, reservoU: Lube.
stop -cock, tvalf- gallon.- measure, bi-ead-board. rolling-pin,,
iiieasiiriri6-61ass, insuJTlator, nu;U'Oiionie, S r.
NATIONAL ACADEMY OF- SCIENCES.
VOL. Ill
FOURTEENTH MEMOIR.
ON A NEW CRANIOPHORE FOR USE IN MAKING COMPOSITE PHOTOGRAPHS OF SKULLS.
117
ON A NEW CRANIOPHORE FOR USE IN MAKING COMPOSITE PHOTOGRAPHS OF SKULLS.
READ NOYEMBER 12, 1885.
By John S. Billings and Washington Matthews.
At the meeting of the Academy in April, 1885, we described an extemporized contrivance for taking composite photographs of skulls, and announced that the construction of a more convenient apparatus was in contemplation. Such an apparatus has since been constructed under the direction of Dr. Matthews, and has been employed by him in taking a number of composite photographs of crania, specimens of which are herewith submitted.
The apparatus itself — of which four photographs are presented — consists of an object-stand, with four hinged frames, and a craniophore with two different attachments for holding the skull.
The object-stand is of walnut, 3 feet and 5 inches high. The top is 18 inches square and 2 inches thick, with a hole in the center through which the main screw of the craniophore descends. Frames bearing fine cross- wires are attached to the top by hinges in such a manner that they may be raised and lowered.
The craniophore is of brass It has a large screw to elevate and depress the skull. This screw is worked by means of a long tubular nut fixed in a frame. The latter slides on two round bars, and is moved by a smaller screw which works in nuts fixed to the bottom of the frame, and secures thereby lateral adjustment. On the summit of the screw is a ball-and-socket joint. In the top of the ball is a hole or well which receives the pin at the base of each attachment and thereby holds the latter in place.
One attachment is for supporting the skull, base downwards, when the facial, lateral, and occipital views are taken. It has a cone which enters the foramen magnum, and a jointed arm elongated telescopically, which supports the palate.
The other attachment is for holding the skull when the basal and vertical views are taken. It has two arms extending horizontally. On each of these there is a vertical bar, movable, in order that skulls of different widths may be accommodated. On each vertical bar is a short, horizontal, obtusely-pointed bar which tits into the auditory meatus and moves ireely on the vertical bar. These movable parts are provided with binding-screws. The horizontal bars are attached to a plate which slides on a frame; this arrangement secures thfe antero-posterior adjustment necessary to insure coincidence of the selected horizontal plane with the lateral vertical wires.
To operate : The skull is placed in the desired attachment; the latter is secured by the pin at its base to the ball in the joint. The joint is tightened by its screw to such a degree that it will move by gentle force, but not by the mere weight of the ill-poised skull. The frames are raised and maintained in their upright position by hooks fastened into eyes on the top of the table. The skull is adjusted on the four sets of cross-wires. Then the anterior frame and the lateral frame next to the window are lowered ; a black velvet background is hung on the posterior frame, a large white card-board is hung on the frame further from the window, the brass-work is occluded with small velvet screens, and the picture is taken. When the work of the day is done, all the frames are folded down, fastened by buttons to the legs of the table, to secure them from injury, and the craniophore is covered.
The craniophore was made by Mr. Edward Kiibel, 328 First street, N. E., Washington, and
cost $55. The object-stand was made by the carpenter who works at the Museum. A coarser
thread for the vertical screw of the craniophore is recommended, as facilitating adjustment.
119
Julius K. en \ I-., lull
APPARATUS FOR TAKIITG COMPOSITE PHOTOGRAPHS OF SKULLS
NO 5 THE ADJUSTMENT. The lYames on dbjecl - stand beanii^ the adjusting wires are raised. The attachment for secunru^ skull at foramen magnum, is here CTi^loyed. Tht; skull is in po.siuon fui- picture of norma facialis.
.sBicti \ r.. I., Ill
APPARATUS FOR TAKING COMPOSITE PHOTOGRAPHS OF SKULLS.
NO 6 TIIK .MWUSTMENT. Same ats No. 5. Diagonal view; enlarged, showra^ only the t«p of the objecL-stajul with frames and crdiiiophore
APPARATUS FOR TAKING COllPOSITE PHOTOGRAPHS OF SKULLS
N'O 7 THK KXI'OSI-Ri-:. Two of Liu- IViiines mt- Um-civit A |.|..iU velvet bacU-i^fOUHfl is hu[i^ on lh(^ posLoruir Iraiiit? , .1 i)ii:( c nl" whiU- ctii-d hoJiril is Imno un oiu-oI'lliP fi-anu's In illiiiiini.ih- diiyU skU' (.1" sUiill Tlu- iill.urlininiil loi' ;;ei;iiiiiv_; Uk* ^knll .ii I lu- ,nulilni\- ii»Mliisn.s IS lu'ir" iMiijiloycd 'riu- bkiill is mpcisili-'ii Ini- Uiltirii^ puliiic iil'tinnnit Ij.isiali s Tlu' sitiiill vclv<'l ficrt'fiis Iim (•orict*;ilitig tin- luiiss ^^■(l^k jiic st'i-n Iviiiq be-sidc llic cr.iiiiopliur-i-
APPARATUS FOR TAJCING COMPOSITE PHOTOGRAPHS OF SKQLLS
X0.8. V\TiEN NOT re USE 'Hie fi-aines oi" the objrrcL-Bt.aiid are folded down and held with buUoiis Uie better Lo protect, tliern . The (raniophore is oovered ,
NATIONAL ACADEMY OF SCIENCES.
^^OTL. Ill
FIFTEENTH MEMOIR.
ON THE SYNCARIDA, A HITHERTO UNDESCRIBED SYNTHETIC GROUP OF EXTINCT MALACOSTRACOUS CRUSTACEA.
121 S. Mis. 154 16
I -ON THE SYNCARIDA. A HITHERTO UNDESCRIBED SYNTHETIC GROUP OF EXTINCT MALACOSTRACOUS CRUSTACEA. PLS. I, II.
BEAD APRIL 21, 1885.
By a. S. Packaed.
For a long time I have been desirous of examining into the relationship of the singular group of Carboniferous Crustacea represented by the genus Acanthotelson of Messrs. Meek and Wortheu, as it has seemed to be a remarkable connecting link between the Edriophthalmata (or Tetradecapoda) and the Decapoda (in the older sense). An unexpected opportunity has been offered in a large series of specimens, which, without solicitation on my part, has been generously offered me by E. D. Lacoe, esq., of Pittston, Pa., and .J. C. Carr, esq., of Morris, 111. Mr. Lacoe's collection was a very rich one, comprising over forty nodules, each containing a usually well-preserved Acantho- telson. Although additional specimens are much to be desired, especially such as may show the eyes and their nature, whether sessile or stalked, a point still unknown, the eyes not having been with certainty identitied, and also to better show the nature of the abdominal appendages, it seems to us that enough characters have been preserved to allow us to present a tolei'ably accurate account of the essential features of the group.
The genus Acanthotelson was first proposed by Messrs. Meek and Wortheu, in 18G0, ' and the species described as A. siimpsoni M. & W. A second species, A. eveni, was described by the same authors in 1868. ^ Additional facts were stated and figures given in the Report of the Geological Survey of Illinois, III, Paleontology, 1868. The specimens we possess enable us to amend and to add to their original descriptions; but in doing so we wish to bear witness to the care and ability displayed by the authors in the examination and illustrations of this form. The genus is referred with doubt by the authors to the Isopoda, who also refer to its resemblance to some of the lower types of macroural Decapods. They remark : " From all the specimens of this genus now known it is evident that, in the nature of its autenuie, as well as in the forward direction of all its thoracic legs, and to some extent even in the nature of its caudal appendages, it differs from the Tetra- decapoda, and approaches some of the lower types of the macroural Decapoda. In the possession of seven distinct thoracic segments, without a carapax, however, as well as in the form of all its thoracic and abdominal segments, it agrees with the Tetradecapoda, particularly with the Isopoda, which have but one pair of the abdominal appendages styliform, instead of three, as in the Amphipoda. One specimen of A. stimpsotii (represented by fig. B, p. 510) also appears to show the eyes (marked I in the cut) to be sessile, though remarkably prominent. If they are sessile, this must be conclusive evidence that it must be a Tetradecapod. Until other examples, showing more clearly the nature of its eyes and some other parts, can be examined, we leave it provisionally where we first placed it with doubt, in the Isopod group of the Tetradecapoda." (P. 550.)
The following description, while embracing the more general characteristics of the group to
' Proceedings Academy of Natural Sciences, Philadelphia.
■^Amer. Journ. Sc.,2d ser., xlvi, 28, 1868.
123
124 MEMOIRS OF THE NATIONAL ACADEMY OP SCIENCES.
which Acanthotelson belongs, also without doubt comprises the generic and specific characters. We will first give a description of the fossils themselves, based on the material we have had for examination, and then endeavor to point out those characters which we suppose to be the essential features of the group to which the genus belongs, and also to indicate the probable aflBnities to the other divisions or suborders of Malacostraca. It may be as well to say that, after examining some forty specimens, we are unable to distinguish between Acanthotelson stimpsoni and eveni, and are inclined to believe that the former is the young of the latter species.
In Mr. Lacoe's No. 501b the head is well preserved; thefli-st arthromere or segment is considerably shorter than any of the succeeding ones; it is slightly less than two-thirds as long as the succeed- ing arthromere; it bears in front a well-marked, small, triangular rostrum, which is acute at the tip, and is about two-thirds as long as the segment itself; the edge of the rostrum is considerably raised, especially at the base. The front edge of the segment on each side of the rostrum is also margined with au elevated ridge. The surface of the segment is rather full and convex on each side, but not so decidedly so as the second segment. The second artliromere is about as long as those succeeding, though not quite so long as the sixth arthromere; on each side is a low boss-like swelling, situated obliquely, and prolonged in an oblique direction to the anterior outer edge. The second segment is distinctly separated by an impressed line from the first, but there is not a true articulation between them, so that the first and second cephalic segments may be said to be consolidated and to represent the carapace of the Schizopoda. The three succeeding segments have a transverse, uninterrupted, smooth ridge situated in the middle on the third, but in the fifth segment near the hind margin. The sixth and succeeding segments are smooth and even. The body is of even width to near the telson. The lower edges of the segments are evenly rounded, those of the hinder abdominal segments are moi'e acutely rounded.
We have been unable to detect any positive traces of the eyes, nor can we state whether they were sessile or stalked, though if they were present and sessile we do not see why they should not have been preserved in some of the specimens (particularly 501" and 406").'
The first pair of antenna} seem to arise directly from each side of the small, short, rudimentary rostrum. The scape is three-jointed, and not very long and slender; second joint not so thick, and about one fourth shorter than the first and twice aslong as thick ; third joint long and slender, considerably longer than the second. The scape bears two tlagella, which are long, slender, mul- tiarticulate branches of unequal length, of which the inner is the thicker and shorter, the outer flagellum much slenderer and longer, the entire length of the antenutB being one-half that of the second or outer pair. The second pair of antenna; have als6 a three-jointed scape (which is not accurately represented in Meek and Worthen's figure). The basal joint is short ; second joint shorter than the first, with two unequal internal spines ; third joint slightly longer than the second and much smaller; there are traces of a small auteuual scale; the flagellum is long and slender, its entire length about half that of the body.
There are twelve pairs of feet (506',"), a pair to each segment situated between the head and penultimate uromere or abdominal segment; these, with the caudal pair of appendages, make in all thirteen pairs of legs.
The number of arthromeres or body-segments is sixteen, counting the head as consisting of two when seen from above, and the telson as a rudimentary arthromere, so that there are thirteen arthromeres between the head and telson, each of them bearing legs. There is no apparent dis- tinction, as regards the segments themselves, into cephalothorax and abdomen (urosome), but there are two cephalic, nine thoracic segments, and seven abdominal, counting the telsou as the seventh. The first seven pairs of (thoracic) legs are much alike in appearance, reminding us of those of Peta- lophthalmus and Gnathophausia; these are succeeded by five pairs of abdominal appendages, which are about half as long and large as the thoracic legs. The first pair of thoracic legs (which do not seem to be mandibular i)alpi) are considerably larger (broader and longer) than the succeeding ones. It is composed of six joints; the first and second rather narrow; the third broad, with, ac- cording to Meek and Wortbeu, " three" spines on the " under side" (these were not to be seen in my specimens, .though undoubtedly existing there ); fourth longer than the third, with three spines;
'Before goin^ to press I received from Mr. Lacoea very large specimen, his No. x*, in which are two large smooth concavities, one on each side of the base of the head ; it is possible that these are sessile eyes.
ON THE SYNCARIDA. 125
fifth joint thicker thiiii tiie foiutli, thiclveninj;' towards the di.stal end, with four spines, the fonrth spine tbc largest and as long as the joint is tiiick ; the sixth about two-thirds as thick as the fifth, with two remote spines on the under side and ending in two spines, one of them very large and stout (there is possibly a third snuill spine). In Meek and Worthen's figures the s[)in('S are errone- ously drawn on the outer side of four joints; we find that the spines ate situated only on the two penultimate joints; the terminal claw is not represented by Meek and Worthen. The succeeding six pairs are all about the same size and length, being large, well developed, long, and slender, about one half to two-thirds as thick as the first pair (406''), with no traces of a gill ; the second pair are a little stouter than the others and apparently spiued on the penultimate joint ; the sev- enth pair the slenderest and nearly as long as the first pair; the three basal joints are long and slender, the third very distinct, long, and slender; fourth joint long, slightly swollen in the mid- dle; fifth equal to the sixth in length, but slender, slightly thickened towards the distal end; the sixth somewhat longer than the fifth, ending in a point ; none of the terminal joints appear to be chelate.
The abdominal appendages are distinctly biramous and schizopodal iu their api)earance. Each apparently consists of a small, narrow, jointed limb and a larger exopodital branch (or gill(?) ; see 406-'''''). We can see traces of the first two pairs. In another specimen (aOL^'^) the first three pairs of abdominal legs are to be plainly seen; the exopodital or respiratory and swimming ramus is sessile, lanceolate-oval, and broad, thickened on the hinder (?) edge. In Mr. Garr's specimen No. 1 are distinct traces of a biramous appendage on the fourteenth and fifteenth (penultimate) seg- ments ; and in his No. 3 there are to be seen the traces of the second-fourth pairs of abdominal feet, with double rami, the hinder ramus the smaller and narrower. In an abdominal foot (in Lacoe's No. 406PS) the second joint is narrow, lanceolate-oval, rounded at the tip, from which arise a series of long slender setie, about twelve in number, which form an oar-like appendage equaling in size the basal joint; total length of the limb 14.5""" (the basal joint 8""", the row of setae 6.5"" ^14.5™'"). These legs remind us somewhat of those of Squilla, as do the first thoracic pair, from their being larger than the others and armed on the under side with stout spines.
The telsou is very long and slender, narrow, acute, the end very slender, with long set£e on each end ; it is a little longer than the caudal feet (uropoda) on each side of it. The caudal feet, or sixth pair of uropoda, are divided into two long, large, acute rami (endopodite and exopodite) arising from a small, short basal joint (Garr's No. 1). The two rami are of nearly the same size and length, both edges of each branch being setose (the setae are not so numerous and close as represented in Meek and Worthen's figure).
Of forty specimens examined, the total length of the largest example, including the caudal appendages, but not including the antennae, was 75°"" (Lacoe's No. SS"""); another still larger (No. X*) ^3s 85""" in length; a specimen received from Mr. Garr was 58"™ in length.
In a specimen of A. eveni, 45""' iu length, 1 made the following measurements: Width of the body, b-T"""' (in Lacoe's 501'' : Width of first cephalic segment, 5.5"""; of second segment, 6™""; length of first and second head-segments together, G"™ ; length of rostrum, l™""; length of sixth seg- ment, 3.5""") ; length of first anteuna3, about 12"""; length of second antennae, 20'"™; length of first pair of feet, 20'"'"; greatest width of filth joint of first feet, 2'""-; length of abdominal feet, 18-19"'"'; length of telson, 13"""; length of caudal appendages, fi™™.
Many of the specimens are preserved flattened out, showing the back, with the legs spread out symmetrically on each side; others are preserved lying on their side, with the body somewhat arched, and then they present a shrimp-like appearance, though on a superficial examination reminding one of an Amphipod lying on its side.
The foregoing remarks apply to the larger specimens described by Meek and Worthen as Acanthotehon eveni. I cannot with certainty point out any distinctions from A. stimpsoni M. & W., the first-described species; the smaller specimens, which might be referred to the latter species, are evidently the young of A. eveni M. and W. Hence the specific name should be Stimpsoni.
The characters of this Crustacean are such as to forbid our referring it to any known group; we therefore suggest that it forms the type of a suborder of thoracostracous Crustacea, which we would designate as the Syncarida.
What we should regard as the diflereutial characters of the group Syncarida, to which Acautho-
126 MEMOIRS OF THE NATIONAL ACADEMY OP SCIENCES.
telson belongs, are the sixteen free segments of the body, which are homouomoiis or of uniform size, the first and second, however, being soldered together; the absence of a true carapace; the seven pairs of schizopod-like legs, the first pair spined and raptorial, slightly reminding one of those of Squilla ; the second pair also spined ; the antennae of both pairs are long and slender, the two flagella of the first pair being very unlike any sessile-eyed or edriophthalmatous Crustacean ; the six pairs of abdominal feet, which are long, slender, and with a general resemblance to those of the Schizopoda; the broader, oar-like swimming ramus, ending in long setae. Any doubts as to the macrouran afflnities of the Syncarida are removed by an examination of the long, acute telson and last pair of abdominal appendages; the appendages are biramous, the divisions flattened from above downwards, so that they with the telson serve, as in schizoi^ods and shrimps, for propelling the body backwards when the animal is disturbed. '"
We should regard the Syncarida as the lowest group or suborder of Thoracostraca, but much nearer the Schizopoda than the Cumacea ; they form a connecting link between the Amphipoda and Thoracostraca, but at the same time in their most essential characters stand much nearer to tbe Schi- zopoda than the Amphipoda ; the lack of a carapace, even a rudimentary one, and the homonomous segmentation, causing them to bear a resemblance to the Edriophthahna, which they would not otherwise present. The Syncarida may be regarded as the homotoxial equivalents of the Decapoda, Schizopoda, or Stomapoda. To the Isopoda, Acanthotelsou presents a superficial resemblance, due to the slightly vertically compressed body and the homonomous segmentation. Tbe Edriophthalma (Arthrostraca of some late authors) are defined by Clans as " Malacostraca with lateral sessile eyes, usually with seven, more rarely with six or fewer separate thoracic segments, and the same number of pairs of legs, without a carapace," but this definition does not express those differences in the form of the antennae, the thoracic legs, and abdominal appendages, especially those of the end of the urosome or abdomen, which are characteristic of the sessile-eyed Crustacea as distin- guished from the Thoracostraca.
From the Isopoda, in which the body is usually broad and vertically flattened, with seven free thoracic segments, while the abdominal legs are lamellar and closely appressed to the short abdo- men, our Acanthotesou plainly difters in the long bi-flagellate Decapod-like first antennae, in the long homonomous segments of the abdomen, and the schizopodal abdominal feet, and esi)ecially the Schizopod-like telson and last pair of feet, adapted, as in the shrimps, for striking the water from above downwards.
The Amphipoda are, in general, characterized by their laterally compressed body, with lamel- late gills on the thoracic feet, and an elongated abdomen, of which the three anterior segments bear the swimming feet, while the three posterior bear postei'iorly-directed feet, adapted for springing (Clans). Now, if Acanthotelsou is not an Isopod, still less should it be regarded as related to the Amphipoda. The first antennae are entirely unlike those of any known Amphipods, the latter having a very short accessory flagellum; the second antennae of Acanthotelsou are strictly decapodous in appearance and very different from those of the Amphipoda, whereas in Gammarus the scape is as long as the tiabellum. Although thei-e are seven free thoracic segments in Acanthotelsou as well as in Grauimarus and other Amphipoda, those of Acauthotelson are not compressed any more than in the Schizopoda, and there are no traces of epimera; on the contrary, the free edges of the thoracic and abdominal segments are much as in the Schizoi)0(la and Caridea. The thoracic appendages of Acanthotelsou are, on the whole, like those of the Stomapoda and Schizopoda. We cannot detect any traces of mouth-parts, mandibles with their pali)us, or maxillae; but the thoracic legs do not present any close resemblance to those of the Amphipoda, the first pair being as much, if not more, like those of Squilla than any Amphipod with which we are acquainted, while the three posterior pairs, which are in form and size like those in front, entirely differ from those of Gammarus and most other normal Ami)liipods, in wliich the basal joint is very large and triangular. Turning to the abdomen, the dift'erence in that of Acanthotelsou from that of the Amphipods is still more marked. The first five pairs of uropoda, or abdominal appendafjes, are, in Acanthotelsou, all formed apparently on the same plan, not essentially different from those of Schizopods, while the last pair are flat and on the same pLine as the telson and intimately asso- ciated with the latter ; in short, these parts are formed on a truly macrurous plan and most approach those of the Schizopods, in which the telson and rami of the last pair of feet are narrow and more
ON THE SYNCARIDA. 127
or less acnte at the end. There is nothing in the strnctnro of the urosome and its uropoda in Acanthotelson to remind us of the same parts in the Ampliii)oda.
Excluded from the sessile-eyed Crustacea, and fonied to place Acanthotelson in the Thoracos- traca, we are confronted by the lack of a carapace and the homonomous segmentation of the body. These are essential fundamental characters, but still the nature of the api)endages and telson is such as to forbid us from rejecting the Syncarida from the ordinal limits of the Thoracostraca. We are compelled, therefore, to regard the group as a suborder standing near or at the base of the Thoracostraca, not far from the Stomapoda and Schizopoda, and with appendages closely homol- ogous with those of these two groups. The Syncarida, from their lack of a carapace, and from the well-formed dorsal arch of the seven thoracic segments, we are obliged to consider as an annectant or synthetic group, pointing to the existence of some extinct group which may have still more closely connected the sessile-eyed and stalked-eyed Crustacea.
Notice of Acanthotelson ? magister (n. sp.).
PL II, Figs. 4, ,5.
I have received from Mr. J. C. Carr, for examination, a specimen from Mazon Creek, collected at the same place as the nodules containing the Acanthotelson, showing the remains of a crustacean closely similar to, if not generically identical with Acanthotelson. Unfortunately the head and anten- nse are not preserved sufiflciently well for description, so that the following account should be regarded as provisional, until better-preserved specimens are found. As seen by the photograph (PI. II, tigs. 4,5), the animal was of the same general shape as in Acanthotelson ; when it died the body was curved on itself, so that the two longer antennse crossed the end of the abdomen with its a[)pend- ages. The abdomen in its dorsal aspect, with the telson and last pair of uropoda, are tolerably well preserved. The faint traces of the head, unless we are mistaken, show that it was of the .same general shape as in Acanthotelson. There are traces of two pairs of anteuni* ; one fragment, the innermost, showing traces of six joints ; and there are faint impressions, not showing the joints, of two long antenniB, which are about half as long as the body. There are no traces of any thoracic or abdominal appendages except the last pair of uropoda.
Description. — Body vei'y broad, being nearly twice as broad as the largest Acanthotelson eveni, M. & W. The penultimate abdominal segment is a little more than one-half as long as the terminal segment. The last segment is very large and square, the sides nearly even, not narrowing poste- riorly, and it is the broad square shape of this segment which will readily enable one to separate it from the previously described species of Acanthotelson. The telson is stout, broad at the base, and rather short, much shorter than the uropoda appended to the same segment. The terminal uropoda are broad and stout, with no traces of setae. The basal joint is broad, triangular, but a little longer than broad ; the outer ramus is of moderate length, eusiform, and slightly longer than the telson; there is only a fragment of the inner telson left in the fossil, which, however, shows that it was considerably narrower and smaller than the outer pair.
Probable length of the whole body, not including the antennae or telson, TO""™. .
Length of pennltimate abdominal segment, 5™™.
Breadth of jjenultimate abdominal segment, 12™™.
Length of terminal abdominal segment, 10™™.
Breadth of terminal abdominal segment, 11™™.
Length of telson, 10™™; breadth at base, 2™™.
Length of basal joint of last pair of uropoda, 4™™ ; breadth, 3.5™™.
Length of outer ramus of last uropod, 11™™ ; breadth, 2™™.
Explanation of Plate I.
Fig. 1. Acanthotelson stimpsoni M. it W., restored, enlarged twice.
Fig. la. Acantlwlelson slimpsoni M. & W., head and antennae seen from above, enlarged twice.
Fig. lb. Acanthotelson stimpsoni M. & W., first thoracic leg x\.
Fig. Ic. Acanthotelson stimpsoni M. & W., sixth thoracic leg xf.
Fig. Id. Acanthotelson stimpsoni M. & W., telson and last pair of uropoda X^.
Fig. 2. Acanthotelson f magister Pack., X\. AH the figures drawn by Dr. J. S. Kingsley.
128 MEMOIRS OF THE NATIONAL ACADEMY OP SCIENCES.
Explanation of Plate II.
Fig. 1. Acanthotelson etinipsoni M. «& W.
Fig. 2. Acanlhottlson slimpsoiii M. & W., reverse of lig. 1.
Fig. 3. Acanthotelson stimpsoni M. & W.
Fig. 4. Acanthotelson ? mayister Pack.
Fig. 5. Acanthotelson ? magister Pack., reverse of fig. 4.
From pbotographs taken by Mr. Eobert L. P. Mason.
Note on an additional specimen. — Since this memoir was sent to the printer I have received a larger speeimeu from Mr. Lacoe, labelled " Braidwood, 111., Q'", whicL, exclusive of the antenna; and telson, measures about 82"'™. There are traces of four pairs of thoracic feet which are long and slender and bent backwards from the head, reminding us of the four hinder legs of an ordinary shrimp seen from one side. There are traces of the antennae, better preserved than in the original specimen. There appear to be a pair of large auteunie, the scape composed of three large joints, the second and third smaller and together equalling in length the basal joint; these antenna appear each to bear a large antennal scale, resembling those of the Macrura, and reaching as far as the middle of the third autennal joint. The characters shown by this specimen lead me to refer it to a genus distinct from Acanthotelson, for which the the name Belotelson (the entire name, Belotelson magister) is proposed. Additional siaecimeus are much desired to complete our knowledge of its affinities.
MEMOIRS NAT ACADEMY 3C,,V0L III
PLATE I
J S Kingsley.ot; .
FIGS. I-|<^ ACANTHOTELSON STIMPS0Nli2 A? MAGISTER.
MEMOIRS NAT. ACAD. SC. VOL. III.
PLATE II.
FIGS. 1 -3 ACANTHOTELSON STIMPSONI: 4. 5. A? MAGISTER.
FROM PHOTOGRAPHS BY rt. L. P. MASON.
ii.-ON THE gampsonychidj:, an undescribed family of fossil
SCHIZOPOD CRUSTACEA. PL III, FIGS. 14 ; VII, FIGS. 1, 2.
BEAD APRIL 21, 1855.
By A. S. Packard.
The opportunity of examining at my leisure about a dozen specimens of Palwoearis, typus of Meek and Wortheu, kindly afforded me by Messrs. R. D. Lacoe and J. C. Carr, has enabled me to work out some characters of this genus not mentioned by the original describers. The study of these specimens has induced me to compare the genus with Gampsonyx, and the result has led to the formation of a family or higher group for the genera, which should probably stand at the base of the Schizopoda, while also serving to bridge over the chasm existing between the Thoracostra- cous suborders, Syucarida and Schizopoda.'
Palaeocaris was first described by Messrs. Meek and Wortben, in the Proceedings of the Academy of Natural Sciences of Philadelphia (1865, p. 48), from specimens occurring in clay-stone concretions in the lower part of tiie true coal measures, at Mazon Creek, Morris, Grundy County, Illinois. Afterwards, in the third volume of the Reports of the Geological Survey of Illinois, 1868, the same authors figured the fossil, and expressed themselves as follows regarding its afBuities: "Hence it would seem to present something cf a combination of decapod (macrourau) and tetra- decapod characters. That is, it possesses the caudal appendages, anteriorly directed thoracic legs, the anteuuiB (some of the specimens appear, also, to show basal scales to the outer antennae) and general aspect of a macrourau, with the distinct head, divided thorax (without a carapace), and seven pairs of thoracic legs, of a tetradecapod. We have not been able to see its eyes, but from its other decapod characters, and its analogy to Gampsonyx, which is said by von Meyer to have pedun- culated, or at any rate movable, eyes, we are strongly inclined to believe that our fossil will be found to agree with Gampsonyx in this character also.
" It therefore became a matter of interest to determine to which of the subclasses, Decapoda or Tetradecapoda, it really belongs. That it belongs rather near Gampsonyx, though not to the same subordinate section (Schizopoda), there can be little doubt. Hence these two forms apparently fall naturally into the same family. Professors Jordan and von Meyer seem to have regarded Gamp- sonyx as a Tetradecapod, connected with the Amphipoda, but also possessing macroaral decapod affinities. Professor Dana, however, regards it as a low type of Macrura, belonging to the section Schizopoda. He and Dr. Stimpson, to whom we sent sketches of our better specimens of Palneo- caris, concur in the opinion, judging from all its characters yet known, that it is a low embryonic type of the Macrura, in which the carapace is not developed.
■ 'We Lave not seen Burmoister's memoir "Ueber Gampsouyclms" (Abh. d. naturf. Ges. in Halle, ii, 191, 1855), but Zittel (Handbucli der PaUeontologie, p. CTO) quotes Burmeister as stating that he regarded it ''as the representa- tive of a special group of Crustacea, which unites in itself some of the most essential features in the organization of the Stomapoda and Amphipoda."
S. Mis. 154 17 129
130
MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES.
"Generically, it is separated from Gampsonyx, figures of which (cuts C and D) we have added for comparison, not only in the nature of its caudal iiiipendages, but in the more important char- acter of having its thoracic legs simple, and not bifid, as in the Schizopoda."
Fig. 1. — Gampsonyx fimbriatus. After Jordan and von Meyer. From Meek and Worthen.
We will now describe in detail Palwocaris typus, restoring it so far as possible in our description from the specimens received from Messrs. Lacoe and Carr, amountiag in all to about a dozen, of which ten were kindly loaned by Mr. Lacoe. Dr. Kingsley has also obligingly drawn a restoration of the fossil from the specimens sent him for the purpose. There ai'e no traces of a carapace, but the head is phiinly distinct from the rest of the body. It is rounded in front, with no traces in my specimens of a rostrum, and is apparently composed of two segments. The body, seen sidewise, is suddenly arched or bent at the articulation of the thoracic and abdominal regions, as in stoma, pods and shrimps, and of the usual proportions. All the segments behind the head are free, and are fourteen (seven of which are abdominal) in number, counting the telson as one. There are thus sixteen segments, the head composed of two, the thorax of seven, and the abdomen of seven. The body thus has apparently the same number of thoracic and abdominal segments as in the existing Stomapoda. It is probable that the head of Palceocaris is composed of the same number of segments as in the Schizopoda, but as the moiith parts have not been preserved, this point must remain undetermined. The thorax, in its general shape, as seen from above, is of the normal shape, as seen in existing Stomapoda. The abdomen is much narrower than the thorax, with the basal segments short, and the penultimate one longer than broad, widening out a little on the hind margin, and excavated behind to receive the base of the telson.
The first antennae are about one-half as long as the body, with the scape long and slender, three-jointed (unless what I regard as the basal joint consists, as appearances suggest, of two); first joint long and slender; second, as thick but only one half as long as the lirst ; third, moder- ately long, considerably longer than tiie second ; flagella nearly equal in size, long and slender.
The second antennse with the scape three-jointed, the basal joint long; second and third, of nearly the same size and length; flagellum thick at base, long and slender, entire antenna nearly half as long as the body of the animal.
Of the thoracic feet, six pairs can be detected, while in front of the tirst pair are two other appendages like the legs, but whether they are gnathopods, like those of other Schizopoda, or thoracic feet, it is difficult to judge. Each thoracic foot is long and slender, tlie three distal joints forming the greater part of tlie limb. The terminal (seventh 1) joint is very long and slender, and probably ends in a single claw. The penultimate joint is about two-thirds as long. as the terminal. It is thickened towards the end, and is perhaps a little siiorter than the third joint from the end.
The endopodites* are distinctly preserved ; those on the last four pairs of legs are long, narrow, lanceolate-oval, acute at the end, each side of the endopodites being alike, i. e., one not being more convex than the other. If extended, the endopodite would reach out to near the middle of the terminal joint of the limb. 1 think I can detect eight pairs of endopodites — six at least- one on each thoracic leg and one on each of the gnathopods, if such they are. This would tend to show that the first two appendages behind the head are true gnathopods, like those of existing Schizo- pods, especially Petalophthalmus.
There are traces of a pair of abdominal legs to each of the seven segments. To the rather
* I had regarded these appendages as breeding lamellae, but Dr. Kingsley suggests that they are endopodites, aud though the joints are very iudistiuct, I am disposed to accept his correction, and will speak of them as endopodites. We should, on general grounds, regard them as endopodites
[ON THE GAMPSOISTTCHID^. 131
thick aud Ions; basal joint of eachVere probably attached two slender rami. The entire limbs were about one-half as long as the thoracic legs (see Lacoe's No. 40^"^). There were at least five pairs (and I think traces of a sixth) besides the last pair. The end of the abdomen, with the telson, and last pair of legs are as described and figured by Meek & Worthen. The telson is large iu size, broad and short, somewhat triangular, being broader at the base than at the end. It is some- what spatulate iu form, being well rounded at the end, and much shorter than the inner rami of the appendages associated with it. Its end is fringed with coarsa sctaj. In the last abdominal ap. pendages, the outer ramus is broader than the inner, with a deep longitudinal crease, or impressed line, which fades out on the outer third, or extends to the end of the basal joint. The second, or distal joint, is fringed with fine sette. The suture between the two joints is externally indicated by two setjB larger than the others, and somewhat curved. The inner ramus is somewhat shorter than the outer; the end well rounded, and fringed with set®. It reaches to the second joint of the longer outer ramus.
Total length of the largest specimen 33°"°.
Total length of the best preserved specimen 25"™ (Lacoe*8 No. 404«'). This specimen gave us the following measurements :
Length of Ist antennae (estimated) 8""".
Length of 2d antenna (estimated) lO-ll"™.
Length of last thoracic l0g(exopodite) 8"".
Length of endopodite 4""™.
Length of telson 3""° ; width 1.5""".
Length of outer ramus of last pair of abdominal feet 4"™.
It should be observed that the endopodites are in part represented in Meek and Wortben's figure, but not referred to in their description. They are also partly represented in their copy of Jordan and von Meyer's figure of Oampsonyx fimhriatiis. In the latter, there is also present what is apparently a large, coarsely spined, mandibular palpus, somewhat like that in the male of the exist- ing deep-sea Schizopod Petaloj^hthalmus armatus described by Willemoes-Suhm.* In the females however, the palpus is small and unarmed. In the figure of Gampsonyx referred to, the thoracic legs themselves, irrespective of the endopodites, are represented as biramous, and the two rami are drawn as of neai'ly equal length. It is probable that there has been a mistake in drawing the legs, as iu none of the existing Schizopods, such as Mysis and its allies Euphausia, Guathophausia, Petalopthalmus or Chalaraspis, are the legs thus thrice divided. It is to be hoped that the fossil itself will be examined anew with regard to this important point.t
It is sufficiently evident, however, that Gampsonyx and Palseocaris are closely allied forms, and as first suggested by Messrs. Meek and Worthen should fall into the same family, which may be called Gampsonychidse. The principal character which separates this group from all other Schizo- pods is the entire absence of a carapace.
It is worthy of notice, however, that the size of the carapace is very variable in the Schizopods, and in the genus Petalophthalmus there is a great discrepancy in the two sexes. In the female it covers the entire thorax, while in the male it is remarkably small, subtriangular, leaving the two hinder thoracic segments entirely exposed, as well as the sides of the two segments in front. In the large size and oval-lanceolate shape of the endopodites, both of the gnathopods (maxilliiJedes) and thoracicfeet, theGampsouychidae]agree with Petalopthalmus, in which they are large and broad. In the shape of the telson and the comparative size and proportions of the last pair of abdominal appendages there is a close relationshi]) in the Gampsonychidae to the Schizopod genera Petalo- phthalmus and Chalaraspis, especially the latter genus, in which the telson is rounded at the end,
* On some Atlantic Crustacea from the Challenger Expedition, by Dr. R. von Willemoes-Suhm. Linnasan Trans- actions. Zoology, vol. i, p. 23, 1874.
tNo light is thrown on the nature of the limbs by the thirty specimens of Palwocaris acoticus described by Mr. B. N. Peach from the lower Carboniferous rocks of Scotland. Nor were eyes with certainty detected in his specimens. " For instance, 'although in most of the specimens there occur small oblong bosses just in the place where their eyes should be, were they decapods, figs. lO-lOrf, yet the facets of the cornea have been looked for in vain. This is unfor- tunate, as it prevents one from saying with certainty that these are the eyes, though there is a strong presumption in favor of their being so. No sessile eyes have been observed on the carapace, neither has a trace of anything been observed that could be construed into such."— Trans. Roy. Soc. Edinburgh, 1882, 'p. 86.
132
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
while the two rami are more as in Petalophthalmus, though broader. The other biramous abdominal appendages in the Gampsonychidte are truly schizopodal.
Fig. 3o.— Telson of Petii- lophthlamuscf.
no. 3.— Petalolplithalmns armatascT.
Fig, 4. — PetalopMhalmns armatns 9 . TMs and Kg. 3 after TV. Snhm.
Fig. 4(1. — Second gna- thopod of Petalopbtlialmua 9. I, breeding lamella.
F I G. 46. — Third
{>ereiopod of Peta- ophthalmus 9 •
Classifying the Schizopoda by the carapace, modifying Willemoes-Suhm's table by throwing out the Nebaliadse and substituting the Gampsonychidae, there would seem to be three groups, as follows :
I. Carapace absent (Gampsonychidae).
II. Carapace free, varying in size (Gnathophansia, Petalopthalmiis and Chaiaraspis).
III. Carapace fastened to tlie tliorax (Mysis, Lopliogaster and Euphausia).
But I should agree with Willemoe.s-Suhm that this is not a natural genealogical classification, and throwing out the Nebaliadse, which, as we have endeavored to show, belong to a distinct order of Cru.stacea, the families of Schizopods may be enumerated thus (after adding the Gampsonychidse to von Suhm's table), all having seven abdominal segments :
Carapace absent, sis pairs of tboracic legs I Gampsonychidae.
Carapace well developed, six pairs of tlioracic legs II Mysidfe.
Carapace well developed, eight pairs of tboracic legs Ill Eupbansiidas.
Carapace well developed, four pairs of tboracic logs IV Cbalaraspidae.
Carapace well developed, seven pairs of thoracic legs V Lophogastridoe.
When we compare the Gampsonychidse with the Syncarida (Acanthotelson), we see that both groups have the same number of body-segments, and that both lack a carapace; and thus, while the Gamp.sonychidae are the ancestors of living Schizopods, the group as a whole probably de-
OK THE GAMPSOKTCHIDJE. 133
scended from Acantliotclsoii, which is thus a truly synthetic form, standing in an ancestral relation to all the Thoracostraca, while it also suggests that the sessile-eyed and stalked-eyed Crustacea may have had a common parentage.
Explanation of Plate III.'
Fig. 1. Palcsocaris typua, M. <fe W. restored, enlarged four times. (The front of the head is partly conjectural and though stalked eyes probably existed, uo attempt has been made to restore them.)
Fig. 2. Pala-ocari'i lypus, seven thoracic segments, showing the disposition of the endopodites, x? (Lacoe's 4046).
Fig. 3. Palwocaris lypus, doTaal view of one side of three thoracic segments, showing the basal joints of the en- dopodites {endop), and exopodites (ejojj), enlarged.
Fig. 4. FalcBocaris typm, telson and last pair of uropoda. Xf.
* All the figures on this plate drawn by Dr. J. S. Kingsley.
PLATl 111
endop
3
PAL/Eij.
\ r. I ;■ I I r ^; .;-) .
Ill -ON THE ANTHRACARIDil, A FAMILY OF CARBONIFEROUS MACRU-
ROUS DECAPOD CRUSTACEA.
SEAB APRIL 21, 1885.
By A. S. Packard.
Having been kindly favored by Messrs. R. D. Lacoe and J. C. Carr with the opportunity of examining their collections of nodules from Mazon Creek containing Anthrapala'mon gracilis Meek and Worthen, I Iiave been able to discover some features probably not shown in the 8j)ecimens examined by Messrs. Meek and Worthen. The newly observed cliaracters are the Ciirapace with its rostrnm, showing that the American species in these respects closely resembles the European ones figured by Salter, the founder of the genus. Moreover, our specimens prove the existence of five pairs of thoracic legs, while the antennae of both pairs are almost entirely shown. The fact that the first pair of thoracic feet were scaicelj' larger than the succeeding pairs, suggests that Anthrapalsemon cannot be pbiced in the Eryouidae, but shouhl form the type of a distinct group of family rank, none of the existing Macrura, so far as we are aware, having sui'-h small anterior legs. Other characteristics which we ahall point out confirm this view.
The genus Anthrapalremon, a Carboniferous fossil, was first described by J. W. Salter in the Quarterly Journal of the Geological Society of London (xvii, 529, 18(il). The name given to tbe fossils has, the author remarks, "only a general signification, and is not intended to indicate a real relation to Palsemon." He also i-emarks that " the genus is not to be confounded with any of the Liassic or Oolitic ones jjublished by von Meyir, Miinster, &c. . . . It is broader than the general form of the Astacida3,or than Glyphcea and its Liassic allies, but much narrower than IJryon." Salter's type-species is Anthrapakemon grossarti Salter.* With this species the American A. gracilis is congeneric. A closely allied English form, A. duhius Prestwich, is referred by Mr. Salter to the subgenus raUcocarabus, a name even less fitting than Anthrapala-mon. Concerning the other form provisionally referred to Authrapalemon by Mr. Salter (his Fig. 5), we will remark In a supplementary note to this article.
The only American species we have seent is Anthrapakemon gracilis Meek & Worthen, first described in the Proceedings of the Academy of Natural Sciences of Philadelphia, 1865, and redescribed and figured in the second volume of the Geological Survey of Illinois, and again in the third volume.
Mr. Salter figured the carapace and rostrum, as well as the abdomen of the Eurojiean species ; while the specimen figured by Meek and Worthen evidently did not possess the carapace, but showed perfectly the telsou and neighboring pair of abdominal appendages.
The specimens loaned us by Mr. Lacoe enable us to give a more perfect description and illus- trations of this important type ; and I am indebted to Dr. J. S. Kingsley lor the restoration and
* In his Handbuch der Palicontologie, Zittel mentionH Pseudogalathea Peach, from the carbouiferous of Scotland. We have not yet seen Mr. Peach's article.
tDr. J. W. Dawsou has described and figured, the carapace of AiithrapaJwmon hiUianum, from the Carboniferous of Nova Scotia. Geol. Mag., iv, new ser., p. 56, fig. 1, 1877. Also figured in his Acadian Geology, 1878.
135
136 MEMOIRS OF THE NATIONAL ACADEMY OP SCIENCES.
details, which he has so faithfully drawn. I am inclined to think that the body was actually broader than Dr. Kingsley has drawn it, and that tlie lateral spines of the carapace were visible from above ; but I leave it as an open question.
The carapace is of the same length as the urosome (abdomen) or slightly longer, being from two-thirds to three-fourths as wide as it is long. It is very thin and delicate, and many specimens have none. The sides are regularly curved, and unarmed behind the middle, but on the anterior third are seven distinct, sharp lateral spines, the seventh being three times as large as the others and situated on the anterior outer angle of the carapace. I cannot with certainty distinguish any spines between this last-mentioned spine and the rostrum.* Casts of the latter are distinctly seen in two specimens (Lacoe's 200/;^ and 200mm) to be small, triangular, short, and acute. The rostrum itself is pretty well preserved in one specimen (Mr. Lacoe's No. 200^). It is rather long, stout, strong, acute, situated between the first auteunse, and extending as far as the middle of the third joint of the scape of the latter. In another specimen (Lacoe's 200oo, 200nn) the rostrum is fairly well preserved ; it is long and slender, and about half as long as the carapace ; also as long as the abdomen is wide in its narrowest part.
In only a single specimen is a side view of an apparently folded carapace preserved. The entire rostrum is long and straight, slender and acute, originating in the anterior third of the carapace, the entire rostrum being about half as long as the carapace itself. (PI. VII, figs. 3. 3a.)
Along the sides are numerous sharp spines. Whether there was, as in the other form (A. grossarti), a series of dorsal spines our specimens do not distinctly show. Behind the base of the rostrum a median ridge extends to the posterior edge of the carapace. The lower edge of the carapace is serrate on the anterior third, as in all the other specimens. On the surface of the carapace an apparently false or superficial suture passes out laterally from the anterior third, and another impressed line, better marked, from the posterior third, extending half-way to the edge of the carapace. The surface of the carapace is seen to be finely shagreened, but scarcely tuber- culated, as iu the European A. grossarti.
Of eyes no traces are visible in any of the specimens except one, and I am inclined to the opinion that they were either wanting or very small, and concealed under the front edge of the carapace. At the same time it should be observed that in none of the fossil macrurous Crustacea from the Carboniferous are the eyes preserved. It may also be borne in mind that in the deep- sea Penlacheles scnl])li(s S nith no corneal area was to be detected, and in Willemcesia and the fossil Eryoniscus the eyes are entirely wanting.! So far as we can decide, the front edge of the carapace is not excavated at the point wliere we should look for eyes or eye-stalks, but, on the contrary, seems to be quite regularly convex. Still, additional specimens are needed to clear up the exact nature of the front edge of the carapace.
In most of the specimens the thin, delicate carapace has not been preserved. When it ife absent the five thoracic segments are distinctly marked, of about the same length. In front of these are three cephalic segments, making eight segments in all apparent iu some specimens.
The first anteunre are large and long ; the scape three jointed, first joint long, the second about one-half as long as the first and of about the same width; third joint a little longer, but smaller, than the second; the two flagella are a little longer than the scape, the inner one about half as thick and evidently only half as long as the outer one. (Lacue, No. 200y.)
The second antennie are, with the sca[)e, considerably stouter than those of the first pair; first joint short and stout, but longer than broad ; second very short, oblique at the end, and consid- erably shorter than the third joint, which is about as long as tliick; the flagellum is very long and slender, multiarticulate, at least as long as the carapace, and directed backward, as in Pentacheles; there is an antennal scale present, but its outlines are very indisfinct.
The five pairs of legs are preserved (Nos. 200/y>, 200"""); tliey are all of nearly equal size, the first pair apparently being no larger than the others, in this respect dift'ering from Galathea and the existing Galatheidea. Of the first pair of limbs there are iu one specimen (200d) traces of nearly
■ Dr. Kingsley li.is, bowtiver, detected a spiue at this point and iuscrted it iu his drawings, as seen in the plate.
t After this paper was written the specimens were sent to Dr. Kingsley to be drawn ; among them the specimen with traces of an eye. He has drawn iu the eye ; and on examining the specimen again, I thinli that he is right iu representing the eyes. It was apparently large and well developed.
J! IG. 6a. — Eumunida picta, end of abdomen enlarged.
Recent deicp-ska Galatheidea. After S. I. Smill: S. Mis. 154— To face page 137.
Fig. 7. — Anoptohts j olitus Smitb.
ON THE ANTHRACARID^. 137
the entire limb, i. e., at least the first and second joints ; the third Joint could not have been of large size, a feature distiuguishiug the Eryouidii? as well as Astacidie and the higher Macrurans in general. The first and fifth pair seem to be of about the same size; the third and fourth pair of legs are a little larger than the others and but little longer than the width of the carapace. It is untortunate that no specimens have yet been found with the first pair of limbs entire, but the fact that the two basal and perhaps the third joints are no larger than those of the other pairs of feet indicates that this form differed from all the fossil and recent Eryonidae, and is a character of so much importance as to forbid our regardinsi' Anthrapahemon as a member of that family; the only other alternative being to consider it as a type of a distinct family. Of the four hinder pairs of legs the three terminal joints of the limbs (these affording the diagnostic characters) are pre- served, and the proportions are much as in the four hinder pairs of thoracic legs of the existing deep-sea Pentacheles; of the three joints the proximal and middle ones ai'e long and slender, the inner one longer than the outer of the two; the distal (terminal) joint is rather short and pointed, and apparently chelate. Meek and Worthen remark that the legs are nordivided; whether they meant that the legs are not divided as in the Schizoi)oda, or simply referred to the terminal joint alone, does not appear, but in the specimen before us (No. 20()/?/j) the last joint appears to be chelate, since what seems to be the smaller inner finger is partly but tolerably well preserved, the crust or derm itself being preserved. Yet we may be mistaken.* lu Meek and Wortheu's figure, the terminal joints are drawn as undivided. If this is the case, they resemble the four hinder legs of Munida, Eumunida, and Anoplotes.
The abdomen is rather short and broad, as in the Galatheidie, and consists of seven segments, counting the telson as the seventh.
The general appearance and relative size of the telson, together with the last pair of abdominal appendages, is much as in the Eryonidie, with some important differences. The telson, unlike that of any other Macruran, fossil or recent, so far as I am aware, is differentiated iuto three portions; the basal central piece is somewhat polygonal, a little longer than broad ; it is separated by a distinct suture froui a small triangular terminal ])iece which forms the apex of the telson. Between the outer Iialf of the entire telson and the inner ramus of the uropoda is a large broad lobe which is fringed with set;e. At first I regarded it as a subdivision of the inner lobe of the last uropoda or abdominal feet, but no instance among the Decapoda is known to us in which the last pair of uropoda have more thau two lobes or divisions, and I have therefore been inclined to associate the innermost of the three setiferous lobes with the telson, and to regard the telson as divided into two median and two lateral lobular setiferous portions. Whether the two lobes belong with the telson or uropoda I will leave for the present an oi)en question. The only group in existence in which the telson is so remarkably differentiated is the Galatheidie. In Munida the telson is divided by sutures into four pieces, the two terminal ones lobate and edged with setai of the same size as those of the uropoda. In Eumunida of Smith the telson is "short and broad, more or less membranaceous, and divided by a transverse articulation, so that the distal part may be folded beneath the basal part." In Anoplotm politus. like the foregoing, a deep-sea Galatheid, ''tbe telson is stiffened by eight distinct calcified plates; a broad median basal plate, with a small one on either side at the base of tlie uropod, and a small median one behind it, and between a pair of broad lateral plates, still behind which there is a second pair, which meet in the uiiddle line and form the tips and lateral angles." Professor Smith's figures of Munida, Eumunida, and Anopotus are here rei)r(Kluceil from electrotypes kindly loaned by Professor Baird, U. S. Fish Commission. t
From the nature of theditierentiation of the telson in the Galatheidte I am inclined to believe that the telson of Authrapahemon is subdivided in somewhat the same manner. If so, we cannot refer the genus to the Eryonida', and we would therefore regard it as the type of a distinct family which may thus be briefly characterized :
Family Anthracaridw : Body rather broad and slightly flattened ; first antennae with two long
* In none of the six Scottish Carboniferous species of AntUrapaUeraon described by Mr. B. N. Peach, do either of the thoracic limbs appear to be chelate.
t PreUmiuary report ou the lirachyura aud Aaomura dredged in deep water o6f the south coast of Now England, by the U. S. Fish Commission, in 1?J80. By S. I. Smith, Proc. U. S. Nat. Museum, 1883, June 18. S. Mis. 154 IS
138 MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES.
flagella ; second anteiiiiie long, withont a scale ; the first pair of thoracic legs no longer than the four succeeding ])airs ; the hfth pair of legs as long and well developed as the others ; carapace ovate, smooth, without transverse impressed Hues, with a long, acute rostrum; with lateral spines on the anterior half; abdomen rather broad, nearly as much so as the carapace ; the telson broad and differentiated into two median pieces, the basal piece with broad, rounded membranaceous lobes, one on each side, fringed like the two rami of each uropod, with long setai.
After the foregoing paper was written, and an abstract published in the American Naturalist for September, 1885, I sent the specimens to Dr. Kingsley to be drawn, and on their return he made the following criticisms, which are here quoted :
" From the characters shown in the specimens before me, Anthrapaliemou apparently has nothing to do with the EryonidiE, but belongs rather to the Schizosomi of Stimpson. The thoracic structure, antenniv, sternum, and telson are all paralleled in that group. The telson is much like that of the Porcellaiu crabs. The absence of the distal pedal joints of the legs renders its family uncertain. It may belong to some of those existing in the fauna of to-day. It certainly shows no features which would justify the creation. of a new family for it."
While I should hardly agree with the view that Anthrapalwmon belongs to the Schizosomi, since Porcellaua is a brachyurau, with a broad, round cephalothorax and small abdomen, folded beneath the body, the differentiation of the telson is somewhat as in Porcellaua, as will be seen by referen(;e to Fig. 7, copied from Milne Edwards.* O n the other hand, I have erred in regarding it as closely allied to the Eryonida?, as defiued by Zittel in his Handbuch der Palaeoutologie. Having already drawn attention to the highly difleren- Fig.7.— tiated telson of the Galatheid.t, 1 am now much inclined to regard the Anthracarid;!? Alulomen as more nearly related to this group. The resemblance to the Galatlieidre is seen in the "^ Poicel- general shape of the body, the proportions of the carapace with its sharp rostrum, and the proportions of the abdomen with its broad telson and uropoda. The tirst pair of auteume differ, however, from those of the Galatheidte in having two well-developed tlagella. and the first pair of legs are much smaller, while the fifth pair are larger in projiortion ; the last pair of uropoda are more as in the Glyphneida?, and Astacida", the outer ramus being divided into a long basal and short broad distal segment.
It seems to us, from what we now know of the characters of Anthrapakemou, as we have wox^ked them out, that it cannot be placed in any kuown family of Decapoda. We should now be inclined to place the Authracaridiie nearest the GalatheidiB, most of which are deep sea forms. It is not improbable that they were the forerunners or ancestors of the Galatheidie.t That the family is a synthetic group is shown by the resemblance of its telson to that of Porcellana, a Brachyurau. It certainly does not beloug among the Palinurida-, nor, on the other hand, among the Glyphffiidse.
In Zittel's valuable Handbuch der Palaeontologie (Bd. 1, 2d Abth., Lief, iv, p. 682), Anthrapa- Iremon is jdaced among the PemBidiB, but its characters appear to be such as to forbid such an alliance. PaltEoutology is an inexact science, but the attempt to seek the natural position of extinct forms leads us to examine their remains more closely, to make further explorations for more perfectly preserved specimens, while the final result is to lead us to enlarge our concep- tions as to the affinities of existing types of life. It seems to us better to establish new groups for Palfeozoic forms of uncertain positions than to crowd them into groups of highly specialized modern forms. Yet this tendency may be carried too far. Whether we have erred in the present instance we leave to the judgment of those who, with a special knowledge of modern Crustacea, also possess both critical skill and broad views in dealing with natural groups.
Note on the Palj30zoic Shrimps {Carididcc).
The form provisionally referred to Anthrapalfemon by Salter (his fig. a. Quart. Journ. Geol. Soc. Loudon, xvii, 1861), occurring in the Carboniferous beds at Lanarkshire, Scotland, which has
"Crustac^s, pi. 22, fig. 7.
t After writing the foregoing remarks I found I had overlooked Professor Dana's opinion, expressed on p. 350 of his Manual of Geology, 3d edition, where, after referring to the British species of Anthrapalaeinon, he adds, " but the broad flattened carapax indicates a nearer relation to ^Eglea and Galathea than to Pahemon."
ON THE ANTHKAGAlilD.^. 139
beeu copied into geological text-books as represoutiug Antbiapala'iiioii (see Dana's Manual of Geology, fig. 686 A), does not belong to tbat genus or the giouj) it represents, but is evidently one of the true shrimps or Carididaj. The carapace and serrated rostrum, as well as the shape of tlio abdomen, the form of the last jiair of uropoda, and the tclson, all indicate genuine prawn like affinities. It may be named Archkaris saltvri.
The other Carboniferous shrimps are Vrdngopsis soliaies (Salter, Quart. Jouni. (Jeol. Soc. 533, fig. 8, 1861). Tliis appears to be a. genuine Caridid; it is from the subcarbonifciuus beds of England. (As synonyms of Criingopsis Salter are Pakeocraiifioii Saltei', non Schaurotii, and i'ro- nectes Salter. (See Zittel's Palaeontologie.)
Pj/goeephal us cooperi, of Huxley, from the Carboniferous beds near Manchester, England, is a doubtful form, which he refers "either to the decapodons or stomaj)odous group of the class.' (Quart. Journ. Geol. Soc, xiii, 363, 1857; xviii, 420, 1862). Professor Dana (Manual of Geology, 3d edit., p. 350) regards this form as a Schizopod.
No Carboniferous Caridid;e have as yet been discovered in America. The oldest known macrurous Crustacean, however, is American, the PaUeopakemon newh^rryi, described by ^Mr. Wliit- field (Amer. Journ. Sc, 33, 1880), from the Upper Devonian of Ohio.
Explanaiion af i'liite IV.
Fig. 1. AnthrapaJoemon graciUs, M. & W., restored, eulargeil 3 times.
2. " " " carapace and eyes, X t-
3. " " " carapace flattened, seen from above x 31. 4 " " " part of first tlioracic leg, x f .
5. " " " four basal joints of tlie fifth leg, x ^
6. " " " telson and last pair of uropoda, X f to f.
All the iigares ou this plate drawn by Dr. J. S. Kiugsley.
AMTHRAPAL/EMON v_.n-..,.,^ _ .
NATIONAL ACADEMY OF SCIENCES.
VOL. Ill
SIXTEENTH MEMOIR
ON THE CARBONIFEROUS XIPHOSUROUS FAUNA OF NORTH AMERICA.
141
(XVI.)
ON THE CARBONIFEROUS XIPHOSUROUS FAUNA OF NORTH AMERICA.
HEAD NOVEMBER IS, 1885.
By a. S. Packard.
By the kindness of Messrs. R. D. Lacoe, of Pittston, Pa., and .J. G. Carr, of jNIorris, 111., I have been able to examine a most valuable collection of rare Xiphosuran fossils from Mazon Creek, Grnndy County, Illinois, besides two specimens from the coal-beds of Pennsylvania. These have revealed the existence on this continent of two genera, hitherto confined to the European coal- measures, viz, Cychis and Beliiuirus. From the Pennsylvanian coal-measures a new species of Prestwichia has been obtained, and it is probable that ultimately we shall find as many species of this family as there are in European strata.
Of still more interest is the discovery of remnants of cephalic limbs in Cyclus and Prestwichia, showing that in these animals the cephalic appendages were like those of the larval Limulus. It also appears that the ontogenetic development of Limulus is an epitome of that of the Xiphosura as a group. Furthermore, our studies have led us to restrict the Xiphosura to the three families of Cyelid(e, BelinurldcB, and Linmlidce, while certain upper Silurian forms referred by Woodward to the Eurypterida, and by Zittel placed among the Xiphosura, are, temporarily at least, referred to a new suborder, the Synziphosura, a group combining with features of its own, characteristics of the Xijihosura and some strong resemblances to the Trilobites.
Family CTCLID^ Packard. Cyclus Americana Packard. PI. V, figs. 1, 1«, ; VI, figs. 4, 4a.
Cyclm americana Pack., Anier. Naturalist, xix, 293, March, 18B5.
In a nodule from Mazon Creek, Illinois, received from Mr. Lacoe, I recognize a species of this rather obscure genus, vvhich has not before occurred in North America, though in Europe nine .species have been described.
In form the animal is perfectly orbicular, the length being exactly equaled by the breadth. The body is regularly disk-shaped, flattened hemispherical, with the edge of the body broadly and regularly expanded, the margin being thin and flat, and apparently a little wider on the sides than on the anterior or posterior end. The inner edge of the rim is separated by an impressed line from the raised portions of the body-disk ; the surface of the rim is not plain and smooth, but ornamented by a series of plate-like, squarish markings, apparently sejjaratedby aslight impressed line, and with a slightly marked, raised tubercle on each plate or scale.
There are no indications of segments either of the head or abdomen, nor are the limits between a head and abdominal region distinguishable, as is the case in Cyclus jonesianus Woodw.* There
* Contributious to British fossil Crustacea. By Henry Woodw.ard, F. G. S.,etc. Geol. Mag.,vii, No. 12, pi. xxili,
Dec, 1870.
143
144 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
are, however, indications of four, and perhaps five, pairs of short, thick, cephalic appendages on the ajiterior tlurd of the body. Unfortunately, they are not well preserved, the basal and distal por- tions not present, and the indications of joints indistinct ; they are directed outwards from near the median line of the body, on each side of the intestine, the hindenuost ((5th) pair being directed somewhat obliquely outwards and backwards. In their position and relative distance apart they seem homologous with the cephalic limbs of the larval Limulus. The indications, slight as they ari", lead us to suppose that they approached iu general shape and relative size those of Prest- wichia, reaching near but not passing beyond the edge of the cephalic shield. The distal portion of the limbs not being preserved, it is impossible to conjecture whether they were forcipicate or not.* Through the middle of the body, from near the anterior to the posterior margin, passes the cast of the digestive caual ; it is swollen in front, the dilatation probably i-epresentine: the pro- ventriculus, and in outline the cast recalls that of the digestive caual of Limulus. Judging by analogy, the mouth was probably, as in the larval Limulus, situated well iu front between fhe anterior pairs of appendages, and the (jesophagus curved forward and upward from the mouth, while the vent was situated very near the hinder edge of the body.
There are no distinct traces of an abdominal region in the specimen, and it will be seen that in some of Dr. Woodward's figures there is also none. It is not probable that there was any spine in the genus, none being indicated in any of the figures or descriptions published.
Length of body, 14"'"; breadth, 14'""'; width of the flattened rim or margin, 1 ■. Locality,
Mazon Creek. No. 218a, b. Collection of Mr. Lacoe.
.Judgingby our specimens and Dr. Woodward's figures, Cyclus if restored would have au orbic- ular body, more or less disk-like or hemispherical, with a cephalic region composed of six seg- ments, which are not, however, indicated externally; this region had a thiu margin, as in Prest- wichia and Limulus. A pair of median ocelli were probably present, but no compound lateral eyes have yet been discovered. An abdominal region was slightly differentiated, and it was composed of three segments, the third representing that of the embryo Limulus, which in that form eventu.ally becomes the caudal spine. The Cyclus was provided with sis pairs of cejihalic appendages, which were short, not reaching beyond the edge of the body. With these the animal could creep over the bottom of the shallow, muddj' ])ortions of the carboniferous sea. It is not improbable that there were two pairs of abdominal lamellated legs, adapted for respiration, short and broad, and not unlike those of the embryo Limulus. In fact, our conception of the form of the living Cyclus is that it was not much unlike the advanced embryo of Limulus, either in the stage represented in Figs. 17 and 17« or IS, 1S«, and perhaps 19 and 19rt, of our memoir* of one of which (19a) Fig. 8 is a copy. At this stage of development the body of Limulus is hemispherical ; seen from beneath the ontline of the body is nearly orbicular, the abdominal region completing the circle. If Limulus were arrested at the stage of development when only three abdominal segments had appeared, and the devel- opment of the teet and claws had been accelerated and then hatched, it would be, so to speak, a Cyclus.
^Li'inuiii^^"c y c° u°s ' ^" our first memoir on the development of Limulus we adopted Dr. Wood- '**'''5e- ward's view tliat Cyclus was a Xiphosuran. In ISGS Dr. Woodward stated : "We
must differ from M. de Konink iu referring this form to the Trilobites. If truly au adult, it must be placed near to Apus, with the other shield-bearing Phyllopods ; if a larval form, it may have been the early stage of Prestwichia, or some other Limuloid of the coal measures. Nor do we think it in the least probable that the shield of Cyclus radialis was flexible or contractUe, its original segments being completely soldered together into one piece " ; and in 1870 he adds that, from the recent inves-
' The Development of Limulus polypheniiis, 1H72, PI. iv. Memoirs Bast. Soc. Nat. Hist., Vol. 1.
Since this article was seut to the printer, I have received, through the kindness of the author, Jlr. B. N. Peach's " Further Researches among the Crustacea and Arachuida of the Caiboniferous Rocks of the Scottish Border. Trans. Roy. Soc. Edinburgh, 1882." In this memoir Mr. Peach figures aud briefly describes the limbs of Cyclns. " From the fact," he says, " that several of the Survey specimens exhibit limbs, the radiating lines of the sternum are most probably the divisions between the coxie." Under Cijdua testudo Peach, he describes six triangular plates on each side, divided from each otlier by deep sulci, and converging upou an oral sternum. He also refers to " the jointed cylindrical limbs, the tips of which have not been observed."
ON THE CARBONIFEROUS XIPHOSUROUS FAUNA. 145
tigatious of Dr. Lockwood aud myself, " these forms may iudeed be the huval stages of Prestwi- ohia, Belinurus, etc., the autetypes iu Carboniferous times of the modern kiug crab." " Were it uot for the hirge size of these fossils, some (C. Harl-nestii) measuring five lines in length, three aud one-half lines in breadth, and three lines in height, we should be disposed to agree with Mr. Woodward ; but, from what is known of the size and form of the freshlj-hatched larvse of Lim- ulus and the Trilobites, T should infer that they were either the larva; of some unknown genus of Limulidii?, or adult but embryonic forms. The larvte of Belinurus and its allies, Prestwichia and Euproops, were, in all probability, closely allied in their form and size at the time of hatching to the larva of Limulus. But on comparing the deep hemispherical form of Cyclus, with the surface of the body <leeply lobed over a more or less extent, with the embryo of Limulus before it is hatched. (PI. iv, figs. 18, 18a), we find a striking similarity; indeed, we seem to be dealing with a distinct embryonic type of Limulida*. In Cyclus we have, in a late larval or possibly adult condi- tion, that state of Limulus in which the body is deeply hemispherical, and the abdomen has just been difl:erentiated from the rest of the body, while the deep transverse lobes of the yolk are uot yet absorbed, as seen in PI. iv, figs. 18, 18rt, in the embryo of Limulus ; the cardiac or median lobe being as distinctly marked in Cyclus as in the embryo of Limulus." (DeveloiJuient of Limulus, 1872, p. 189.)
After again reviewing the characters of Cyclus, with the specimen of C, americanus before us, we feel confirmed in the views above presented, and would regard Cyclus as the representative of a family of Xiphosura, being an adult form, and embryotypic, to coin a word, of a Limulus, while the Belinuridse represent the larval Limulus.
Family DIPELTID^ Packard. DiPELTis DiPLODiscus Packard. PI. V, tigs. -*, 2». Dipeltia diplodisotia Pack., Amer. Naturalist, xix, 293, March, lSf*5.
This name was proposed for a singular form which is not satisfactorily preserved, so that its exact relations are not readily determinable. The body is suborbicular, flattened, disk-like, slop- ing regularly and gradually from the median area to the edge ; it is divided into two portions ; the larger one to be regarded as anterior or the cephalic shield, and the other as posterior, constituting the abdomen (urosome). The edge of the body is very slightly margiuate, not broadly so as in Cyclus; nor is the body distinctly trilobate, as in the Belinuridie and Limulidse, though unfortu- nately the median area of the cephalic shield is wanting. The integument is rather thin, showing- no traces of segments ; its surface may have had a few scattered small tubercles, at least there are slight indications of them. The surface is smooth and shining.
The cephalic shield is nearly twice as broad as long ; the posterior lateral angle is well-rounded, with no sign of a lateral spine; in front the edge was probably obtusely rounded; the surface is slightly convex, the disk being low and flat, with no traces of a glabella ; the hind edge of the shield is moderately concave, the limits between it and the urosome being clearly indicated by a slight, but distinct, regular, curvilinear suture.
The urosome is about three-fourths as long as, but equal in width to the cephalic shield. The front edge is somewhat arcuate, so that the projecting anterior-lateral angle is directed a little forward, and is quite free from the lateral angle of the cephalic shield, which turns away anteriorly from it, leaving a triangular space between the sides of the two regions. Posterior edge of the urosome regularly rounded, and with a slight margin. No traces of a caudal lobe or spine. Total length, 20""" ; total breadth, 20""" ; length of cephalic shield, 11'"™ ; breadth, 20""' ; length of urosome, 9°"°; breadth, 19.5""'. Collection of R. D. Lacoe, 2017 "•''•'■ in a nodule from Mazou creek, Morris, Illinois.
This remarkable animal was disk-like in shape, composed of two regions, the head and abdo- men or urosome, which are more distinctly separated than in the Cyclidte ; while there are no posi- tive characters to separate it from this groujj, we would, for the present at least, refer it to an allied family, as it is orbicular, tailless, aud consists of a broad, large cephalic shield, with a shorter, distinct, non-segmented urosome. S. Mis. 151 19
14(5 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
Family BELINURID^ Packard. Pkestwiohia dan^ )Meek) PI. V,figs. 3, S''; VI, 1, 1", 2, 2\
}ittnini(ni>i dance, Meek and Wortheu, Proc Acad. Nat. Sc, Phil., llarch 1865, Rt. Geol. Surv., 111. ii, 395,
1860. Prestwichia datuv Meek, Amer. Jouru. Sc, 2d ser., xUii, 257, 1867. Enproops danw, Meek, Amer. Journ. Sc, xliii, 394, 1867.
Meek and Worthen, Rt. Geol. Surv. 111., iii, 547, 1868.
Packard, Amer. Naturalist, March, 1885.
Head aud abdomen (urosome), iii the largest specimens, of the same length; in younger speci- mens the head is rather shorter than the abdomen ; head about one-third as long as broad ; geual spine about two-thirds as long as the head, and turning at nearly a right angle with the straight hinder edge of the cephalic shield ; the spine as a whole is directed somewhat outward, nearly reaching a point about opposite the hinder edge of the third abdominal segment. Median lobe of the head or glabella, rather deeplj' excavated in front; at the bottom of the excavation are situated traces of the simple ej^es, which have the same situation and shape as in Limulus. The small compound eyes are situated on the outer anterior angle made by the sides of the glabella and are of nearly the same relative size and in the same general situation -as in the larval Limulus, though placed a little nearer the front margin. The eyes themselves are small, oval and promi- nent. The sides of the glabella are produced behind into a sharp spine, projecting backwards over the base of the abdomen.
The abdomen (or urosome) is from one-fourth to one-third broader than long, and is composed of eight distinct segments, including the caudal spine; the body of the abdomen is full, convex, and distinctly trilobate, the median or cardiac lobe being in general about a third narrower than the lateral lobes or pleura, and contracting in width towards the fifth segment. The sutures be- tween the segments on the lateral lobes are very distinct, being raised, narrow ridges, prolonged into and forming the hinder edge of the long, sharp, slightly curved, lateral spines; of these lateral spines those on the first and second segments are the narrowest and most acute, that on the seventh the widest and most obtuse. In the cardiac lobe the third abdominal segment bears a high rounded tubercle, and there is one about twice as large on the sixth segment ; those on the other segments are small, and in most of the specimens there are traces only of those on the third aud sixth seg- ments. The caudal spine (representing the eighth abdominal segment) is somewhat enlarged at the base; it is three-cornered in section, much as in Limulus, the surface is smooth, and it is about three-fourths as long as the abdomen.
Length of eutire body (largest specimens), 60""" ; breadth, 53"'™.
Length of cephalic shield, 24™"' ; breadth, 53™™.
Length of lateral cephalic spine, 15™™ ; breadth, near base, 3.5™'°.
Length of abdomen (urosome) (not including the caudal spine), 23'"™ ; breadth 35'"'".
Length of longest lateral abdominal spine, 6™'".
Length of caudal spine (telsou), 15'"'".
The smallest specimen is 10'"™ in length, and 12""" in width, the caudal spine being less than one half as long as the abdomen.
Description of the cephalic appendages.
In a nodule from Mazon Creek received from Mr. J. C. Carr, containing the remains of a speci- men 55™™ across the shield (PL VI, figs. 2, 2"), the cephalic appendages are more or less distinctly preserved. Of the first pair there are faint traces, the two small limbs Ijing parallel to each other aud in the same position as in the larval Limulus, and of nearly the same proportions. The impressions of the succeeding limbs are distinct ; the second third, fourth, and fifth pairs are of the same size, the fifth pair being perhaps a little longer, as the tips extend near the edge of the cephalic shield. All four pairs, i. e., second to fifth, are chelate, the forceps being well developed and plainly visible in the third and fourth pail's, as these limbs are turned on their side; the fifth pair are undoubtedly chelate, but lie so that the outline is a simple point. The sixth pair differs
ON THE CARBONIFEROUS XIPHOSIJROUS FAUNA. 147
from the otiicrs in (Ending abruptly, tlie p(Muiltiiuate Joint beiii;^- lon^ and of the same width throughout, and truncate at tlie distal end, where it gives rise to three small, sharp sjiines ; there are also traces of a terminal minute joint from which two spines arise.
Length of second, tuird. fourth, and fifth pairs of legs, 16">"'. Length of sixth pair, 17""". Length of pennltlniate. joint, 6""". Thickness, 1""".
The legs are nearly identical in shape and length with those of the larva of Limulus described and figured in my Development of Limulus (PI. 1, figs. 24% 25*, and 23''), though perhaps a little shorter, as they do not reach beyond the edge of the cephalic shield. It thus appears that in respect to its limbs as well as the shape and proportions of the bodj^ the Prestwichia resembles the larval Limulus. Thus Limulus in its development passes through a trilobitic, and afterwards a Belinurid stage.
Prestwichia longispina Packard. PI. V, fig. 4.
Kiii)ro(}i)n JonijiapUui Pack., Amer. Naturalist, xix, iJ92. March, 1885.
The specimen upon whicli this species is founded is Mr. Lacoe's Nos. 215'*'' (impression and reverse), and was probably a molted skin (PI. V, fig. 4). The body is considerably distorted by pressure, but the specific distinctness from P. danw is marked. The species will be readily dis- tinguished by the very long genal spines; they extend nearly or quite to a point opposite the base of the caudal spine. The abdomen appears to be narrower in proportion to the cephalic shield than in P. daiuv while the genal spines are longer and narrower. The caudal spine is not well preserved.
Length of body (not including the caudal spine), 20™"'.
Length of head, 10'>>'".
Length of abdomen, 10"'".
Breadth of cephalic shield, 24""".
Breadth of abdomen, 13""".
Length of lateral cephalic spine, 13"'™.
Pittstou, Pa., Butler mine, Nos. 215*'', collection of Mr. Lacoe.
In another larger specimen (Lacoe's No. 214", PI. VI, fig. 3), the glabella, with the eyes, ocelli, and a part of the left lateral spine are preserved. Whether this is the same species as P. lo7igispina I caanot tell with certainty, as the genal spines are not sufficiently well preserved, but'provision- ally it may be regarded as belonging to the species under consideration. The median lobe of the head is larger in proportion to the entire cephalic shield than in P. dawe, and the eyes are nearer the lateral margin. The ocelli are situated on the median ridge of the lobe, somewhat behind the indentation between the lobes. The individual is without doubt a Prestwichia having the same number of abdominal segments as in P. dame.
Length of body (without the caudal spine), 30""". Breadth of cephalic shield (estimated), 37""". Length of cephalic shield, 17-18'"'". Length of abdomen, 13'"™. Breadth, 23™™.
Estimated length of lateral cephalic sjiiue, l.^""". Distance between the compound eyes, 17™™. Distance from ocelli to the front edge of body, 6""". Distance from ocelli to hinder edge, 21™"'.
Oakwood Colliery, Wilkes Barre, Penn., collection of Mr. Lacoe, No. 214*.
Regarding the position of the Illinois and Penn.sylvania beds containing these fossils, Mr. Lacoe ■writes me: "The horizon of the Pennsylvania specimens of Euproops is much higher than that of Mazon Creek. The latter is at the very base of the productive coal-measures in shale over the bottom seam of coal. The specimen from the Butler mine, Pittston, is from shale over coal 'PI' (Mammoth vein), at the top of the lower productive coal-measures, about 300 feet above, and that from the Oakwood colliery is either from the same horizon or the bottom of the lower barren
148
MEMOIRS OF THE NATIONAL ACADEMY OF SOIENOES.
measure next overlying it. The shaft from which it was taken, penetrating both, the exact posi- tion of the rock containing it could not be ascertained when we discovered it in the 'dump' or rock pile." Another specimen from Scotch Hill railroad cut, Pittston, Pa. Coal E. Lacoe's No. 6'. 8f-34.
Note on the validity of the Genus Euproops.
By referring to the synonymy of Prestwichia dance, it will be seen that in 1865 it was referred by Messrs. Meek and Worthen to Belinurus for reasons given in Palfeontology, vol. iii, of the Geological Survey of Illinois, p. 547. After the appearance of Dr. H. Woodward's paper read before the Geological Society of London in 1866* in which the genus Presticichia was separated from Belinurus, the American form was referred to the new genus, Prestwichia, by Mr. Meek.
"At a later date (February, 1867), Mr Woodward published excellent figures in the Quart. Jour. Geol. Soc, London, vol. xxiii, pi. 1, of the typical forms of both Preswtichia and Belinurus. From these it became evident that the peculiarities of the ridges of the head of the form on which he founded the genus Prestwichia, and which we had supposed probably due to some accident^ really exist. Consequently, our type was I'egarded as being generically distinct, and the name Euproops was proposed by one of us for it. Mr. Woodward, however, has since expressed the opinion that these differences are probably of scarcely more than specific value. (See Geol. Mag., Jan, 1868, vol. v., p. 2.) Without professing to have made an especial study of the fossil Crustacea, on which Mr. Woodward is well known to be an eminently reliable authority, we would state that we can scarcely doubt that a comparison of specimens would lead him to the conclusion that the American form is at least subgeuerically, if not generically, distinct from Prestwichia."
Finally the authors state that Euproops differs from Prestwichia "not only in the position of the eyes, and the form and size of the glabella, or central ai'ea of the cephalothorax, but in the entire arrangement of the ridges and included areas of the same." Fig. 9. is from an electrotype of a cut published by Messrs. Meek & Worthen in illustration of their genus Euproops.
rff-m ^
Fig. 9. — Euproops dance. M. Si.'W. After Meek.
Fig. 10. — Prestwichia roUtndatus. After Woodwai'd.
After repeated examinations of the series of about a dozen specimens from the collections of Messrs. Lacoe and Carr, I am at a loss to find valid characters for the genus Euproops. In one ex- ample of P. dance, the glabella or middle lobe of the head, is distinctly divided into four sublobes, as in Woodward's figure of P. rotnndatus; again the lack of lateral abdominal spines in his figure of P. rottindatus appears to me to be due to the imperfect state of preservation of the specimen, as some of the Illinois specimens do not show them ; again the spines projecting from the sides of the glabella over the base of the abdomen, and represented as wanting in Woodward's figures, are wanting in certain Illinois specimens. As to the position of the compound eyes in P. rotundatus as represented in Woodward's figure. I am inclined to believe that the author and artist have been in error. I should not venture to make such a statement if in our Illinois and Pennsylvania specimens of Prestwichia and Belinurus the position of the eye were not invariably on the outer
•"On some points in the structure of the Xiphosnra, etc.. Quart. Jonrn. Geol. Soc, Feb. 1867,
ON THE CARBONIFEROUS XTPflOStlROUS FAUNA. 149
angle of the glabella, in a position homologous with their situation in Limulus. I venture then to give the oi^inion that the apparent diflferences between Prestwichia and Euproops, as stated by Messrs. Meek and Worthon, did not exist in nature, and that the genus Prestwichia was common to botii Europe aiul North America during the Carboniferous Period. It is interesting in this connection to observe that the descendants of the BelinuridfB in Europe, survive in the Solenhofen Limuli until the Jurassic, and disappear daring the Cretaceous period, not to arise again on the western coasts of the old world, while in North America, so far as the record shows, the type became extinct during the Mesozoic and Tertiary, to reappear in the Quaternary and ])resent period.
As regards the differences between Belinurus and Prestwichia, the former genus is the higher form, approximating Limulus in the consolidation of the eighth and ninth abdominal segments (forming the "abdomen" so regarded by Dr. Woodward) and in the very long caudal spine. In Prestwichia there is one abdominal segment less than in Belinurus, the short caudal spine forming the eighth.
Belinurus laooei Packard. PI. V, fig. 5.
Belinunis lacoei Pack., Amer. Naturalist, xix, '292, March, 1885.
Cephalic shield of the usual shape and length in proportion to the abdomen ; the front margin as usual ; the genal spine long, acute, extending obliquely outwards to a point parallel with one either a little behind the middle of the abdomen, or, in the older, larger .specimens, nearly to a point parallel with the base of the caudal spine. The median lobe is, as usual, divided by the median line into two sublobes, so that the front edge of the entire lobe is indented in the middle ; each sublobe contracts in width posteriorly behind the ocular or lateral angle bearing the com- pound eyes. The ocelli are not visible, but the compound eyes ai'e partly preserved ; they are small, and of the usual kidney shape. The abdomen is much more rounded than in the European B. regince, being twice as broad as long. It consists (including the caudal spine) of nine seg- ments. The median lobe is as broad at the end as at the base next to the thorax ; there is a median tubercle on each segment, those on the third and last segment being larger than the others. The margin of the abdomen is broad and thin, giving rise to broad, acute, lateral spines. The caudal spine is very long and slender, a little swollen at the base; it is also triquetal, as in Limulus; it is nearly one-half longer than the body, i. e., longer than the whole body by the length of the head, and ending in a fine, slender, needle like point.
Length of the best preserved specimen SS""'" (including the caudal spine).
Length of body, 15™™.
Length of caudal spine, 18™™.
Length of cephalic shield, 7™™ ; breadth at base of lateral spine, 16™™.
Length of lateral spine, 4-5™™.
Length of abdomen, 8™™; breadth (not including the spines), 12™™.
In nodules at Mazon Creek, Illinois; Nos. 210'", 210y, 210"% 212**; 213», collection of Mr. Lacoe.
While having the same number of abdominal segments, this species, the first representative of the genus which has occurred in America, diS'ers from B. regince chiefly in the more rounded, less triangular outline of the abdomen, and in the smaller lateral abdominal spines. It is prob- able that in Dr. Woodward's figure of B. regince the compound eyes are not correctly placed. In our specimens of Belinurus they have the same relative situation as in Prestwichia dame and longispina.
150 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
SYNOPSIS OF THE NORTH AMERICAN XIPHOSURA.
Suborder XIPHOSURA.
Family 1. Cyclid^ Pack.
Body disk-like, orbicular; abdomen composed of three segments, scarcely if at all diftereii- tiated fi-om the cephalic shield; cephalic limbs nearly as in the larval Limulus; size small. Genus Cyclus De Koninck, with the characters of the family.
Gyclus americanus Pack. Family 2. Dipeltid^ Pack.
Body disk-like, elliptical ; abdomen differentiated from the cephalic shield, smooth, no seg ments indicated.
Genus Bipeltis Packard, with the characters of the family.
Dipeltis diplodiscus Pack.
Family 3. Belinurid^ Pack.
Body limuloid in general shape; cephalic limbs as in the larval Limulus; shield with long slender genal spines ; abdomen with the segments distinct; caudal spine short or long.
Genus Frestwichia Woodward. Eight abdominal segments, including the short caudal spine.
Prestwichia dance Meek. Prestwichia longispina Pack. Genus Belinurus Konig. Nine abdominal segments, including the very long, slender caudal
spine ; segments 7 and 8 consolidated.
Belinurus lacoe'i Pack.
Family 4. Limulid^ Zittel.
Body longer than broad ; abdomen with segments consolidated ; six pairs of abdominal limbs, Ave pairs having over a hundred jjairs of gill-leaves.
Genus ProtoUmulus Packard.* Seven abdominal segments, including the large thick caudal spine.
ProtoUmulus eriensis (Williams). Genus Limulus Miiller. Cephalic limbs large ; body longer than broad ; abdomen with 9 seg- ments ; caudal spine longer than the body.
Limulus polyphemus {Linu.).t
* In a notice of a new Limuloid Crustacean from the Devonian, Amer. Journ. Sc, July, 1885, p. 45, Prof. H. S. Williams described an interesting Limuloid from the Devouian of Erie Couuty, Peunsylvania (associated with typioal Chemunglbssils). Itis described as Prestwichia eriensis, the author remarking that "its identitication with Prestwichia must be regarded as provisional." He then adds : " The following characters exhibited iu the sijecimeu are regarded as generic and as locating it with genus Prestwichia of Woodward : (1) the elliptical head shield ; (2) the genal spines which proceed backwards more directly than in any described species of the genns ; (3) the thoracico-.abdominal segments auchy- losed to form a buckler, to which is attached (4) a longtelson. The general outline of the whole animal resembles that of the modern Limulus." We have ventured, without having seen the specimen, to regard this form as probably a mem- ber of the family Limulidic, and the forerunuer of Limulus. It is certainly not a Prestwichia. The body is apparently longer than broad, and in outline it leaves a strong resemblance to the young Limulus after its first moult. This is seen in the shape of the .abdomen and the caudal spine and in their relations to the rest of the body. It also seems probable that the abdominal segments were not free; in this respect it diflers from the Belinuridaj, especially Prest- wichia. Judging by the number of lateral spines, the abdomen was composed of 11 segments exclusive of the caudal spine, thus differing from Prestwichia, which has 7, also from Limulus, which has8 pairs of lateral spines. We therefore venture to give it the generic name of ProtoUmulus, and to regard it as standing at the base of the family to whicli Limulus belongs. Its occurrence in the Devonian makes it a connecting link between the Upper Silurian Neolimulus and the Carboniferous and Jurassic Limuloids. We are indebted to Prof. Williams for the use of figures illustrating his P. eriensis.
t Besides the American species, there are three others living, viz, L. moluecanun ; (East India) L. longispina Van der Hoven, Japan ; L. rotundicauda Latr., Molucca Is. and Malacca.
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ON THE CARBONIFEROUS XIPHOSUROUS FAUNA. 151
The individual development of Limulus an epitome of that of the Xiphosura.
It is interesting to observe a clearly marked exemplification of the parallelism between the embryonic or ontogenetic development of Limnlus and the geological succession as well as evolu- tion of the suborder of which it is a type. We have already compared the orbiculo-hemis- pherical form of Cyclus with that of Limulus in the early stages of its embryonic life. The par- allelism is striking. Cyclus may therefore be called an embryonic form. Again, in Prestwichia there is a close resemblance to Limnlus shortly before it leaves the egg, in what we have called the trilobitic stage, a stage antecedent to the true larval stage, in which the abdominal segments become consolidated. Prestwichia may then be properly designated as a larval form, while Cyclus was an embryonic form. The latter genus embraces eleven species (ten in Europe), which exist in beds containing the species of Belinuridae. One cannot regard it as a retrograde form however, but as an embryonic Xiphosuran, whose development became accelerated, adapting it for active adult life. WLile the specimens of Cyclus have not yet shown the presence of compound lateral eyes, it is not impossible that the animal was provided with a pair of median simple eyes. This indicates that these were the primitive visual organs, and that the compound lateral eyes of the Belinuridse and Limulidaj were secondary acquisitions, and that their simple eyes ai'e legacies left by their Cyclus-like ancestors.
Cyclus, and perhaps Dipeltis, appear to represent Agnostus among Trilobites, and the sim- ilarity between all these simple types indicates a community of descent.
The Suborder SYNZIPHOSURA.
In the Upper Silurian beds of Europe have been revealed a number of exceedingly interesting forms, which appear to be Merostomata, but not true Xiphosura. They serve, on the one hand, to connect the Xiphosura with the Eurypterida, and also strongly suggest the community of origin of the Merostomata and Trilobita. They have been associated by Dr. Woodward with the Euryp- terida,* but it seems to us, in the light of our present knowledge of the latter suborder and of the Xiphosura, that they are types of a third group or suborder. Perhaps the more aberrant form is Buuodes of Eichwald. All the genera have a caudal spine or telsou. They are, besides Bunodes, Hemiaspis Woodward, Pseudoniscus Nieszkowski, Exapinurus Nieszk., and perhaps JSTeolimulus Woodward belongs with them, though the last form connects the Xiphosura and Synziphosura. They possess nearly as high an antiquity as the Eurypterida, but did not persist so long, as none have been discovered in the Devonian or Carboniferous rocks ; hence we would infer that they were the forerunners of the Xiphosura rather than actual members of the group. In a word, the mero- stomatous ordinal tree divided into three main branches — /. e., the Eurypterida; the forms under consideration, which may be designated as the Synziphosura ; and the genuine Xiphosura. In the Synziphosura the head forms a solid plate, with a slightly marked glabella or median lobe. Compound eyes are present in Pseudoniscus, and in Exapinurus the head is produced laterally into large genal spines. All have free uromeres or abdominal segments, and in all except Bunodes, in which the pleurum is shaped and marked as in Trilobites, the uromeres possess lateral projec- tions or spines. None of them show traces of limbs or of simple eyes, and all are of moderate size.
The Synziphosura may be divided into three families, which may be diagnosed as follows (these groups appear to be, on the whole, equivalent in rank to the families of Trilobites) :
1. Head rounded; no geual spiue; abdomen divided into a "thorax," consisting of six trilobite-like segments, with diagonal pleural lines; "abdomen" of four segments, besides the large telson (Bunodes and Exapinurus).
Bunodidw Packard.
2. Head one-half broad as long, with several genal spines; abdomen triangular, with nine segments and a short telson (Hemiaspis). Bemiaspidce Zittel (restricted).
3. Body oval ; head short ; large compound eyes ; nine abdominai segments besides a short telson (Pseudoniscus).
Pseudoniscida; Packard.
4. Head-shield short and broad ; abdomen very broad, of nine segments besides the telson (Neolimulus).
NeolimulidcB Packard.
' Quart. Journ. Geol. Soc, Feb., 1667.
152
MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
Fig. 14. — nodes. .After Nieszkow- ski.
Fig. 15.— Bunodes. Aftei F. Schmidt
Fig. 16.— Psendouiscu.'*. After Niesz- kowski.
r \
Fig. 17. — Exapinnrus.
ter Nieszliowski.
Fig. 18.— Hemiaspis. Af- t«r Woodward.
Fig. 19. — Neolimulus. After Woodward.
After the foregoing classification was mostly written out, we found that Professor Zittel, in his excellent Handbuch der Palseontologie, Bd. i, 640, 1885, has divided the suborder of Xiphosura into two families :
1. Uemiasplda; with tlie foUewing genera: Bnnodes (Exapiuuius Mieszk.) subgenus Hemiaspis, PseudouiaciLs, Neolimulus, Belinurus, and Piestwichia; wliile Cyclus and f Halycine are regarded as genera of uncertain position, y. Limulidai, Liuiulns.
It seems to us that this is scarcely a natural classification, and that it would be better to sep- arate the Silurian forms mentioned above from the genuine Xiphosura, especially as we know noth- ing of the nature of their appendages, and to assign them, at least provisionally, to a group dis- tinct from the genuine Xiphosura, especially since we now know something definite as to the nature of the cephalic appendages of Cyclus and Prestwichia, their resemblance to those of the existing Limuli being remarkably close. Certainly Bunodes, in which there are, according to F. Schmidt's late researches,* as stated and figured by Zittel, besides a four-jointed abdomen, a "tho- rax" composed of "six trilobite-like, movable segments," cannot well be allowed ti position in the genuine Xiphosura. Moreover, the pleura of the single segments show a diagonal longitudinal ridge. This mark is a peculiarity of the pleura of some trilobites, and does not occur in any genu- ine Xipho.sura, and aids in lending to Bunodes a trilobitic appearance.
If we separate Bunodes from the true Xiphosura, Hemiasi>is will have to go with it, since it has a rounded cephalic shield, shaped somewhat as in Bunodes, but broader. We should not, with Zittel, regard it as a subgenus of Bunodes, because the " thoracic" segments have on the free sides no diagonal ridge, and the cephalic shield is ornamented with large spines, which perhaps indicate the head segments of the embryo. In both genera no eyes have yet been discovered. For the present we should, on the whole, regard the two genera as representing different families.
*F. Schmidt, Miscellanea Silurica III. Die Crustaceea fauna der Eurypteruschichten von Rootzikiill auf Oesel. M6m. de I'Acad. inip^r. de St. P^terbourg, 7" ser., xxxi, 1883.
Johuues Nieszkowski, Zusiitze zur Monographie der Trilobiten dor Oatserprovinzen uebst der Besebreibuug einiger neuen obersilurischen Crustaceeu. Dorpat, 1859.
ON THE OARBONIFEROCrS XIPBOSTJROUS FAUNA. 153
lu Pseudouiscus we have another form which suggests a relationship to the Trilobites. Our figure is copied from Woodward's restoration. Nieszkonski, the original describer, remarked, "On the inner side of the shield we notice a place cut out, with the convexity looking outward, which should certainly be regarded as the outer edge of the eye."
The foregoing remarks are suggested by a study of the figures and descriptions of these remark- able forms, and as they are not based on a study of the specimens themselves, they will be taken only for what they are worth. But the fact remains that we have, side by side with the Euryp- teridiB in the upper Silurian strata, a group which does not apparently belong to either the Euryp- terida or genuine Xiphosura of the Carboniferous and later periods, and to which it seems best to assign, temporarily at least, an intermediate position. The group also is of great interest as serving to bridge over the gap between the Merostomata and Trilobita.
The following view will express the relations of the three suborders :
Order MEROSTOMATA.
1. Burypterida. 2. Synziphosura. 3. Xiphosura.
HISTORICAL REVIEW.
I. — History of the Xiphosura.
In 1764 Gronovius, in the second fasciculus of his Zoophylacium Gronovianum, p. 220 (according to Van der Hoeven, for we have not seen this work), proposed the name Xiphosura. His work appeared in three fasciculi, bearing date 1763 to 1781, the second fasciculus dated 1764.
The name Limulus was first proposed by O. F. Miiller (Bntomostraca, 1785, p. 124), and adopted by Fabricius (Ent. Syst., 487, 1893).
The name Linmlus polyphenms (Linn.) was bestowed by Latreille in his Histoire Naturelle des Crustac^s et des Insectes, torn. 4, p. 96, 1802.
In 1798 Latreille, in Cuvier's Tableau 616mentaire de PHistoire Naturelle des Animaux, placed the Limuli in the Crustacea, under the Monoculi.
Previous to 1806, the exact year we have not been able to ascertain, Latreille (Suite a Buffou, Sonnini, Paris, 1798-1807) assigned Limulus to the Entomostracan order 1 Xiphosura (fide Milne Edwards).
In 1806 Latreille (Genera Grustaceorum et Insectorum, i, 10) placed Limulus in order 1 Xiphosura of Legio 1 Entomostraca.
In the same year Dumeril (Zool. Anal.) associated Limulus with Oaligus, etc.
In 1809 W. Martin " gave a figure and short description of a Limulus crustacean from the coal measures, which he included with the Trilobita."
In 1810 Latreille (Considerations g6n6rales, etc.) assigned Limulus a place under the Entomo- straca in Family 1, Clypeaces, Aspidiota, associating it with Apus, Oaligus, and Binoculus. The term Xii)hosura does not appear.
In 1835 Latreille (Families naturelles du Rfegne Animal) places the Xiphosura between the Phyllopods, the Trilobites, and the Siphonostoma.
In 1828 Straus Durckheim (Considerations generales sur I'anatomie compar^e des Animaux articules) referred Limulus to a new order, Gnathopoda, forming the eighth order of Crustacea, which he placed between the Deca[)oda and Arachnida.
After the publication of his " Considerations," Straus-Durckheim removed the Gnathopoda from the Crustacea to the Arachnida, as Will be seen by the following extract from Lankester's "Lim- ulus an Arachnid" (Quart. Journ. Micr. Sc, 506, 1881) :
Straus Durckheim maiutained that Limulus should be classified with the Arachnida, but the publication of his views on the subject appears never to have talieu a very definite or satisfactory form. In fact, the only record of Straus Durckheira's teaching on this subject which I can find is in the Frencli translation of Meckel's "General Treatise on Comparative Anatomy." MM. Reister and Alph. Sanson carried out this translation and added many notes in the form of appendices to each volume. At the end (p. 497) of the sixth volume, which bears the date 1829-1830, there is a note headed " Sur I'appareil locomoteur passif des Arachnides," which appears to bean abstract of a memoir "On the S. Mis. 154 20
154 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
Comparative Anatomy of the Arachnida," read to the Academy of Sciences June 1, 1829, but never, I believe, pub. lished. M. Strans Durckheim communicated its contents to MM. Reister and Sanson. From this note I submit a few extracts. The authors commence :
"La classe des Araehuides, dans laqnelle M. Straus comprend le genre Limule, formant a, lui-seul un ordre design^ sons le nom de Gnathopodes et dont il isole les Pycnogonides qu'il renvoie aux (Jruatac^es, oifre dans la disposition de son squelette et des muscles qui en meurent les diverges pifeces. des particularit^s tellement trauch6es qu'onne pent, y m^connaltre uu type different. C'e.st de ce squelette que sout tir^s les traits principaux propres ^ caracteriser la classe des Arachnides en g6u6ral, et qui consiste dans la disposUion des pattes raijotinunt siir un steniiim cominnn,dans la presence d'liii sfeniiim carlUafilneur intdrieur, dans Vahsence d'antennes."
The Arachnida are then divided into three orders, "les pulmonaires, le^branuhifiires, et les trach^ens," but it is not explained whether the term "gnathopodes" Is to be regarded as simjjly a synonym of the order " branchif feres."
With regard to the internal sternum, the citation of the views of M. Straus runs as follows:
"Dans I'int^rienr du thorax de tons les Arachnides, h I'exceptiou peut-etre des Acarides dont la plupart des espfeoes sont trop petites pour qu'on puisse les dissequer et connaltre leur organisation, on trouve une pifece cartilaginense diversemeut configur(5e suivaut les families, et plac^e dans le thorax on dessus du sternum, cette pifece, a. laquelle con- vient le nom de sternum iut^rieur, est maintenue librement par le moyen de plusiers muscles qui ce conduit de diff^- rents points de sa surface sur le bouclier, on sur le sternum ext^rieur auquel ils se fixent. Elle sert en outre de point d'insertion ^ un certain uombre de mu.scles des pattes."
In Cuvier's Efegue Animal, uouv. 6dit., 1829 (torn, iv), tbe group named by Latreille, Poeeilopoda, i s characterized and described a.s the second order of Entomostraca. The order consists of two fami- lies: Xiphosura (genus Limulus) and Siphonostoma (Caligus, Argulus, etc.). As the group Poeeilo- poda, by its founder, includes the parasitic Copepoda besides Limulus, it seems advisable to drop it, retaining the term Xiphosura, which has never been applied to any other animal than Limulus and its allies. On p. 46 he remarks: "De cet ordre de crustaces on arrive a la classe des Arach- nides, dont I'organisation, en g^n^ral, approche beaucoup de celle des Limulus."
In 1830 Milne-Edwards (Ann. des Sc. Nat., xx. mars 1830) adopted the order Xiphosura, placing it below the Siphonostomata.
In 1834: Milne-Edwards (Hist. Nat. des Crustaces) retained the order Xiphosura.
StrausDiirckbeim's views were more explicit than supposed by Professor Lankester, as in Straus's work, published in 1842, entitled " Traite pratique et th^oretique d'Anatomie compara- tive," etc., vol. 2, 169, we find the following statement :
J'ai form6 I'ordre des Gnathopodes avec le seul genre LiniiiUis. Cus siuguliers animaux out 6t6 rangfc parmi les Crustaces par tons les naturalistes ([ui, ue connaissant pas lear organisation, les plafaient dans cette classe par cela seul qu'ils out des branchies, tandis (lu'ils s'en distinguent essentiellemeut par le reste de leur organisation, en offrant les plus graudes analogies avec les Ara.hnides S et ('existence des. branchies ue saurait a elle seule constituer un caractfere snffisant pour les Eloigner de oes derniers, vu que dans cette classe les organes de la respiration u'ont plus cette grande preponderance sur les autres appareils du corps, pour les tenir sous leur d(5pendance, comme cela a lieu chezles vertebras; ce qui est prouv^ par I'analogie qui existe eutre les Arachnides pulmonaires et les trach^ens, qu'on ne saurait s^parer.
Dana (1852) in his Crustacea of the U. S. Exploring Expedition, proposed the order Merosto- mata for Limulus exclusively, which he places in the tribe Limuloidea. He makes no mention of the Eurypteridie. The Fcecilopoda in Dana's system forms the first suborder of Gormostomata, and fnclude the Ergasiloidea, Caligoidea, and Leruisoidea.
In 1866 Hi^ckel (Generelle Morphologic der Organismen, ii, Ixxxix) regarded the Trilobita as forming the third legion of Branchiopoda. They are in his system succeeded by the sixth subclass of Crustacea, the Poeeilopoda, which embraces the two legions of Xiphosura and Gigantosiraca. The latter name is proposed for the Pteri/gotidw and Euryptcridw alone. As Hfeckel's Gigantostraca appears to be exactly synonymous with Dana's Merostomata as amended by Woodward, tbe awk- ward, meaningless term, which has never been defined, should be discarded. It has, however, been adopted by Dohrn in 1871 (Zur Embryologie uud Morphologic des Limulus Polyphemus, Jena. Zeits, vi, 1871), and by Chins, though in a greatly extended, and it seems to us an unwar- rantable, sense. Dohrn remarks:
Limulus is nearest related to the Gigantostraca. Both appear to be "related to the Trilobites, though this rela- tionship cannot be established in all the details. The morphological ami genealogical relations of these three fami- lies to the Crustacea are not such as to be surely determined ; perhaps they will remain always doubtful. That they are related to the Arachnida we are not, as the matter now stands, in a position to allow. So it only remains for us to put these three groups under a common name, for which I might adopt Haeckel's expression "Gigantostraca," and let.them take their place in the system with {nehen) the Crustacea.
ON THE CARBONIFEEOUS XIPHOSUROUS FAUNA. 155
II. — Affinities of the Eurypterida to the Xiphosurn {Limulidm) and the formation of the order Mere-
stomata as at present received.
In 1825 Dr. J. E. De Kay described and fi};iired the fii-st (iiu American) species of Eurypterus known (E. reniipes), and referred it to the class Crustacea and to the order Branchiopoda. In ISi^ L. Agassiz remarked of Pterygotus :
I am rather iuclinetl to believe that this singular auimal will become the type of a family intermediate between the TVilobites and the Entomosiracans in which perhaps, the Eurypteri and the EidothecB w\]\ some day be included.
We have given on pp. 177, 17S'of our essay on " The Development of Limulns" (1872) a history of the views of James Hall, Salter, and others, especially the first-named, who proved that the Eurypterida belonged to the same order as Limulus.
In 1866 in his elaborate " Monograph of the British fossil Crustacea, belonging to the order Mesostomata," Dr. H. Woodward formally united the Eurypterida in the same order with Limu- lus, remarking :
Having long been eonvinced of the propriety of expressing in some suitable manner the correctness of the conclu- sions of Professors Agassiz and James Hall as to the close affinity existing between the Eurypterida and thw Xijyhosura, and being fully persuaded at the same time that they naturally form two distinct although closely related groups, I have ventured to unite them in the Order Merostomata— a name proposed by Dr. J. D. Dana for the recent king- crabs only, retaining at the same time the names Eurijpterida and Xiphosiira as suborders.
In 1872 we adopted this classification, which seems eminentlj' natural, and has since been adopted by a number of leading zoologists.
In 1868 Clans (Gruudziige der Zoologie) characterized the order Poecilopoda, but in the third edition of this work (1876) the Poecilopoda (restricted to Limulus), though placed between the fourth order, Phyllopoda, and fifth order, Arthrostaca, in the Crustacea, and at the end of the Phyl- lopoda, are associated with the Trilobita in a special group to which no special rank is assigned.
III. — Transfer of the Merostomata {tcith the Trilobita) to an independent class.
In 1869 Huxley stated in the "Academy" (November 13) :
The Xiphosura have such close morphological relations with the Arachnids, and especially with the oldest known Arachnidan, Scorpio, that I cannot doubt the existence of a genetic connection between the two groups.
In 1871 Prof. E. Van Beneden (Comptes Rendus de la Soc. Ent. Belgique, October 14, 1871 ; Annals and Mag. Nat. Hist., .January, 1872) remarked :
The Limuli are not Crustacea ; they have nothing in common with the Phyllopoda, and their embryonic devel- opment presents the greatest analogy with th.at of the scorpions and other Arachnida, from which they cannot be separated. ♦ » • The Trilobites, as well as the Eurypterida and the Pcecilopoda, must be separated from the class Crustacea, and form with the Scorpionida and the other Arachnida a distinct branch, the origin of which has still to be ascertained.
In 1872 A. Milne Edwards (Annales des Sc. Nat.) published his important researches on the internal auntomy of Limulus, which showed that Limulus essentially differs from the Crustacea. In the same year we attempted to show the close aflauities of Trilobites to Limulus.
In 1876, according to Claus's own statement (Annals and Mag., July, 1886, p. 56), referring to his change of views as to the position of Limulus, he remarks :
Even in the work entitled " Uutersuchungen uber die gonealogi.sche Grundlage des Crustaceensystems" (Vienna, 1876) I adhered to the views of those who, like Straus-Diirckheim, regard Limulus and Branchiate Gigantostraca as allied to the air-breathing Aracbnoidea, and the latter as baving proceeded from the former, although, having regard to the possibility of a still uudemonstrated Nauplius stage, I considered it probable that the common origin of the true Crustacea was rather after than before the Nauplius period of the Stem-Crustacean. In the case of Limulus and the Scorpions I also asserted the homology both of the six pairs of limbs of the cepbalotborax, and, with reference to the developmental history, of the six pairs of limbs of the pneabdomen, of which the second pair repre.seuts the comb-like organ of the Scorpions, while the following four pairs immediately undergo retrogression (p. 110). In the " Gruud- ziige der Zoologie" of the year 1880 I went so much further as to divide the Branchiata, or Crustacea, sensu laiiori, into Encrustacea (with the Entomostraca and Malacostraca) and Gigantostraca (with no certain traces of the Nauplius stage), and accordingly I affirmed expressly of the Tracheata that in opposition to the more ancient Branchiata they "ictre not referable to a unitary origin, sinct the Arachnoidea, which are derivable from the Gigantostraca, stand opposite to the Myriapoda and Insecta, which are united by a closer affinity " (p. 515).
156 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
In 1885 and 1886 (Annals and Mag. Nat. Hist., July, 1880) Glaus regarded the Gigantostraca as a class intermediate between the Crustacea and Arachnida. He thinks that ttie Arachuida descended from the Gigantostraca, adding, " I by no means affirm the Arachnoidal nature of Limulus."
In 1879, in our Text-book of Zoology, as the result of Milne Edwards's researches, we divided the Crustacea into two subclasses, the Neocarida aad Palceocarida, the latter group comprising the Merostomata and Trilobita. In a previous paper we had shown the close homologies of the eye of Trilobites to the compound eyes of Limulus.
In April, 1881, Mr. C. D.Walcott (Bull. Mus. Comp. Zooi., viii. No. 90, p. 209), under the class Pcecilopoda, places two subclasses, viz, Merostomata and Palseadfe (Trilobita), giving definitions of the groups.
In 1881, in his article "Limulus an Arachnid" (Quart. .Tourn. Micr. Sc.) Prof. E. Ray Lan- kester proposed the term Hcematobranchia, which he regarded as the equivalent of Merostomata. This group of the class Arachnida, as understood by Lankester, embraces the three orders : 1, Trilobita; 2, Eurypterida; and 3, Xiphosura.
In 1885 (Embryology of Limulus Polyphemus, III, Proc. Am. Phil. Soc, January, 1885), we referred Limulus, with the Eurypterida and Trilobita, to a class by themselves.
In 1885 Mr. J. S. Kingsley associated the Limulus with the Arachnids as a group by them- selves, to which he gave the name Acera (Science News and Quart. Journ. Micr. Sc).
In 1886, in the 5th edition of our Text-book of Zoology, we suggested the term Podostomata for the class comprising the two orders Merostomata and Trilobita.
IV. — The cluss Podostomata.
It thus appears that while at the present date (1886) A. Milne Edwards, E.Van Beneden, and E. E. Lancaster regard Limulus and its allied forms as belonging to the Arachnida, and J. S. Kingsley associates the Limulus and the Arachnida in a group by themselves under the name Acera, the present writer and Professor Claus regard the Merostomata with the Trilobites as forming a class intermediate between the Arachuida and Crustacea.
We have endeavored to show that the names Pcecilopoda and Gigantostracea have been applied in such different senses by different authors that they cannot well be retained for the Merostomata and Trilobita taken together in the sense we advocate. We have therefore proposed the term Podostomata for this class of Arthropoda. It is derived from nov?, nodo'?, foot, and aro na, mouth, in allusion to the foot-like or ambulatory nature of the cephalic appendages which surround the mouth in a manner characteristic of the group.
The class Podostomata may be defined as a group of Arthropods, in which the cephalic (Limulus) or cephalo-thoracic (Trilobites) appendages are in the form of legs, i. e., ambulatory appendages, usually ending in forceps, or large claws (chela), which in the sole living representa- tive of the class are arranged in an incomplete circle around the mouth; the basal joint of each leg is spiny, so as to aid in the retention and partial mastication of the food. No functional antennae, mandibles, or maxillae. Eyes both compound and simple. Respiration by branchiae attached to the abdominal appendages, which are broad and lamellate in Merostomata and probably cylindrical with narrow gills in Trilobita. The brain (procerebrum) supplying nerves to the eyes alone; the nerves to the cephalic or cephalo-thoracic appendages originating from an oesophageal ring; the ventral cord ensheathed by a ventral arterial system more perfectly developed than in insects or scorpions ; coxal glands highly developed, with no external opening in the adult. This class differs from the Arachnida, among other characters, in having no functional cheliceres (" man- dibles") or pedipalps ("maxilhe"); in the cephalic appendages either ending in large claws or forceps, or simple, the terminal joint not bearing a pair of minute claws or ungues like those of Arachnida and Insecta, enabling their possessors to climb as well as walk. Podostomata have no urinary tubes. Limulus undergoes a slight metamorphosis, while in Trilobites the adult differs from the larva in having a greater number of thoracic segments.
OF THE CARBONIFEROUS XIPHOSUROUS FAUNA. 157
From the. Crustaceii the Podostoiuata diflfer iu the lack of fuuctioiial autennse and mouth parts ; in the brain iunervatinj? the eyes (compound and simple) alone; in the shape of the head and of the pygidium or abdominal shield, and in the arterial coat enveloping the ventral nervous cord.
The Podostomata are divided into two orders :
I. Mefostomata with three suborders, Xiphosura, Synziphosura, and Eurypterida.
II. Trilobita.
Explanation of Plate T.
Fig. 1. CycluK americautis Pack. xf. la, lateral view restored. X^.
Fig. 2. Dipellis diplodiscus Puck. Natural size; 2a, the same restored. Xf.
Fig. 3. Prestwichia danw Meels. Natural size ; restored ; dorsal view.
Fig. 3a. Prealwichia danw Meek. Natural size ; partly restored ; ventral view.
Fig. 4. Preslwichia longispina Vsti'k. Partly restored. Xf.
Fig. 5. Belinurus lacoei Pack. Partly restored. x2.
All the figures on this plato drawn by Dr. J. S. Kingsley, with corrections by the author.
Explanation of Plate VI.
Fig. 1. Prestwichia dana; showing the limbs; la, the reverse.
Fig. 2. Prestwichia danw, showing the interior; 2a, the same, another specimen.
Fig. 3. Prestwichia longispina, natural size.
Fig. 4. Cyclus americana, natural size; 4a, reverse of the same.
From photographs taken by Mr. R. L. P. Mason, Providence, R. I.
Explanation of Plate VII.
Fig. 1. Palwocaris typus M. & W., natural size.
Fig. 2. Palwocaris typus M. & W., natural size.
Fig. 3. AnthrapaUimwn gracilis M. & W., carapace laterally flattened.
Fig. 4. AnthrapnUrmnn gracilis M. & W., from a small specimen without tlie carapace.
Fig. 5. Anthrupala'nion gracilis M. & W., carapace wanting.
Fig. 6. Anthrapalamon gracilis M. & W., carapace wanting.
All the figures of natural size and from photographs taken by Mr. F. O. Draper, Pawtucket, R. I.
PLAT E
iDONirLnUL i ai^t
iVitlVJOlKb iNAI, AUAU iL.. V'.JL II
PLATE VI.
^..,ik
'^
-v^-
FIGS. 1. 2, PRESTWICHIA DAN/E; 3 P, LONGISPlNA: 4 CYCLUS AMERICANUS
FROW PHOTOGRAPHS BY H. I. P. Ii/ASON-
MEMOIRS NAT. ACAD. SC. VOL. III.
PLATE VII.
~J»--
\
FIGS. 1- 2. PAL/€0CARIS TYPUS; 3—6, ANTHRAPAL/EMON GRACILIS,
FROM PHOTOGRAPHS BY F. 0- DRAPER.
NATIONAL ACADEMY OF SCIENCES.
VOL. Ill
SEVENTEENTH MEMOIR.
ON TWO NEW FORMS OF POLYODONT AND GONORHYNCHID FISHES FROM THE EOCENE OF THE ROCKY MOUNTAINS.
159
ON TWO NEW FORMS OF POLYODONT AND GONOEHYNCHID FISHES FROM THE EOCENE OF THE ROCKY MOUNTAINS.
HEAD NOVEMBER 12, 1885.
By E. D. Cope.
CROSSOrnOLIS MAGNICAUDATUS Copo, American Naturalist, 1883, p. 1152; ' loc. cit., 1885, p. 1000.
Since tbe description of tbe part of tlio body of tbis fisb was publisbed, I bave obtained a considerable ])ortion of tlie skull of au individual of tbe same genus, if not species. It belonjjs ai)parently to a lavi^er individual tbau tbe one first described. Altbougb it was found at tbe same locality .as tbe latter, and at near tbe same time, it is not part of tbe same individual. Tbe cbar- acters of tbe family Polyodontidce are easily discerned in tbe skull, and tbose of tbe body coincide.
Tbe sknil displays typical ordinal and family cbaracters. Tbe postempoia! bone is produced backwards, and is separated froui tbe parietal by a large foramen, wbicb continues between tbe dermospbenotic and parietal. It is bounded in front by a i)rocess of tlie dermospbenotic, wbicb joins a correspondinn: one from tbe frontal. Anterior to tbis connecting bridge, anotber large fora- men extends, separating tbe derinos])benotic and an element continuous wiili it anteriorly, pcrbaps a brancb of tbe nasal, (rom tbe frontal. Tbe maxillary and mandibular bones occujiy tbeir usual position; and tbe byomandibular extends posteriorly from near tbe junction of tbe jiterotic and tbe epiotic. Tbe eiiiclaviclet is simjile, and tbe oi)erculum arises from near tlie distal end of tlio byomandibular. Immediately below its anterior portion is a flat element, wbicb does not occur apparently in Polyodon. It may be preojjerculum or suboperculum, or tbe interoperculum of Polyodon in a different position.
Interneural and interbremal basilar bones are large and are ossified, and tbe caudal baiina- po]d)yses ("liypurals") are but little less so. Tbe caudal fin is entirely beterocercal. Vertebral axis consisting of notocbord only.
Char. (jen. — Tlie bone in tbe position of preoperculum above mentioned, is in contact witb tbe inferior face of tbe superoanterior extremity of tbe operculum by its superior extremity. Its an- terior border is entire, snbvertical, and convex. Its posterior edge is not preserved, but tbe impres- sion of its external surface is deeply grooved, as tbougb tbe bone were ridged anteroposttrioily. Tbere are i)reserved several loose tbin plates of bone covered witb small teetb en brosse, wbicb bave come from tbe premaxillary and dentary bones. Tbere are preserved a number of stellate bones of tbe muzzle.
Scales numerous, in oblique series, not in contact, formed of a small grooved disk and several posterior spines. Dorsal and anal fins sbort, posterior; tbe former commencing in advance of tbe latter. Caudal fulcra posteriorly slender, continued into broad flat scuta extending forwards on tbe median line of tbe caudal peduncle. Superior lobe of caudal fin mucb more produced tbau inferior. A lateral Hue of tubules.
" By a typographical error, Crassopholis at this reference.
tl employ the uouienclature of Bridge in liis paper on the Osteology of Polyodon folium, Pliilosojih. Transac. Eoyal Society, 1878, p. 688.
S. Mis. 154 21 161
162 MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES.
In the form of the muzzle aud in the large caudal fulcra this genus resembles Psephurus rather than Polyodon. In its numerous slender fulcra it is, however, like the latter genus, while the anterior fulcra are more scutiform, and extend further forwards than in Psephurus. The prob- lematical opercular bone differs from anything seen in Polyodon, even if it should prove to be a suboperculum, which is present in that genus. It is, however, separate from and below the operculum in that genus, and is separated from the cartilaginous ? quadrate by a cartilaginous peduncle.
The identification of the true afiflnities of this form is an important step in the history of the Chondrostei. Hitherto our knowledge of the Polyodontidse has been restricted to the two recent genera named, and their relations to the ancient world have been unknown. We can now date the history of the family from the early Eocene period.
Char, specif. — On comparing this fish with the Polyodon folium, various differences appear be- sides those already referred to. The bones of the skull proper are as large as those of a middle- sized individual of the recent species named, while the muzzle is considerably shorter than would be found ou such individniil. Although the muzzle has been pressed obliquely, the sizes of its axial lenticular elements indicate that but little of its length is wanting. There is not much indication of the free lateral edges characteristic of the Polyodon folium, although the stellate bones are vis- ible near the edge aud at the base.
To commence at the posterior extremity of the skull : The epiclavicle is more robust than in the Polyodon folium. Its superior extremity is openly notched on the anterior edge, i)robably to fit a corresponding surface of the dermospheuotic. Its external face has a narrow, oblique ridge commencing opposite this notch and extending diagonally across to the posterior edge, with a, gradual inclination. It forms the posterior edge of a groove which widens below and narrows above, reaching to within a centimeter of the articular notch. A similar groove exists in the paddle-fish, but it only extends as high up as the line of the superior border of the operculum. The posttemporal is shorter and more robust than in the paddle fish, and has the same wide, bridge- like connection with the parietal. Its external border is in a straight line with that of the dermo- spheuotic. The parietal bones are lost from this specimen. The dermospheuotic is a more slender bone than in the paddle fish, and the foramen separating it from the frontal bone is shorter and wider. It sends down a postorbital process, which is much like that of the paddle-fish, but is narrower, and ends in three tooth-like processes. There is a small preorbital process, and below it a palmate ossicle, which may have been brokpn from it or may be distinct. Shortly anterior to this, the element terminates in a laciniate suture, with a narrow, straight band, which is coiitiinH)us as a posterior divergent branch of the possible nasal bone. The junction of the latter with the frontal closes the foramen above described in front. The bone exterior to this band, which occupies the place of a prefrontal in the Polyodon gladius, is either wanting or is represented by a spiculuin which has become separated. The muzzle presents several of the lenticular spicnlar bones seen in the living species. Some stellate bones lie about the base of the muzzle, out of place, and a band of them lies on the slab at a short distance on one side. These are characterized by smaller size aud more slender radii than in the paddle-fish.
The premaxillary bone is gently convex upwards, instead of straight as in the P. folium. The dentaries have a corresponding form. They are widely and deeply grooved on the inner side for Meckel's cartilage, which is covered by a small subtriaugular bone (? splenial) at the symphysis. TLis element is very much smaller than in the paddle-fish. The alveolar edge of the dentary bone is iicute, and bounds a rabbet whose floor is the superior roof of Meckel's cartilage. The hyoman- dibular bone is a robust, flattened rod, and is apparently curved so as to be convex forwards, although this appearance may be due to injury of the specimen. It is in any case shorter than in the paddle-fish, where it is also straight. The operculum is relatively and absolutely larger than in the P. folium. Its anterior inferior border is concave, and is thickened on the descending portion. Its anterior extremity is beveled on the external side for attachment with an element already mentioned, which may be preoperculum. The greater part of the latter is lost.
Several dentigerous laminae lie among the jaw bones, from which they have been separated. They are concave on the inferior side, so as to embrace the alveolar borders, ijrobably of the premax-
ON TWO NEW FORMS OF POLYODONT AND GONORHYNCniD FISHES. 163
illary bones, as those of the dentaries are too acute. Determinable palatine bones are not visible ill the spec'inicn. The bases of the teeth are round and are close together. They measure .000"'"".
The body of the originally described individual presents the following cliaracters :
Intenieural basilar bones 10 to 18; body slender at dorsal tin and contracted at caudal pe- duncle. Dorsal and anal fins moderate, caudal very large, with strong anterior fulcral rays. The posterior fulcra are elongate aud subcylindric, and overlap each other extensively. Anteriorly they flatten so as to approach the form seeu iu the paddle-fish, but these are well distinguished from the fulcral scuta iu front of them. The latter are longitudinally oval, and have a groove along the middle line. The caudal h.-emapophyses are short and expanded distally. They soon disappear in the superior lobe or axis of the caudal fin. I count nine to the anterior more or less cylindric ones. At the base of the inferior lobe of the caudal fin are five fulcra lying on each other, the inferior ones more flattened than the superior ones, all with acute posterior apices.
The scales are subquadrate in form aud measure about a millimeter each way, including the spines ; they are uowhere in contact and are more widely separated anterior to the dorsal fin than posterior to it. The sides of the axis of the superior lobe of the caudal flu are covered with closely packed oat-shaped scales.
Length from notch of caudal flu to line of anterior base of dorsal, M. .170 ; depth at anterior base of anal, .060; depth of caudal peduncle, .035; length of inferior lobe of caudal, .110. Length of an iuterneural basilar, M. .012 ; of an interhaemal basilar, .014. Probable number of dorsal radii, 24, Anal fln imperfect.
NOTOGONEUS OSCULTJS Cope, American Naturalist, Nov., 1885, p. 1091.
Family char. — The location of this genus is rendered quite possible by the excellent preserva- tion of two specimens of the typical species which have come into my possession. The form is plainly isospondylous, and belongs to a family in which the parietal bones are separated by the supraoccipital ;* the superior border of the mouth is formed by the premaxillary boue exclusively; the pterotic and intercalary bones are normal ; the caudal fln is homocercal, and the dorsal and anal fins posterior, and with few radii. There is no indication of adipose fln under most favorable cir- cumstances for its preservation, and the branchiostegal rays are three or four. These characters place the genus within the limits of the family Gonorhynchidse, of which but a single genus aud species have been hitherto known. This flsh is now living iu the waters of the Cape Colony of South Africa, and of South and West Australia, and, it is said, also iu those of Japan. The dis- covery of this type in the Eocene beds of North* America is a notable addition to ichthyological science. It is parallel with the occurrence of the family of the Osteoglossidte in the same forma- tion, a family also now couflned to the Southern Hemisphere. It will be seen on comparing the generic characters that this genus is very nearly allied to the living one.
GJiar. gen. — Body covered with scales whose borders have a fringe of rather long spines. Mouth small, probably a barbel on each upper lip, as a spicule of bone projects downwards and backwards from each side of the end of the muzzle. No traces of teeth iu the jaws or on the pterygoid or hyoid bones. An oval body at the superior extremity of the posterior branchihyal arches below the vertebrje. Caudal fln bifurcate.
In the above diagnosis the only character which separates this genus from Gonorhynchus is the absence of the dental apparatus of the hyoid aud pterygoid bones which characterizes the latter. It is probable that if the suprabranchial mass above referred to be the homologue of the similar organ in Gonorhynchus, there is here also an important differeuce. In Notogoneus this is sacciform. In Gonorhynchus it is lamina. The muzzle of the fossil species is not so prominent as iu the recent one, but this being a matter of proportion only, may be only a specific character. The addition of a new genus to a family hitherto so little represented is a circum- stance of interest, but not entirely unexpected. It is iu generalized families like this one and the Galaxiidae, that we are to look for additions in the faunse of the early Tertiary aud Mesozoic periods.
Some characters which do not enter the speciflc category may be here referred to. The max- illary boue is bordered on its entire anterior edge by the premaxillary, and has no supplementary
' I fiod on renewed examination of tlie Gonorhynehua greyi that the frontal bone8 extend far backwards, so that parietals are entirely separated by the supraoccipital.
164 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES.
bones. The mandibular ramus is very deep at the coronoid region, and if tlie fissures are not fnictures, the angular bone is distinct. The frontal bones are extended well forward to a point above the mouth. The probable ethmoid in front of them is short and wide. The frontals ex- tend also well posteriorly, meeting the snpraoccipital. The superior face of the latter is rather large and is subtriangular in outline and has a produced nuchal crest. The Intercalaries each present a sharp angle posteriorly. The branchiostegal rays are robust. No entire vertebra in- cluded in the caudal fin, but the usual modified one.
Char, specif. — The general form is elongate, and the head is short. The dorsal and ventral fins, which are opiiosite each otiier, are posterior in position, while the short anal is not far removed from the caudal. The lobes of the latter are long and divergent. The muzzle overhangs the mouth a little, but the latter is so short that the end of the piemaxillary bone only reaches half way to the anterior boiderof the orbit. The operculum is convex downwards and jiosteriorly. The length of the head enters the length with the caudal fin six and a half times; and the greatest dei)tli, which is in front of the dorsal fin, enters the same six and three-quarters times. Vertebrae: abdominal, 3-1; caudal, 14.J. Radii: Br. Ill or IV,robust; D. I (very short), 12; A. II (very small), S; V. (very small), G or 7; P., not countable. The scales are of medium size, five longitudinal series in a centimeter anterior to the ventral fin. Their surface is sculptured by longitudinal, parallel, fine, sharp grooves of .03""" in width. The fringe on the free edge of the scale is composed of flat, acute, and rather long, closely-set spines.
Measurements.
Total length 485
Length to base of caudal fin 395
Length to line of aual 332
Length to Hue of dorsal 224
Length of head 081
Length of gape of mouth 015
Width of skull at orbits 019
Width of skull at pterotics 030
Depth at front of dorsal fin 070
Depth at front of anal fin 050
From Twin Creek, Wyoming Territory.
PEISCACARA HYPSAOANTHTJS sp. nov.
The specimens of this species which have come under my observation are the smallest of the genus, and I have therefore questioned their maturity. They have, however, all the characters of adults, and as I have now seen a number of specimens which agree in various peculiarities as well as in size, I am satisfied as to their representing a species which has not as yet been recorded.
The Priscacara hypsacanthits belongs to the section of the genus with a small number of soft dorsal rays, and with robust ventral spine. It difiers from all the species in the length of its slender dorsal spines, especially the fourth, fifth, and sixth. The superior outline of the head and body are but little arched from a straight line. The form is moderately robust. The scales are small. Length of head equal to greatest depth, i. e., at front of dorsal fin, and entering length with caudal fin, 3.4 times. Orbit large, entering length of head four and one-half times. The origin of the dorsal fin is a little anterior to that of the ventral. Its superior outline is notched to two-fifths the length of the spine of the second dorsal. The border of the caudal fin is a little concave. The first anal spine originates below the third soft ray of the dorsal, and the soft rays of the ventral reach the same point. Vertebrae: Abd. X; caud. XIV. Rays: Br. VII; D. X, 9; the last soft ray split into two: A. Ill, 9. Scales in eight rows in an oblique band from the last soft ray of the anal fin to the vertebral column. Total length, M. .002; to base of caudal fin, .019; to line of first aual ray, 0.33; to line of base of ventral, .023; of head, .0108; depth at ventral fin, .010 ; at last ray of dorsal, .011 ; at base of caudal, .007. The specimens are from Twin Creek, Wyoming Territory.
Besides other peculiarities, the presence of an elongate spinous ray at the front of the second
ON TWO NEW FORMS OF POLYODONT AND GONORHTNCHID FISHES. 165
dorsal fin distiiiguislies this species from all the others of the genus. The number of spinous rays is the same as in them.
I may add that a newly acquired specimen of the Priscacara serrata displays the massive superior and inferior pharyngeal bones, covered with obtuse grinding teeth.
EXPLANATION OF PLATE.
Figs. 1-3. CrossophoUs magnioaudatus Cope, one-half natural size, except tig. 3, whicU is iiiaguified four diameters.
Fig. 1. One side of skull lacking the parietal bone, and other elements more or less disarranged ; from the left side. Na nasal bone; J^r., frontal ; Bapo., Dermosphenotic; Pa., parietal; Pot., post-temporal; -BcZ., Epiclaviclo ; Prmr., premaxillary; D., Deutaries; Hin., Hyomandibular; Op., operculum ; P., problematical element; S(., stellate bones ; Dp., Deutigerous laminae.
Fig. 2. Part of the left side of the body, lacking a piece of the caudal peduncle. Nb., neural basilars ; H b., hfemal basilars; Ch., caudal haemal spines (" hypurals").
Fig. 3. Scales of the same magnified four diameters.
Fig. 4. Notogonctis oscidus Cope, two-thirds natural size; A., accessory ? branchial organ; B., ? barbel axis.
Fig. 5. Scales of do., natural size.
Fig. 6. Priscacara hypsacanthus Cope, natural size.
MEMOIRS NAT ACADEMY 30. VOL
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NOTES ON THE THIRD MEMOIR, PAGE 45.
By Alfred M. Mayer.
R£.S0M£ of SIBLIOQBAPET pertaining to the paper "ON A METHOD OF PRECISELT MEASURING THE
TIBRATORX PERIODS OF TUNING-FORKS, ETC'
Since the publicatiou of the above memoir I have been enabled to look into publications of learned societies of Holland and Germany, heretofore inaccessible to me, and deem it proper to give the results of those examinations, as it allows me to render credit to others who have antici- pated me in methods described in my paper, and which 1 thought I was the flrst to originate. These methods I Lave, however, developed by my researches into a degree of precision not attained bj those investigators who have anticipated me. The paper of Beetz in Pogg. Ann. I overlooked, although that journal is in my jjossession, and had previously been examined for investigations allied to those of my memoir.
Apart from the pure pleasure afforded by original investigation, the only reward the man of science has is the credit given him by his fellow-workers in the same lines of research, and as I, like other Americans, have had the experience of seeing my endeavors to advance science overlooked, I know of the injustice thus done — we hope inadvertently — by those who should at least have taken the trouble of searching in accessible journals the cognate work of other investigators before pub. lishing their own.
Donders, 1865, in Nederl. Archie/, voor Oenus en Natvrlunde, II, page 332, discovered that the spark of the secondary circuit of the inductoiium is conii)osed of several separate sparks, and that one spark is obtained only when the striking distance in the secondary circuit is great. He used a slowly revolving mirror in the same manner as was used by Feddersen (Pogg. Ann., CXIII) in his observations on the electric spark of the Leydeu jar.
Bonders, 1SC8, Onderzolxingeii gednati in liet Physiologisch Laboraforium der Utrechtsche Eooge- schoul, II, pages 310-318. He sent the spark of the iuductorium from a metallic style attached to the prong of a vibrating fork. The style made its trace on the surface of smoked paper, aud the number of sparks in the discharge and the duration of the discharge were given in the sinuous trace of the vibrating fork.
Nyland, 1870, Archives NeerlandaiseSj pages 292-337, with ten photographic prints of experi. meuts. Nyland, at the request of Bonders, continued the hitter's experiments of 1868. He shows that the number of sparks iu the discharge diminish with current of battery and with the increase of striking distance in the secondary circuit; shows the effect of increasing the resistance of the medium through which the secondary spark passes ; also, that the duration of the discharge does not diminish iu the same ratio as the resistance to its passage. He obtained a ]>arabolic curve by making the resistance abs(;issas and the durations of discharges the ordinates. On placing a Leyden jar in the secondary circuit and passing the discharge between the points of two styles which were placed near each other, and with tliose points on a line parallel to the axis of rotation of the cylindfir covered with smoked i)aper, he obtained traces which showed an oscillatory action or to-and-fro discharge between the i)oints, similar to the figures obtained by Feddersen (Pogg. Ann., 1862) on a photographic plate, which received from a revolving concave mirror the image of the discharge of a Leyden jar charged with static electricity. Of these traces Nyland says : It is
167
168 MBMOIES OF THE NATIONAL ACADEMY OF SCIENCES.
certain that these images yield nothing to those of Feddersen in fineness of detail. Nyland in this paper also first describes the method of obtaining the vibratory period of a fork by passing the secondary spark of an iuductorium from a style, fastened to the fork, to the smoked paper covering a revolving metallic cylindei". The primary circuit was closed and opened each second by a clock. He, however, did not experiment to bring this method to give precise results.
Helmholtz, 1869, Verhandlungen des naturhistorischen medizinischen Vereitis zu Heidelberg, ob- served that the discharge of an inductorium, with a Leyden jar in the secondary circuit, into the nerve of a frog caused 45 maxima antl minima of contractions, but that these vibratory phe- nomena were not observed when the Leyden jar was absent.
Rood, 1872, American Journal of Science, observed the multiple character of the discharge of an iuductorium, with a Leyden jar in the secondary circuit, by means of a revolving mirror and a ro- tating disk. The revolving disk was formed of two superposed disks, each with a radial slit. By rotating the smaller disk an angular separation of the slits could be obtained, so that when the re- flection of the discharge from white paper was viewed through these slits the images of the multiple slits could be brought together, so that the end of one set of images given by one slit just touched the set of images given by the other slit. Knowing the velocity of rotation of the disk and the angle separating its two slits, the duration of the composite discharge was obtained. He thus ob- served as many as 10 to 20 separate sparks in a discharge (with jar of 114 square inches of surface in circuit) whose duration was about ^^ of a second. With platinum points as electrodes, and sep- arated by 1, 2, 3, 4, and 5 millimeters, the number of sparks observed at these distances of the electrodes were respectively, 4, 3, 2, 1, and 1. With ajar of only 11 square inches of surface, and the electrodes formed of brass balls, the discharge was more complex. Observing in the revolving mirror he saw the discharge formed of a bright spark followed by a violet discharge, and the latter followed by four sparks. The total duration of this discharge was -^g of a second. The violet portion lasted j^o of a second, and the four sparks lasted Yxftrg of a second. Other forms were sometimes present, consisting of a faint violet streak teruiinated at each end by a spark, the whole duration being ^ of a second. On increasing the striking distance between the balls to 2, 3, 4, .5, 0, 7, 9, and 10 millimeters, the total number of sparks forming the discharge for the striking distances was, respectively, 5, 8, 4, 3, 3, 3, 2, and 1 spark. In the series of papers (lSG9-'72) containing the above results, Eood, by novel, refined, and precise methods, first succeeded in obtaining the duration of one of the separate sparks which go to make up the number forming the composite discharge. This he did by examining through a microscope a series of flue rulings on smoked glass of bright and dark bands of equal breadths when illuminated by the discharge. These lines "ere so fine that the magnified inuige of one of these measured 3^ of an inch. When viewed in the revolving mirror they appeared as they did when the mirror was stationary, till the mirror ap- proached 180 revolutions in a second. Then the lines grew fainter and fainter, and, finally, when the mirror reached 183 revolutions in a second the lines disappeared by the mirror making the reflection of a black band of the ruling to be displaced to its own width during the duration of the spark. Eood thus found that the duration of this portion of the discharge was .000000175 of a second. With a jar of only 11 square inches of surface in circuit, and by using finer rulings and a more rapidly revolving mirror he determined that the spark lasted only forty-eight billionths of a second. "With this light" (lasting only forty billionths of a second) "distinct vision is possiltle. Thus, for exami)le, the letters on a printed page are plainly to be seen. Also, if a i)olarisc<)pe be used, the cross and rings around the axis of crystals can be observed, with all their peculiarities, and errors in the azimuth of the analyzing prism noticed. * * * AH of which is not so wonderful, if we accept the doctrines of the undulatory theory of light, for, according to it, in forty billionths of a second nearly two and a half millions of the undulations of light reach and act on the eye."
Cazin, 1873, Journal de Physique, observed the multiple character of the discharge of induc- torium with an ajjparatus similar to Rood's.
Mayer, 1874, American Journal of Science, in this paper he refers to the previous work of Henry, Feddersen, Rood, and Cazin. He used a large inductorium, having a "striking distance" of 21 inches. With electrodes of platinum points, one millimeter apart, and no jar or condenser iu circuit, he found the discharge of this inductorium to consist of 33 sparks, lasting ^ of a second.
NOTES ON THE THIRD MEMOIR, PAGE 45. 169
AVith ajar of 242 square centimeters in circuit, the discbarge contained 91 sparks, anil lasted bV"' a second. The nictliod nsed and resnlts readied are described in his miMiioir in Vol. Ill, Nat. Acad. Sci.
Beetz, 1868, Pogg. Ann., devised a chronoscope by flashing the sparks of a Leyden jar charged with static electricity from the style of a tuning-tork drawn orer a smoked snrface of tin-foil. He snbsequently replaced the sheet of foil witli a metallic cylinder covered with smoked paper. With this apparatus he measured the time of falling bodies, and obtained ±.001.5 of a second as the dif- ference between the observed and computed times of fall.
Rice, 1875, made seven determinations of the velocity of fowling-piece shot. The shot was of numbers 2 and 7. With a charge of 3 drachms of powder and 1^ of No. 7 shot he obtained a mean velocity, in a range of 50 yards, of 855 feet per second. He used in these experiments a Le Boulangt^ chronograph. Professor Rice, U. S. N., was, 1 believe, the first to determine accurately the velocity of bird-shot. His interesting paper is published in "Rod and Gun," July 31, 1875.
Errata.
In memoir "On a Method of Precisely Measuring the Vibrafory Periods of Tuning-Forks," &c., Vol. Ill, Pt. II, of Mem. Nat. Acad. Sci., by Alfred M. Mayer, on pages 54, 55, and 50, wherever "Tuileries fork" occurs read Feydeau fork, and wherever "Feydeau fork" occurs read Tuileries fork.
S. Mis. 154 22
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