5 MEMOIES OE THE MANCHESTER LITERARY AND PHILOSOPHICAL SOCIETY. Ui, E^H- OJOIES OF THE MANCHESTER »* * LITERARY AND PHILOSOPHICAL SOCIETY, THIRD SERIES. TENTH VOLUME. LONDON: TAYLOR AND FRANCIS, Red Lion Court, Fleet Street. 1887. AliEKE FLAM MAM. PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. CONTENTS. ARTICLE PAGE I. — Some Novel Phenomena of Chemical Action attending the Efflux from a Capillary Tube. By R. S. Bale, B.A i II. — On the Composition of Projections in Geometry of Two Dimensions. By James Bottomley, B.A., D.Sc., F.C.S. ... 6 III. —On some Undescribed Tracks of Invertebrate Animals from the Yoredale Rocks, and on some Inorganic Phenomena, produced on Tidal Shores, simidatiug Plant-remains. By Professor W. C. Williamson, LL.D., E.R.S., President. (Plates I., II., III., IIP.) 19 IV. — On the Structure, the Occurrence in Lancashire, and the probable Source, of Naias grcminea, Delile, var. Belilei, Magnus. By Charles Bailey, F.L.S. (Plates IV.-VII.)... 29 V. — Notes on the Subgenus Cylinder (Montfort) of Conus. By J. Cosmo Melyill, M. A., F.L.S. (Plate VIII.) 76 VI.— Memoir of Robert Angus S.mitii, Ph.D., LL.D., F.R.S., F.C.S., &c. By BnwARD Schunck, Ph.D., F.R.S., &c 90 VII. — On a Property of the Magneto-electric Current to control and render Synchronous the Rotations of the Armatures of a number of Electro-magnetic Induction-machines. By Henry Wilue, Esq 102 VIII. — On the Influence of Gas- and Water-pipes in Determining the Direction of a Discharge of Lightning. By Henry Wilde, Esq 1 12 VI CONTENTS. ARTICLE PAGE IX. — On the Origin of Elementary Substances, and on some new Relations of their Atomic Weights. By Henry Wilde, Esq ii8 X. — On the Velocity with which Air rushes into a Vacuum, and on some Phenomena attending the Discharge of Atmospheres of Higher into Atmospheres of Lower Density. By Henry Wilde, Esq. (and Table.) 146 XI. — On the Flow of Gases. By Professor Osborne Reynolds, LL.D., F.R.S 164 XII. — On the Efflux of Air as modified by the Form of the Dischar- ging Orifice. By Henry Wilde, Esq 182 XIII. — On the Morphology of Pinites oblongus {Abies ohlonga of Lindley and Hutton). By Wm. Ck.awpord Williamson, LL.D., F.R.S., Professor of Botany in Owens College. (Plate IX.) 189 XIV. — On the Plymenoptera of the Hawaiian Islands. By the Rev. T. Blackburn, B.A., and P. Cameron 194 XV. — The Pollution of the River Irwell and its Tributaries. By Charles A. Burgiiardt, Ph.D. (Plates X.-XIII. & Table.) 245 XVI. — On the Relations of Calamodendron to Calamites. By Pro- fessor W. C. Williamson, LL.D., F.R.S. (Plates XIV.- XVI.) 255 NOTE. The Authors of the several Papers contained in this Volume are themselves accountable for all the statements and reasonings which they have offered. In these par- ticulars the Society must not be considered as in any way responsible. MEMOIRS OP THE MANCHESTEE LITERARY AND PHILOSOPHICAL SOCIETY. I. Some Novel Phenomena of Chemical Action attending the Efflux from a Capillary Tube. By R. S. Dale^ B.A. Read December i6th, 1884. The results obtained in the experiments I propose to describe were the outcome of a desire to know what, if any, mechanical action took place when two solutions capable of forming a precipitate were slowly mixed ; next to find the nature of such mechanical action, and latterly, if possible, to measure it. I have made no attempt in the latter direction, but propose describing a series of experiments which have yielded some very novel effects. No. I. Solutions of lead acetate and potassium dichromate were allowed to travel in opposite directions along SER. III. VOL. X. B 2 MR. R. S. DALE ON SOME NOVEL PHENOMENA OF a thread placed in the field of a microscope. At the moment of mixing^ very considerable disturb- ance took place, accompanied with a whirling motion. This method not olfering results which could be easily registered, it occurred to me to cause one solution to flow into the other through a capillary tube or syphon. The apparatus used was of the simplest possible description, consisting of a pair of cylinders connected by a capillary syphon, the efiluent end of which was bent upwards. One cylinder was raised slightly above the other to ensure a flow. I have a photograph of the general arrangement adopted. No. 2. Solutions of lead acetate and potassium dichromate were allowed to mix in this manner. The latter salt was passed into the former. The capillary syphon was charged with water, and after this had passed through the heavier fluid a series of vortex rings began to be formed at the point of the tube. Later one attached itself to the tube, and others to this, until a tube was built up through which the potassium ‘ dichromate was passed, without any chemical action taking place, to the top of the lead acetate. This action continued until the system reached an equilibrium. Fearing that I could not show the experiments before the Society, I photo- graphed some of them, and they show exceedingly well the curious growths of lead chromate which were thus produced. With these two substances to obtain a single tube was most difficult, and only a series could be obtained with anything like cer- tainty. An experiment was made reversing the fluids. CHEMICAL ACTION FROM A CAPILLARY TUBE. 8 The same results were obtained^ though the growth was less stable, as the potassium dichromate being of much smaller specific gravity, no support was given to the lead chromate formed, and thus the growth continually fell off the point of the syphon. No. 3. A cold saturated solution of sodium sulphate was passed into a saturated solution of barium chloride. A perfectly straight tube was obtained, which formed with great rapidity and was very stable. This result was most unlooked for, taking into con- sideration the great density of barium sulphate. No. 4. A solution of ammonium oxalate was passed into a solution of calcium chloride. These particular solutions were chosen because the amorphous cal- cium oxalate first produced, on mixing these solu- tions rapidly, becomes crystalline, and the effect could not be surmised on mixing with a capillary tube. The usual phenomena took place until the tube reached the height of about one inch, when the amorphous calcium oxalate suddenly changed to the crystalline variety, and apparently stopped the action, as no further upward growth took place. On careful examination, however, of the point of the growth, a fluid was noticed to emerge, which had no action on the surrounding calcium chloride, showing that chemical action was still going on. Now, the upward growth having ceased, it was inevitable that the tube should become wider, and this is what really took place. On another expe- riment I obtained a nearly spherical body about half an inch in diameter. No. 5. Action of ammonia on ferrous sulphate. A very B 2 4 MR. R. S. DALE ON SOME NOVEL PHENOMENA OF thick tube of ferrous hydrate was formed, which I am able to show you, as it is by no means fragile. It has, of course, been, since out of the fluid, par- tially converted into ferric oxide. No. 6. Sodium carbonate on copper sulphate. In this case a crystalline copper earbonate was obtained of two shades, one a bright blue resembling azurite (if it be not actually that substance), and another a bright green resembling malachite. I am able to show this tube. No. 7. Ammonium sulphide on copper sulphate. An action closely resembling, in many particulars, the action of ammonia on ferrous sulphate. No. 8. Sodium carbonate on calcium chloride. The com- mencement of the action was marked by the for- mation of a perfectly transparent and highly refractive sheath of calcium carbonate, which did not show any signs of crystallization until about half an inch in length. On examination, after the lapse of about twelve hours, a crystalline tube of calcium carbonate had made its way to the top of the containing cylinder. This tube was composed of -minute, but well-defined crystals. I found it impossible to retain it in its perfect shape for inspection here. No. 9. Sodium carbonate on barium chloride. A very similar action to that mentioned in experiment No. 7, but at no time Avas a transparent substance noted, the growth being quite opaque and not palpably crystalline. No. 10. Hydrochloric acid on sodium silicate. Here a AA^ell-marked action took place, and a tube of silica CHEMICAL ACTION FROM A CAPILLARY TUBE. 5 was produced, a portion of which I am able to show. No. II. Knowing the silica produced by the action of ammonium chloride on sodium silicate was much denser than that obtained in the previous experi- ment, I caused these substances to act on each other, and succeeded in obtaining a very long tube of silica of considerable thickness. I am able to show this also. No. 12. Ferrocyanide of potassium on ferrous sulphate. Notwithstanding the extreme lightness of the blue precipitate produced by these solutions, a perfect tube was obtained, which reached the surface of the ferrous sulphate. Many experiments on the above lines will readily suggest themselves ; but I think I have described sufficient to call attention to this, to me, novel method of experi- ment, and I must leave it to some future occasion to describe such others as may show any peculiarities worth noting. I purposely refrain from making any theoretical deductions, with the one exception that it is pretty certain that these phenomena are inseparably connected with vortex-action, the tubes being undoubtedly built up of a series of vortex-rings. 6 DK. J. BOTTOMLEY ON COMPOUND II. On the Composition of Projections in Geometry of Two Dimensions. By James Bottomley^ B.A.^ D.Sc.^ F.C.S. Read January 13th, 1885. In previous papers (ProeeedingSj vol. xxi. page i88 et seq. ; Memoirs^ vol. viii. 3rd series^ page 218 et seq.) it has been shown how, by the eomposition of two projeetions, namely, of that of a line on a line, and of that of a plane on a plane, we may derive from a solid another solid of which the volume bears to the volume of the former the ratio where n denotes the cosine of the angle between the primi- tive axis and the fixed axis. The kind of projection there contemplated has its analogue in geometry of two dimen- sions. The projections to be compounded in this case are those of tu'o lines on two lines. As the simplest case, let Oj7, Oy be two fixed rectangular axes, and ABC a rectangle in the plane of these axes ; let / and m be the cosines of the angles made by AC with Ox and Oy. Project AB on Ox ; then we shall have PROJECTION IN TWO DIMENSIONS. 7 If AC were projeeted on Oy, the length of the projection would be mkC ; from the point D draw a perpendicular such that DF=mAC, (2) and complete the parallelogram. Multiplying together (i) and (2)^ we get DE.DF=m"AB. AC; AB . AC is the area of the primitive parallelogram^ and FD . DE is the area of the parallelogram FDE. By pro- jecting on the line Oy, we may obtain^ in a similar manner, another parallelogram such that NK.KL = Z^AB. AC. Hence A,; and A^ denoting the projected areas, we have A,; -p Ay=AP + Am^ , = A- for If the rectangle CAB have any motion of translation, this will affect the positions, but not the magnitudes, of the projections ; if the rectangle have a motion of rotation round any axis perpendicular to its plane, each projection will vary in magnitude, but their sum will be constant. The reasoning of the above simple case may be extended to any plane area bounded by curved lines ; for we may suppose the area to be rigidly connected with two straight lines on its plane, and at right angles; then the whole area may be considered as the limit of a series of elemen- tary parallelograms whose sides are parallel to these axes. If a denote the area of one of these elements, its projection Uj, on a line parallel to the axis of x, will be m^a, and summing, we have 8 DR, J. BOTTOMLEY ON COMPOUND '^^a denoting the area of the primitive figure, which we may also write A, and denoting the area of some geometrical figure built up by piling one on another the successive projected rectangles. This area we may also denote by A^. In a similar manner we may pile one on another the projections on lines parallel to the axis of y, and if Ay denote the area of the figure so generated, being the limit of we shall have on addition A^. -|- Ay = AV“ 4" Atn^ — A. Of the two axes rigidly connected with the movable area, one may he termed the primitive axis, and the other the complementary axis. If L be the greatest dimension of the curve parallel to the primitive axis, and if we draw parallel to the axis of x two straight lines distant from each other vrih ; then, in building up the a?-projection, we have some choice in the manner of doing so, provided that none of the curve so generated lie outside the above- hounding lines. In what follows I have proceeded accord- ing to the method adopted in projecting a solid, given in a previous j)aper. Let the primitive axis AB and complementary axis ED PROJECTION IN TWO DIMENSIONS. 9 intersect in a point C, of which the coordinates are x=a, y = b. Draw FG parallel to ED, and GK parallel to Oy ; on GK take a length KL, so that NG being parallel to AB, KL=mNG; then L will be a point on the projected curve. If through L we draw parallel to O.*’ a line LM such that LM=mFG, then M will be another point on the curve. By proceed- ing in this manner, the entire curve may be constructed. A curve generated in this manner from the primitive curve may, for brevity, be termed its projectrix. The equation to the primitive being given, that of its projectrix may be deduced as follows : — NG=CG cosGCH, X and y being coordinates of G, we shall have cos GCH = {x — a)l+ {y — b)m _ CG ^ therefore and NG —{x — a)l-{-{y — b)m ; KL = m{(x — a)l+ (y—b)m} ; therefore, if y and ^ be coordinates of the corresponding point on the projectrix, we shall have l=OK = ^, (3) 'q = m{l{x — a)-\-m{y—b)], ... (4) and if the in imitive curve be /(./;, y) =0, 10 DR. J. BOTTOMLEY ON COMPOUND the projectrix will be ,f(^ m )=0. From the relation between the eoordinates^ we may infer that the equation to the projeetrix will be of the same degree as that of the primitive. Also sinee vanishes d^y when vanishes, if the primitive has any singularities, the projectrix will have some singularity at the corre- sponding points. That portion of the primitive area lying below the line ED will on projection be situated below the axis of x. The relation between the areas of the primitive curve and its projectrix may readily be obtained by means of equations (3) and (4) : — or J by substitution this becomes — a) + {y—b)m}dx, In equation (4) make v = o, then we obtain {x — a) I + {y — b)m = o. This is the equation to the complementary axis, and the limits in (5) show that the integration is to extend from PROJECTION IN TWO DIMENSIONS. 11 this axis to all points above ; hence^ between corresponding limits, we have Ax=ni^A. Also if be any arbitrary function of x, we may show in a similar manner that 9 d^dt] = rrd' 9 y dx dy. i h (o?— a) m As a particular example of the foregoing remarks, suppose the primitive curve to be a circle of radius c, and suppose the primitive axis to be a line through its centre ; then {x—ay+ {y — by = c^. By substitution we obtain for the projectrix m‘^{x—a)-\{y—lm(x — a)Y = m'^c^. . . (6) To simplify this remove the origin to the point x=a, y=o, and then refer it to new axes, so that 6, the angle between the new and old axes of x, fulfils the following condition : — tau26>=^; (7) then the equation assumes the form _ , -f- — — '' — I j I — 4-3»i^) (i —ni^) i 4-m^ + ^(i +3?%^) (i —m^) this represents an ellipse of which the area is If we suppose the primitive circle to revolve round an axis perpendicular to its plane, then m becomes a variable quantity, and equation (6) will contain a single variable 13 DR. J. BOTTOMLEY ON COMPOUND parameter. Differentiating with regard to m, we obtain the following equation : — I 7Yh^\ \y — ml{x — a) [s iy — {x — a) y j- =o. The condition y —ml{x — a) = o, along with equation {6), gives the condition x=a±c; the two lines represented by this equation touch all the ellipses generated by varying m. The condition 2y-{x-a)-j=o, gives for m and I the values _ ‘^y ^ _ x—a \/¥f+{os—aY These values introduced into equation (6) give the follow- ing equation : — i6y*-\-^y^{x — aY + [x—aY= an equation which is resolvable into the two following : — each of these equations represents an ellipse^ of which the major axis is equal to the diameter of the circle, and the minor axis to the radius j both ellipses touch the axis of PROJECTION IN TWO DIMENSIONS. 13 X and each other at the point x — a, y = o, one being situate above the axis and the other below. Locus of the Extremities of the Major and Minor Axis. — Both the magnitude of the major axis of the projectrix and its inclination to the axis of x are functions of m. If r be the length of the major axis^ from equation (8) we have m^c\/ 2 r = —j= - ; V I ^^(i + 3m^) (i— m^) eliminating m between this equation and (7), we obtain for the polar equation to the curve traced out by the extremities of the major axis V'i+(sec^6»-|-)" From the form of the equation it is evident that the major axis will have a maximum value and this will be the case when cos 6— The form of the curve is shown in the annexed figure, where the dotted curve represents a circle of the dimen- sions of the primitive circle. The curve cuts the axis of 14 DR. J. BOTTOMLEY ON COMPOUND X at the origin and at the point x — C', it cuts the circle at the point r—c, (9=45°; point the inclination of its tangent is tan~’^. Below the axis of x there is a branch PBC similar to the one above the axis^ and to the left of the axis of y there is a branch PDEF similar to the one on the right. The major axis of the ellipse is generally greater than the radius of the circle. But of the curve just described a portion lies within the circle, and for such points the radius is less than c ; the connection of this portion of the curve with the axes of the ellipses may be established as follows. Let r, be the length of the minor axis of the projectrix ; then from (8) we have m^cs/i ^ I — / / • ' * V I +m^+ V (i 4- 3m^) (i — m^) Eliminating m between this equation and (7) we obtain the equation _ c ' V/I-+ (cosec^^— 1-)^ But if 6^ be the inclination of the minor axis to the axis of X, measured in the positive direction, we shall have hence the polar equation to the minor axis is c V'|+ (sec^^,— 1-)^ This equation is of the same form as (9), but the minor axis is generally less than c ; hence it follows that those portions of the curve which lie outside the circle are traced out by the extremities of the major axis, and those portions lying within the circle are traced out by the PROJECTION IN TWO DIMENSIONS. 15 extremities of the minor axis. By the aid of this eurve we may readily obtain any ellipse which may be derived by projection from a given circle — any line through the centre and terminated by the external branches will be a major axis j to obtain the corresponding minor axis, draw a line at right angles, then the portion intercepted between the internal branches will give the magnitude of the minor axis. The equation to the curve in rectangular coordinates is y^ = ocf^[c^ — X^') ; its area is two thirds the area of the primitive circle. As previously stated, we have some choice of method in constructing a projected curved area ; in (6) the elemen- tary rectangles have been so piled up that their centres lie on the line m ma that is, on a line parallel to the primitive axis. If the locus of the middle points were the line y= m ma we should obtain an equation of the form m‘^[x — aY + \ml{x — a)y (4— = representing an ellipse of which the perimeter is equal to the perimeter of the primitive circle. If any line y = h cut this ellipse, the length of the section will be — this will also be the length of the section made by the same line with (6) . Invet'se Problems in Projection. — In the foregoing remarks it has been supposed that the primitive curve has been given and the projectrix obtained by means of 16 DR. J. BOTTOMLEY ON COMPOUND equations (3) and (4) ; but it is evident that by means of the same equations we may solve inverse problems, viz. given the equation to the projectrix to deduce that of the primitive. If the equation to the projectrix be given in the form Suppose the projectrix to be the circle — we shall obtain for the primitive the ellipse {x — «)^(i + 2,m}l[x — d) {y — b) — = The semiaxes of this ellipse are Cs/2 Although the projection of this ellipse on the axis of x may be a circle, its projection on the axis of y will not simultaneously be a circle. The projectrix in this case will be {x—lm{y — b)y + [y — by = l^c^, representing an ellipse of which the semiaxes are cV- sj 2 Mcn)=o, that of the primitive will be of the form and \/ 1 +>/(! + 3m^)(i — cs/ 2 \/ 1 +m^— \/(i +3^^) (i —m^) and \/ 1 + 2mH^ + + I Cf i/2 \/ 1 + — i/4»^^/^ + 1 PROJECTION IN TWO DIMENSIONS. 17 Relation of Perimeters of the Primitive and its Projec- trices. — In a former paper it was shown that if on a primitive solid we draw any arbitrary eurve of length s, and if s^, Sy, s^ denote the lengths of the eurves passing through the eorresponding points of the projeeted solids, then a simple relation ean be found amongst the differ- entials of these quantities. A similar proposition holds in geometry of two dimensions, the relation in this case being between the perimeters of the primitive and its projeetriees. Differentiating (3) and (4) and squaring we obtain drf = nd [I dx -h m dy) and 77, being the corresponding points on the y-projec- trix, we shall have Vi = y, = iy-b)m), whence dr)f = dy^, d^f = r (/ dx -t- m dy) By addition we have + drf‘ + d^f + dyf = dx^ + dy^ + {I dx -1- m dy)^ . (10) ds being the arc of the perimeter extending from the point X, y to the point x + dx, y + dy, and ds^, dsy being the arcs of the projeetriees between corresponding points, we shall have ds^ =dx^ -\-dy^, dsf = d^"- -\-drf, dSy" = d^f-\-dyf‘, also if be the angle between the direction of the primi- SER. III. VOL. X. c 18 ON COMPOUND PROJECTION IN TWO DIMENSIONS. tive axis and the tangent at any point to the primitive curve^ we have , ,dx dy cos (6 = / -^ + m : ^ ds ds therefore, by substitution, equation (lo) may be put in the form v' + dSy = \/ 1 + cos^<^ . ds. If we suppose the primitive area to revolve round any axis perpendicular to its plane, since the primitive axis is rigidly connected with it, the expression J'v/i +cos^^ . ds will he invariable ; replacing it by c, we shall have then j* V dSx + ds^ = c. Relation of Projectrices of Higher Orders. — From a primitive may he derived two projectrices ; but each of these may in its turn he regarded as a primitive that may be operated upon in a similar manner; then, on a repe- tition of the process, we shall obtain four projectrices. The relation of the area of these to that of the primitive may be obtained as follows. A^. being the primary pro- jectrix on the axis of x, the secondary projectrices which may be derived from it may be denoted by (Aa,)^ and (Ax)y, and we shall have (Ax);^ = ^W'^A, (ll) {k^)y — 7n^l^A (12) If {kfjx and {Afjy denote the secondary projectrices which may be derived from Ay, we shall have (Ay)x = /WA, (13) ~ (^4) ON SOME TRACKS OF INVERTEBRATE ANIMALS. 19 By addition of these four equations we obtain (A-a;)a; + (Aa;)y + + (A^)^ = A(m'^+ 2171^1^ + Z‘^) = A(m" + r)^=A. From this it seems likely that if we repeated the operation n times the aggregate of the 2^* areas obtained would be equal to the primitive area, and it may be readily shown that if the proposition be true after n operations, it will be true after n+i operations. But it has been shown to be true when n is equal to 2, therefore when n is equal to 3, therefore when n is equal to 4 &c., and so the proposition is generally true. III. On some Undescrihed Tracks of Invertebrate Animals from the Yoredale Rocks, and on some Inorganic Phenomena, produced on Tidal Shores, simulating Plant -remains. By Professor W. C. Williamson, LL.D., F.B.S., President. Read February lotb, 1885. [Plates L, II., III., & III'.] About two years ago I reeeived from the Bev. Isidore Kavannah, of Montreal, then a student of Stonyhurst College in Lancashire, some interesting objects which he had discovered upon some loose blocks of stone strewing the shore of the river Kibble, close to the College. The raised bank of the river, at that point, consists of hard beds of Yoredale rock separated by thin layers of softer material. A careful examination of the locality left no doubt on my mind that the specimens had fallen from the under surface of one of these hard beds. Though we failed c2 20 PROF. W. C. WILLIAMSON ON SOME UNDESCRIBED at that time to discover any such in situ, at a later date Mr. Kavannah was more successful. He then obtained some fine examples from the under surfaces of some of these undisturbed beds^ making it certain that the objects immediately to be described belong to the Yoredale division of the Carboniferous strata. Like so many allied remains obtained from Silurian deposits^ these objects stand out in bold relief from the inferior surfaces of the rock-layers_, of which their sub- stance is a mere extension. The peculiar sculpturings characterizing these convex surfaces are wholly superficial,, indicating that they are but casts of concave tracks once existing on the surface of the subjacent stratum. The dimensions of those excavated tracks are faithfully, though invertedly, represented by the prominent configurations of the objects before us. The specimen (Plate I. fig. i) represents a slab twice the size of the photograph, upon which are three more or less defined meandering ridges. The longest of these runs from a to a. A considerable portion of it is almost obliterated ; but at each extremity it preserves its characteristic features. At b and c are two shorter ones, each of which commences in an undefined irregular elevation ; b near the centre of the slab, and c at c? ; but both acquire their peculiar sculpturings at the extremities b and c. Assuming that the creatures which made these tracks moved towards the lower margin of the specimen, the appearances suggest that in the cases b and c they terminated their strolls by sinking into the sand, as many recent invertebrates do, on reaching the spots where each of two of the tracks end in an irregular mass, as represented at d. The average diameter of each of these tracks is from five to six tenths of an inch. Their elevation, represent- ing the depth of the original tracks, is sometimes four TRACKS OF INVERTEBRATE ANIMALS. 21 tenths of an inch; usually, however, they fall short of this depth. A median furrow runs along the entire length of the track in these casts, representing some median abdo- minal groove in the living organism. Numerous parallel ridges and alternating furrows proceed outwards, down- wards, and backwards (?) from this groove, about ten such ridges occurring in each lineal inch. Along the summit of each of these lateral ridges we have a row of small tubercles, about twenty to an inch. These tubercles sometimes appear to be the summits of obtuse elevations which pass obliquely down one side of each ridge, disap- pearing as they reach the median line of the contiguous furrow, the opposite side of which presents no such appearances. These small sculpturings suggest that the appendages (legs ?) of the animal to which the primary and secondary ridges and furrows are due had serrated or crenulated margins. Fig. 2, Plate III., represents the arrangements in question diagrammatically, the appear- ances being made rather stronger than in reality to illus- trate their general features. The surface of the slab (fig. i) is covered with parallel, rounded ridges and furrows of varying depths and eleva- tions. These may represent drainage- lines, but they also suggest somewhat strongly the idea of a wind-blown surface of sand. Fig. 3 represents a second fragment, in which the lateral ridges and furrows of one of the two tracks are less uniformly regular, some of them being stronger than in the case of fig. i ; but here again the track is connected at the end on its right with an irregular boss, representing a corresponding depression on the primaeval beach. These objects correspond closely to those supposed vegetable organisms to which Schimper has assigned the name of Chrossocorda. Though I am altogether unable 22 PROF. W. C. WILLIAMSON ON SOME UNDESCRIBED to share Schimper^s belief in their vegetable origin, I see no objection to retaining his name. So far as I am aware, all the examples of Chrossochorda hitherto known have been obtained from strata of much older age than the Yoredale series. But, besides this difference of age, these Carboniferous forms differ from all the older ones in pos- sessing the line of tubercles along the summit of each of the secondary ridges already referred to. These objects may therefore be distinguished as Chrossochorda tuberculata. What animal produced the hollow tracks of which these fossils are casts in relief, we have no means of knowing. There is an obvious resemblance between them and the tracks which Dr. Nathorst obtained by allowing the Crustacean Corophium longicorne to walk and swim over prepared mud*. In several similar tracks figured by Dr. Nathorst we find the line of footsteps terminating in enlarged irregular depressions, corresponding to the bosses seen in figs, ic? & 3. Plate I. fig. 4 represents a track of an entirely different kind, from a quarry of Carboniferous flagstones near Hawes t- I presume that in this case we have not the cast, but the actual indented track of the animal that has left its footsteps on the smooth sands. The length of the stone is lyf inches. Each separate group of impressions consists of four pairs of slightly curved indentations, each octant occupying a square i^ of an inch from a to b, 41 of an inch from c to d, and nearly- from e to / of the accompanying lignograph. The markings suggest the idea of having been made by four pairs of abdominal plates rather than by crustacean limbs. The distances between * Om spar af nagra evertebrerade Djur m. m., och deras paleontologiska betydelse, af A. G. Nathorst. Stockholm, 1881. Tail. i. figs. 1-2. t Mr. J. W. Davis says, “ The footprints are from a quarry of flagstones and grey slates about a mile from Hawes, on the road to Muker. The horizon is above the Hardrow Limestone.” TRACKS 01’ INVERTEBRATK ANIMALS. 23 the anterior pair a and h, and the corresponding pair h and c in fig, 4, is exactly of an inch. There is no trace of any defined median vertical line^ but there is a distinct elevation in each of the areas separating the parallel curved grooves, and the vertical median line between each two rows is also faintly raised, as if, in the latter case, a slight concavity existed at the corresponding part of the living animal. What that creature may have been is more than doubtful. Except what appears in the successive octants, no continuous trail of any kind appears on the slab, making it obvious that the creature possessed no Trilobite-like tail or sternal ridge. The object may safely he placed in the genus Protichnites , and he distin- guished as P. Davisi, after my friend J. W. Davis, Esq., E.G-.S., of Halifax, by whom the specimen was found, and who has kindly allowed me to describe it in this memoir. Leaving these two relics of a past age, I would now direct attention to some phenomena of modern origin, which I have recently observed on the sea-shore. Two summers ago my attention was arrested by some remark- able appearances on the sands left bare by the retreating tide at Llanfairfechau in North Wales. Watching the formation of these appearances, it soon became obvious that they were formed by small drainage-streams flowing either towards the sea or towards large temporary depres- sions in the sand running more or less parallel with the 24 PROF. W, C. WILLIAMSON ON SOME UNDESCRIBED sea-line. The contours produced by many of the smaller tributaries, where they united to form larger streamlets, suggested to my mind the extreme probability that the casts of such sculptured areas would, if found in any of the older strata, be undistinguishable from many of the so- called fossil Fucoids found in these strata. Working carefully, I succeeded in obtaining a number of plaster casts of these grooved surfaces, some of which are accu- rately represented, through the aid of photography, by the several figures 5-1 1 on Plate II., and figs. 12 & 13 on Plate III. The leaf-like peripheral outline of some of these figures has no significance, it being merely that assumed by the flowing of the semi-fluid plaster of Paris when poured upon the sand; but it is otherwise with the plant-like ramifications revealed on the surface of each cast. Had such specimens been found on the inferior surfaces of ancient flagstones, I have little doubt but that they would have appeared in the pages of Schimper, and other authors with similar views, as Palaeozoic Fucoidal forms of plant-life ; anyhow their publication may benefit some of our younger and more ardent palaeontologists, by suggesting caution ere they give names and places in the annals of Palaeophytology, to objects which may be as wholly inorganic as those which I have just described. Nearly all the configurations of this kind which I discovered at Llanfairfechan were of the same character as those represented by figures 5—13 of my Plates. On visiting the sands to the north of Barmouth during the summer of 1884 I made diligent search, in the expectation of finding there similar configurations. Products of tidal action and drainage were not wanting, but to my surprise those of the new locality were wholly diflFerent from what I found on the Carnarvonshire coast. Figs. 14 & 15 are photographs of casts made at Bar- mouth, and represent the results of a double action, viz. the TRACKS OF INVERTEBRATE ANIMALS. 25 production of ripp]e-marks_, and a subsequent seulpturing by drainage-currents. Tbe ripple-marks^ at the point in question, curved diagonally across the lines subsequently followed by tbe drainage-streamlets. Hence tbe surface of the sand was cut up into tbe very regular, diagonally arranged, contours represented in Plate III. fig. 14. We have here two sets of regular ripple-marks, one of which passes from the upper to the lower margin of the figure, from right to left. A second and more sharply defined set crosses these diagonally, i. e. from left to right. These lines were, of course, formed under the water. When the tide had retreated sufficiently, drainage-lines began to form j but these pursued their direct course down the sloping sand-bank towards the sea. The result of this triple action was the formation of a series of regularly arranged, acuminate contours, the surfaces of which were characterized by longitudinal flutings, resembling the over- lapping scale- leaves of some Cycadean stem. They readily might, an-d probably would, have been mistaken for such, had they been discovered on some slab of Oolitic sandstone. Fig. 15 exhibits a slight difference from fig. 14. Here we had only one diagonal series of ripple-marks, followed by the formation of drainage-lines as before. The result is an effect not unlike that of two or three corrugated Laminarian fronds overlapping one another. I have no doubt that further investigation will bring to light other examples of inorganic configurations simulating organic forms. I am somewhat surprised that so little attention has hitherto been paid to the results of littoral drainage-lines. Sir J. W. Dawson figures an example of one such result, but of very different aspect from those now described, in his memoir on tracks of Invertebrata in Silliman^s American Journal, entitled “ On the Foot- prints of Limulus as compared with the Protichnites of the Potsdam Sandstone^’’ (1862). But I have not met with any 26 PROF. W. C. WILLIAMSON ON SOME UNDESCRIBED other detailed illustrations of drainage-lines contributing towards the formation of pseudo-orgauic structures*^ still less to the combination of drainage-lines and ripple-marks in producing analogous results ; yet the literature of the subject of tracks and pseudo -vegetable forms has now become a very copious one. In his extremely valuable memoir some Tracks of Invertebrate Animals &c.^ and their Palaeontological Import^"’ t. Dr. Nathorst has published a bibliography of the subject treated in his memoir, containing no less than 130 references to writers who have dealt with various aspects of the subject between the years 1823 and 1881 inclusive. Many of these writers have regarded the objects to which they have referred as the tracks or footsteps of various invertebrates left upon the sandy or muddy shores which they frequented; but a large proportion of the authors have referred these objects to the vegetable kingdom, especially to the Pucoidal section of it. The extent to which this has been done is shown in the pages of Schimper^s ^ Paleontologie Vegetale,^ where a large number of genera, and a still larger one of species, have been created out of extremely vague and indefinite objects. More recently the Marquis de Saporta has published his volume, entitled ^L^Evolution du Regne Vegdtale^ (Paris, 1881), in which he adopts freely the conclusions of Schimper, and recognizes in these doubtful objects vai’ious definite forms of marine Algae. The Marquis de Saporta first replied to the memoir of M. Nathorst in a volume entitled ^ Les Organismes pro- blematiqucs des anciennes Mers,^ 1882, and two days ago I received from him a second volume, entitled ‘A projios * My ignorance of the Swedish language has led me to overlook the fact that Dr. Nathorst figures an example of this kind on p. 21 of his memoir supplied to him from Gothland by Professor Lindstrom (July 25th, 1885). t Om spar af nagra evertebrerade Djur m. m., och deras paleontologiska betydelse, af A. G. Nathorst. Stockholm, 1881. TRACKS OF INVERTEBRATE ANIMALS. 27 des Algues Fossiles/ having the same objeet as the pre- ceding one*. These two volumes embody every argument that can he advanced in favour of the v^egetable origin of the objects in dispute. Much of the discussion turns upon the point illustrated by figs, i & 3 of my present memoir^ viz. that nearly all the debated structures stand out in prominent demi-relief from the undersides of the slabs of which they form a part; and thatj as is conspi- cuously the case with my specimens^ what ought to repre- sent the substance of the supposed organism is merely an extension of the inorganic rock overlying the sculptured surfaces. M. Saporta takes much pains to show that many unquestionable fossil plants are found in this same condition of demi-relief. This is true ; but we find abundance of the same plants in different conditions, in which substance and even structures are equally preserved. Hence we are able to identify the specimens seen only in semi-relief by the aid of the more perfect examples. But in the case of such specimens as my figs, i & 3, we have hitherto failed to obtain any trace of either substance or structure. M. Saporta, in his latest memoir, seems to have found some specimens of the genus Biserites, in which he can trace what he describes as le contour entier de la Bilobite.'’^ This only shows a possibility that one of the many objects to which the name of Bilobites has been given may have been plants. These views were attacked in a formidable manner by Dr. Nathorst in the memoir above referred to. This important memoir embodies the results of a series of exact experiments, in which various aquatic animals were allowed to travel under water, leaving behind them very definite tracks in fine mud as they did so. Dr. Nathorst succeeded in obtaining very perfect casts of those tracks, and, in * The resemblance of M. Saporta’s figure of Vexillmn Besglandi, on p. 42 of the latter volume, to ray fig. 15 on Plate IIT. is too striking to be overlooked. 28 ON SOME TRACKS OP INVERTEBRATE ANIMALS. order that his representations of them should owe nothing to the imagination of his artist, he employed photography, that unerring delineator, in illustrating his memoir ; an example which I have followed on the present occasion. Examples of what are prohahly concretionary objects occasionally occur of such a magnitude as to make it improbable in the highest degree that they can have been of vegetable origin. Some of these might be regarded as a huge form of Dictyonema, in which the fibres forming the network are six inches in circumference, and the enclosed meshes a foot wide. At the junction of the lowermost beds of the Coralline Oolite with the uppermost beds of the Calcareous Grit at Filey Brig in Yorkshire, acres of the contiguous surfaces of the two rocks are covered with such a huge network of coarse inorganic sandstone, in which the cylindric form is sufficiently perfect; but after prolonged study of these ramifying objects, all that Professor Phillips could say of them is that ‘^Ghey are ramified masses of doubtful origin, which appear like dichotomous cylindrical sponges Thoroughly familiar with these structures, I never for a moment doubted their inorganic character. Such objects can have no weight with the student of Evolution, and until we obtain more definite proofs than we have hitherto obtained of the vegetable nature of most of these dubious Palaeozoic Algae,^^ we must reject their testimony when framing a pedigree for the vegetable kingdom. At the same time I regard the existence of an abundant marine vegetation during the Palaeozoic ages as an inevitable corollary of the fact that the rocks of those ages abound in the remains of Phytophagous animals. But many sources of error surround us when we endeavour to demonstrate that existence by means of the anomalous objects which those rocks have already supplied to us. * Geology of tlie Yorkshire Coast, 2nd edition, p. io6. ON STRUCTURE ETC. OF NAIAS GRAMINEA^ VAR. DELILEI. 29 INDEX TO THE EIGUEES. Plate I. Fig. I. Slab of Yoredale rock, with tracks of Chrossocarda tuberculata, Will. Half the nat. size. 2. Diagrammatic repre.sentation of a portion of one of the above tracks. 3. A second fragment, with two tracks of somewhat moi’e strongly defined contour than those of fig. i. Nat. size. 4. Track of Protichnifes Bavisi, Will. Two fifths of the natural size. Plates II. & III. 5-13. Casts of a series of drainage-lines from the coast of North Wales at Llanfairfechan. Plate III'. 14, 15. Two similar casts from the coast north of Barmouth. These figures are all copied by an autotype process from photographs, kindly taken for the pui-pose of illustrating this memoir, by Alfred Brothers, Esq., F.E.A.S., of Manchester. IV. On the Structure, the Occurrence in Lancashire, and the probable Source, of Naias graminea^ Delile, var. Delilei, Magnus. By Charles Bailey, F.L.S. Eead April 29th, 1884. (Plates IV.-VII.) Page Pago I. Introduction 29 XII. The Pollen 55 II. The Genus and its Divi- XIII. Fertilization 57 sions 31 XIV. The Fruit 58 III. Synonymy of the Plant. . . 32 XV. The Eoots 62 IV. The Stem 34 XVI. The Lancashire Locality 63 V. The Leaves 36 XVII. Geographical Distri- VI. The Leaf-spines 37 bution 66 VII. The Leaf-sheath 40 XVIII. Its probable Source ... 67 VIII. Leaf-structure 45 XIX. A Histological Peculi- IX. The Inflorescence 47 arity 69 X. The Pistilliferous Flower 50 XX. Explanation of the XI. The An theriferous Flower 52 Figures 72 I. Introduction, Naias qraminea, Del. (Plate IV. fig. i), aud Ohara Braunii, Gmel., were first reported as occurring in a natural state 30 MR. C. BAILEY ON THE STRUCTURE ETC. in England at the Meeting of tlie British Association at Southport in September 1883. Their addition to the flora of South Lancashire and of Britain is due to the Biological Society of Ashton and to Mr. John Whitehead^ of Dukin- field. They were discovered during the exploration of the Ashton-under-Lyne district in acquiring tlie necessary material for the compilation of a fauna and flora of the neighbourhood,, for presentation to the Biological Section of the British Association. An abstract of this communi- cation^ made by Mr. J. R. Byrom^ of Ashton, is printed on pp. 541-543 of the ‘^Report of the Fifty-third Meeting of the British Association.^ Few portions of Great Britain are so well known, hotanically, as most of the northern counties of England, and yet a concerted systematic examination of so well- worked a district as Ashton has brought to light many novelties, besides tv/o, if not three, plants not previously known to he British. To those who know what a large number of practical botanists there are in the north of England, and with what zest so many of their number pursue botanical studies in their hard-earned leisure, it has always seemed a matter for regret that so little of their accumulated knowledge finds its way into print ; and the instance of what has been done by the Ashton botanists should stimulate other local societies to make similar efforts. The actual discoverer of the Naias was Mr. James Lee, of Denton ; he brought it to Mr. Whitehead, who sent it to me early in September of last year as a possible Naias ^ and, from plants which I afterwards gathered in situ with the discoverer and Messrs. Whitehead and Byrom, it was finally determined by Mr. H. N. Ridley, of the British Museum, to be Naias graminea^ Del., or Caulinia alag- nensis, Pollini. Subsequently Dr. Magnus, of Berlin, has OF NAIAS GRAMINEA, VAll. DELILEI. 31 given it tlie varietal name of Delilei, on account of a structural peculiarity referred to on pages 46 and 69. II. The Genus and its Divisions. The genus gives its name to the natural order Naiadacese, which is allied to the Potamogetonace8e_, but systematists are by no means agreed as to the respective limits of either family. Willdenow separated the group to which N, graminea belongs from Naias proper under the generic name of Caulinia'^, on account of the male flowers not having the quadrifid perianth of Naias proper ; but Robert Brown reunited the two groups of Naias and Caulinia into Naias, Linn. There is no doubt_, however^ that each of these divisions forms a very natural group sharply sepa- rated from the other by well-marked characters drawn from the leaf_, stem, and fruit. All these points have been carefully worked out by Dr. P. Magnus in a work which he modestly entitled ^ Beitrage zur Kenntniss der Gattung Najas, L.^ (Berlin, 1870); and no one can investigate the morphology and anatomy of a plant of this genus without admiring the minute and conscientious investigations of this author. In preparing the following notes I have referred again and again to this memoir, and I cannot speak too highly of the help derived from it. Dr. Magnus gives the following diagnoses of the two subdivisions of the genus, viz. : — § Eunajas, Asch. — Spine-teeth chiefly on the stem and backs of the leaves. Flowers dioecious (? in all) . Anther four- chambered (? always). Seed-shell consisting of a many-layered stony parenchyma. Conducting bundles of the stem divided from the intercellular spaces by two to three layers of parenchyma-cells. Leaf furnished with a * ‘Memoires de rAeaderaie Eoyale des Sciences de Berlin, 1798, classe de Philosophie Experimentale,’ page 87. 32 MR. C. BAILEY ON THE STRUCTURE ETC. small-celled epiderm^, which rises very sharply from the large parenchyma-cells of the leaf. “ § Caulinia^ Willd. — Spine-teeth absent from the stem and hacks of leaves, blowers in most species monoecious (? in all). Anther one- to four-chambered. Seed-shell formed of three layers of cellular tissue. Conducting bundles of the stem divided from the intercellular spaces by a layer of parenchyma-cells ; leaf without the small- celled epiderm.^^ — Beitrdge, pp. 55, 56. The plant which forms the subject of this notice belongs to the section Caulinia, and its synonymy and principal book-references are the following : — III. Synonymy of the Plant. Najas Delile, Flore de I’Egypte; Memoire sur les plantes qui croissent spontaneraent en Egypt®, par Alire Eaffeneau Delile, p. i ; Florse AEgyptiacffi illustrat.io No. 874, p. 75 ; Explication des planches, p. 282, pi. 50. fig. 3. Chamisso, Aquatics qufedam divei-Eas afiinitatis; Linnsea, vol. iv. 1829, pp. 502, 503- Kunth, Enumeratio Plantarum. &c., tom. iii. p. 115. Boissier, Flora Orientalis, vol. v. p. 28, Compendio della Flora Italiana compilato per cura dei Professor! V. Cesati, G. Passerini, e G. Gibelli, par. i. p. 205. Najas alagnensis, Pollini, Hort. et provinc. Veron. pi. nov. vel min. cogn. p. 26 ; Flora Veronensis quam in prodromum Florae Italiae septen- trionalis exhibit Cyrus PoUinius, tom. iii. p. 49 (1824). L. Eeichenbach, Flora Germanica Excursoria, No. 920, p. 151. Chamisso, Aquaticae quaedam diversie affinitatis; Linnasa, vol. iv. p. 502 (1829). Antonii Bertolonii, M.D., Flora Italica sistens plantas in Italia et in insulis cir cum stantibus sponte nascentes, tom. x. fasc. iii. p. 296. Naias serristipula, Nocc. et Balb. Ic. FI. Ticin. tab. 1 5 ex specim. sicc. delineata. Naias tenuifolia, Aschers., Atti della Societa Italiana di Scienze naturali, pp. 267 & 268 ; non E.. Br. Najas graminea, Del., var. Belilei, Magnus, Berichte der deutschen bota- nischen Gesellschaft, Band i. Heft 10, Jahrg. 1883, pp. 522 & 523. Caulinia alagnensis, Pollini, Plant. Veron. 26. Diar. Brugnatelli Gioru. ann. 1816, t. ix. p. 175. i OP NAIAS GRAMINEAj VAR. DELILEI. 33 IjlufF efc Fingerhuth, Compenclivim Florte Germanije, sectio i. ed. alt. ii. P- 5^5- Flora Italiana, . . . . di Filippo Parlatore, toI. iii. pp. 665, 666. Caulinia intermedia, Balb. Flench, recentium stirpium, quas Pedemon- tante florae addendas censet &c. ; in Mem. della E. Accad. di Tor, ann. 1818, tom. 23. p. 105. Balb. et Nocca, Flor. Ticin. tom. ii. p. 163, tab. 15. Nocca, Clay. ii. p. 91. Caulinia microj^hylla, Nocc. et Balb. Flor. Ticin. tom. ii. p. 163, tab. 16. It still remains a question whether this plant should bear Delile^s name or Pollini^s name, according as the one or the other had priority in publication, as has been pointed out by Prof. Ascherson in ^Atti della Societh Italiana,^ vol. x. p. 267, where he shows that the descrip- tion of the plant of Pollini was certainly published in 18143 whilst the Memoir of Delile, although perhaps printed in 1813, was not published until some later year. I cannot elucidate this point further, as my copy of Delile has no titlepage, and my edition of Pollini’s ^ Flora Veronensis^ is that of 1824. Pollini^s herbarium-specimen of the Italian plant is preserved among the possessions of the Society of Naturalists of Rhenish Westphalia, in Bonn. The Italian plant is not the same as Robert Brownes Naias tenuifolia, Prodr. FI. Nov. Holland, p. 545, published in 1810, on account of the entirely different structure of the male flower (see Plate VI. fig. 15)3 otherwise the name would have taken precedence of Pollini^s and Delile^s. Whether the plant found in Japan, at Yokohama, is identical with Naias graminea, Del., is uncertain 3 but the description of it by Herr C. J. Maximowicz may stand for the Lancashire plant : — Mollis elongata, foliis verticil- latis patentibus rectis argute spinoso-serrulatis, apice 2-3 cuspidatis, dentibus incurvis 1-cellulosis minutis3 stipulis distinctissimis lanceolatis foliaceis folii ad instar serrulatis 3 SEE. III. VOL. X. D 34 MR. C. BAILEY ON THE STRUCTURE ETC. fructu lineari-oblongo^ granulato. Nippon, in fossis circa Yokohamam semel inveni fructiferam^'’*. IV. The Stem. The stems vary in length from a few inches to upwards of two feet, and they have many branches. Considering the large number of leaves which they support, the stems are comparatively weak ; they do not vary much in diameter from the base to the summit; vertical sections of the upper internodes are not quite so circular as those of the lower internocles. Fig. 42. If we examine one of these internodes we find that the centre of the shaft consists of a small channel, surrounded by two or three layers of elongate cells somewhat closely * Diagnoses breves plantariim novarum Japonic et Mandsburia?., in Bul- letin de I’Acad. Imp. des Sciences de St. Petersbourg, vol. sii. pp. 71, 72 (^868). OF NAIAS GRAMINEA, VAR. DELILEI. 35 aggregated ; surrounding these is a layer of much larger cells^ hexagonal in outline^ and having thinner walls than those which protect the central channel. From this cen- tral mass radiates a series of from eight to twelve prolon- gations of the central hexagonal cells^ meeting as many outgrowths from the tissue which forms the circumference of the internode^ and arranged like the spokes of a wheel. See fig. 42. The rays enclose an equal number of large intercellular cavities^ each cavity being bounded by the central and peripheral parenchyma at either end. The cavities occur in every internode^ whatever its age^ but they are limited in the direction of the axis by the node. The rays consist of a single row of cells, except at the points where they join the circumference and centre ; they are not always as regular as they are drawn in fig. 42, as they occasionally branch at each end so as to enclose a smaller intercellular cavity. The circumferential tissue of each internode consists of three or four rows of elongate cells having a hexagonal outline, with sinuous edges. The cells are all uniform in size, the outermost layer not being smaller than the rest, as it is in Naias flexilis. The external edge of the outer row of cells is slightly thickened, but I cannot detect any epidermal cells. In the posthumous work of Prof. Parlatore, entitled ‘ Tavole per una Anatomia delle piante aquatiche,^^ ^ a drawing is given of the transverse section of the Italian Naias graminea ; hut it differs from my drawing (fig. 42) in showing an epidermis of distinct square-shaped cells. The central bundle is also made to consist of about half a dozen rows of cells, smaller in size than I find them in the Reddish plant. I reproduce Parlatore’s figure on Plate VII, fig. 36. D 2 36 MR. C. BAILEY ON THE STRUCTURE ETC. Chatiiij in liis valuable but incomplete work^ ^Anatomie comparee des Vegetaux/ did not quite reacli the Naia- dacese in tlie volume devoted to aquatic plants^ or bis drawings would have been useful for comparison j it is much to be desired that this fine work bad been completed, as well for tbe parasitic plants as for tbe aquatic. Tbe Naiadae are not yet figured by Eeicbenbacb in bis ^ leones Florae Germanicae et Helveticae/ &c. Tbe leaves grow in tufts at tbe side of each internode, and they are ratber more lateral than they are represented in Delile^s figure, reproduced two thirds tbe original size in Plate V. fig. 3. In tbe living state, as seen in tbe water from above, they have a light olive-green shade, much duller than that of tbe bright green leaves of Naias flexilis. In the dried state they become much darker, particularly in tbe older leaves, but tbe younger tufts retain the light green colour of tbe living plant. In shape tbe leaves are linear, broadly channelled in V. The Leaves. Fig. 43, Fig. 44. OF NAIAS GRAMINEAj VAR. DELILEI. 37 their lower portion (figs. 64 & 65), thiekened in the region of the midrib (figs. 60-63), and slightly keeled on their lower surface; in length they vary from ^ inch to if inch, and they are ~ inch broad or less (see Plate IV. fig. 2) . The sides of the fully-developed leaf are parallel for the greater portion of their length, but at their base they widen out into a broad sheath bearing two upright auricles applied to the stem and half-clasping it (figs. 52-55). The extremity of the leaf is gradually attenuated, and ends in from one to three spines (fig. 43) ; the extremities are frequently truncate, so that the spines give it a cuspidate character (fig. 44). The margins of the sides, sheath, and free extremity are studded with erect, unicellular, yellowish-brown spines (figs. 47-49), whose colour presents a contrast to the transparent marginal cell-walls, and to the green contents of the cells of the lamina of the leaf. The spines are acuminate, slightly curved, and gradually narrowed from the base to the sharp point, VI. The Leaf-spines. The form of the spine, or tooth, on the margin of the leaf furnishes good discriminating characters between the various species of Naias, as was long ago pointed out by the late Al. Braun in. the Journal of Botany,^ vol. ii. 1864, pp. 274-279. The simplest form of tooth is that of N. flexilis, where, in Dr. Boswelbs Loch-Cluny specimens, the base of the spine is in the same plane as the leaf-margin. The spine springs from a dilatation between two of the marginal leaf-cells (fig. 45), each of which nearly equally supports the spine to the extent of one third its length, rarely more. Sometimes the two marginal cells are separated from each other by the spine (see fig. 46). 38 MB. C. BAILEY ON THE STRUCTURE ETC. In Naias graminea the type of spine is similar^ hut it differs from that of N. flexilis in having a bi-celled base whose sides unequally support the spine. The lowermost of the two basal cells diverges^ at its upper end_, from the line of the leaf-margin^ so as to wholly support the lower end of the spine (see fig. 47). The uppermost cell^ on the other hand_, acts as a support to the inner side of the spine for fully one half its length j it also partially underlies the upper end of the lowermost basal cell_, and thus its three- sided profile fills up the axil of the spine and adds con- siderably to its rigidity, as compared with the arrangement in N. flexilis (comp. fig. 45) . Occasionally a third cell makes its appearance, as shown in fig. 48, and not infre- quently there is an auxiliary spine between the upper supporting cell and the original spine (see fig. 49) . In all these cases, however, the axillary, or nppermost, basal cell distinguishes the type of tooth from the characteristic tooth of N. flexilis. Cesati gives figures of the dentition of these two species in plate ii. of ‘ Linnsea,^ vol. xxxvi. ; OF NAIAS GRAMINEAj VAR. DELILEI. 39 but he makes that of N. alaganensis much nearer to that of N. flexilis than I find it to be in the Manchester plant. A third type of spine is furnished by Naias minor, All. {Caulinia fragilis, W.). This shows an advance upon the basal arrangement of the spines of N. flexilis and N. gra- minea, in being formed of more than three cells (see fig. 50). The entire tooth stands much above the line of cells which forms the margin of the leaf. Upon comparing these figures (which I have carefully made from typical specimens) with those given by Braun on p. 275^ vol. ii. of the ^Journal of Botany^ (1864) it will be seen that my drawings present considerable variation from his, particularly in N. flexilis. It is possible that Braun^s figures were meant to be diagrammatic, and representative of groups rather than of species ; for con- venience of reference I have reproduced them in Plate VI. figs. 6-8. The other end of the series of types of spines is repre- sented by the tooth of N. major, where there is not only a multicellular base, but the spine itself is compound ; one 40 MR. C. BAILEY ON THE STRUCTURE ETC. terminal dark brown cell resting upon several elongate dark brown cells_, tbe whole forming a very conspicuous tooth standing well out from the plane of the leaf-margin. Fig. 51 gives a tooth of this speeies from one of the late Dr. Wirtgen^s specimens from the mouth of the Moselle, near Coblentz. In N. graminea the spines are situated on the leaf- margins only (never on the midrib) at intervals equal to from one half to the whole breadth of the leaf. Figs. 47-49 have been drawn from spines on the edge of the middle portion of the leaf. Their shape is constant on the sides of the lamina, but they become longer on the sheath and at the apex of the leaf. VII. The Leaf-sheath. The leaf-sheath is another important character in distin- guishing the species of Naiadse, the extent of the dilatation. Fig. 52. OF NAIAS GEAMINEA, VAR. DELILEI. 41 and the form of the auricle when present^ furnishing useful marks of discrimination. The types given by Braun in the ‘'Journal of Botany/ vol. ii. p. 274^ are redrawn on Plate VI. figs. io-i4j hut, as will be seen from what follows, the Beddish plant differs considerably from Braun^s figure of N. graminea, unless he meant it to serve as a general figure of the type of sheath in his super-species N. tenuifolia. In the English Naias graminea the base of the lamina of the outermost pair of leaves suddenly dilates into a pair of upright auricles or ears, which are continued below so as to form a more or less ample sheath (see fig. 52) ; the size of the sheath presents considerable variations, accord- ing to the age and the position of the leaf to which it belongs (see figs. 52-55). I see no trace of any intra- vaginal scales (squarnulae) at the base of the leaf-sheath, such as are found in Naias major and in the allied genus I'ig- 53- 42 MR. C. BAILEY ON THE STRUCTURE ETC. Phucagrostis. Fig. 29^ Plate VI., shows the scales of Naias major in situ ; one of the scales is drawn separately in fig. 30 on the same Plate. The auricles in their turn vary in shape and size, but I have not met with them so regularly oval nor so acute as they are represented in Braun^s figure (fig. 14, Plate VI.) ; on the contrary, I never find them acute, and, though somewhat parallel-sided, they gradually taper from their base to their elongate truncate apex (see figs. 52 & 54). More often than not the auricle is larger on one side than the other, as in figs. 54 & 55. The auricles are confined Fig. 54- Fig. 55. principally to the first pair of leaves of each fascicle, and the sheaths of the pair embrace the leaf; most often these are the only leaves in the fascicle which possess auricles (see Delile^s figure on Plate V. fig. 4). The next pair of leaves has auricles which, when present, form a more acute sinus with the lamina (fig. 55) ; but as we approach the OF NAIAS GRAMINEA^ VAR. DELILEI. 43 centre of each fascicle the leaves are destitute of auricles^ and pass into short lanceolate bracts^ in the midst of which we find the flowers. In Scotch specimens of Naias flexilis the leaf-sheath is of another type ; the base of the limb widens out into a sheath more than twice the breadth of the limb, and at an angle of about 45° ; but there is no approach to an auricle on either side. The shoulders of the sheath are crowded with teeth, but they are infrequent on the sides. See figs. 56 & 57^ and compare them with the slightly different figure of Braun on Plate VI. fig. 10. For drawings of the leaf-sheaths of Naias minor and N. major, see Plate VI. figs. 9 & 29, and compare the former with Braun^s figure, Plate VI. fig. ii. The margins of the auricles of N. graminea, and more particularly their free extremities and inner sides, are crowded with strong, spiny, tawny-brown cells, similar to those on the lamina; but they occur at much shorter intervals, and the cells at the base of the spines are more Fig. 56. Fig. 57- 44 MR. C. BAILEY ON THE STRUCTURE ETC. loosely aggregated (see fig. 58)^ so that there is no well- defined series of marginal cells as in the lamina. The basal cells which support the spines have their longest diameter in the direction of the spine. Fig. 58. Fig- 59- In N. flexilis (fig. 59) the cells are more loosely aggre- gated also, but the line of marginal cells, though not so well defined as in the lamina, is more clearly apparent than it is in N. graminea. The cells of the sheath, as well as the marginal cells of the lamina, of N. flexilis are larger and longer than they are in N. graminea) but the two species maybe distinguished by the length of the imbedded portion of the spine, which, in N. flexilis, is less, and in N. graminea is more, than one third of its free length. The leaf-cells of N. flexilis generally are larger than those OP NAIAS GRAMINEA_, VAR. DELILEI. 45 of N. graminea (compare figs. 45 & 46 witli figs. 47-49^ and fig. 58 with fig. 59^ all of which are drawn to the same scale) . VIII. Leaf-structure. The anatomy of the leaves of iV. graminea is simple. The margins of the lamina to the extent of one third the breadth are composed of two layers of cells (see figs. 63 & 65)^ which, in the Reddish specimens, do not present that contrast in the size of the eells of the superior and infe- rior layers which Dr. Magnus mentions on p. 51 of his ^Beitrage.^ No doubt the cells of the convex side of the lamina are slightly the smaller, hut the difierence is not so marked as represented in Plate VII. figs. 31-33, which are copied from the figures given by Dr. Magnus. There are no stomata on the leaves and no epidermis ; hut the surface-cells in all parts of the plant have intermixed with them reddish-pink pigment-cells, which become brown with age. They are probably resinous, as they are the last to decay; similar cells occur in other species of Naias. The eentral portion of the leaf is much thicker than the sides, because at this point the two layers of the lamina diverge from each other so as to enclose a central bundle of small-sized cells, surrounded by a layer of six or eight larger-sized cells. On either side of this central tissue are two intercellular cavities, which greatly exceed in size the cells whieh bound them (see figs. 60-65). 46 ME. C. BAILEY ON THE STRUCTUEE ETC. In his ^ Beitrage/ pp. 51 & 52, Magnus describes Naias graminea as possessing bast -cells in certain fixed positions in the leaf^ namely close to the margin^ and immediately above and below the central bundle on the upper and lower surfaces of the leaf (see figs. 31-33 on Plate VII.) . These bast-cells I cannot discover^ after prolonged search, in any portion of the Reddish plants ; but as Magnus states (p. 52) that Damietta specimens collected by Ehrenberg, and Cairo specimens collected by Schweinfurth, also have these bast-cells wanting, it is clear that the Reddish plant corresponds in this particular with the plants from Lower Egypt. On the other hand, the plant from the Italian stations possesses bast-cells. I found them clearly marked in specimens in my herbarium col- lected by Signor Malinverni, “ in stagnis fossis et oryzetis circa Quintum Vercellensis ditionis pagum sestate 1875;'’^ the accompanying figure has been drawn from the leaf of one of these plants (fig. 66). The line of libriform cells is the central one of the three series which I have drawn j it is most clearly apparent, when viewed as a trans- parent object, from the circumstance that its cells do not contain chlorophyll, and hence it is visible as a transparent colourless line in the midst of green tissue. An isolated bast-cell is given in fig. 34 on Plate VII., and their position in the leaf is shown in figs. 31-33 on the same Plate at the points marked b. In the upper part of fig. 32 the single cell seems to have been multiplied into three, but, as Dr. Magnus explains in his memoir, these long Y-shaped cells are arranged in a single linear series at the edge OF NAIAS GRAMINEA, VAR. DELILEI. 47 of the leaf; the bifurcating end of one cell encloses the solitary attenuated end of. the one next to it; a section at such a junction severs the three interlocked ends of two contiguous cells. The absence of this libriform tissue in the Lancashire plant has a bearing in determining its source^ as will be noticed further on. Between the Italian and the Lancashire plants I notice one other point of difference, which may be due to the period of growth. Above and below the central bundle of the leaf, but particularly on the lower surface, the external cells of MalinvernTs specimens from Vercelli are densely packed with starch-grains, very similar to what is met with in the external membrane of the fruit. Although starch-granules are present in the membrane of the fruits of the Lancashire plant, I have failed to discover a single instance of their occurring in quantity in the leaves. All the cells of the leaf exhibit a very striking circu- lation of their contents against the cell-walls ; the chloro- phyllean granules and other protoplasmic bodies being very large, and the cell-walls being very transparent, the plant furnishes a splendid illustration of circulation, more than any plant which I have examined. IX. The Inflorescence, The construction of the flowers of the genus Naias and their morphology have been minutely studied by Dr. Magnus, and the results given in his ^Beitrage,^ pp. 26-33. referring to the development of a side- shoot of N. graminea, he says that many of the internodes are suppressed, and that from three to five pairs of leaves spring from the axis before we reach the flowers, which occur to the number of from two to four all in one node. 48 MR. C. BAILEY ON THE STRUCTURE ETC. He adds that it is worthy of notice that the male flowers are found on those parts of the shoots which have long internodes^ while the female flowers occur only on those shoots where the internodes are suppressed. This was not the structure in the Lancashire plant. Quite as often as not pistilliferous flowers were found in the axil of the first pair of leaves of the tuft. Anthe- riferous and pistilliferous flowers are found side by side (see figs. 67 & 68) in the axil of the same leaf. Both Fig. 67. Fig. 68. kinds of flowers are also found in all stages of develop* mentj quite yonug ones lying side-hy-side with those more developed. The great majority of the plants produced fully-deve- loped flowers^ both male and female^ the latter being much OP NAIAS GRAMINEA^ VAR. DELILEI. 49 the more numerous. The species is monoecious ; even in those instances in which I found only female flowers on the individual branch, I could not be sure that male flowers had not been produced, or would not have been produced later on. It was not usual, though by no means infrequent, to find both sexes in the same fascicle, at equal stages of development (figs. 67 & 68), and mature and immature flowers enclosed by the same bract (see figs. 81 & 86). Fig. 69. The flowers begin to occur immediately within the axil of the first pair of leaves in each fascicle, but there is frequently an outlying pair of leaves below the fascicle which does not contain flowers. The oldest flowers are always at the base of the fascicle. When mature, the fruits are plainly visible to the naked eye (see Delile^s figure on Plate V. fig. 4), but they can be detected, when present, by the touch. The female flowers are rarely solitary, but occur in twos, threes, or fours ; in the earlier SER. III. VOL. X. E 50 MR. C. BAILEY ON THE STRUCTURE ETC. stages of development they are sometimes more nume- rous. The male flowers are more often solitary. In the centre of the fascicle are the youngest flowers (see figs. 68 & 69). In appearance the flowers look as if they were ordinary anthers and pistils, i. e. as if they possessed no perianth ; but Dr. Magnus has shown that their outermost covering is really a perianth which more or less closely invests the anthers and pistils. In fig. 16 on Plate VI. the perianth has been drawn back from the exposed anther of N. major. Figs. 22, 24, 25, and 28 show the natural reflexion of the perianth-leaves in the male flower of N. major. All the flowers are sessile, and I have endeavoured to convey, in the accompanying figures, accurate represen- tations of each. X. The Pistilliferous Flower. The female flower consists of an elongate flask-shaped body, with a long neck which bifurcates at its free end (figs. 68 & 70), like the bifid stigma of a Car ex, such as C. ovalis. The outer covering is the perianth ; the body which it encloses is the pistil. In its early stage the lower, or flask-shaped, portion consists of a globose or ovate body, surmounted by a flat parallel-sided band, of nearly the same breadth as the lower portion (fig. 67) . The upper portion, or neck of the flask, divides about halfway up into two divisions, like the stigma of an ordinary flowering plant (see fig. 71). This stigmatoid portion attains its maximum length very early. The basal portion contains a single anatropous ovule, and it enlarges both outwards and upwards until it is twice the length of the style-like portion (see fig. 70). The investing membrane (fig. 88), which can be removed Like the calyptra of a Polytrichum, is made up of one or OF NAIAS GRAMINEAj VAR. DELILEI. 51 two layers of cells, whieh vary in shape aceording to their position. The portion which covers the ovule consists of elongate cells with truncate ends, and these cells are densely packed with rounded grains of starch very uniform in size. The starch makes its appearance in the later Fig. 70. stages of the growth of the membrane. The portion which covers the long neck of the flask-shaped body is also mostly composed of long cells ; hut the cells which occur on the margins of the stigmatoid divisions of the free ends are only one third the length of the central cells, and their outer ends are somewhat enlarged, so as to make the edge of the stigmatoid divisions minutely papillate, as if to afford better attachment for the grains of pollen (fig. 72). The cells of the base of the neck are much broader than any of those in other parts of the investing membrane, and they are also more loosely aggregated at that point. A central canal runs throughout the narrow portion 52 MR. C. BAILEY ON THE STRUCTURE ETC. whicli simulates the style^ and at the point where it reaches the chamber which contains the ovule it becomes slightly constricted (fig. 71) ; hut immediately below the constriction it widens out into a cupola-shaped cavity, whose upper portion, or roof, is lined with a few unicellular hairs (figs. 72 & 73). Below this cavity is the ovule. The accompanying drawings (figs. 67-73) illustrate the female fiower in some of its stages of development. No portion of the pistilhferous fiower hears any spines similar to those which occur on the bracts and leaves ; such spines are present in some of the species of Naias, XI. The Antherieerous Flower. The male flowers are not so numerous as the female flowers, and they grow intermixed with them. Although I have frequently found plants of Naias graminea in which none hut pistilhferous flowers could be detected at the period of examination, such tendency towards dioecism never showed itself when anther-bearing flowers were present. When the latter occurred on a plant pistilhferous flowers were invariably present, and oftener than not side by side with them (see figs. 67 & 68). My observations of the anther do not quite coincide with the descriptions and figure given by Dr. Magnus ; I have consequently given a larger number of illustrative drawings of this organ. The drawing of Dr. Magnus is reproduced on Plate VII. i,n fig. 35. When young they are oval-shaped bodies borne upon a very short stalk (see figs. 74 & 76). So much do they resemble the anther of an ordinary flowering-plant that I was a long time in realizing that the outer body which I was examining was the membrane which formed the peri- anth. The perianth closely invests the anther throughout OF NAIAS GRAMINEAj VAR. DEHLEI. 53 all its stages of growth, and, from all that I have seen, it keeps pace uniformly with the growth of the membrane of the anther. The anthers of this genus, according to Dr. Magnus, are axis-growths which, when ripening, are pushed through the perianth, rupturing that membrane somewhat irregu- larly, and they finally dehisce at their apex. That the anthers of the Deddish plant dehisce at the apex there is no doubt, hut I have seen no trace of the rupturing of the outer perianth-membrane through the emergence of the anther proper ; on the contrary, the summit of the flower presents a regularity of parts for which Dr. Magnus’s observations did not prepare me. The rupturing of the perianth in N. major is shown in fig^s. 22 & 28 on Plate VI. Fig. 74. Fig. 75. Fig. 76. In an early stage the antheriferous flower of N. graminea has its outer membrane prolonged into two erect rounded ears, which are continued down the sides as keels or ridges (figs. 67 & 75). The young pollen at this stage is distinctly seen through the membranes of the flower and of the anther (fig. 76). The anther then becomes more elongate by its upward growth ; a slight groove makes its appear- ance longitudinally, corresponding with the principal dissepiment of the anther (fig. 68) ; the upright ears and the keels lose their prominence, and the separate pollen- grains are not so distinguishable (fig. 77). Finally, the mature quadrilocular anther is an ovoid cylindrical body 54 MR. C. BAILEY ON THE STRUCTURE ETC. having two narrow parallel ridges passing over the summit, and descending about halfway down the covering of the flower (fig. 78). For comparison, see an antheriferous flower of N. minor in Plate VI. fig. 17; a transverse sec- tion of N. major in fig. 18; a vertical section of V. major in fig. 23 ; a vertical section of V. minor in fig. 27 ; and a vertical section of N. major in fig. 21. Fig. 77. Fig. 78. The membrane which invests the anther is formed of close-ranked, elongate, translucent cells, six to twelve times as long as broad, and tinged with a beautiful rose- colour ; the superposition of this rosy membrane over the lemon-coloured pollen of the anther gives the flower a tawny-orange appearance, which readily attracts notice, even without the aid of a lens. The cells which compose the ridges in the upper half of the flower are larger and broader than those of the rest of the membrane. Robert Brownes V. tenuifolia has considerable affinity with the Manchester plant, but, independent of other diflPerences, the anther is very dissimilar on account of its external tunic terminating in a narrow elongate beak, which bears a number of brown spiny teeth at its free end (see fig. 15, Plate VI.). At the period of dehiscence the OP NAIAS GRAMINEAj VAR. DRLILEI. 55 internal tunic which contains the pollen separates itself from the external membrane^ hut, instead of its emerging through the summit of the beak of the perianth, it is thrust through a rupture in the side. In N. graminea the external membrane closely invests the inner membrane, but it is not projected beyond it in the form of a beak ; and I have not seen a vestige of a brown spiny cell on any portion of the male flower. XII. The Pollen. The pollen of the various species of Naias does not seem to have been much noticed by observers. Magnus does not allude to it, nor give any figures of pollen-grains for any of the species ; and contradictory statements are made by some authors. Thus the drawings of Braun, engraved in fasc. x. plate i. of the ‘ Genera plantarum florse ger- manicse^ of Nees ah Esenbeck, show a globose pollen for Naias minor {Caulinia fragilis) in situ, and for Naias major in separate grains (see PI. VI. fig. 19), and in his diagnosis of the genus {Caulinia) he specifies pollen glohosum, magnum This statement seems to he the foundation for the similar statement in the works of later authors, one of the most recent being given in the ‘ Genera plan- tarum^ of Bentham and Hooker, vol. hi. p. 1018, viz. pollen glohosum.'’^ In the ^ Compendio della Flora Italiana^ of Cesati, Passerini, and Gibelli, part i, p. 204, tab. xxvii. fig. i, the pollen of N. major is elliptico-cylin- drical, like a grain of rice, say from two to three times longer than broad (see PI. VI. fig. 26) . In the ‘ Flora Danica,’ plate 2121, the pollen of Najas marina [Caulinia fragilis) is of an elliptical form, not quite twice as long as broad. This divergence of form in the pollen-grain of Naias major suggests, at first sight, inaccuracy of observation 56 MR. C. BAILEY ON THE STRUCTURE ETC. but I have found botb globose and elongate pollen in tbe antbers of tbe Lancashire Naias graminea. Tbe globular form is represented in fig. 79, and the elliptical form is given in fig. 80j botb drawn to tbe same scale. Undoubtedly Fig. 79. Fig. 80, the pollen is globular in its early stages^ but^ after select- ing what appeared to be perfectly mature anthers just at the period of dehiscence, the pollen which emerged was found to be globose, as drawn, in one anther, and elliptico- cylindrical in another anther. Whether the globose pollen ultimately passes into the elliptical form, and thus the latter represents the mature pollen, or whether there is a dimorphism in the pollen-grain, I cannot pronounce; I can only certify to the occurrence of both forms in plants from the same station, and that the globose form is much the rarer of the two. In its fresh state the pollen-grain is of a pale yellow colour, and its contents are granular. It must be produced in great abundance, as I have frequently found it in a free state in the water of the glass jars which have held the living plant during these investigations ; grains also occur floating about in the chloride of calcium solution which I use for mounting the dissections of the plant for perma- nent microscopic examination. OF NAIAS GRAMINEA^ VAR. DELILEI. 57 XIII. Fertilization. The pollination of Naias graminea is entirely effected in the watei’j as there is no provision for an elongation of the peduncle to raise the pistilliferous flowers up to the sur- face of the water, as in Potamogeton Zizii, Valisneria, Anacharis, and other aquatic plants. The structure of the inflorescence forbids its being considered a cleistogamous flower ; whether it is an aquatic type of an anemophilous or an entomophilous plant I cannot determine. Some observations I have noted for recording here are of some interest, as they suggest that pollination is effected in two ways. In the station in which the Naias occurs near Manchester the very slight natural flow of the water in the canal towards the locks is quite sufiicient for the transport of the pollen, and, though I have not purposely taken any of the canal water to see if it contained free pollen, my home observations leave me no doubt that pollen is carried to the pistilliferous flowers by the cur- rent j in such case the plant would be hydrophilous. While, however, examining portions of a living plant on which were ripe anthers, I noticed a colony of Vorticellidse attached to one of the fascicles of leaves ; the grace and activity of its movements led me to watch it for a con- siderable time, and whilst so watching it I witnessed grains of pollen whirled in all directions, or drawn into the vortex of the animal by its marginal cilia. The alternate contraction and elongation of the elastic and thread-like pedicles of the colony kept the pollen-grains in constant motion, which left me no doubt that at times the grains would be directly borne to the stigmatoid appendages of the pistilliferous flowers. The canal-water is most prolific in animal life ; beetles, molluscs, leeches, rotifers, polyps, larvie of insects, &c.. 58 MR. C, BAILEY ON THE STRUCTURE ETC, must surely prove potent factors in transporting pollen not only in the tepid water of the Reddish canal^ but in the still water of pools and ditches. If we carefully look for instances of their intervention we cannot fail to find distinctive protozophiious plants^ dependent for their fer- tilization upon animal life in the aqueous worlds in muck the same way as we find entomophilous plants in the aerial world. It is a very happy circumstance that Sir Joseph Hooker should have indicated, in the new edition of his Students Flora ^ recently published, the forms of pollination which prevail in many of our native plants, where known. Sprengel, Darwin, Muller, Lubbock, Kerner, and many others have largely increased our knowledge of this sub- ject for terrestrial plants, but its extent after all is very limited ; we have but ascended a few steps leading up to the vestibule, whilst the great temple of truth is beyond ; while, as regards aquatic plants, and particularly those which are wholly submersed throughout their lives, like Naias graminea, St?'atiotes, &c,, our knowledge is even more limited. Hence Sir Joseph Hooker has earned the thanks of British botanists by bringing into prominence this important feature in the economy of our native plants. XIV. The Fruit. Up to the time of the fertilization of the ovule the outer membrane of the flower — the perianth — and the investing membrane of the ovule contained within the perianth, both remain transparent or semitransparent. After pollination has taken place the membrane of the ovule becomes turbid and thickens, while the ovule itself enlarges and becomes a mature fruit, covered with a testa formed of thick- walled cells (figs. 81-83). The fruit is sculptured with a network of raised ridges. 59 OF NAIAS GRAMINEA, VAR. DELILEI. which thus produce depressions in the shell ; this sculpture Fig. 8 1. Fig. 83. Fig. 82. seems to have its seat in one of the inner membranes of the shell, since it cannot always be distinguished through the most external layer. As far as I have been able to make it out, it is somewhat after the character of the aceompanying fig. 843 but this must be looked upon as Fig. 84. Fig. 85. a diagrammatie interpretation of what is supposed to be seen, rather than an actual representation of fact. In the same way I have drawn the testa of Naias flexiUs in fig. 85 from a single mature fruit in one of Dr. Boswelks Loch-Cluny specimens ; I am more sure of the correctness of this figure than of that of N. graminea, but it repre- sents what is seen in a single fruit only. It would there- 60 MR. C. BAILEY ON THE STRUCTURE ETC. fore appear that the sculpture of N. flexilis is quadran- gular^ while that of N. graminea is hexagonal ; but too much must not be made of observations founded on such a limited basis. According to the observations of Cesati* the fruits of the Italian N. alaganensis are granulose -punctate^ which fairly well describes the appearance of the outer covering of the Manchester plant ; but Cesati^s figure in ‘ Linnsea/ Z. c. table ii. fig. id, makes the fruit much more papillate than I find it in the Lancashire form. On the other hand, this same observer makes the fruit of N. flexilis shining and obscurely angular, and he so draws it in his plate. The explanation of this difierence in the form of sculp- turing is probably due to the fact that the external mem- brane more or less obscures the underlying layer, and thus the latter is seen by observers according as the trans- parency of the outer layer admits of it. For the further elucidation of this point, I have reproduced the figures of Dr. Magnus in Plate YII., where figs. 40 & 41 show the arrangement of the coats of the fruit of N. graminea from Cairo, and figs. 37-39 those of A^. flexilis. At Reddish mature fruits of N. graminea are produced in great abundance; scarcely a plant occurred without fruits. In the many hundred plants which I have examined I have not seen a single instance where the beak of the fruit was other than bifid, unless it had broken ofiT altogether, as represented in figs. 81 & 83, and in the middle fruit of fisr. 86. This division of the beak into two branches is a o constant character, and very clearly distinguishes it from the four-rayed beak of Naias flexilis (fig. 87). One other point of differentiation between Naias gra- minea and N. flexilis rests in the shape of the fruit. In * “ Die Pflanzrrelt im Gebiete zwiscben dem Tessin, dem Po, der Sesia und den Alpen” (Linnaa, Tol. xxxii. 1863, pages 259 & 260). OF NAIAS GllAMINEA, VAR. DELILEI. 61 the former the ends are more abruptly narrowed into the base and the beak than they are in the latter, which has gradually narrowing ends; compare figs. 86 & 87. CesatFs figures in ^ Linnsea,^ xxxii. plate 2, confirm this conclusion. Fig. 86. The perianth easily separates from the fruit ; it is repre- sented in fig. 88. The portion which covers the body of the fruit consists of a single layer of cells. 62 MR. C. BAILEY ON THE STRUCTURE ETC. XV. The Roots. The roots are o£ great lengthy creeping in the soft black mud of the bed of the canal ; they are given off from the nodes in verticils. They are capillary^ uniform in diameter, even when nine inches long, tawny-orange in colour, and I have not seen them branch. In internal structure they bear some resemblance to the stems. There is a central channel surrounded by a mass of elongate cells hexagonal in outline, smaller in size, and with thinner walls than those of the rest of the cells within the cylinder. Outside this area is a row of cells whose walls are darker coloured than any of the others (except the cells which form the exterior of the cylinder), and they so arrange themselves as to form a sheath round the central cells ; from this row of cells numerous short branches are given off which enclose intracellular cavities similar to those in the stem, but much smaller and more circular (see fig. 89) . These cavities are regularly arranged Fig. 89. in one series round the central mass, as in the stem, but there are occasionally outlying cavities in the neighbour- hood of the external orange-coloured cells, as shown in or NAIAS GRAMINEA, VAR. DELILEI. 63 fig. 89. Enclosing the whole is a layer of larger- sized cells of a dark brown colour, and more angular in outline than any of the other cells. In the midst of these cells, but on the outermost side, are a few eells filled with a rich tawny-brown pigment. The walls of the eircumferential cells are all very thin, and they have the rich colour of the pigment-eells. In addition to the roots proper the plant gives off adventitious roots from the stem-nodes, as represented in Plate IV. These are generally given off singly from between the first pair of leaves of the fascicle ; oceasion- ally two proceed from the same node, but in sueh case the seeond root emerges on the opposite side of the node. In the lower portions of the stem the adventitious roots become more numerous from each node, and they begin to aequire the orange colour of the roots proper. They attain a length of from half an inch to six inches or more, and they have a similar internal strueture to that of the roots proper ; the peripheral cells, however, do not possess the angular character nor the tawny colour of the outer layer in the lower roots. The tissue is more loosely aggregated ; the intracellular cavities are fewer in number and smaller, scarcely exceeding the size of the cells which surround them. The central cavity is present, as well as the surrounding sheath, but the cells of the latter are fewer than they are in the root proper. The external cells do not differ much from the inner cells either in shape or in colour, the rich pigment of the corresponding layer in the root being absent. XVI. The Lancashire Locality. The occurrence of a Naias in Lancashire was so unexpected a eireumstance that I was pleased, through Mr. Whitehead^s kindness, to have the opportunity of 64 MR. C. BAILEY ON THE STRUCTURE ETC. seeing the plant in its station in the canal at Reddish, near Manchester. The precise locality was not intended to he published, but as the station seems to be well known to so many local botanists, there is no further need to suppress it. When I first visited, the canal, on the 14th September, 1883, the Naias grew in an area of about a quarter of a mile in length ,* in some portions of this space it was the prevailing plant, wholly covering the canal-bed, while in other portions it was intermixed with Potaniogeton rufes- cens, P. obtusifolius, P. crispus, P. pusillus, Myriophyllum, and Anacharis. Except in so far that the station, like most canals, was an artificial one artificially supported, there seemed nothing in the accompanying vegetation to suggest that the Naias was not aboriginal. All the other plants were of the prevailing canal character, the non- native Anacharis being as much at home as any of them. The temperature of the canal water is, however, arti- ficially raised by the discharge of hot water from boilers and condensing-tanks attached to the cotton-mills and other works which are erected on the banks of the canal. In the declining evening of my first visit the water was quite warm, say about 90° Fahr. This abnormal tempe- rature must be looked upon as the important factor in the struggle for existence maintained by this plant. In sub- sequent visits to the canal the temperature of the water was not met with so high as it was found on the first occasion ; still, with the fitful discharge of hot water into the canal at many points, its average temperature must be many degrees above the normal point for the neighbour- hood. It might have been expected that the vegetation which grows in this tepid body of water would have shown signs of luxuriance, but such does not appear to be the ease. The most striking variation is met with in Pota- OF NAIAS GRAMINEA, VAR. DELILEI. 65 mogeton crispus, which becomes dwarfed^ particularly in stations where there is an inflowing stream of warm water. Two other plants which grow in the same canal ought to be noticed in this connection. The first of these is the Chara Braunii, Gmel.^ which the Messrs. Groves figured and described in the Journal of Botany^ for January 1884^ t. 242^ p. 3. This plant affects the edges of the canalj but it also occurs in the deeper water of the centre, where it is more liable to be cut down by the passing barges. Another interesting plant grows with the Chara, whose identity is by no means settled, and it may prove worthy of a more detailed notice, viz. a species of Zanni- chellia. Mr. Whitehead had mentioned to me, on the occasion of our joint visit, that Z.palustris had been recently found in the canal, and, as it was an infrequent plant in the district surrounding Manchester, I was anxious to procure specimens, although it involved a moonlight search. It was while hunting for this plant that, unknown to myself or to my companions, I collected the Chara in the dark- ness ; the specimens were very fragmentary, but from them Mr. Arthur Bennett determined the plant to be the Chara Braunii, new to the British Mora. In justice to Mr. Whitehead it ought to be stated that he and Mr. Armitage had collected it in the same station a fort- night or so prior to my visit. The Zannichellia grows in the soft mud, in the shallower parts of the canal, with Chara Braunii and Potamogeton pusillus ; it also occurs in places where the water scarcely covers it. It would appear to flower and fruit in the mud as well as in the water, but the fruits which are produced in mud are of a very pale yellow-green, on account of their imperfect exposure to the light. From the dwarf SER. III. VOL. X. F 66 MR. C. BAILEY ON THE STRUCTURE ETC. creeping habit of the plant it seems to have an affinity with the form of Z. palustris, named Z. repens, Boenningh. The characters of the Reddish plant agree with the description of Z. repens in essential points^ hut the stigma is not usually more enlarged than in Z. palustris, whereas this feature is a decided character^ both in the diagnosis and in Reichenbach’s plate*. In the spring and early summer it has large reserve-buds of the size of peas^ from which the shoots take their rise. One of its peculiarities is^ that it has four or five rows of spines or protuberances on the dorsal and ventral edges of many of its carpels, and much more prominent than they are in Z. pedunculata, Z. gibberosa, and Z. polycarpa. Delile reports f finding Zannichellia palustris in a lake near to Fareskour in Lower Egypt, along with Naias muricata. It would be interesting to determine whether the form is the same as that which occurs in the canal at Reddish. Local botanists also ought to keep an eye upon the possible occurrence of the rare Naias muricata, figured and described by Delile •, so far, it has only been recorded for Egypt and Arabia. The locality which produces such an extra-anglican species as Naias graminea must be worth exploring for the animal life which is fostered by the same high temperature which has sustained the Chara and the Naias. XVII. Geographical Distribution. Naias graminea is distributed over a wide area. It occurs in a natural state in the northern and central parts of Africa, in Syria (Plain of Sharon : ‘ Memoirs of the Palestine Exploration Fund,^ Fauna and Flora, p. 416), and Persia, in the Indian Archipelago and other warm * ‘leones Flora Grermanica,’ &c., vol. vii. fig. 20, pi. xvi. t ‘Flore de I’Egypte,’ vol. ii. p. 281, and also on page 75 imder No. 872. OP NAIAS GRAMINEA^ VAR. DELILEI. 67 regions of Asia, and probably in Japan. It does not occur in Europe except as a colonist, it having been introduced (according to the Italian botanists) with East-Indian rice, into districts where that cereal is cultivated, as in the plains of Lombardy and Venice; the Italian localities are given in Cesati^s ^ Compendio della Flora Italiana,^ as Alagna in Novara, Balzola between Vercelli and Casale, Merlato near Milan, Upper Vercellese, Strasoldo nel Friuli near Palmanavo. It has also been reported from the extreme north-eastern portion of Austria; but it is not native in any of its European stations, and it is an intro- duction in Lancashire. It becomes, therefore, an inter- esting question to account for its appearance in a country which does not grow the rice which it consumes. XVIII. Its probable Source. When this plant was exhibited at the British Association at Southport, in September 1883, I expressed the opinion in the Biological Section that it had probably been intro- duced into the Reddish locality with Egyptian cotton. This class of cotton is not one of the staple articles of consumption in the Stockport district, but there is one mill on the banks of the canal (HouldswortUs) which consumes Egyptian cotton largely, and from it, if not from others, the fruits of the Naias may have been transported to the canal. Last autumn Mr. J. Cosmo Melvill and myself carefully examined the large condensing-tank in the yard of this mill, but we could not find a trace of the plant; the water was of a high temperature, and little vegetation was found in it, but its depth was beyond our means of properly exploring it. Alire Raffenau Delile* gives an account of the culture * ‘ M6moire sur les plantes qui croissent spontan6ment en Egypte,’ vol. ii. pp. 16, 17. 68 MR. C. BAILEY ON THE STRUCTURE ETC. of rice in Egypt^ and shows that the water used for the young plants is drawn from the Nile by fixed machines during the principal part of the year; but in times of inundation^ during the rising of the river^ the water is naturally distributed^ its partieular eourse being regulated by the embankments whieh proteet the fields. He states that the Naias graminea grows in the canals of the rice- fields at Eosetta and in the Delta^ but he considered it only a variety of Naias fragilis, whieh grows in the same waters. The irrigation of modern Egyptian eotton-plantations will be effected by mueh the same means^ the Nile^ with its artifieial ramifieations^ being the chief water-supply of the country. Fruits of the Naias may reaeh Egypt from Abyssinia^ or from the great lakes of Equatorial Africa; the Nile water supplied to the growing cotton-plant will be accompanied by these fraits_, some of which would be left dry upon the surface after the water had pereolated through the upper soil^ hut they would not germinate there. Either by the ageney of the wind^ or through accidental contaet with the soil, they become mixed with the cotton exported to England. When the bales of cotton reach the Lancashire mills, the fruits of the Naias would be removed in the blowing-room, or by the carding-engines. The refuse is turned out of the mill into the yard, whence the wind and other ageneies transport the fruits into the tepid water of the canal ; here they meet with a suitable nidus for germination and growth, and the result is the appear- ance of an alien in our flora. If these surmises have any substratum of truth, the Naias may occm* in any mill-pond eonnected with works where Egyptian cotton is used, and where the water is raised to a permanently high temperature by the conden- sation of steam from the boiler. As Egyptian cotton is OF NAIAS GRAMINEA, VAR. DELILEI. 69 largely used in Bolton^ the mill-ponds and canals of that neighbourhood may be expected to contain Naias graminea and other Egyptian aquatic plants, as Naias muricata, Del., Chara Braunii, Gmel., &c. The Egyptian origin of the plant is to some extent confirmed by the form of Chara Braunii which grows at Reddish being very near the form of that species which occurs in Northern Africa. Whether there is anything showing an affinity to the Egyptian plant in the peculiar form of Zannichellia which grows in the same canal, I have not the means of determining ; but both it and the Chara Braunii are so often associated together as to give a strong colour to the surmise of their common origin. There is nothing in the recorded distribution of Chara Braunii, however, to forbid its being ultimately shown to be aboriginal ; but until it is recorded from other British stations, with fewer doubtful surroundings than it has in the Manchester station, it can only be looked upon as a colonist. XIX. A Histological Peculiarity. A strong proof of its Egyptian extraction is furnished from the histological side. This part of the case has been dealt with by Dr. Magnus, in a paper read to the German Botanical Association at Berlin, December nth, 1883, and I make no apology for reproducing here the substance of this interesting communication. In describing the struc- ture of the leaves of Naias graminea on page 46, I mentioned that there were two forms of the plant — one possessing peculiar libriform cells near the margin of the leaf; the other destitute of these bast-cells. This latter form Dr. Magnus names the var. Delilei, and he states that the English specimens belong to this variety, and indubitably prove their Egyptian source. The following 70 MR. C. BAILEY ON THE STRUCTURE ETC. are some extracts from tlie paper of Dr. Magnus, published iu the ^Berichte der deutsch. botauischeu Gesellschaft/ Jahrg. 1883, Baud i. Heft 10 : — “1 have examined the specimens of Najas graminea collected by Delile in the rice-fields near Rosetta, as also those obtained by Schweinfurth near Benha-el-assl in the Nile Delta, and have found them to be without bast- nerves. They are also wanting in a specimen collected by Gaillardet, near Saida in Syi’ia, which has been kindly communicated to me by M. Boissier. I was further enabled, through the kind communication of Professor Ascherson, to examine specimens of Najas graminea, Del., collected by him during his travels in the Libyan Desert, in the Oasis of Dachl, as also specimens collected by Schweinfurth in the Great Oasis (Chargeh). From this it would appear that the Najas graminea, Del., collected in a brook at xAin-Scherif near Kasr Dachl, as well as those collected by Ascherson near El Chargeh, likewise have leaves without hbriform cells, like the plants of Lower Egypt. On the other hand, the N. graminea col- lected some weeks later in the same ditches in Ain-Scherif by Ascherson, as well as from a warm spring-hole in Kasr Dachl, as also the specimens collected by Schweinfurth near Chargeh, have all well-developed bast-nerves, similar to the plants of Cordofan, Djur, Algeria, Celebes, &c. . . . The absence of these bast-nerves in a variety of Najas graminea is the more peculiar, as through the construc- tion of the male fiower of N. tenuifolia, R. Br. [see fig. 15, Plate VI.], from Australia, which difiers so materially, has precisely the same bast-nerves in exactly the same shaped libriform cells on the leaves ; consequently these bast-nerves represent the distinctive character of a group of allied species, but still subject to valuations “ I have mentioned above that the one set of specimens OF NAIAS GRAMINEAj VAR. DELILEI. 71 from Kasr-Dachl and Chargeh had leaves without bast- nerves^ and that another set had them ; that is, that the one set belong to the var. Delilei, while the other agrees with the form which appears in Cordofan, Djur, Algiers, &c. This would appear to be a clear proof that the oases of the Libyan Desert have received their flora from Egypt as well as from Central Africa. This agrees with the results of the investigations which Ascherson furnished to the ^Botanische Zeitung^ for 1874, pages 641-644. These explanations would, however, seem to be some- what contradictory, seeing that the English specimens are remarkable for their great length of leaf, whereas the leaves of N. graminea from Cairo and Damietta are very short. But a minute examination of form teaches us that we must not attach much importance to the question of the length of leaves, which is influenced, as in most water- plants, by the depth, current, bed, and temperature of the water. Thus we find that the specimens collected by Professor Ascherson in the Dachl Oasis, from the deeper pools (half a metre deep) , have long leaves as well as bast- nerves, and yet the Enghsh specimens have longer leaves without bast-nerves ; while the Egyptian specimens have shorter leaves without bast-nerves. Thus, again, we find the N. graminea, Del., growing in the shallow ditches of the rice-fields of the plains of Lombardy, has short leaves with bast-nerves, whereas the Najas graminea from Celebes has very long leaves with bast-nerves. In short, we see that the length or shortness of the leaves has nothing whatever to do with the formation of the variety, and nothing to do with the histological formation of the leaf- tissue. It is nevertheless possible that the var. Delilei, deprived of the bast-nerves, has been developed in the quiet stag- nant waters of the overflowed Nile, as in these stagnant 72 MR. C. BAILEY ON THE STRUCTURE ETC. waters the meehanical eells would become deprived of their functions. Thus we find Schwendener_, in his ex- haustive work, ‘ The Mechanical Principle in the Anato- mical Construction of Monocotyledons/ Leipzig, 1874, page 122, remarking that Potamogeton fluitans in its cus- tomary habitat of running water has a developed system of bark-hundles, whereas the var. /3 stagnalis, Koch, is completely deprived of same. The var. Pelilei, found in the stagnant waters of the overflowed Nile, is a most persistent and constant one, as during a period of a hundred years it has been indubitably collected by Delile, Schweinfurth, and Ehrenberg in Lower Egypt. Its unaltered appearance in England and in the oases shows its constancy and total independence of habitats, whilst its formation has probably been caused by the same."’^ It now only remains to me to tender my acknowledg- ments to Mr. Ridley, Mr. Arthur Bennett, Dr. Magnus, Professor Ascherson, Mr. Beeby, and Mr. James Britten, for their kind assistance during the preparation of this paper. XX. Explanation of the Figures. Plate IV. Fig. I. The upper portion of a branch of V. graminea, from Eeddish; nat. size. 2. Two of the leaves from same, drawn rather broader than the natural size, the sheaths and auricles flattened out. Plate V. 3. Upper portion of a branch of N. graminea from Lower Egypt. Copied from Delile’s drawing in his ‘Flore de I’Egypte,’ but reduced to two thirds original size. 4. Base of a leaf-fascicle, showing leaf-auricles, fruits, &c. ; slightly- enlarged. From Belile’s ‘ Flore de I’Egypte.’ 5. Section of fruit; enlarged. From Delile’s ‘Flore de I’Bgypte.’ OF NAIAS GRAMINEA^ VAR. DELILEI. 73 Plate VI. Pigs. 6-8. Arrangement of the cells of the marginal spines on the leaf of ; — (6) N.Jlexilis, (7) N. graminea, (8) N. minor and iV. arguta. From Dr. Alexander Braun’s sketches in ‘Journal of Botany,’ 1864. vol. ii. p. 275. 9. Form of sheath at base of leaf of N. minor. From ‘ Compendio della Flora Italiana ’ of Oesati, Passerini, and Gibelli, tav. xxviii. fig. I n. 10-14. Form of sheath at base of leaf of : — (10) N.Jlexilis, (i i) iV. minor, (12) N. minor, var. setacea, (13) N. falciculata, and (14) N. gra- minea. All copied from Dr. A. Braun’s woodcuts in ‘ Journal of Botany,’ 1864, vol. ii. p. 274. 15. Male flower of N. tenuifolia, E. Br. ; enlarged J/-. From Magnus’s ‘ Beitrage,’ plate iv. fig, 5. 16. Anther of N. major, with the perianth reflexed; enlarged. From ‘ Genera Plantarum Florae Germanic®,’ Th. Fr. Lud. Nees ah Esenbeck, fasc. vi. Naias, fig. 5. 17. Male flower of N. minor; enlarged. Nees ah Esenbeck, 1. c. fig. 24. 18. Transverse section of male flower of N. major. Nees ah Esenbeck, 1. c. fig. 7. 19. Pollen of N. major; enlarged. Nees ab Esenbeck, 1. 0. fig. 8. 20. Male flower of N. major, with the perianth drawn back ; enlarged. From ‘ Iconographia familiarum naturalium regni vegetabilis,’ Dr. Adalbert Schnizlein, Heft v. pi. 71. fig. 4. 21. Vertical section of male flower of N. major ; enlarged. Schnizlein, 1. c. fig. 6. 22. Male flower of N. major, showing the separation of the perianth from the anther ; enlarged. Schnizlein, 1. c. fig. 7. 23. Vertical section of a male flower of N. major. From ‘ Compendio della Flora Italiana,’ 1. c. fig. i b. 24 & 25. Dehiscence of the perianth of N. major, after the observations of Braun; enlarged. Nees ab Esenbeck, 1. c. figs. 9 & 10. 26. Grains of pollen of N. major, with fovilla ; enlarged From ‘ Compend. FI. It.’ 1. c. fig. i d. 27. Vertical section of a male flower of N. minor. All. ; enlarged. ‘ Compend. FI. It.’ 1. c. fig. i e. 28. Male flower of N. major; enlarged ‘Compend. FI. It.’ 1. c. fig. 1 a. 29. Base of leaf of N. major, with the sheath opened. Intravaginal scales at the base of the sheath, one on each side ; enlarged |. ‘ Compend. FI. It.’ 1. c. fig. i m. 30. Intravaginal scale of N. major ; enlarged ‘ Compend. FI. It.’ 1. c. fig. 1 0, Plate VII. 31. Transverse section of the middle of the leaf of N. graminea, Del. enlarged -I-. Magnus, ‘Beitrage,’ pi. vi. fig. 3. 74 MR. C. BAILEY ON THE STRUCTURE ETC. Fig. 32. Transverse section of the side of the leaf of N. graminea, Del., from Celebes ; enlarged Magnus, ‘ Beitrage,’ pi. vi. fig. 2. 33. Transverse section of the leaf of N. graminea, Del., from Celebes; enlarged Magnus, ‘ Beitrage,’ pi. vi. fig. i. In figs. 31-33 the leading bundles are drawn schematically: intercellular spaces, 6= bast-cells. 34. Isolated bast-cell from the leaf of N, graminea, from Celebes ; enlarged -®-. Magnus, ‘ Beitrage,’ pi. vi. fig. 46. 35. Male flower of JV. graminea-, enlarged -\®. Magnus, ‘Beitrage,’ pi. iii. fig. 6. 36. Transverse section of the stem of Caulinia alaganensis. From ‘ Tavole per una Anatomia delle piante aquatiche,’ Parlatore, pi. vi. fig. 3. 37. Surface-view of the outer cell-layer of the unripe seed of N, flexilis ; Magnus, ‘ Beitrage,’ pi. v. fig. 9. 38. Diagonal section of the nearly ripe seed-shell of N.fleocilis; enlarged Lf Magnus, ‘ Beitrage,’ pi. v. fig. 8. 39 & 40. Diagonal sections of the still (? if not always) unripe seed-shell of N. graminea, from Cairo ; enlarged Magnus, ‘ Beitrage,’ pi. V. fig. II. 41. Diagonal section of the quite ripe seed-shell of N. graminea, from Cairo; enlarged Magnus, ‘Beitrage,’ pi. v. fig. 12. Figures in the Letterpress. All the figures are drawn from Reddish specimens of Naias gra- minea, Del., var. Belilei, Magnus, except when stated otherwise. 42. N. graminea. — Transverse section of stem, drawn diagrammatically ; enlarged -j-. 43 & 44. N. graminea. — Ends of leaves, showing dentition ; enlarged 45 & 46. iV. Jlexilis. — Spines on margins of leaves, from specimens col- lected by Dr. Boswell in Loch Cluny, near Blairgowrie, Perth- shire; enlarged See ‘Journal of Botany,’ No. 154, 1875, p. 297. 47-49. N. graminea. — Spines on margin of middle portion of leaf ; enlarged if-. 50. N. minor, — Tooth of leaf from one of Archbishop Haynald’s spe- cimens, from ponds in his park at Kalocsa, Hungary; enlarged 15 6 “Y-. 51. N. major. — Tooth of leaf from plant collected near Coblentz by Dr. Ph. Wirtgen ; enlarged J-f 52. ~N. graminea. — Large leaf-sheath from leaf of first pair ; enlarged V- 53. N. graminea. — Usual form of leaf-sheath from leaf of first pair; enlarged 54. Is. graminea. — Usual form of leaf-sheath from leaf of first pair, with irregular-sized auricles ; enlarged -V^. OF NAIAS VAR. DELILEI. 75 Fig. 55. N. graminea. from leaf of second pair ; enlarged Jy^. 56 & 57. N.Jlexilifi- — Leaf-sheath from Scotch specimens ; enlarged 58. N. gramm^- — Spines on margin of auricles ; enlarged 59. — Spines on margin of auricles from Loch Oluny; they are the first four which occur on the left shoulder of fig. 57, above the minute spine, nearest the base of the sheath ; enlarged 60-65. N. graminea. — Transverse sections of leaves, beginning near the summit ; enlarged 66. N. alaganensis. — Libriform cells in margin of leaf, from Malin- verni’s Italian specimens ; enlarged if-. The libriform cells are the long cells without cell-contents. 67. N. graminea. — Young antheriferous and pistilliferous fiowers grow- ing side by side ; enlarged y®-. 68. N. graminea. — Older antheriferous and pistilliferous flowers grow- ing side by side ; enlarged -y-. 69. N. graminea, — Portion of central infiorescence ; enlarged 70. N. graminea. — Pistilliferous fiower with contiguous bracts ; enlarged I 8 T'* 71. N. graminea. — Young pistiUiferous flower ; enlarged -y-. 72 & 73. N. graminea. — Young pistilhferous flowers, showing the stig- matoid appendages ; enlarged -\®-. 74 & 75. N. graminea. — Young antheriferous flowers; enlarged 76. N. graminea. — Young antheriferous flower, showing immature pollen ; enlarged 77. JV. graminea. — Antheriferous flower not fully ripe; enlarged 78. N. graminea. — Mature antheriferous flower; enlarged 79. N. graminea. — G-lobose pollen ; enlarged 80. N. graminea. — Elliptico-cylindrical pollen ; enlarged if 81. N. graminea. — Fruit, vrith immature pistilliferous flower in the same bract ; enlarged V'- 82 & 83. Y. graminea. — Fruits nearly mature; enlarged -\®-. 84. N. graminea. — Supposed ridges and pits, of hexagonal outline, on surface of fruit, as seen with a yfy objective, Lieberkuhn, and Kelner B eyepiece. 85. N.flexilis. — Eidges and pits, of quadrangular outline, on surface of fruit, as seen with a y"V objective, Lieberkuhn, and a Eelner B eye- piece. 86. N. graminea. — Three mature fruits and an immature pistilliferous flower in the same verticil ; enlarged 87. Y. flexilis. — Mature fruit from Loch-Gluny specimen ; enlarged 88. Y. graminea. — Perianth removed from fruit; enlarged -V-. 89. Y. graminea. — Transverse section of the root; enlaz'ged V. 76 MR. J. COSMO oN V. Notes on the Subgenus Cylinder {Moui^fort) of Conus. By J. Cosmo Melvill, M.A., F.L.S*. Eead before the Microscopical and Natural-History Section, February i6, 1885. Few genera stand out more naturally and prominently in ^ the animal kingdom than the large assemblage of Mollusca associated under the name of Conus (L.). Few fall so naturally into subdivisions and^ as a rule^ present such well-marked specific difFerences. Recognized as they all are at a glance by the inversely conical shell, with length- ened narrow aperture and simple inner lip, they are, with but one exception, natives of tropical or subtropical seas, the exception being a not uncommon S. Mediterranean shell (C. mediterraneus, L.). They approach in form, through C. Orbignyi and others of the section Leptoconus, to the Pleurotomse, especially shells of the section Genota, e. g. mitriformis and papalis ; and, on the other hand, through C. mitratus, of the subgenus Hermes, to the anomalous genus Dibaphus, and, through that, again, to the Mitres. This is as regards the form only : for the mollusc itself differs in some important particulars, and hence the Cones are classed by themselves in the suborder Toxifera, of Gasteropoda Pectinibranchiata, differing from the other allied suborder Proboscidifera — to which the Pleurotomse and Mitres, just alluded to, belong — by the proboscis being furnished with a tube containing bundles of sharp, needle- like, barbed teeth at the end, instead of the usual lingual band, covered with short teeth. This tube, according to Adams, is extended below, at right angles to the cavity. THE SUBGENUS CYLINDER. 77 into a conical prolongation, provided with two series of hooked and subulate teeth. Indeed, the bite of C. textile, C. aulicus, and C. marmoreus is most severe, espeeially as it is supposed that venom is introduced into the wound, causing great difficulty in healing, while the pain continues intense for a long period. Many monographs and illustrated descriptions of this diversified genus have been published, the best known being Reeves's ^ Conchologia Iconica,'’ vol. i. (1843-44), with a Supplement of 8 plates, dated some years later, 337 species being described in all, and Sowerby^s 'The- saurus Conchy liorum'’ (1869), forming vol. iii. of the work, 450 species. Kiener, ' Coquilles Vivantes,^ 324 species. WeinkaulF, in Kiister^s continuation of Martin and Chemnitz^s ' Conchylien Cahinet-* (1875), describes ’411 species. The latest monograph is that of Mr. G. W. Tryon, jun., of Philadelphia (published 1884), in which about 450 species, not including varieties, are recognized. He bases his classification on WeinkaulF^s Catalogue, dividing the genus into seventeen sections, of which the Texti, forming the last or 17th group, are equivalent to the suhgenus Cylinder, of Montfort, now under discussion. Most conchologists, however, including the brothers Paetel, in their 'Conchylien Sammlung,'’ 2nd ed. 1884, still follow the lines of Messrs. H. & A. Adams, as given in their recent ' MoUusca^ (1858), and which appears to me to he simple and less artificial. As all agree, however, in the limitation of the group now under discussion, it is out of place to enter into the merits or demerits of the various plans proposed for the arrangement of the whole genus. Out of 450 species known of Conus, but 26 are cata* logued by H. & A. Adams, as appertaining to Cylinder-, 78 MR. J. COSMO MELVILL ON but in Sowerby^s ^ Thesaurus^ (1870) 36 are mentioned. Tryon^ of Philadelphia, in his elaborate monograph just alluded to — the ‘ Manual of Conchology/ vol. vi. — calls but 17 of these true species, with 10 subspecies, and also cites 12 slight varieties, classed almost as synonyms, the total number of named forms coming up to 39. Of these 37 are exhibited in the present collection. The subgenus Cylinder may be briefly thus charac- terized : — Shell subconic, smooth, or very lightly striated ; spire elevated ; whorls never coronated, numerous ; body -whorl ventricose, notched at the suture; aperture effuse at the fore part. The species,^^ writes Mr. Arthur Adams, of this section are all very rich in the style of their colouring, and a somewhat similar reticulated kind of pattern runs through the entire series. Some very widely differing Cones, e. g. C. arcMthalassus, ammiralis, acuminatus , and cordigerus (a var. of nobilis) among the Leptoconi, and G. araclinoideus and C. nicoba- ricus, among the Marmorei have a similar reticulated pattern. All these differ, however, materially in form, either, as in the last section mentioned, by the coronation of the whorls, or, in the former, by the grooved and sculptured spire, and more truly conical shape. The only species which presents any difficulty at first sight is a variety of C. cordigerus (Sowb.), which, in the specimen exhibited, approaches so nearly to C. omaria, as to suggest a mimetic principle among the molluscs similar to that which is known to exist in other branches of the Animal Kingdom. The geographical distribution of Cylinder, so far as known, is almost exclusively eastern, many species being found ubiquitously in the eastern tropics, from E. Africa THE SUBGENUS CYLINDER. 79 to Ceylon, Mauritius, the Philippines, and New Caledonia. Two speeies, or forms of one {C. victoritB (Reeve) and complanatus (Sowb.)), occur in Australia; C, pyramidalis (Lam.) is also a native of the same seas; C. racemosus (Sowb.), an unique form in my collection, is from the Sandwich Isles ; C. lucidus (Mawe) from the west coast of Central America; and a doubtful form, C. Dalli (Stearns), recently described from a single specimen, is reported from the Gulf of California. This shell, apparently, from the figure, a variety of C. textile (L.), is especially interesting as aflbrding a western habitat for a species very universally distributed in the east, but not known before to impinge on American shores The locality in which these Molluscs are found, in common with others of the family, is in fissures of rocks, especially in coral-reefs, where they lead a predatory existence, feeding on other Mollusca &c. After a very careful study of the Protean forms of the Textile Cones, the forms would seem to come under five heads, the first head having three divisions. I propose to class them as follows ; — I. Textilia. a. vera. b. abbates. c. pyramidalia. II. Retiferi. III. Lucidi. IV. Aulici. a. crocati. b. episcopi. V. Aurei. Of these the first and fourth, as might be expected. 80 MR. J. COSMO MELVILL ON harbour the largest number of species, the second and third containing one species apiece, and the last two or three species. I. Textilia. a. vera. Shell yellow-brown, with undulating longitudinal lines of umber, interrupted by triangular white spaces; spire raised, similarly marked. Under this I group the well-known C. textile (L.), the “ Field of the Cloth of Gold of the old conchologists : an exceedingly variable shell, whose forms and limita- tions it is almost impossible to define. It abounds in all eastern tropical seas, and, as before observed, a form, the C. Dalli (Stearns), has been detected once on the Califor- nian coast. The named forms of C. textile are as follows : — i. tigrinus (Sowb.). More or less destitute of the brown bands and brown longitudinal markings. ii. vicarius (Lam,). Pattern coarser and larger in detail, greater preponderance of white triangular patches. iii. verriculum (Peeve). Short and stumpy, and coarsely marked. iv. concatenatus (Sowb.). Like No. iii., but of simple zigzag marking. V. scriptus (Sowb.). A delicately striated form, more finely marked than canonicus, but otherwise similar. vi. canonicus (Brug.). No brown markings, more finely marked than vicarius ; a very distinct and well- known form. vii. condensus (Sowb,). A beautiful small shell, with constant pink tinge, marked as scriptus. THE SUBGENUS CYLINDER. 81 viii. corbula (Sowb.). Of very effuse growth^ ventricose^ confusedly marked. ix. euetrios (Melvill & Sowb.). Similar to corbula, but of different shape, and the markings more regular. Unique in my collection. Locality unknown. X. (Stearns). Of lighter build. Spire convex j mouth roseate. California. Unknown in European col- lections as yet. All these, except tigrinus, are called actual species by most authors ; but it seems best to merge them as varieties. b. abbates. The texture and markings finer, and spire, as a rule, more depressed than in the first group. C. abbas (Brug.). Very beautif ully and intricately marked with smaller reticulations ; very distinct from any other species. C. panniculus (Lam.). Perhaps a form of abbas. Var. textilinus (Kiener). Of more pyriform shape, but similar markings. I possess Kiener ’s original type. C. archiepiscopus (Hwass). Very richly and minutely ornamented. C . panniculus seems to connect this and abbas : it is, in fact, with some hesitation I keep them separate. C. Victories (Beeve) . Of much lighter growth than any of the preceding ; the greyish flames peculiar. From Australia. It is a most distinct species. Var. complanatus (Sowb.). Only a more ventricose, squarely based variety of C. Victories. c. pyramidalia. It is in this group that the Textile group reaches its SER. III. VOL. X. G 82 ME. J. COSMO MELVILL ON maximum of beauty and perfection. The lengthened and graceful pyramidal shape and straight lip amply charac- terize it. C. pyramidalis (Lam.) . “A. species/"’ "writes Tryon^ “ often misunderstood. Its lengthened form and simple interlaced network fully distinguish it.” A var. con- volutus has been described of more brilliant colour- ing. There can be no doubt but that this species, through the var. tigrinus, is connected with the true Textilia. C. telatus (Reeve). Is more conical than most of the Textile Cones. In’ the British Museum this is placed among the Leptoconi, next to ammiralis, which, in its markings, it much resembles. C. Pauluccice (Sowb.). Allied on the one hand to C. aureus and on the other to C. gloria maris. Of very straight pyramidal growth, very richly and handsomely marked with warm chestnut and orange. A native of Mauritius, it was only recently (1877) described by Mr. G. B. Sowerby, from a specimen in the col- lection of the Marchioness Paulucci, at Florence. Three or four specimens besides the type are known, one of which is here exhibited. C. gloria maris (Chemn.) . Larger, very gradually taper- ing j mouth very straight and long ; spire squarely elevated ; reticulations exceedingly fine, regular, and minute ; orange blotches not so conspicuous pro- portionately. To this I will refer later. C. legatus (Lam.). A distinct form, not, to my mind, the young of canonicus, to which Tryon assigns it. Noticeable, by great prominence in the longitudinal chocolate blotches, with a suffusion of pink, which THE SUBGENUS CYLINDER. 83 is always present in the speeies^ over the whole shell, and by its somewhat eompressed eonical shape. II. Retieeri. C. retifer (Menke) = solidus (Sowb.). One speeies only. Amply charaeterized by its pyriform outline, great solidity, and eoarse retieulations. Native of Eastern seas. III. Lucidi. C. lucidus (Mawe) —reticulatus (Sowb.) . The only speeies. Very peeuliar in its more eonical shape, areolate and regular marking, and violet aperture. The locality also is curious : La Plata Island, west coast of Central America. IV. Aulici. Shells, as a rule, narrow in proportion to their length ; spire rounded, elevated, marking, on most of the species, very bold and distinct dark chestnut or chocolate-brown blotches, alternating with lines of large white spots inter- laced with coarse network. a. crocati. Surface orange-yellow, often nearly suffusing the entire shell. Though the type (C. crocatus) is distinct enough, it is connected by intermediate gradations with the Aulici proper. C. colubrinus (Lam.). Yellow, with oblong white spots. A very uncommon and curious species. C. crocatus (Lam.). A very handsome orange-yellow conical species, with white spots and markings broader than long, very variable in their disposition. Some specimens are almost unicolorous yellow. This species, at first sight, has less resemblance to g2 84 MR. J. COSMO MELVILL ON the Textile Cones than any other of the group. Native of Ceylon. C. racemosus (Sowb.). Shell brownish orange, solid, smooth ; spire convex, with obscure articulated brown and white revolving lines and clusters of tri- angular white spots sparingly agglomerated. Unique in my collection; formerly in that of Mr. Bewley, of Liverpool, and subsequently in S. PrevosUs, of Alen9on. b. episcopi. Under this head come a very variable assortment of shells, grouped mostly, hut, I think, wrongly, by Tryon under the head C. omaria, with the exception of aulicus and Elisce. C. Elisce (Kiener). Shell very closely reticulated with chocolate-brown, so as to appear like a uniform brown surface with innumerable white specks. From Madagascar. A very distinct species, though somewhat like C. racemosus. C. prcelatus (Hwass). Always suffused and clouded with grey ; very distinct. C. magnificus (Reeve) . A truly magnificent species, very variable, hut always recognizable. In form like episcopus, with very obtuse spire marked as in the body of the shell in a regular continuation ; shell pink, much sufiPused with dark chocolate and very delicate reticulation. From the Philippines. C. episcopus (Hwass). Variable, and no doubt allied to omaria, but the greater size and greater boldness in marking are always sure to distinguish it. Native of all Eastern seas. C. omaria (Hwass). Very variable. Among the speci- mens exhibited are some resembling C. cordigerus THE STJBGENUS CYLINDER. 85 (Sowb.)j and others like C. nocturnus and Bandanus in other sections, to which I provisionally give the name marmoricolor. Another specimen, again, re- sembles C. magus, a variable Eastern species, here called magdides. A detailed description of this species seems impossible. C. pennaceus (Born.) is a variety. C. ruhiginosus (Hwass) is likewise a variety, but both are more constant than some of the forms of the type. C. Madagascariensis (Sowb.). Though placed by Tryon as a variety of C. archiepiscopus, it is far removed from that species, and really approaches C. omaria. It is a small, neatly marked, very finely reticulated species, native, as its name implies, of Madagascar. C. aulicus (L.). The largest and boldest-marked species of the genus, attaining sometimes a length of nearly 6 inches. It is distinguished by its form and revolving striae, and cannot be mistaken for any species but the next. C. auratus (Lam.). Merged into C. aulicus by Tryon, with which I can hardly agree ; the curious zigzag efiiect of the alternations of warm chestnut-brown coloration and small articulations well represented in the specimen here exhibited, as well as in the plate in Reeve, Conch. Icon., sufficiently serve to distinguish it. V. Aurei. Shells subcylindrical, merging into the next subgenus Hermes, ribbed transversely ; spire elevated, very obtuse, convex. C. aureus (Hwass). A distinct species, though similar in its markings to C. Pauluccice and some others. 86 MR. J. COSMO MELVILL ON C. claviis (Linn.). A very beantifnl species, delicately marbled witb orange-brown and white reticulations ; its form is oblong ; spire convex, spotted. Native of Java and the Philippines and New Caledonia. Try on and Adams place this species in Hermes, between C. Nussatella and circumcisus, but I think it falls more naturally in here. Besides the foregoing, one more species of the Textile Cones has been lately described, C. Prevostianus (Sowb.). The specimen is unique, and I have not seen it, but it would seem to come under the section Pyramidalia. But my chief object in calling attention to the arrange- ment of the Textile Cones was to compare the Conns gloria maris (Chemn.) with its congeners. Although I placed it near pyramidalis, it really stands per se, prominent among all of its kindred for beauty of shape and excellence of pattern. As Beeve observes, the reticulations are so fine as to defy the skill of the litho- grapher. Hence no drawing ever does the species justice. It was originally described by Chemnitz (Conchylien Cabinet) in the year 1788, ^^ex Museo Moltkiano ; ” but the shell seems to have received its name, though no description was published, about the year 1756 or 1758, in the Museum Schluyterianum, Berlin. The nomenclature of Chemnitz, describing in the pre- binomial era, is not always accepted by writers, but this species will always be especially associated with him, although Hwass is sometimes given as the authority for the name. The following is the bibliography relating to this species, C. gloria maris (Chemnitz) : — Chemnitz, Conchylien Cabinet, lo. p. 73, t. 143. f. 1324-25. Bruguiere, Encycl. Method, p. 756, n. 146, Tabl. pi. 347. f. 7. Blainville, Diet, dee Sciences Nat. tom. x. p. 260. THE SUBGENUS CYLINDER. 87 Lamarck, Annal. du Mus. vol. xv. p. 438, n. 176. Dillwyn, Cat. i. p. 424. Wood, Ind. Test. t. 16. f. 134. Delessert, Rec. 40. f. 16, Sowerby, TankerTille Catalogue, 1825, pi. 8. f. 1, 2. Deshayes, Lamarck, 2 ed. xi. p. 126. Reeve, Conchologia Iconica, pi. 6. f. 31. Kiener, Coquilles Vivantes, p. 326, t. 76. f. i. Sowerby, Thesaurus Conch, pi. 24. f. 526. Tryon (G. W.), Manual of Conchology, 1884, vol. 6. pi. 29. f. 90, There is also a figure of the species in Chenu, Manuel de Conchyliologie, p. 249, f. 1525. Dr. S. P. Woodward, in ^Eecreative Science^ (i860), says : — The rarest of all Cones, and perhaps of all shells, except the living Pleurotomaria, is the Conus gloria marls, which those old Pagan Dutchmen worshipped, as did the Greeks the Paphian Venus. Perhaps it was this Cone of which a Frenchman is related to have had the only specimen except one belonging to Hwass, the great Dutch collector, and when this came to the hammer he outbid every rival, and then crushed it beneath his heel, exclaiming, ^Now my specimen is the only one.’ Doubt- less many traditions respecting this species yet linger in the marts of Amsterdam; with us it is still worth ten times its weight in gold.” In 1825 the elder Mr. Sowerby, in cataloguing the shells of the late Earl of Tankerville — which catalogue formed the medium for the description, for the first time, of many now well-known species — notes, in his preface at the lot 2463, which contained a gloria maris : — We have never seen more than two specimens of this shell, namely, that which is in M. Saulier’s collection in Paris, and that which adorns the Tankerville collection.” It will not be out of place now to enumerate the where- abouts of the II or 12 specimens known to exist. It is a 88 MR. J. COSMO MELVILL ON curious fact that while nearly every other shelly hitherto highly esteemed^ has been brought home in abundance by explorers and collectors_, this and one or two others like the Cyprcea leucodon, C. princeps, C. Broderipii, C. gut- tata, and Conus cervus remain as they were in the days of the Duchess of Portland, the first English collector, in the middle of the last century. The land of its nativity is known : Jacna, I. of Bohol, Philippines, where the late Mr. Hugh Cuming found two examples, one very juvenile, scarcely more than an inchin length. But its rarity there was so great that, although he employed all the available natives in dredging- expeditions, and the place has been searched frequently since, nothing of the kind has again occurred. Bumour has it that the original very circumscribed locality has been annihilated by an earthquake, but I cannot hear confirmation of this, though it is exceedingly likely, the whole of that region being extremely volcanic. The total number of specimens known to exist is 1 2 ; of these half are either immature or in very poor condition. There are five in this country, disposed as follows : — Three in the British-Museum Collection at South Ken- sington. Of these two are the small specimens, one only an inch and a half long, the other a little larger, collected at Jacna by Mr. Hugh Cuming in 1838. The third is the specimen formerly in the Portland Collection, then in the Tankerville, from whence it passed into the hands of the late Mr. W. J. Broderip, F.B.S., and thence into the National Collection. This is a fine, full-grown, though pale-marked specimen, and is illus- trated in Sowerby^s ‘ Catalogue of the Tankerville Collec- tion,^ but very highly coloured. The fourth specimen in this country is in the private collection of the late Mrs. De Burgh, of 61 Eccleston THE SUBGENUS CYLINDER. 89 Square^ London^ S.W., and is, perhaps, the finest speei- men known. Formerly in Mr. Norrises possession, of Preston. The fifth is the specimen now exhibited, as being in my collection at Prestwich. It is not quite so large as Mrs. De BurgVs or the TankerviUe specimen, but as finely marked, and of mature growth. Formerly in Mr. Lombe TayloFs hands, it passed into that of the late Dr. Prevost, of Aleu9on, and subsequently into mine. The sixth specimen is in France, but a very poor one, collected by M. Carl Bock in his eastern travels, and which I saw sold with a great deal of competition at Stevens’s Auction Booms in July 1880. It was very water-worn, and with a disfiguring sea-break. It was purchased by Mr. Bryce Wright, of Regent Street, for M. Dupuis, of St. Omer. The seventh specimen is in Italy. One formerly in the collection of the Hon. Mrs. MacAdam Cathcart, sold to the Marehese Paulucci, of Florence. This specimen is described by Mr. G. B. Sowerby to me as being fairly marked, but filed in the mouth and not in good con- dition. The eighth, a very poor, small example, is in the col- lection of Madame Macard, of Utrecht, Holland. In the same country it is also reported that there is a specimen in the Amsterdam Museum ; but, on writing for more particulars to Mr. Sowerby, to whom I am much indebted for details, he assures me there is some mistake as to this. There is, however, I believe, one in the Museum at Rotterdam. The tenth example known, originally in M. de Verreaux’s possession, is now in that of the King of Portugal, at Lisbon, to whom it was sold by Mr. Damon, of Weymouth. In the United States, Mr. Tryon writes me, there is a 90 DR. EDWARD SCHUNCK. MEMOIR good specimen in the American Museum of Natural History, New York ; but I know nothing of its history, or whence it was obtained. In Australia the fine, full-grown, but pale-coloured shell, formerly in the collection of Mr. J. Dennison, of Liverpool, was, in April 1865, bought by Mr. Lovell Reeve for the Melbourne Museum. There are, therefore, eleven or twelve specimens at most recorded of the shell not inaptly termed ^^The Glory of the Sea.^^ VI. Memoir of Robeut An&us Smite:, Ph.D., LL.D., F.R.S., F.C.S., ^c. By Edward Schunck, Ph.D., F.R.S., &c. Eead April 21st, 1885. By the death of Robert Angus Smith the Literary and Philosophical Society has sustained a great loss. His was a life of which it is difficult to form a just estimate, on account of the many-sidedness of his character and attain- ments. His contributions to science and literature will, indeed, always remain accessible to the judgment of pos- terity, but there is much in his character and his relations to the world which should be recorded ere those who knew him have also passed away. In his case, fortunately, the record may be perfectly unreserved, for here there are no defacing blots to be concealed, no dark shadows to be passed over. Robert Angus Smith was born in Glasgow, February 15th, 1817, being the twelfth child and seventh son of John Smith, a manufacturer of that city, and of Janet his OF ROBERT ANGUS SMITH. 91 wifoj daughter of James Thomson^ who was an owner of flax and other mills at Strathavon, where he held the offlce of baron-baillie. Of the brothers^ those who attained to maturity were all men of remarkable intellect. The eldest^ John Smithy was for many years a master in the Perth Academy,, and paid great attention to optics. A paper by him ^^On the Origin of Colour and the Theory of Light will be found in vol. i. ser. 3 of the Society's Memoirs. James Smithy a man of highly original character^ was the author of several works on religious and philosophical subjects. Another brother^ Michaiah^ was a distinguished oriental scholar^ while J oseph^ the youngest, devoted him- self to science, but unfortunately died early. The father was, by all accounts, a very earnest man, with profound religious convictions, and though not highly successful in worldly pursuits, was able to give his sons a good educa- tion, such as the schools and universities of Scotland were and are presumably still able to ofier even to men of moderate means. Two of the sons, James and Michaiah, were ordained ministers in the Scotch Church. At that time, however, the Irvingite schism was exciting the minds and engaging the sympathies of many, especially the young, and it is probable that the father as well as several of the sons felt attracted by the doctrines promulgated by Irving, doctrines which could not possibly find sufficient scope within the somewhat contracted sphere of a Calvi- nistic communion. So far as the subject of this memoir is concerned, it is certain that his sympathies led him more in the direction of Anglicanism, and from the hints he let drop at various times, it seems that it was only through circumstances that he was prevented, when a choice was possible, from taking orders in the English Church. After passing through the usual course at the Glasgow High School, and spending some time at the 92 DR. EDWARD SCHUNCK. MEMOIR University of Glasgow^ a period of his life of which he seldom spoke, simply perhaps because there was little to say, Smith accepted a post as tutor to a family in the Highlands, but was soon compelled to leave from ill-health. He then proceeded to England, where he was employed in a similar capacity in families whose peculiar religious opinions afford some indication of the direction in which his sympathies at that time tended. With the Rev. and Hon. H. E. Bridgeman he spent two years, and with him proceeded to Germany. So far Smithes tastes and pursuits had been purely literary and theological. His education had been entirely classical, being confined to acquiring a knowledge of ancient languages, such as was in his day thought sufficient for all the purposes of life, an acquaint- ance with science, mathematics, or modern languages being then considered comparatively of little consequence. During his stay in Germany one of the tendencies of his many-sided mind revealed itself. Hearing of Professor Liebig, whose fame was then spreading through Germany, his attention was directed towards science, this tendency being perhaps encouraged by the example of his brother Joseph, who had engaged in the study of chemistry under Professor Penny, of Glasgow, and with whom he corre- sponded. He accordingly proceeded to Giessen, where he worked in Liebig^s laboratory during the years 1840-41, and where, before leaving, he took the degree of Ph.D. During his stay at Giessen he extended his knowledge of the German language and literature, and also paid much attention to German systems of philosophy, a subject that at all times interested him greatly. It may perhaps be considered a matter for regret that Dr. Smith’s early training in science was not more exten- sive, and that it continued for so short a time. On the other hand it is possible that a more rigorous training in OP ROBERT ANGUS SMITH. 93 natural science and mathematies might have detraeted from the catholicity of mind and wide culture which were prominent charaeteristies of his. He afforded, indeed, a conspieuons example in favour of the prineiple held by the conservatives in edueation, viz. that a thorough classieal training affords a basis on which a superstructure, what- ever it may consist of, may be confidently ereeted, though, on the other hand, it would be hazardous to found general rules on such exceptional cases as his. Soon after leaving Griessen, Dr. Smith published a translation of Liebig^s work ^ On the Azotised Nutritive Principles of Plants.^ After his return to England, at the end of 1841, he was engaged in various capacities with families of distinetion, and at this time the early inclination towards a theological career seems to have revived, and was probably only given up when it was found that eircumstances, such as the necessity for a preliminary education at an English Uni- versity, plaeed an insuperable barrier in the way. In the year 1843 we find him working as assistant to Dr. Lyon Playfair, with whom he had become acquainted at Giessen, and who was then engaged as Professor of Chemistry to the Manchester Loyal Institution. At Manehester Dr. Smith finally settled down ; here, with the exception of intervals of travel, he spent the rest of his life, and here all his most important work was done. With characters com- bining many-sidedness with great intensity of purpose it is often a mere aecident that determines the direction the energies shall take. Such an accident occurred in the career of Dr. Smith. The Health of Towns Commission, of which Mr. Edwin Chadwick was the moving spirit, instituted inquiries in Manchester as in other towns. Dr. Playfair was much interested in these inquiries, and Dr. Smith was engaged in conducting some portion of them, their object being more practical than scientific. 94 DR. EDWARD SCHUNCK. MEMOIR This circumstaDce directed Dr. Smithes attention to sani- tary matters, and led him to commence the series of investigations which occupied a great part of his time and attention from the year 1844 up to the time of his death. At the time when Dr. Smith commenced his researches sanitary science could not be said to exist, unless a mere collection of unconnected facts can be dignified with the name of science. Since that time much more system has been introduced into the subject, and a great portion of the merit of having developed the purely scientific side of it is due to Dr. Smith. The pathological department of the subject did not, as may be supposed, receive so much attention from him as the physical ; nor did he, I think, at any time pronounce decidedly on the question whether the phenomena with which sanitary science deals are purely organic in their nature, or whether they are not also partly due to merely physical causes. What he did was to investigate patiently the physical and chemical conditions as regards outward agents, more especially the air we inhale and the water we drink, on which health and disease seem to depend. No doubt, since the time when he entered the field, our views on this subject have altered considerably. It is now held that most diseases, especially those of the zymotic class, are due to the development of organic germs, but the most ardent advocate of the germ- theory must allow that there are physical and chemical phe- nomena attending disease which should not be neglected, and to these Dr. Smith chiefly confined his attention, now and then only reverting to the general question of the causes of disease, as to which he was always prepared to modify his opinions when the progress of discovery required bim to do so. The results of his labours are contained in a series of papers, of which the Hoyal Society's catalogue contains a list, though an incomplete one, beginning with OF ROBERT ANGUS SMITH. 95 one entitled “^^Some Remarks on the Air and Water of Towns/^ published in the Chemical Society's Journal, 1845-48. His results are summed up in an independent work entitled ^Air and Rain/ and published in 1872. Much of Dr. Smithy’s work was necessarily of a purely qualitative character, for the phenomena which he inves- tigated are concerned with almost infinitesimal quantities of matter. Nevertheless, whenever it was possible, he introduced quantitative methods, as when examining the amount of acid contained in the atmosphere, of which an account will be found in his paper On Minimetric Analysis,^^ read before this Society in the Session 1865-66. This paper contains a description of a very simple and ingenious little apparatus, called by him a “ finger-pump,^^ by which the amount of impurity in the atmosphere, in the shape of carbonic acid or hydrochloric acid, can be rapidly and easily determined. On disinfectants, to which Dr. Smithes attention was naturally directed, he worked much, his general views on the subject being contained in a separate work published in 1869, and entitled ^Disin- fectants and Disinfection.^ The practical result of his studies in this direction was the invention of a very useful disinfectant, which was introduced by Mr. McDougall, and is still largely employed. This short resume may perhaps suffice to give some idea of Dr. Smithes labours on air and water in their hygienic relations ; but before closing it some allusion should be made to his able report “ On the Air of Mines,^"’ chiefly those of Cornwall, presented to Government, by whose directions the inquiry into the atmospheric conditions prevailing in mines was under- taken. Dr. Smithes memoirs on purely scientific subjects are not numerous. Among them may be mentioned those on rosolic acid, on the absorption of gases by charcoal, which he supposed to take place in certain definite propor- 96 DR. EDWARD SCHUNCK. MEMOIR tionSj and on tlie “ Measurement o£ the Actinism of the Snn^s Rays and of Daylight (Proceedings, Royal Society, XXX. p. 355), in which a novel method of measurement is described. His study of peat, which treated of a favourite subject of his, was perhaps more practical than scientific in character. Those who take an interest in the subject of the formation and utilization of peat should refer to his papers relating to it, published in the Society’s Memoirs. This is perhaps not the place to mention in detail his work in connection with technical subjects, but one of his inventions must not be passed over in silence, viz. that for coating iron tubes with an impermeable varnish, so as to preserve them from corrosion. Of this invention experts entertain the very highest opinion, and it may safely be said that had be been endowed with more worldly pru- dence, he might by this invention alone have amassed a considerable fortune. Like many other inventors he never enjoyed the rewards to which his ingenuity entitled him. It is for the world to acknowledge, by words at least, the benefits he conferred on it ; for those who are unable or unwilling to fight and struggle for wealth and position it has no other recompense to offer. In the year 1864 Dr. Smith was appointed chief inspector under the Alkali Act, which had just previously been passed by the legislature, a post for which he was, from his intimate knowledge of atmospheric contamination, eminently fitted. Great complaints having arisen regard- ing the injury done to crops and other things by the emanations from alkali-works, an Act was passed, the object of which was to limit the amount of injurious gases, especially hydrochloric acid, which should be allowed to escape from the flues of alkali-works. It was this Act, the provisions of which Dr. Smith, with OF ROBERT ANGUS SMITH. 97 the aid of his sub-inspectors^ was to see carried out, by constant supervision on the part of the sub-inspectors and frequent periodical visits to various districts by himself. That he was eminently successful in his attempts to secure for the public the benefits which the legislature had in view when the act was passed, and, on the other hand, in conciliating by his prudence and tact those who were to some extent restricted and interfered with by the pro- visions of the Act, is universally conceded. It is quite possible that in other hands the task which Dr. Smith was called on to perform might not have been accomplished, and the result might have been complete failure. To continue what he began according to methods initiated by him is a comparatively easy task. As chief inspector under the Alkali Act Dr. Smith had each year to present a report of the proceedings under the Act for the preceding year. These reports, of which the last (presented in 1884) was the twentieth of the series, contain much information over and above what mere official summaries might be expected to give, and they should be carefully studied by all who are interested in hygiene in its relation to manu- factures. In the year 1876 an act similar to the Alkali Act, though of a less stringent character, was passed, styled the Hivers Pollution Prevention Act.^^ Under this Act Dr. Smith was appointed to examine polluted waters, more especially the state of effluent fluids from sewage-works, and he presented two reports to the Local Government Board as an inspector under the Act. To the results set forth in the second of these reports, presented shortly before his death. Dr. Smith attached the greatest import- ance. It will be for others to judge of the value of these results, but he himself considered that the discoveries described in the report would open up a wide field of SER. III. VOL. X. H 98 DR. EDWARD SCHUNCK. — MEMOIR research, throwing quite a new light on the relations between disease and water and soil. To those who take an interest in sanitary science it must be a matter for vivid regret that his labours in this novel field of research were cut short just when they seemed to promise impor- tant results. It remains to say a few words on such of Dr. Smith’s publications as are not of a strictly scientific or profes- sional character. These are partly philosophical in their tendency, partly literary, or simply popular in character, and in part treat of antiquarian and historical subjects, for which Dr. Smith had a great liking, and seem often to have been hastily penned to fill up a leisure hour or at the request of friends. Many of them were anonymous, but Dr. Smithes style and the current of his thought were so original that to those who knew him the disguise was only a thin one. One of the works belonging to this class must not, however, be passed over without special notice. During several years of the latter portion of his life he was in the habit of spending his autumn vacation on the shore of Loch Etive in Scotland, where he employed him- self— his active mind never being satisfied without some special object to occupy it — in exploring this part of his native eountry with a view of throwing some light on its state in prehistoric times. The result was a work which is not only instructive, but highly entertaining in the best sense, called ‘‘ Loch Etive and the Sons of Uisnach,'’^ a work which all should read who are interested in pre- historic research and ethnology. Dr. Smith paid great attention to Celtic languages, and made a large collection of works in Gaelic. These, with the rest of his books, have, since his death, been presented to the library of Owens Collegv^. Dr. Smith was elected a member of this Society in the OF ROBERT ANGUS SMITH. 99 year 1844. several years he acted as one o£ the Secretaries of the Society^ subsequently he was elected a Vice-President^ and during the sessions 1864 1865 he filled the post of President. He at all times took a lively interest in the welfare of the Society^ and was always ready with advice and active assistance when such were required in the transaction of business. In connection with this Society he will, however, be chiefly remembered by two works, the ^Life of Dalton and the Atomic Theory’ and Centenary of Science in Manchester,^ which were written at our request, and form two volumes of our series of Memoirs. The ^Life of Dalton^ was a work written con amove, as it gave the author an opportunity of setting forth his ideas on two favourite subjects — the rise and development of scientific thought among civilized nations, and the consideration of the metaphysical notions out of which the theory of atoms has sprung. The other of the two works named shows the original turn of thought and terseness of style found in all his writings, though undertaken at a time when his health was declining and he was overburdened with other work. To the same class of writings belongs the preface to the beautiful edition of Graham^’s ^ Chemical and Physical Researches,^ undertaken at the cost of the late James Young. In this preface he gives a short history of the atomic theory, beginning with its rise in the schools of Greece and tracing its development in modern times. Dr. Smith was a Fellow of the Royal Society and of the Chemical Society of London, and a member of several learned societies on the continent. Had he been more of a specialist it is probable that the list of societies that sought to honour him by membership and in other ways would have been longer. In the year 1881 the degree of h2 100 DR. EDWARD SCHUNCK. MEMOIR LL.D. was conferred on him by the University of Glasgow, a distinction which, coming from his alma mater, the seat of learning in his native town, he valued highly. The same degree was awarded to him by the University of Edinburgh in 1882. Dr. Smithes health had evidently been declining for some years. Not endowed with a very robust constitution, and unable, as it appeared to some, to take the amount of sustenance required for so active an existence as his, the great labours which were partly imposed on him, and partly undertaken voluntarily, began in time to tell on his health. To the entreaties of his friends to allow himself some rest, he did not reply by a direet refusal, but con- tinued to work on with unabated zeal, as if the stock of vigour he had to draw on were inexhaustible. Various ehanges of scene were tried, but without effect, and he gradually sank, the bodily strength declining, but the mind remaining clear to the last. He died at Colwyn Bay, in N. Wales, on the 12th May, 1884. His remains were interred in the churchyard of St. PauFs, Kersal. This notice would not be complete without some refer- ence to Smithes moral characteristics. To those who knew him these were familiar, but those who come after us should know that in his case an intellect of high order was united to a eharacter of the purest and noblest type. The most marked trait in his character, it always seemed to me, was a wide, to some it might seem an almost incon- ceivably wide benevolence, a benevolence which seemed capable of embracing all except the unworthy within its folds. It was this that led him to associate with men of the most diverse character and aims, extracting from each specimen of humanity a something with which he could sympathize, putting on one side or excusing what was uncongenial to his nature in each, and establishing bonds. OF ROBERT ANGUS SMITH. 101 some stronger some weaker^ which^ in their totality^ gave him a sense of relationshij) to humanity at large. This wide toleration may serve to explain the fact which may sometimes have been observed^ that two men mutually repellent and unwilling to associate together might both have been warm friends of his. He appeared, indeed, to be the centre of a system or constellation, the individual members of which knew little of each other, but were all united to him by bonds of sympathy. His extreme con- scientiousness and high sense of honour appear even in his works, leading him scrupulously to weigh all that could be said on either side of an argument, and to give every man his proper share of merit, refusing sometimes even to credit himself with what was manifestly his due. This great conscientiousness was occasionally even injurious to himself by preventmg his arriving at positive and precise conclusions, such as the world requires even when there is no thorough conviction. Of the charms of Hr. Smith’s conversation, only those are able to form an idea who had the pleasure of his per- sonal acquaintance, for it was not of a kind to be literally reproduced. Without being at all eloquent or indulging in harangue, and always giving due weight to everything his hearers had to say, he was able, from the fulness of his knowledge and the originality of his views, to throw a new light on almost every subject he touched on, and thus he would sometimes continue to instruct without dogmatizing, and entertain without wearying, until it Avas found that not minutes but hours had slipped away in listening. One trait in Smith’s character must not be passed over, though to mention it in this age of materialism may seem to require some apology — he was a firm believer in a spiritual world, that is of a world above and beyond the 102 MR. H. WILDE ON A PROPERTY OF senses^ of the reality of whieh^ whether we can communi- cate with it directly or not (and of this he never seemed quite sure) he was firmly convinced. Those who remain to lament his loss, and who share the same belief, may unite in the fervent trust that in the world of which he thought much, but spoke little, his spirit may have found not merely rest and satisfaction, but also a continuance of that mental activity and development which to him were life. Dr. Smith was never married, but for many years his niece. Miss Jessie Knox Smith, was his constant com- panion and confidante, ministering to him with a zeal and devotion which could not have been exceeded had the relationship been that of father and daughter. VII. On a Property of the Magneto-electric Current to control and render Synchronous the Rotations of the Armatures of a number of Electro-magnetic Induction- machines. By Henry Wilde, Esq.* Read December 15th, 1868. The discovery of the property which I am about to describe arose out of the efforts which have been made, during the last two years, to reduce the internal heat generated in an electro-magnetic machine by the induction- currents set up in the electro-magnet and armature by the rapid magnet- ization and demagnetization of the latter. This heating of the armature, as is well known, was first observed by * The subjects treated of in this and the two following papers having acquired great interest in recent years, it is believed that the papers woidd be increasingly useful if they were embodied in the more permanent records of the Society. THE MAGNETO-ELECTRIC CURRENT, 103 Dr. Joule in 1843, the result of a delicate investigation on the quantitative relation existing between ordinary mechanical power and heat*. In the electro-magnetic machines of my invention this phenomenon unfortunately manifests itself on an alarming scale_, so much so that the armature of the lO-inch machine rises in the course of a few hours to 300° F. and upwards ; and were the action of the machine to be continued for any lengthened period^ the insulation of the armature- coils would be en- dangered. One method of mitigating this evil was to construct the machine of smaller dimensions, so as to afford greater facilities for the dissipation of the heat by radiation and conduction. But even in the smaller machines an incon- venient residuum of heat still remained when they were worked continuously for a considerable time, so as to render it desirable to adopt some means for abstracting the heat more rapidly. By means of a current of water circulating in the hollow brass segments which form part of the magnet-cylinder, Mr. Charles E. Byder, the skilful manager at the works of Messrs. Elkington and Co., has happily succeeded in so far reducing this heating as to permit of the machines being worked for days and nights together without intermission, and without any sensible diminution of the power of the current. The machines which have been found to be the most efficient and economical in their working are those which have armatures from 3f to 4 inches in diameter. The ar- matnres are driven at about 2000 revolutions per minnte ; and the water, after having passed through the magnet- cylinder, is used for supplying the boilers which furnish the power for driving the machines. I have already shown elsewhere that the current from a * Phil. Mag. S. 3. vol. x.xiii. p. 264. 104 MR. H. WILDE ON A PROPERTY OF small magneto -electric or electro-magnetic machine is sufficient to excite the great electromagnet of the lo-inch machine ; and it has been further founds by my friend Mr. Gr. C. Lowe^ that the current from one small machine is sufficient to excite simultaneously the electromagnets of several small machines. In a number of 3i-inch ma- chines which have been constructed under my direction for Messrs. Elkington and Co.^ for the electrodeposition of copper on a large scale, the currents from two 3 f -inch electro-magnetic machines are made to excite the electro- magnets of twenty similar-sized machines to a degree sufficient to bring out the maximum dynamic effect of each machine. The electromagnets of the two 3f-iuch exciting machines are charged by the current from a small 2f-ineh magneto-electric machine; but I have found that nearly as good a result may be obtained from the twenty machines by dispensing with the small magneto-electrie machine, and employing the residual magnetism of the two 3f-inch exciting machines in a manner similar to that deserihed, almost simultaneously, by Mr. Farmer*, Messrs Varleyt, Mr. Siemens J, and Sir Charles Wheatstone §. So far I have adverted principally to the means by which a very serious defect in the practical working of the new induction machine was remedied, a defect which many of my friends, who were unacquainted with the efforts which have been made to overcome it, have considered to be fatal to the success of what seemed likely to he a use- ful invention. But while the difficulty arising from the * Letter to the Author, November 2, 1S66, Salem, Mass. U.S., Proceed- ings of the Literary and Philosophical Society of Manchester, February 19, 1867. t Spe the original determination, shall be the classical one, as the atomicity has been fixed by diff’erent chemists at 75'^j ’'^3; ^50; tbc number assigned to SER. III. VOL. X. K 130 MR. H. WILDE ON THE it in the Table. The relations whieh the double atomic weights of In and Yt have to each other, and with their homologues of position Cs, Ba, and Ag, Cd, in Tables II., III., render it highly probable that the atomic weights of Yt and In in the table are correct. For similar reasons it is probable that the atomic weight of erbium will be found to be 177. It is only very recently that any investigations of the atomic weight of this rare element have been made, from the difficulty attending its isolation from yttrium, with which it is found associated in nature. According to some chemists, the atomic weight of erbium is ii2'6, which, in relation to 177, is nearly in the ratio of 5 to 8. The more recent researches of M. Cleve on the quanti- valence of this element have, however, raised its atomic weight to i70'55 *, which, considering the wide difference between it and the previous determination, is a near approximation to the number in the Table. The researches of the same chemist have also raised the atomic weight of yttrium from 61 *7, the accepted determination, to 89' 5, or three fourths the calculated value. Now the history of chemical science abundantly shows that it is only after long and repeated investigation that the highest quantiva- lence of an element can be ascertained, and the result of M. elevens researches is a further confirmation of the correctness of the atomic weights of yttrium and erbium given in the Table. By comparing the electro-positive members of the series Hn with those of H2?2, it will be seen that a complete parallelism exists between them ; the light alkaline, and alkaline-earth metals alternating with the heavy members in homologous positions in both series. Odling has already indicated that this is the natural order of the dissimilar members of the zinco-calcic group of elements f, * Bull. Societe Ohemique, Paris, tome xxi. p. 344 (1874). t Watts, Die. Ohem. 1865, yoI. iii. p. 963. — “Classification of Metals.” ORIGIN OF ELEMENTARY SUBSTANCES. 131 and similar alternations in other natural groups have been recognized in the arrangement of elements proposed by Mr. Newlands * and MendeleeflF f. Just as Cu=62, Ag=io8j and alternate with Rb = 85j Cs = 131^ and x= 177, in the series Hw; and Zn = 64^ Cd = 1 12, and x= 160, alternate with Sr = 88^ Ba= 136, and ^=184; so in the series H3/ij do x=6g, Yt = 123, and Eb=i77, alternate with x = ()6, In=i50, and T1=204. Again^ just as K, Rb^ Cs, and ^=154, are analogues of each other in the series Hn, so are x = 42, ^ = 96^ In, and Tl, analogues of each other in the series H3»^, and are in homologous positions with the alkaline, and alkaline-earth metals in the series Hw, and H2n. The specific gravities of analogous members of these two series, except glucinum, which is anomalous, increase in the order of their atomic weights, and so far as the specific gravities of the members of the series H3« have been ascertained, they follow the same order. Now, M. Lecoq de Boisbau- dran has shown that the new metal which he has discovered, and named gallium is, from its spectral reactions and other properties, the analogue of indium and thallium. The position of the new metal in the series H3re, should therefore be either — =42, homologous with Ca, and K, or — =96, homologous with Sr and Rb. In comparing the alkaline metals of the series Hn, the specific gravity of sodium (o‘97), as will be seen, is greater than that of potassium (o’ 8 6), although Na has a less atomic weight; and the same inversion of specific gravities in relation to atomic weights is observable in their homologues of jiosi- tion Mg (sp. g. 174), and Ca (sp. g. i‘58), in the series * Ohem. News, vol. xii. p. 83 ; vol. xiii. p. 113. t Die periodische Gesetzmafsigkeit dex* clieniischen Elemeixte. — Ann. Cheui. Plxai’ni. Siippl. Band. viii. pp. 133-229 (1872); Phil. Mag. 5th ser. vol. i. P- 543- J Coniptes Rendiis, tome Ixxxi. pp. 403, 1000 (1865). K 2 132 MR. H. WILDE ON THE Haw. It may therefore be assumed that the missing member .2? = 42, H3W, would have a less specific gravity than A1 (sp. g. 2’56), probably 2*5 . Now, the specific gravity of gallium, as determined by M. Lecoq de Boisbau- dran, is 5*9 *, and its analogues indium and thallium have specific gravities of 7^42 and ii‘9 respectively, conse- quently a? =42 is not gallium. If gallium were x = 6c) it would be the analogue of Yt, E, and Th, and homologous in position with Zn and Cu, whereas it has been shown to be the analogue of In and Tl, and homologous in position with Sr and Bb. There is then no other place for a metal having the physical properties of gallium but the one assigned to it in the series H3W, with the atomic weight = 96, and forming a triad with indium and thallium. If, however, the experimental determination of the atomicity of gallium pass through the same stages as the atomicities of indium, yttrium, and other members of the series, its atomic weight will be represented by the submultiple and proportional numbers 48 and 72 f. Just as silver and copper are analogues of each other, and are frequently associated in nature ; and just as their homologues, cadmium and zinc, are analogues, and are also found together, so is yttrium the analogue of ^ = 69, and will be found associated with it in nature. Now, if x=6g be not the terbium of Mosander and Delafontaine, and the researches of Bahr and Bunsen render the existence of this element doubtful, it is probable that x — 6g is * Phil. Mag. 5th ser. vol. ii. p. 398. t From a calcination of the gallo-ammoniacal alum, M. Lecoq de Bois- baudran has recently found for gallium the equivalent 70'03, and from a calcination of the nitrate, 6g‘6. — Comptes Bendus, 15th, 1878. The researches of M. Berthelot on the specific heat of gallium indicate, however, a higher equivalent for the metal than 70-03, as the atomic heat calculated from this determination (5-55 solid) is lower than that of any other metal except silicium. — Ibid. April 15th, 1878. ORIGIN OF ELEMENTARY SUBSTANCES. 133 cerium^ as this element and yttrium are nearly always found assoeiated in the mineral species cerite and yttroce- rite. Moreover^ it will he observed that x=6() is just i*5, or 0.75 the atomic weight of cerium^ according as it is regarded as 46 or 92. Mendeleeff and other chemists have already proposed 138 as the atomic weight of cerium*, which is double that of x = 6(). MM. Hildebrand and Norton have recently obtained cerium, lanthanum, and didymium in a massive state, and have thereby been able to investigate some of the physical properties of these rare metals f. According to these experimenters the specific gravities of Ce, La, and Di, range between 6 and 6-7, Bearing in mind that elements of approximately the same atomic weights and specific gravities generally belong to diflerent series, and that the specific gravities of analo- gous members in each series increase in the order of their atomic weights, it would appear that cerium does not belong to the same series as lanthanum and didymium. Moreover, consid'Cring the important position which ,27=69 occupies in relation to its analogues Al, Yt, and the posi- tion which these three elements occupy in relation to their homologues Mg, Zn, Cd, and Na, Cu, and Ag, it may be doubted if x = 6g should, up to the present time, have remained undiscovered, especially as all its analogues of the series Th, E, Yt, and Al, are well known. If, there- fore, 37 = 69 be cerium, the only element missing in the series llSn is 37 = 42, the analogue of Ga, In, and Tl. As these elements have been discovered by spectrum analysis, it is probable that 37=42 will also be found by the same means. It may, however, be observed, that the character- istic lines of the alkaline metals in the series Hw, and of their homologues H32^, advance in the blue or violet end of * Ann. Chem. Pharm. Suppl. viii. pp. 185-190. t Chem. Soc. Journal, 1876, vol, ii. p. 276. 134 MJl. H. WILDE ON THE the spectrum, towards the more refrangible parts in the inverse order of their atomic weights. The spectral lines of ^=42 must therefore be sought for in the violet or ultra violet part of the spectrum. The high refrangibility of the lines which the missing element will have, may he the reason why it has hitherto escaped detection, as from the wide distribution in nature of its homologues of posi- tion Ca, and K, in relation to their respective analogues Sr and Plb, a? = 42 ought to be more abundant in nature than gallium *. From the physical and chemical relations which subsist among the halogens F, Cl, Br, I, and the alkaline metals Li, Na, K, Rb, Cs, chemists have already justly considered these elements as positive and negative analogues of each other and of hydrogen. In accordance with this view, I have classified the halogens as negative forms of the series H7^. By assigning to these elements the positions shown in the table, it will be seen that besides the triad of atomic weights formed by Cl, Br, and I, there is a common diffence of 4 between the atomic weights of the halogens and their positive homologues of position Na, K, Rb, and Cs. Now if the groups of oxygen elements O, S, Se, Te, be considered as negative forms of H2^^, homologous in character and position with the negative forms of H^^, it will be seen that besides the triad of atomic weights formed by S, Se, and Te, there is a common difierence of 8 between them and their positive homologues Mg, Ca, Sr, and Ba ; or double the common difference between the positive and negative members of the series The oxygen elements are multiples of 2, 4, 8, and 16, and may accordingly be * Nilson discovered in 1879 (Oomples Eendus, Ixxxviii. p. 645) a metal with an atomie weight of 44, which he regards as trivalent, and has named scandium. This metal, from several of its properties, would appear to be ^7=42, H3W, and as all its homologues of position are well-known elements, I have placed scandium (symbol 80=42) in the Table. — H. W. 1886. ORIGIN OF ELEMENTARY SUBSTANCES. 135 considered as products of the firsts second, third or fourth power of H2I^. Whichever view be taken of the formation of the first negative member of the series H2I^, it is probable that both fluorine and oxygen were not formed direct from and H2i2, but from members homologous in position with Li, and Gl, but which have become extinct by absorp- tion into F and O. Another numerical relation subsisting among the halo- gens which it may be of interest to point out is, that the difference of a unit in their atomic weights will make them mnltiples of 3 and 9, and these numbers, commencing with 01=36, are all respectively three times the atomic weights of the first three members of the series H3I^. These rela- tions would indicate that the halogens, usually regarded as monatomic, are also built up in multiple proportions, and may also throw some light on the variable quantiva- lence which Wanklyn and other chemists have shown the alkaline metals and halogens to possess. The recent researches of chemists leave no doubt that all the elements which I have classified as forms of H5W, except boron, belong to the same group. Now, boron bears a greater resemblance to phosphorus in its combi- nations and occurrence in nature than it does to other elements, and whether the first three members of the series be considered as forms of H5W, or H5I^+I, they form a triad as well defined as their homologues of position in H3W, H2I^ and HI^. Triads are also formed by anti- mony, arsenic, and phosphorus, — bismuth, antimony, and phosphorus, — tantalum, niobium, and boron, — ^^=140, As = 75, and B=io, — x=i\o, Nb=95, and V=50. The atomic weights of boron, phosphorus, and vanadium have been so carefully determined by chemists, as to preclude any doubt of their being represented by Bsn -f I, rather than H5?^ ; but the fact that arsenic. 136 MR. H. WILDE ON THE antimony, and bismuth are better represented by the formula H5%, and that Cu, and Zn, in the series Hw, and H2n, exhibit the same constant minus difference from the classical atomic numbers as B, P, and V, are further indications of some unknown property of the elements which conceals their exact multiple relations from view. If the discovery of two new elements of this group by Hermann to which this chemist has given the names of neptunium and illmenium, be confirmed, the former element will have an atomic weight of 140, and the latter element an atomic weight of 165, as shown in the table. Although the numerical relations of the members of the series H5W are very interesting, yet, it will be seen that the ratios are not so simple as those of the series H7^, Hzw, H3W, as multiples of the second member, minus the first, do not give the atomic weights of the other members of the series. The series H4W is incomplete, not only by reason of the absence of several of its members, but also because the atomicity of lanthanum and didymium is not yet agreed upon by chemists. There can, however, be no question as to the position of titanium as the third member of this series, as there is no other place vacant where an element with an atomic weight of 48 would fit, while the isomor- phism of rutile with cassiterite and zirconia indicates the relation of tin and zirconium with the same series. The classification of uranium presents some difiiculty on account of the fewness of its analogies with other elements, but there can be little doubt that the atomic weight assigned to U= 120, until recently, is much too small, as there are no elements with atomic weights so low, correlated with specific gravities so high as that of * ‘Nature,’ April 12th, 1877. H. Kolbe’e ‘Journal fur praktische Cbemie,’ Feb. 1877, pp. 105-150. ORIGIN OF ELEMENTARY SUBSTANCES. 137 U, sp. gr. = i8’3. From a study of the chemical combina- tions of this element^ Mendeleef has assigned to it the atomic weight of 240*, or double the number formerly re- ceived, and which number I have adopted. The admission of this high atomic weight, however, separates uranium from chromium, molybdenum, and tungsten, with which it has been classified, as there are no elements of approximately the same high specific gravities as tungsten= i8‘26, and uranium = 1 8’3, correlated with so great a difference of atomic weights as 11 = 240, and W=i84, From the fact that the highest places in all the series, except that in H4W, are filled up with their highest members, and that uranium is generally found in combination with the mineral species yttrotantalite, fergusonite, polykrase, pyro- cJilore, pyrrhite, containing elements of the series H3W on the one side, and in combination with minerals containing elements of the series H5% on the other, I have classified uranium as the highest form of H4W. The two lower forms of H4W, as will be seen from the table, are missing f; but, assuming that titanium is the highest member in a triad with the missing elements, the atomic weights of the latter are 16 and 32, isomeric with oxygen and sulphur. It may, however, be surmised that no elements now exist to fill the gaps in the series, as they may have become extinct by absorption into titanium and its analogues, or by trans- formation into the negative forms of H2%. The el6ments which I have classified as forms of \l6n * Ann. Chem. Pharm. Suppl. Tiii. pp. 178-184, t Prof. Winkler of Freiberg has recently discovered a new element which he has named “Germanium” (symbol Ge). (‘Nature,’ March 4, 1886 ; ‘ Berichte’ of the Berlin Chemical Society, No. 3). Germanium was first considered by Winkler to belong to the antimony and bismuth group ; but the subsequent determinations of its specific gravity S‘469, and atomic weight 7275, place the new element in the vacant position x=^-jz in the series Il4«, and in the group of titanium and tin. — H. W., 1886. 138 MR. H. WlLDli ON THE are ouly three in number, and the atomic weight of chromium = 52‘2 establishes its position as the third member of the series, and there is no other place for an element with the chemical and physical properties of chromium vacant in the table. For like reasons the positions in the series of molybdenum and tungsten (the analogues of chromium) are also determined. By assign- ing to chromium the constitution 9 H6, it forms a triad with the missing elements <*’ = 36, and a?=i8, which are, within a nnit, the atomic weights of fluorine and chlorine. In the arrangement of the elements which I have classifled as H7%, little assistance is derived from known analogies, when nitrogen and silicium are admitted in the same series with the iron and platinum groups of metals ; yet, it might be expected that elements so abundant, and so widely diffused in nature as nitrogen, silicium, and iron, would occupy important positions in any rational classiflcation of elementary species. We have seen that the first three places in the preceding series Hw, H2n, H'^n, H5W, are all occupied by elements with atomic weights which exclude nitrogen, silicium, and iron, while the latter element is excluded from the series H4W, and H6w, by chromium and titanium. The atomic weights of N, Si, and Fe, besides being whole numbers, are exact multiples of 7. N and Si are, consequently, excluded from the vacant homologous positions in the series H4W, H6/^. Since the investigation of the properties of silicium by Berzelius, who regarded silicic acid as a trioxide, much discussion has arisen as to whether the atomic weight of silicium be 21 or 28 ; or the formula for its oxide SiOj or SiOj. Chemists are now generally agreed upon the latter formula for silicic acid, and have accordingly classified silicium with titanium, as the oxide SiO^, agrees ORIGIN OF ELEMENTARY SUBSTANCES. 139 with titanic acid TiO^. Now, if siliciura were the true analogue of titanium, the oxides of these elements should be isomorphous, whereas the erystalline form of quartz is hexagonal, while rutile, anatase, brookite, zirconia and tinstone (similar oxides of members of the series H4W), are tetragonal ; consequently, silieium does not belong to the series H4vz. By assigning to silieium the atomie weight 35, it forms with nitrogen and iron a triad similar to the first three members of H^, H2w, H3%, H5W. The position of Si= 35, as the seeond member of the series H7W, not only throws new light on the disputed atomieity of this element, hut also explains the anomalous atomic heat which has been assigned to it. Through the classieal researehes of Regnault the speeific heat of silieium was found to be O' 176*. The determi- nation was made with speeimens of the metal of consi- derable size, and in a state of compactness and purity to receive a polish whieh formed a perfeet mirror. The above number multiplied by 28, the highest atomic weight assigned to Si, gives the produet 4*93, while the law of Dulong and Petit requires the value 6' 25. In diseussing the eause of the anomalous atomic heat of silieium, Begnault pointed out that in order that it might enter into the law of the specifie heat of other elements, it would be necessary to write the formula of silicic acid Si^Oj ; it would then resemble that of nitric, phosphoric, and arsenic acid. The atomic weight of silieium would then be 35, and the prodnet of this number and the speeific heat would be nearly 6' 25, whieh agrees with the analogous products which other simple bodies give. By assigning to silieium a higher atomic weight * ‘ Annales de Chimic et de Physique,’ tome Ixiii. pp. 24-31 (1861). 140 MR. H. WILDE ON THE and a polyhasic character like that of phosphorus or nitrogen^ Regnault remarked that it is easy to explain the existence of the great number of silicates which nature presents in well-defined and beautiful crystals^ and to understand the existence of the natural hydro-silicates. Whichever view chemists may ultimately adopt in regard to the constitution of silicic acid^ or whether its atomic weight be fixed at 3H7J 4H7, or 5^7^ silicium will still retain its position as the second member of the series Yi'jn. The chief properties which distinguish the elements of the series are their high fusing-point, their occlusive affinity for hydrogen, and their passivity in the presence of ordinary reagents, to which iron, under peculiar con- ditions, forms no exception. In regard to their occlusive affinity for hydrogen, the relation of nitrogen to iron and palladium may explain the existence of the ammonium amalgam, in which nitrogen and hydrogen are held together in the nascent state by means of mercury. The formation of silicium hydride by electrolysis, in a manner analogous to that of the ammonium amalgam, would also indicate for silicium a similar occlusive affinity for hydro- gen to that possessed by nitrogen. Although gold in some recent classifications of elements has been separated from the platinum metals, yet, in its primary qualities, it exhibits closer analogies with them than with the members of any other series, and there is no other place vacant in the groups which an element with the atomic weight and physical properties of gold would fit. The constant association in nature of quartz, hematite, and specular iron ores with gold and platinum is a fact fully recognized by chemical geologists*, and * BischofFs ‘ Cliemical and Physical Geology,’ vol. iii. p. 5 34. Cavendish Soc. Works. Murchison’s ‘Siluria,’ chap. xvii. pp. 433-439. ORIGIN OF ELEMENTARY SUBSTANCES. 141 confirms the positions assigned for Si, Fe, and An, in the table as forms of H7^^. The remarkable resemblance which the members of the iron group have to one another, while their atomic weights are nearly, if not exactly the same, has long been a subject of much interest to philosophical chemists, and if the views which I have enounced respecting the formation of elementary species by condensation be correct, the cause of these resemblances admits of a possible explanation. From the great abundance and wide distribution of iron in nature, it is probable that the vapour of this element would form a zone of considerable depth ; the upper and lower regions of whieh, by differences of pressure and temperature, might produce allotropic varieties before a definite change to the next higher members in the series occurred. When once varieties of an element were formed, these varieties would be propagated through suecessive condensations into the next higher members of the series, just as they are found in the palladium and platinum groups of metals. Chemists have already obser- ved that eaeh of the metals of the palladium group appears to be more especially correlated with some particular member of the platinum group, and all are found associated together naturally in the metallic state. If the four members of the platinum group be considered the analogues of the corresponding members of the iron and palladium groups, it will be seen that one of the members of the latter group is missing. M. Sergius Kern, a Russian chemist, has recently discovered a new metal which he classifies with the platinum group, and has given to it the name of davyum*. The specific gravity of the new metal was found to be 9‘39, and pre- Comptes Eencliis, teme Ixxxv. pp. 72, 623, 667 (1877). 142 MR. H. WILDE ON THE liminary experiments on its equivalent show that it is greater than loo and supposed to be 150-154. Now the specific gravity and atomic weight of the new metal exclude it from the platinum group, and also from the iron group of metals; davyum is therefore the missing element in the palladium group, and will have a specific gravity of about ii, and an atomic weight of 105 ; or the same density and equivalent as the other members of the group. The state of aggregation of the small quantity of the new metal obtained by M. Kern, may have prevented the same specific gravity being found for it as for the other members. Although I have designated the highest members of the series H7W, as the platinum group, yet if the slight differences in their atomic weights and physical properties admit of explanation by the assumption of their being allotropic varieties of each other, then gold, palladium, and iron, may stand at the head of their respective groups, and determine the species to which the varieties belong. It is no objection to the theory of the members of the respective groups being varieties of each other, that they cannot by any known power of analysis be resolved into their primaries, as the same objection would apply to the natural varieties of organic species determined by natura- lists. We have seen that the quantivalence of most of the members of the preceding groups Hw, H6I^, is in some way correlated or dependent on the construction of the typical molecules at the head of each series ; but in the series the only element which is known to he septi- valent is manganese, but the relation which this metal has to the iron gronp, and bearing in mind that the determination of the highest quantivalence of elements is limited by the knowledge of chemists at particular times. ORIGIN OF ELEMENTARY SUBSTANCES. 143 and is only arrived at after mueli researeh^ the septivalency of , manganese indicates a much higher quantivalence for the other members of the series Hyw than has up to this time been accorded to them. I have hesitated to introduce hypothetical elements alternating with the iron, palladium, and platinum groups, as the regular sequence of elementary forms is broken by varieties, and from the density of the typical molecule Hy, it may be that the members of this series are limited to those shown in the table. The density of the typical molecule H6/^ may also explain the absence of members alternating with Cr, Mo, and W, and I have therefore only introduced one hypothetical element in this series, the analogue of Cr, with the atomic weight=i44. Considering how nearly the numbers representing the molecular constitution and atomic weights of the members in homologous positions in the higher groups approximate, the idea occurs that the subsequent condensations of these higher groups are in some way influenced or determined by the antecedent condensations of homologous members of the lower groups, and may be the cause of the departure in the higher groups from the simple ratios and multiple relations observed amongst the elements of the series H/* and H2I^. Such perturbations would appear to be similar to those which the planetary bodies exercise on each other to produce modifications in the forms of their orbits, but I leave this question to the further consideration of physi- cists and astronomers. The complete parallelism of the halogens and oxygens to each other, and their intensely electro-negative character, point irresistibly to the conclusion that at one period of their history these elements existed in a state of isolation from all the others. How, and under what conditions, they acquired their electro-negative properties can in the 144 MR. H. WILDE ON THE present state of knowledge be only a matter of conjecture ; but it may be conceived that these elements may have existed originally in the form of a ring or rings revolving within the moon^s orbit, but high above the incandescent terrestrial surface, probably before the lunar substance changed from the annular to the globular form. These intra-lunar rings may have gradually acquired their electro- negative properties by lunar and terrestrial induction, and by the loss of their primitive heat by radiation into space. Their orbits being too near the earth to permit the rings to assume the spheroidal form, they would upon rupture become incorporated with the positive terrestrial elements, and remain dissociated till the temperature of the mass was sufficiently reduced to enable chemical combination to take place. If Draper^s discovery of oxygen in the sun be confirmed, the hypothesis of the existence of an intra- mercurial ring of negative elements which subsequently united with the solar positive elements is at least as probable as the assumption of an intra-mercurial planet which has recently been discussed by astronomers. May not the sudden increase in the brightness of variable stars like T Coronse, Nova Ophiuchi, 1848, and Nova Cygni, 1876, be due to the intense heat generated by the union of rings of negative elements with the central bodies round which they revolve, or by the condensation of lower into higher forms of elementary species. All the positive forms of H2w, except glucinum and lead, are well-ascertained solar elements, and the remarkable relations which the members of this group have to those of render it highly probable that, besides sodium and copper, other members of Hw are present in the solar atmosphere. From the fact that aluminum, titanium^ chromium, and the irons are solar species, higher forms of these elements may also be expected to be found in the sun. To face p. 144] H4w I H6/ H6» I H7-; [2 — — lb 7 — = 32 .2 ! Ti = 48 9 Ge = 72 B = 10 P = 30 V = As = 50 75 = 18 = 36 Cr = 54 N = 14 Si = 35 Fe -- 56 Mn = 56 Ni = 56 Co — 56 56 55 58 58 Zr 92 Sn =116 La = 140 — =165 D =188 V = 240 Nb= 95 Sb == 120 — = 140 — =165 Ta .= 185 Bi =210 Mo = 96 = 144 Pd =105 Eh 105 Eu = 105 Da = 105 106 105 105 W =186 Au = 196 Pt = 196 Ir = 196 Os =196 196 197 197 198 To face p. 144] I + Hrt - + H2w - i 13.371 H4ra H5» H6n 1 H.7n 2 Li = '7 1 G1 = 8 C = [2 — =16 B = 10 — = 18 N = 14 3 Na = 23 F - 19 Mg = 24 0 = 16 A1 = — = 32 P = 30 — = 36 Si = 35 4 K = 39 Cl = 35 Ca = 40 S = 32 Sc = 1-2 Ti = 48 V = 50 Cr = 54 Fe = 56 Mn= 56 Ni = 56 Co = 56 5 Cu = 62 Zn = 64 Ce = 39 Ge = 72 As = 75 6 Rb = 85 Br = 81 Sr = 88 Se = 80 Ga = )6 Zr = 92 m= 95 Mo = 96 7 Ag- =108 Cd =112 Y =i 23 Sn =116 Sb =120 Pd = 105 Rh =105 Ru = 105 Da = 105 8 Cs =131 I = 127 Ba - 136 Te = 128 111 = I 50 La = 140 — = 140 — =144 9 — =154 — = 160 E =1 77 — =165 — =165 10 — =177 — = 184 T1 =2 D =188 Ta =185 W =186 Au = 196 Pt = 196 Ir =196 Os =196 1 1 Hg =200 i Pb =208 Th =21 31 U =240 Bi =210 56 55 58 58 ro6 105 105 196 197 197 198 ORIGIN OF ELEMENTARY SUBSTANCES. 145 The numerical relations of the atomie weights to which I have directed attention^ and the brief outline of a theory of the origin of elementary species which I have founded upon them^ give new force to the doctrine of the trans- mutable nature of elementary substances. But when the synthetical formation of organic compounds is regarded as the greatest triumph of modern chemical science^ the prob- lem of building up the higher elements from the lower may well be deemed insoluble^ as they have been formed under cosmical conditions of which we have little or no acquaint- ance. Very different, however, is the aspect of the problem of resolving the higher elements of each series into their respective types or into hydrogen. For just as by the application of heat the higher members of homologous series are resolved, through their lower members, into their ultimates, so may it be expected that the elements themselves will, in their turn, give way to more powerful instruments of analysis. When it is considered that through the investigations of Dumas, Cooke, Odling, Mendeleeflf and others, nearly all the mathematical relations of the atomic weights to each other have been unfolded during the brief interval of thirty years, so that but few steps are now required to render the natural classification of the elements complete, the resolution of elementary species into their primordial ultimates would not appear to be far off. SER. TII. VOL. X. L 146 MR. H. WILDE ON THE VELOCITY X. On the Velocity with which Air rushes into a Vacuum, and on some Phenomena attending the Discharge of Atmospheres of Higher into Atmospheres of Lower Density. By Henry Wilde, Esq. Read October 20th, 1885. Considering the present condition of our knowledge respecting the mechanical properties of air and other gases, some apology might appear to be needed in bringing before this Society the results of an investigation touching some fundamental principles in pneumatics which for more than a century have been considered to rest on foundations as secure as the law^s of gravitation of the heavenly bodies. A survey of the history of the dynamics of elastic fluids will, however, show that, great as are the advances which have been made in this branch of science, the laws of the discharge of elastic fluids under the varied conditions of elasticity and volume are still left in much obscurity. The several circumstances which have combined to produce this anomalous state of our knowledge of this subject are: — (i) The application of the laws of discharge of inelastic fluids, without any modification, to those which are elastic; (2) the confusion of the quantity of the discharge of elastic fluids after leaving the vessel, with the velocity of discharge through the aperture in the vessel ; and (3) the want of a sufficient number of experiments, under varied conditions and through sufficient range of pressure, to compare with the deductions derived from theory. It has hitherto been assumed, as a leading proposition in pneumatics, that air rushes into a vacuum with the WITH WHICH AIll RUSHES INTO A VACUUM. 147 velocity which a heavy body would acquire by falling from the top of a homogeneous atmosphere of the same density as that on the earth^s surface; and since air is about 840 times lighter than water, if the whole pressure of the atmosphere he taken as equal to support 33 feet of water, we have the height of the homogeneous atmosphere equal to 27,720 feet, through which, by the free action of gravity, is generated a velocity of 1332 feet per second. This, therefore, is the velocity with which air is considered to rush into a vacuum, and is taken as a standard number in pneumatics, as 16 and 32 are standard numbers in the general science of mechanics, expressing the action of gravity on the surface of the earth. Now, so far as I am aware, no experiments have hitherto been made directly proving this important pro- position. It is true that attempts have been made to determine the initial velocity by discharging air at extremely low pressures into the atmosphere ; but, apart from the conditions of the discharge into the air and into a vacuum being different, the history of physical science shows that it is unphilosophic to predicate absolute uniformity of any law through the order of a whole range of phenomena of the same kind ; as nature is full of surprises when pushed to extremes, or when interrogated under new experimental conditions. It was long ago shown by Faraday* that, in the passage of different gases through capillary tubes, an inversion of the velocities of different gases takes place under different pressures, those which traverse quickest when the pressure is high moving more slowly as it is diminished. Thus, with equal high pressures, equal volumes of hydrogen gas and olefiant gas passed through the same tube in 57" and ^35"' 5 respectively; but equal volumes of each passed * Quarterly Journal of Science, 1818, vol. yii. p. 106. L 2 148 MR. H. WILDE ON THE VELOCITY through the same tube at equally low pressures in 8' is" and 8' 1 1" respectively. Again, while the velocities of discharge of inelastic fluids are as the square roots of the heads, some mathematicians have justly considered that this law does not apply to those which are elastic, and have assumed with good reason (though what appears unlikely at first sight) that the velocity of air discharged into a vacuum is the same for all pressures. But whatever differences of opinion there may be amongst natural philosophers on this point, all are agreed in estimating the quantity of air discharged from a higher into air of a lower density, from the difference between the two densities, as in the similar case of the discharge of inelastic fluids, by the difference or effective head producing the pressure. This mode of determining the amount of the discharge from a higher to a lower density, like that of the velocity of the atmosphere into a vacuum, has not, so far as I know, been made the subject of experiment through any considerable range of pressure. It therefore appeared to n;e that, as each gas has its specific velocity of discharge, such a series of experiments might be useful in confirming and extending our knowledge of the dynamics of elastic fluids. In the course of these experiments 1 have met with some results which I thought of sufficient importance to bring before the Society. The apparatus employed in this investigation consisted of two strong cylinders of cast iron, shown in the engraving. The small cylinder. A, had an internal capacity of 573 cubic inches, while the large cylinder, B, had a capacity of 8459 cubic inches, or about fifteen times the capacity of the cylinder A. To the top of this cylinder was fitted a syringe for condensing the air up to nine atmospheres, and also a Bourdon^s pressure-gauge of an improved construction, graduated through every pound of WITH WHICH AIR RUSHES INTO A VACUUM. 149 the above pressure. The aceuracy of this gauge was tested in my presence by the constructors, Messrs. Budenberg and Co., through the whole range of pressure. by comparing its readings with a column of mercury of equivalent height. For pressures of 15 pounds above, and for pressures below the atmosphere, a mercurial gauge and 150 MR. H. WILDE ON THE VELOCITY a Bourdon^s vacuum-gauge were employed, the readings of which were compared with each other : 30 inches of mercury were considered equal to one atmosphere, and 2 inches of mercury to one pound of pressure. The upper part of the glass tube of the mercurial gauge was fitted with a brass cap and screw-stopper, so that it could readily he used as a pressure-gauge, or as a vacuum-gauge when required. The diseharging arrangement on the cylinder A consisted of a stopcock and union for securing a thin plate, through which the discharge was made. The orifice ’^u the plate opened as required, either directly into the atmosphere or into the end of a short iron tube two and a half inches internal diameter, eommunicating with the bottom of the cylinder. The thin plate was a small disk of tinned iron, three quarters of an inch in diameter and one hundredth of an inch in thickness. The centre of the disk was pierced with a circular hole two hundredths of an inch in diameter. The size of the hole was accurately determined by means of a wire expressly drawn down to the above diameter; the wire being calibred by one of Elliott’s micrometer-gauges, divided into thousandths of an inch. The hole in the plate was enlarged so as to fit tightly the gauged wire, and the burrs on each side of the hole were carefully removed, as this small amount of projection, as Dr. Joule has shown*, exercises a notable influence on the rate of discharge through apertures in thin plates. The general reasonings, and the inferences drawn from the experiments to be described, are based on Boyle and Mariotte’s law of the density of a gas being as the pressure directly, and the volume as the pressure inversely for constant temperatures. Memoirs of the Manchester Literary and Philosophical Society, vol. xxi. WITH WHICH AIR RUSHES INTO A VACUUM. 151 I have said that the capacity of the cylinder A was 573 cubic inches^ which represents the same number of cubic inches of air in the vessel at atmospheric pressure of 1 5 lb. on the square inch ; and, generally, n times 573 cubic inches of air forced into the cylinder would be the equivalent of n atmospheres of absolute pressure. In converse manner, 5 lb. of pressure, or one third of an atmosphere, is the equivalent of one third of 573 cubic inches, or the equivalent of 19 1 cubic inches of air at atmospheric pressure ; and, generally, 5 lb. of pressure is the equivalent of 191 cubic inches of air at atmospheric pressure and for all the higher pressures. The mode of experiment was as follows : — Air was forced into the cylinder to the required density, and after the heat of compression had subsided, the time of each 5 lb. reduction of pressure was taken by means of a half-seconds pendu- lum, commencing its oscillations at the moment of dis- charge; and the stopcock was suddenly closed, and the number of oscillations noted for every definite discharge and reduction of 5 lb. of pressure. In my earlier experi- ments, it was found that when the air was compressed to nine atmospheres, and successive reductions of 5 lb. were made to the lowest pressure, the cooling of the air pro- duced a notable effect in diminishing the rate of discharge. By commencing the experiments with the lower pressures and increasing them by 10 lb. successively after each dis- charge of 5 lb., the changes of temperature attending the changes of density of the air were kept within the limits of 5 lb. of pressure till the highest density was attained. The small changes of pressure attending each discharge by the addition and abstraction of heat to and from the cylinder were after a little practice easily corrected, so that each discharge may well be considered as having been made under conditions of constant temperature. The 152 MR. H. WILDE ON THE VELOCITY large cylinder B was first used as a vacuum-cliamber to receive the discharge from the small cylinder. The chamber was fitted with an exhausting pump and suitable vacuum-gauges^ and the pressure within the chamber was reduced to six tenths of an inch of mercury ; and that degree of vacuum was maintained during the experiments. The following Table shows the velocity of air flowing into a vacuum^ as deduced from the time and difference of pressure for every 5 lb. from 135 lb. to 5 lb. absolute pressure. The velocities of the first column are deduced from actual experiments, and in the next column the velocities are calculated from the difference of the area of Table I. — Discharge into a Vacuum o*6 inch Mercury. Barometer 29*42. Thermometer 54° F. Absolute pres- sure, in pounds per square inch. Time of discharge, in seconds. Velocity, in feet per second. Velocity coefficient ■62. 135 7'5 750 1210 130 775 753 1214 125 8*0 759 1225 120 8-5 743 1198 ”5 9-0 734 1184 no 9‘5 726 II7I 105 10*0 724 1168 100 io'5 722 1165 95 I 1*0 725 1169 90 12*0 703 1134 85 13-0 688 I 109 80 14*0 678 1094 75 15-0 675 1089 70 16-5 657 1060 65 i8'o 650 1048 60 20*0 632 1020 55 22*0 628 lOI I 50 24' 5 620 1000 45 27*0 624 1007 40 31-0 613 985 35 36-0 602 971 30 43'o 589 950 25 53'o 573 924 20 bq'o 550 887 15 97-0 522 842 10 1700 446 720 WITH WHICH AIR RUSHES INTO A VACUUM. 153 the discharging orifice and the vena contracta by applying the hydraulic coefficient •62. From this Table it muII be seen that the time of discharge of 5 lb. from 135 lb. absolute pressure is 7*5 seconds. Now, as 5 lb. pressure is the ~ part of the total pressure. ^ 7 ^ we have = cubic inches of air from 135 lb. 27 pressure discharged into the vacuum chamber in 7*5 seconds : or, in another form, since 5 lb. and 19 1 cubic inches of air at atmospheric pressure are equivalents, so 19 1 cubic inches condensed at 9 atmospheres =2i'22 cubic inches of discharge, as in the above calculation. Again, we have for a cubic inch extended into a cylinder 0’02 of an inch in diameter (the size of the dis- charging orifice), 265-25 feet x 21-22 = 5628 feet. Hence y_^628^eet _ second for the discharge of 7-5 seconds ' air from 135 lb. to 130 lb. into a vacuum through a hole in a 7^0 thin plate. Or V = ^^=i2io feet per second when the orifice is formed to the contracted vein. By the like method of calculation the velocities for the discharge of of each 5 lb. of pressure from 135 lb. to 10 lb. have been found. The velocity with which air rushes into the vacuum, as seen from the table, is considerably less than that which has hitherto been assigned to it by theory, and is not constant for all pressures, as might have been expected from the known ratio of elasticity and density : the difference in the velocities between each discharge for the higher pressures, as will be seen, is so small as to be exceeded by experimental errors. The amount of this difference will, however, appear more clearly when we are 154 MR. H. WILDE ON THE VELOCITY considering tlie velocity of air discharged into the atmos- phere. Meanwhile I may remark that the velocities increase with the pressures by small asymptotic quantities^ so that the theoretic velocity of 1332 feet per second would he obtained at a pressure of 40 atmospheres if the law of Boyle and Mariotte held good for so high a density. While the rate of each discharge may he considered approximately uniform for the higher pressures, the initial and terminal velocities of each discharge of 5 lb. for the lower pressures would he much different. This is specially noticeable for the velocity (842 feet per second) assigned to atmospheric pressure of 15 lb. ; and as it was a matter of much interest that this important constant of nature should be determined with all the accuracy attainable, experiments were made to ascertain the velocity of dis- charge for every pound of pressure from 15 lb. to 2 lb. In these experiments the readings were taken from the mercurial gauge, and the vacuum in the chamber was reduced to 0’4 of an inch of mercury. The results obtained are shown in the Table. Table II. — Discharge into a Vacuum 0*4 inch Mercury. Barometer 29’q6. Thermometer 60° F. Absolute pres- sure, in pounds per square inch. Time of discharge, in seconds. Velocity, in feet per second. Velocity- coeiBcient •62. 15 i6‘o 633 102 1 14 17-5 621 lOOX 13 19*0 614 990 12 21*0 606 977 1 1 23-0 600 968 10 25-5 596 961 9 28-5 593 956 8 32’5 584 942 7 37'5 577 931 6 45-0 563 908 5 55-0 559 901 4 70*0 542 874 3 102*0 497 802 2 i8o'o 421 679 WITH WHICH AIR RUSHES INTO A VACUUM. 155 By a calculation similar to that for the higher pressures, we obtain for the initial velocity with which the atmos- phere rushes into a vaeuum through a hole in a thin plate V = X = 622 feet per second, 15 16 ^ or ()22 V = 1021 feet per second for the contracted vein. •62 ^ That the dilferenees between the theoretic and experi- mental velocities was not caused by the friction of the stream of air against the circumference of a smaller orifice being greater in proportion to that of the eireumference of a larger orifiee, was proved by diseharging air of 15 lb. pressure through a hole one hundredth of an inch in diameter in another similar thin plate, when the times of discharge through the short range of i lb. of pressure were found to be in the ratio of 4 to i, or inversely as the areas of the orifices. Taking into further account the difference between the initial and terminal velocities due to the reduction of pressure from 15 lb. to 14 lb., the results of these experi- ments show that with an absolute pressure of 30 inches of mercury, and at a temperature of 60° Fahrenheit, the atmosphere rushes into a vaeuum with a velocity not greater than 1050 feet per second, or less than the velocity of sound. Some anomalous rates of diseharge which I obtained when air of different densities was discharged into the atmosphere, induced me to repeat the experiments with the same apparatus and under precisely the same con- ditions as those which had been made into a vacuum as 156 MR. H, WILDE ON THE VELOCITV Table III. — Discharge into the Atmosphere. Barometer 30*1 7. Thermometer 59° F. Effective pres- sure, in pounds per square inch. Time of discharge, in seconds. Apparent velocity, per second. Velocity- coefScient •62. 15 8*0 1266 2043 14 8-25 1318 2126 13 8-5 1373 2214 12 9-0 1413 2280 11 9‘5 1454 2345 10 10*0 1519 2450 9 10-5 1609 2595 8 II-5 1652 2664 7 I2'5 1734 2797 6 13-5 1876 3026 5 15-5 1985 3202 4 17-5 2110 3403 3 22'0 2300 3710 2 29*0 2616 4219 above described. The results are shown in Tables III. and IV. On comparing the times of discharge in Table III. and the velocities calculated therefrom with the times and velocities in Table II., a remarkable difference will be observed in them for the same effective pressures. Thus, the velocity of discharge from 15 lb. to 14 lb. appears to be double that assigned to the same pressure when the discharge is made into a vacuum ; while in the discharge from 2 lb. to I lb. (the lowest pressure in the Table) the velocity appears to be more than six times greater, or 4219 feet per second. No less remarkable than this apparent increase in the rate of discharge is the complete inversion of the order of the velocities as compared with those when the discharge was made into a vacuum for the same effective pressure. Now, we have knowledge of several causes competent to diminish the velocity of air of constant temperature flowing into the atmosphere, but none to increase the velocity except the form of the aper- WITH WHICH AIR RUSHES INTO A VACUUM. 157 ture^ which in this case remained unchanged. Recogniz- ing the fact that when air of 15 lb. effective pressure was discharged into the atmosphere the cylinder actually con- tained two atmospheres of absolute pressure^ we are led to the conclusion that the phenomenal increase in the rate of discharge observed is caused by the external atmosphere acting as a vacuum, and offering no resistance to the dis- charge into it of air of 15 lb. pressure, which thereby be- comes 30 lb. effective pressure. The velocity of air of 1 5 lb. effective pressure discharged into the atmosphere based on this conclusion is 1021 feet per second, the same as the velocity found for the discharge into a vacuum. For effective pressures below 15 lb. the velocities are com- pounded of the rate of discharge into a vacuum, and the Table IV. — Discharge into the Atmosphere. Barometer 29’64. Thermometer 58° F. Effective pressure, in pounds per square inch. Time of dis- charge, in seconds. Apparent velocity, per second. Velocity- coefficient •62. 120 7'5 843 1360 "5 775 852 1374 I 10 8-0 862 1390 105 8-5 852 1374 lOO 90 843 1 360 95 9‘5 842 1 360 90 lO'O 843 1360 85 io'5 851 1372 1 80 I i‘o 863 1392 75 IZ'O 844 1362 70 13*0 836 1348 65 i4‘o 833 1344 60 15-0 843 1 360 55 i6'5 837 1350 50 i8'o 843 1360 45 20‘0 843 1360 40 22'0 863 1392 35 24-5 886 1429 30 z7'o 935 1509 25 3ro 980 1581 20 36-0 1053 1699 15 43-0 1178 1900 1 10 58*0 j 1311 21 14 I 158 MR. H. WILDE ON THE VELOCITY resistance of the atmosphere without any regular ratio^ but approximating to the square roots of the pressures. That the atmosphere acts as a vacuum to the discharge of air into it of 15 lb. effective pressure^ is further evident from the results obtained, and shown in Table IV. In this Table it will be observed that the times of each discharge from 120 lb. to 15 lb. effective pressure into the atmosphere are identical with the times of discharge from 135 lb. to 30 lb. absolute pressure into a vacuum. Hence we are able to formulate and prove the general proposition that the atmosphere acts as a vacuum, and offers no resist- ance to the discharge of air of all pressures above two absolute atmospheres. Although the times of discharge for each reduction of 5 lb. of pressure, as we have seen, are the same as those for pressures one atmosphere higher, when the discharge was made into a vacuum, yet it seemed to me that a table showing the apparent velocities due to the effective pressure would be useful as exhibiting some further points of interest, and revealing the fallacy involved in estimating the velocities from the effective pressures. On comparing the velocities of each discharge from 120 lb. to 40 lb., it will be seen that the theoretic velocity of 133^ second is as nearly attained as the units of pressure and time adopted in these experiments would permit. We have therefore in the Table a measure of the difference of the theoretic and experimental velocities with which air rushes into a vacuum by the same method of calculation. This difference, as will be seen, amounts to exactly one atmos- phere of pressure. For each reduction of 5 lb. from 120 lb. to 40 lb. the times of discharge are inversely as the pressures ; and as the density of the issuing stream of air diminishes in the same proportion, the velocity of discharge is the same for WITH WHICH AIR RUSHES INTO A VACUUM. 159 all the pressures from 120 lb. to 40 lb., as shown in the Table. Hence it appeared to me at the commencement of this investigation, that the theoretic and experimental velocities with which air rushes into a vacuum were rigorously exact. The anomalous and apparent increase in the velocities from 40 lb. to 10 lb., however, led me to suspect that the atmosphere in some manner affected the results, and induced me to make the discharge into a vacuum with the results shown in Table I. That the phenomenal rate of discharge which I have described should not hitherto have manifested itself in some form, or be associated with some facts explanatory of it, would indeed be surprising considering the varied circumstances in which the discharge of elastic fluids comes into play. Hence, it has long been known that a jet of air issuing from an aperture in a vessel produces a rarefaction of the atmosphere near to the discharging- orifice. This phenomenon was first observed on a large scale by Mr. Eichard Roberts in the year 1824, and is described in a paper read before this Society in 1828*, Roberts noticed that when a valve was placed over an aperture in a pipe used for regulating a strong blast of air for blowing a furnace, the valve, instead of being blown off by the force of the blast, remained a short distance from the aperture, and required considerable force of the hand to remove it to a further distance. Subsequent experiments showed that the adhesion of the valve was caused by the partial vacuum formed between the valve and its seating by the expansion of the issuing air. These experiments were repeated and extended by Mr. Peter Ewart to similar effects produced by the discharge of steam * Memoirs of the Literary and Philosophical Society, 2nd series, vol. v. p. 208. 160 MR. II. WILDE ON THE VELOCITY through various apertures. Some of these experiments were deseribed before this Society^ and afterwards published in the Philosophieal Magazine in 1829*. The degree of rarefaetion produced by the discharge of air and high- pressure steam was carefully measured by Ewart by means of gauges inserted in different parts of the jet. He also noticed the sudden fall of temperature from 292° to 189° F. in the rarefied part of the jet when steam of 58 lb. pressure was discharged into the atmosphere. Sir William Armstrong also, in his experiments on Hydro-electricity in the year i842t, described a singular effect of a jet of steam by which a hollow globe made of thin brass, from tw'o to three inches in diameter, remained suspended in a jet of high-pressure steam issuing from an orifice; and when the ball was pulled on one side by means of a string, a very palpable force was found requi- site to draw it out of the jet. It is abundantly evident from these experiments, that whenever elastic fluids escape into the atmosphere a partial vacuum is formed near to the discharging orifice, the degree of vacuum depending on the density of the issuing stream. EwarEs ingenious explanation, that the vacuous space formed near the discharging orifice is caused by the joint action of elasticity and momentum of the suddenly released particles repelling each other beyond the distance necessary to produce equilibrium with the external pressure, has a high degree of probability ; but that this vacuous space should have the effect of increas- ing the rate of discharge could only be ascertained, as we ^ “ Experiments and Observations on some of the Phenomena attending the Sudden Expansion of Compressed Elastic Fluids.” t “ On the Efficacy of Steam as a Means of producing Electricity, and on a Curious Action of a Jet of Steam upon a Ball,” Phil. Mag. ser. 3. Tol. xxii. p. I. WITH WHICH AIR RUSHES INTO A VACUUM. 161 have seen^ by a direct comparison^ under like conditions, with the amount of the discharge into a vacuum. Having established the fact that the atmosphere acts as a vacuum to the discharge of air of all pressures above two atmospheres within the range of my experiments, it appeared to me that this phenomenon might only be a particular case of a general law of the discharge of elastic fluids, and that it would be interesting to know through what range of relative pressures in two vessels the one would act as a vacuum to the other. With this object air was compressed into the large receiving cylinder from two up to eight atmospheres absolute pressure, while air was condensed into a small discharging cylinder up to nine atmospheres of absolute pressure. The air was discharged from the same orifice as in the former experiments, and the time of discharge recorded for each atmosphere was for a reduction of 5 lb. of pressure. The results obtained are shown in the Table. Table V. In this Table the first vertical column to the left shows the number of atmospheres in the small cylinder from which each discharge of 5 lb. was made into the receiver. :^i SER. III. VOL. X. 162 MR. H. WILDE ON THE VELOCITY The ordinal numbers at the bead of the table indicate the atmospheres in the receiver when the discharge was made, eommencing with vaeuo ; and the time of each discharge, in seconds, is shown against the pressure in the discharg- ing and receiving cylinders respectively. The times in the second and third vertical columns are obtained from those in Tables I. and IV., when the discharge was made into a vacuum and into the atmosphere. On examining these results, commencing with the lower pressures, it will be seen that for two atmospheres of absolute pressure, the time of discharge (43 seconds) was the same for a vacuum as it was when made into the atmosphere, as has already been demonstrated. It will also be seen that a pressure of two atmospheres in the receiver acts as a vacuum to four atmospheres in the discharging cylinder. This is evi- dent from the equality of the time (20 seconds) when the discharge was made into one atmosphere or into a vacuum. The like ratio will also be observed up to three atmo- spheres in the receiver, which act as a vacuum to the dis- charge of six atmospheres of pressure from the small cylinder. As the pressure in the receiver was increased, the diminution of resistance of the recipient atmospheres becomes still more marked, till for the highest pressures we have the remarkable phenomenon of six atmospheres acting as a vacuum to the discharge of nine atmospheres of pressure. That this peculiar relation of the discharg- ing and receiving atmospheres has not reached its full limit will be obvious from a comparison of the numbers in the Table, from which it would appear that, for pressures exceeding those used in these experiments, the resistance of the recipient atmospheres would be still further dimin- ished correlatively with an increase in the amount of discharge. WITH WHICH AIR RUSHES INTO A VACUUM. 163 With the object of giving more completeness to this research, experiments were made to ascertain through what range of relative densities the air in two vessels would act as a vacuum to the other for pressures below that of the atmosphere. The results are shown in Table VI., which are arranged in the same manner as those in Table V. The times in the second vertical column are taken from those shown in Table II. Arhen the discharge was made into a vacuum for each pound of pressure, and the other times in the Table are those obtained for suc- cessive discharges into air of different densities below tlie atmosphere, the larger cylinder being again used as a receiver. Table VI. As equality in the times indicates equality in the quan- tities and velocities of the discharge for constant pressures, a simple inspection of the Table shows that, for discharg- ing pressures as low as 6 lb., the recipient air still acts as a vacuum up to half the density of the discharging stream, and the regularity of this law is maintained within the limits of 6 lb. and go lb. absolute pressure, as shown in Table V. For discharging pressures below 6 lb. the rela- tive times of discharge and the resistance of the recipient air increase •, and as we have already seen that the similar M 164 PROF. OSBORNE REYNOLDS ON times and resistances for discharging pressures above six atmospheres diminish, the continuity of regular law is broken at both ends of the series of pressures^ just as it is in the series of planetary distances and some other quauti- tative phenomena of nature. XI. On the Flow of Gases. By Professor Osborne Reynolds, LL.D., F.R.S. Read November 17th, 1885. I. Amongst the results of Mr. Wilders* experiments on the flow of gas, one, to which attention is particularly called, is that when gas is flowing from a discharging vessel through an orifice into a receiving vessel, the rate at which the pressure falls in the discharging vessel is independent of the pressure in the receiving vessel until this becomes greater than about five tenths the pressure in the discharging vessel. This fact is shown in tables iv. and v. in Mr. 'NYilde's paper : thus, the fall of pressure from 1 35 lbs. (9 atmospheres) in the discharging vessel is 5 lbs. in 7'5 seconds for pressures in the receiving vessel, ranging from one half-pound to nearly 5 or 6 atmospheres. With smaller pressures in the discharging vessel the times occupied by the pressure in falling a proportional distance are nearly the same until the pressure in the receiving vessel reaches about the same relative height. What the exact relation between the two pressures is when the change in rate of flow occurs is not determined * Proc. Manchester Lit. and Phil. Soc. Oct. zo, 18S5, or present vol. of Mem. p. 146. THE FLOW OF GASES. 165 in these experiments. For as the change comes on slowly, it is at first too small to be appreciable in such short in- tervals as 7'5 and 8 seconds. But an examination of Mr, Wilde’s table vi. shows that it lies between ‘5 and '53. This very remarkable fact, to which Mr. Wilde has re- called attention, excited considerable interest fifteen or twenty years ago. Graham does not appear to have noticed it, although on reference to Graham’s experiments it appears that these also show it in the most conclusive manner (see table iv., Phil. Trans. 1846, vol. iv. pp. 573- 632 ; also Beprint, p, 106). These experiments also show that the change comes on when the ratio of the pressures is between ’483 and ’531. R. D. Napier appears to have been the first to make the discovery*. He found, by his own experiments on steam, that the change came on when the ratio of pressures fell to *5 (see Encyc. Brit. vol. xii. p. 481). Zeuner, Fliegner, and Him have also investigated the subject. At the time when Graham wrote, a theory of gaseous motion did not exist. But after the discovery of the mechanical equivalent of heat and thermodynamics, a theory became possible, and was given with apparent mathematical completeness in 1856. This theory ap- peared to agree well with experiments until the particular fact under discussion w^as discovered. This fact, however, directly controverts the theory. For on applying the equations giving the rate of flow through an orifice to such experiments as Mr. Wilde’s, it appears that there is a marked disagreement between the calculated and exjoe- rimental results. The calculated results are even more * The account of E. D. Napier’s expei’iments is contained in letters in the ‘ Engineer,’ 1867, xxiii. January 4 and 2 5. They were made with steam generated in the boiler of a small screw- steamer and discharged into an iron bucket, the results being calculated from the heat imparted to a constant volume of water in the bucket in which the steam was condensed. 166 PROF. OSBORNE REYNOLDS ON remarkable than the experimental ; for while the experi- ments only show that diminishing the pressure in the receiving vessel below a certain limit does not increase the flow, the equations show that by such diminution of pressure the flow is actually reduced and eventually stopped altogether. In one important respect, however, the equations agree with the experiments. This is in the limit at which diminution of pressure in the receiving vessel ceases to increase the flow, which limit by the equations is reached when the pressure in the receiving vessel is ‘527 of the pressure in the discharging vessel. The equations referred to are based on the laws of thermodynamics, or the laws of Boyle, Charles, and that of the mechanical equivalence of heat. They were inves- tigated by Thomson and Joule (see Proc. Roy. Soc., May 1856), and by Prof. Julius Weisbach (see ^ Civilingenieur,^ 1856) ; they were given by Rankine (articles 637, 637 a. Applied Mechanics), and have since been adopted in all works on the theory of motion of fluids. Although discussed by the various writers, the theory appears to have stood the discussion without having re- vealed the cause of its failure; indeed. Him, in a late work, has described the theory as mathematically satis- factory. Having passed such an ordeal, it was certain that if there were a fault, it would not be on the surface. But that by diminishing the pressure on the receiving side of the orifice the flow should be reduced and eventually stopped, is a conclusion too contrary to common sense to be allowed to pass when once it is realized ; even without the direct experimental evidence in contradiction, and in consequence of Mr. Wilders experiments, the author was lead to reexamine the theory. THE FLOW OF GASES. 167 2. On examining the equations, it appears that they contain one assumption which is not part of the laws of thermodynamics or of the general theory of fluid motion. And although commonly made and found to agree with experiments in applying the laws of hydrodynamics, it has no foundation as generally true. To avoid this assumption, it is necessary to perform for gases inte- grations of the fundamental equations of fluid motion which have already been accomplished for liquids. These integrations being effected, it appears that the assumption above referred to has been the cause of the discrepancy between the theoretical and experimental results, which are brought into complete agreement, both as regards the law of discharge and the actual quantity discharged. The integrations also show certain facts of general interest as regards the motion of gases. When gas flows from a reservoir sufficiently large, and initially (before flow commences) at the same pressure and temperature, then, gas being a nonconductor of heat when the flow is steady, a first integration of the equation of motion shows that the energy of equal elementary weights of the gas is constant. This energy is made up of two parts, the energy of motion and the intrinsic energy. As the gas acquires energy of motion, it loses intrinsic energy to exactly the same extent. Hence we have an equation between the energy of motion, i. e. the velocity of the gas, and its intrinsic energy. The laws of thermodynamics afford relations between the pressure, temperature, density, and intrinsic energy of the gas at any point. Substituting in the equation of energy, we obtain equations between the velocity and either pressure, temperature, or density of the gas. The equation thus obtained between the velocity and pressure is that given by Thomson and Joule ; this equation 168 PROF. OSBORNE REYNOLDS ON holds at all points in the vessel or the effluent stream. If, then, the pressure at the orifice is known, as well as the pressure well within the vessel where the gas has no energy of motion, we have the velocity of gas at the orifice ; and obtaining the density at the orifice from the thermodynamic relation between density and pressure, we have the weight discharged per second by multiplying the product of velocity with density by the effective area of the orifice. This is Thomson and Joule^’s equation for the flow through an orifice. And so far the logic is perfect, and there are no assumptions but those involved in the general theories of thermodynamics and of fluid motion. But in order to apply this equation, it is necessary to know the pressure at the orifice ; and here comes the assumption that has been tacitly made : that the pressure at the orifice is the pressure in the receiving vessel at a distance from the orifice. 3. The origin of this assumption is that it holds, when a denser liquid like water flows into a light fluid like air, and approximately when water flows into watei. Taking no account of friction, the equations of hydro- dynamics show that this is the only condition under which the ideal liquid can flow steadily from a drowned orifice. But they have not been hitherto integrated so far as to show whether or not this would be the case tvith an elastic fluid. In the case of an elastic fluid, the difflculty of inte- gration is enhanced. But on examination it appears that there is an important circumstance connected with the steady motion of gases which does not exist in the case of liquid. This circumstance, which may be inferred from integrations already effected, determines the pressure at the orifice irrespective of the pressure in the receiving vessel when this is below a certain point. THE PLOW OF GASES, 169 4. To understand this circumstance, it is necessary to consider a steady narrow stream of fluid in which the pressure falls and the velocity increases continuously in one direction. Since the stream is steady, equal weights of the fluid must pass each section in the same time ; or, if u be the velocity, p the density, and A the area of the stream, the joint product upk. is constant all along the stream, so that gpu W . where — is the mass of fluid which passes any section per second. In the case of a liquid p is constant, so that the area of the section of the stream is inversely proportional to the velocity, and therefore the stream will continuously con- tract in section in the direction in which the velocity increases and the pressure falls, as in flg. i, also flg. 2 a. In the case of a gas, however, p diminishes as the velocity increases and the pressure falls ; so that the area of the section will not be inversely proportional to u, but to u X p, and will contract or increase according to Avhether u increases faster or slower than p diminishes. As already described, the value of pu may be expressed in terms of the pressure. Making this substitution, it appears that pu increases from zero as p diminishes from a definite value until p=‘S^7Pi j after this pu diminishes to zero as p diminishes to zero. A varies inversely as pu, 170 PROP. OSBORNE REYNOLDS ON and therefore diminishes from infinity as jo diminishes from jo, till p=’S'^7Pi then A has a minimum value and increases to infinity asjo diminishes to zero, as in fig. 2. The equations contain the definite law of this variation, which, for a particular fall of pressure, is shown in fig. 2 a. For the present argument it is sufficient to notice that A has a mimimum value when p=' ^2"] ; since this fact THE FLOW OF GASES. 171 determines the pressure at the orifice when the pressure in the receiving vessel is less than '527^0,, that being the pressure in the discharging vessel. 5. If, instead of an orifice in a thin plate, the fluid escaped through a pipe which gradually contracted to a nozzle, then it would follow at once, from what has been already said, that when was less than *5277?,, the nar- rowest portion of the stream would be at N, for since the stream converges to N the pressure above N can be no- where less than '5277?,; and since emerging into the smaller surrounding pressure the stream would expand laterally, N would be the minimum breadth of the stream, and hence the pressure at N would be *5277?,. In a broad view we may in the same way look on an orifice in the wall of a vessel as the neck of a stream. But if we begin to look into the argument, it is not so clear, on account of the curvature of the paths in which some of the particles approach the orifice. Since the motion with which the fluid approaches the orifice is steady, the whole stream, which is bounded all round by the wall, may be considered to consist of a number of elementary streams, each conveying the same quantity of fluid. Each of these elementary streams is hounded by the neighbouring streams, but as the boun- 172 PROF. OSBORNE REYNOLDS ON daries do not change their position they may be considered as fixed. The figure (4) shows approximately the arrangement of such stream. But for the mathematical difficulty of inte- grating the equations of motion, the exact form of these streams might be drawn. We should then be able to determine exactly the necks of each of these streams. Without complete integration, however, the process may be earried far enough to show that the lines bounding the streams are eontinuous curves which have for asymptotes on the discharging-vessel side lines radiating from the middle of the orifice at equal angles, and, further, that these lines all curve round the nearest edge of the orifice, THE FLOW OP GASES. 173 and that the curvature of the stream diminishes as the distance of the stream from the edge increases. These conclusions would he definitely deducible from the theory of finid motion could the integrations be effected, but they are also obvious from the figure and easily verified experimentally by drawing smoky air through a small orifice. From the foregoing conclusions it follows, that if a curve be drawn from A to B, cutting all the streams at right angles, the streams will all be converging at the points where this line cuts them, hence the necks of the streams will be on the outflow side of this curve. The exact position of these necks is difficult to determine, but they must be nearly as shown in the figure by cross lines.' The sum of the areas of these necks must be less than the area of the orifice, since, where they are not in the straight line A B, the breadth occupied on this line is greater than that of the neck. The sum of the areas of the necks may be taken as the effective area of the orifice; and, since all the streams have the same velocity at the neck, the ratio which this aggregate area bears to the area of the orifice may be put equal to K, a coefficient of con- traction. If the pressure in the vessel on the outflow side of the orifice is less than •527^9,, this is the lowest pressure possible at the necks, as has already been pointed out, and on emerging the streams will expand again, as shown in the figure, the pressure falling and the velocity increasing, until the pressure in the streams is equal to p^, when in all probability the motion will become unsteady. If p^ is greater than '527791, the only possible form of motion requires the pressure in the necks to be p^, at which point the streams become parallel until they are broken up by eddying into the surrounding fluid (fig. 5), 174 PROF. OSBORNE REYNOLDS ON 6. There is another way of looking at the problem, which is the first that presented itself to the author. Suppose a parallel stream flowing along a straight tube with a velocity u, and take a for the velocity with which sound would travel in the same gas at rest, the velocity with which a wave of sound or any disturbance would move along the tube in an opposite direction to the gas would be a—u. If then a — u, no disturbance could flow back along the tube against the motion of the gas ; so THE FLOW OF GASES. 175 thatj however much the pressure might be suddenly dimi- nished at any point in the tube^ it would not atfect the pressure at points on the side from which the fluid is flowing. Thus_, suppose the gas to be steam, and this to be suddenly condensed at one point of the tube, the fall of pressure would move back against the motion, increasing the motion till u = a, but not further; just as in the Bunsen^s burner the flame cannot flow back into the tube so long as the velocity of the explosive mixture is greater than the velocity at which the flame travels in the mixture. According to this view, the limit of flow throiigh an orifice should be the velocity of sound in gas in the con- dition as regards pressure, density, and temperature of that in the orifice ; and this is precisely what it is found to be on examining the equations. 7. The following is the definite expression of the fore- going argument. The adiabetic laws for gas are : p being pressure, p density, r absolute temperature, and y the ratio of specific heats at constant pressure and constant density. The equation of motion, u being the velocity and x the direction of motion, is Y-» . . (I) or (2) Substituting from equations (i), C’’dp _ 7 Po r ^ 'o P 7-^ Po 176 PROF. OSBORNE REYNOLDS ON O' PoropJpV PoT^ \pi/ ’ (4) (5) Hence along a steady stream, since W is constant, equation (5) gives a relation that must hold between A and JO. dA. Differentiating A with respect to p and making zero, it appears y-» y-i 2/>, y ={y+l)p y , .... (6) or (7) p, V7+1/ For air 7=1 ’408. ^=-527. Pi (8) It thus appears that as long as p falls, the section con- tinuously diminishes to a minimum value when jo = ’527jo,, and then increases again. Substituting this value of p in equation (3), (9) (10) (11) / ^yppoT, (7+i)PoTo = A / (Pi^~w ^ (7+l)/^oVj0o/ ’ = A / ^ydPo ( p^-^ ( F Ay V (^yj^l)p\pj \p) Hence by equation (6), '=\/' 'igpoT JoTo ’ (12) THE FLOW OF GASES. 177 which is the velocity of sound in the gas at the absolute temperature r. It thus appears that the velocity of gas at the point of minimum area of a stream along which the pressure falls eontinuonsly is equal to the velocity of sound in the gas at that point. 8. From the equation of flow (5) it appears that for every value of A other than its minimum value, there are two possible values of the pressure which satisfy the equation, one being greater and the other less than '527i>i. It therefore appears that in a ehannel having two equal minima values of section A and C, as in flg. 6, the flow from A to B may take place in either of two ways when the velocity is such that the pressure at A and B is •527^0,, i. e. the pressure may either he a maximum or a minimum at C. In this respect gas differs entirely from a liquid, with whieh the pressure ean only he a maximum at C. 9. For air through an oriflee, since 1*408, when the pressure in the receiving vessel is less than '527^9,, the numerical value of U„, the velocity in the neek of the oriflee, is U„ = 997 (feet per sec.) ; . . . (13) * Tq SER. III. VOL. X. N 178 PROF. OSBORNE REYNOLDS ON and if the temperature is 57° F., as in Mr. Wilders expe- rimentSj Vn=I022. (14) Reducing this in the ratio of the density at the neek to the density in the discharging vessel_, I Pn={-5^7y\ ^,=•6345 i’ We have the reduced velocity U„— =650 (feet per sec.) (16) Pi Therefore the discharge will be given in cubic inches per second, KO being the effective area of the orifice, by PjQ — i2TJ„p,jKO 1 (17) = i2x65oKOJ Or, since the actual area in square inches 0 = *000314 sq. inches, Q = 2*44K (cubic inches per sec.). . (18) 10. In order to compare the experimental discharges with those calculated, it is necessary to know, besides the size of an orifice and the pressure and temperature of the discharging vessel, the coefficient of contraction or the effective area of the orifice. To obtain this from the equations requires that the terms depending on viscosity should be introduced, which renders the integration so far impossible. The only plan is to obtain this coefficient by comparing the theoretical results with the experimental. Such comparisons have been made by Prof. Weisbach for air ; and in the case of short cylindrical orifices such as that used by Mr. Wilde (a cylindrical hole through a plate having a radius equal to the thickness of the plate). THE FLOW OF GASES. 179 the value of K, the eoefficient of eontraetion^ given by Weisbach The Steam Engine/ p. 324^ E-ankine) is from •73 to ’833, Whether these are the real coefficients of contraction may^ however, well be doubted, as it is ex- tremely difficult to determine the experimental quantities of gas discharged owing to the great eflFect of slight varia- tions of temperature on the relations between changes of pressure and changes of temperature, such changes of tem- perature being almost necessarily incidental on changes of pressure. 1 1 . In Mr. Wilders experiments the pressure was allowed to fall in the discharging vessel during the discharges ; this would cause a corresponding fall of temperature, which would again cause heat to flow from the metal vessel into the gas within. It is difficult therefore to say what the change of tem- perature was except in the extreme cases. With the experiments on the highest pressure, however, the times 7'5 seconds, and the greatest possible falls of temperature 5°’5, were so small that the communication of heat from the walls of the receiver would have been very slight ; and hence we might expect that the discharges, calculated on the assumption of no communication of heat, would agree with the theoretical discharges multiplied by the real coefficient of contraction. This would be shown by an agreement in the successive coefficients obtained from the experiments with the higher pressures. On the other hand, with the lowest pressures the times were so con- siderable, 1 70 seconds, and the greatest possible falls of temperature (assuming no conduction, 94°) so great, that the communication of heat would have been very great and, considering the comparatively small mass to be heated (only one thirteenth of what it is in the highest experiments), might maintain the temperature approxi- n2 180 PROF. OSBORNE REYNOLDS ON mately constant after falling some considerable amount below tbe initial temperature. In these last experiments, therefore, it would be expeeted that the discharge might be estimated as taking place at nearly constant tem- perature. The intermediate experiments would give intermediate results. According to this view, for the high pressures, since and (19) (20) or putting V for the volume 573 eub. in. of the discharg- ing vessel. dp . Pi (21) where t is the time. Or, since tdp=$ lbs., K = Pit (22) Substituting the value of pj, in the first six experiments. we have : — v„ Y P” T n — • p- K. Velocity at orifice. 9 135 •825 1022 650 130 •826 „ >> 125 •83s >> 120 •820 „ ”5 •810 „ no 790 >> For the first three of these experiments K is nearly con- stant, showing that the conduction of heat eould have but slight if any effect, but the effect is decidedly apparent in the next three. THE FLOW OF GASES. 181 Proceeding now to the other extreme, and assuming that the temperature, after undergoing some diminution, remains constant, we have dp _Ql or, integrating. log,^=Vi, l0gPi-l0gPz = from which, taking the last three experiments in Table II., T- K. v„. V — V n — • Pi 4 •95 1022 650 3 •98 „ 2 •89 ,, ,, In these it appears that the values of K are approxi- mating to the value ‘825 ; but the great differences show that the temperature effect is far from having become steady, and are quite sufficient to explain the discre- pancies in the actual values of K. There is thus no reason to doubt but that '825 is about the real value of the coefficient of contraction for the orifice, and that the experimental results are quantitatively in accordance with the theory. Pipe No. I. — Water (see fig. 2 a, page 170). Vb= \J Pipe No. 2. — Gas. Vb=\/ ^W=\/^ T, + 4bi 32 + 461' 182 MR. H. WILDE ON THE EFFLUX OF AIR AS Air. ■41 3 (feet per second) 997 (feet per second) XII. On the Efflux of Air as modified by the Form of the Discharging Orifice. By Henry Wilde, Esq. In my former paper on the efflux of air, the hydraulic coefficient ‘62, as commonly applied to the discharge of elastic fluids through an oriflce in a thin plate, was taken as the value of the contmction of such orifice, and from this coefficient the highest velocities shown in the several Tables were deduced. A review of the results of my expe- riments hy Prof. Osborne Beynolds* led me to doubt the value of this coefficient, and to make further experiments with the object of determining the maximum rate of discharge from an orifice of the best form. Five disks of brass had each a hole drilled through its centre two -hundredths of an inch in diameter. Equality in the size of the holes was accurately determined by means of a standard cylindrical gauge. These disks I shall designate A, B, C, D, E. * Proceedings Manchester Lit. and Phil. Society, vol. xxv. p. 55, or present voh of Mem. p. 1 64. Read March 23rd, 1886. MODIFIED BY THE DISCHARGING ORIFICE. 183 The disk A was three diameters of the orifiee in thiek- ness^ and was equal to a plain eylindrical tube three diameters in length. Disk B was the same thickness as A, but the hole was coned out on one side to a depth of one diameter and a half. C was six diameters in thickness, and was coned out on one side to a depth of three diameters. D had a thickness of twelve diameters of the ori- fice, and was coned out on one side to a depth of six diameters. E was eighteen diameters of the hole in thickness, and was coned out on both sides to a depth of six diameters, which left a plain tube in the centre of the disk six diameters in length. The wide sides of the coned orifices were equal to two diameters, and their outer edges were rounded off to a conoid al form. The thin iron disk O was *007 of an inch in thickness, or nearly one third the diameter of the orifice, which was two-hundredths of an inch. One side of the orifice was chamfered to reduce the cylindrical part of the hole as much as possible to a sharp edge. The effect of the chamfering had, however, so small an effect in diminishing the rate of discharge that the determinations might have been taken from the cylindrical orifice without interfering with the general accuracy of the results. The mode of experimenting was similar to that already described. Air of an initial absolute pressure of 135 lbs. was discharged into the atmosphere through the orifice in the thin plate O, and through the orifices in A, B, C, D, E successively, and the times were recorded for the reduction of 10 lbs. from each of the atmospheres of pressure, as shown in the following Table ; — 184 MR. H. WILDE ON THE EFFLUX OF AIR AS Table I. — Discharge into the Atmosphere. Lbs. per square inch absolute pressure. Orifice in thin plate. 0 Plain tube orifice. A Conoidal orifice inside. B Conoidal orifice inside. 0 Conoidal orifice inside. D Double conoidal orifice. E Coeffi- cient for orifice. 0 sec. sec. sec. sec. sec. sec. 135 i5'5 14-5 i4'5 i4'5 15-0 i5’5 •935 120 17-5 i6'5 i6'5 i6'5 17*0 i7‘5 •943 105 20‘5 19*0 19*0 19*0 20*0 20*5 •927 90 25’0 23'5 23-5 23'5 24-5 25’0 •940 75 3i'5 29-5 29-5 29-5 3°'5 3i'5 •936 60 42*0 39'5 39'5 39‘5 41 "O 42*0 •940 45 58'o 54‘5 54' 5 54'5 56-5 58‘o •940 Mean coefficient for orifice in thin plate '937. An examination of this Table will show that the form of the orifice has very little infiuence on the rate of discharge of elastic finids compared with what it has on those which are inelastic. No difference was observable in these experiments in the rates of discharge through the orifices A^ and C, notwithstanding that A was a plain cylinder, and B and C were coned to a depth of half their thickness and formed tubes from three to six diameters in length. Moreover, although the results shown in the Tables were obtained with the coned sides of the orifices inside the vessel ; yet, when the sides were reversed, the rate of discharge through A, B, and C was only diminished by one-thirtieth part, and there was no difference in the rate of discharge through D whether the coned side of the orifice was inside or outside the vessel. Taking A, B, and C as the orifices producing the maxi- mum rate of discharge, we have '935 as the value of the coeflScient of discharge from an orifice in a thin plate for the highest pressure of 135 lbs. This value, as will be seen, is the same for all the pressures in the Table within MODIFIED BY THE DISCHARGING ORIFICE. 185 errors of observation and experiment, and the mean value of the coefficient for all the pressures is "937. Applying this coefficient to the velocity deduced in Table I. of my former paper for an orifice in a thin plate, we have for the maximum velocity with which air of 135 lbs. pressure rushes into a vacuum, before expansion, 7 V = =800 feet per second. '937 Some anomalous rates of efflux from the same orifice which were obtained when air of less than 15 lbs. effective pressure was discharged into the atmosphere, induced me to make a series of experiments on the discharge of air of an initial pressure of 15 lbs. through the same orifices as in the last experiments, and the times were recorded for each reduction of 2 lbs. of pressure. All the discharges were made with the conoidal orifices inside the vessel, but they were also made through C and D with these orifices outside the vessel. The results are shown in the following Table ; — Table II. — Discharge into the Atmosphere. Lbs. per square inch effec- tive pres- sure. Orifice in thin plate. 0 Plain tube orifice. A Conoidal orifice inside. B Conoidal orifice inside. C Conoidal orifice outside. C Conoidal orifice inside. D Conoidal orifice outside. D Double conoidal orifice. E Coeffi- cients for orifice. 0 sec. sec. sec. sec. sec. .sec. sec. sec. 15 i6'o 135 14*0 i4'o 14*0 14-5 14-5 15-0 •829 13 17-5 H'5 15-0 15-0 15-0 16-5 i6'o i6'o •829 I I 195 1 6*0 16-5 i6'5 16-5 i8-5 i8’o 17-5 •820 9 22'5 i8'o iS'5 i8-5 i8-5 20*5 19-5 19*0 •818 7 26'0 21*0 21'5 22*0 21-5 24*0 21-5 22*0 •808 5 330 260 26'5 27-5 26'5 30-0 25-5 27*0 •788 3 51-0 39-0 40-5 42-5 40-5 47-0 38-5 42-5 •765 186 MR. H. WILDE ON THE EFFLUX OF AIR AS On comparing the times of discharge through the several orifices among themselves,, and with those in Table I., a marked difference is observable in them. Thus the ratio of discharge through the tube orifice A and the orifice in a thin plate is greater than that for the same orifices in Table I., the coefficients for the highest and lowest pres- sures in this Table being "935 and '940 respectively ; whereas the coefficients for the same orifices in Table II. are "829 and *765 respectively. Again^ while there is little difference in the times of discharge from* the tubular orifices among themselves^ a remarkable change occurs duriag the fall of pressure from 15 lbs. to i lb., when the discharge is made through C and D with the conoidal orifices outside the vessel. The discharge through D from 15 lbs. to 13 lbs. is the same whether the conoidal orifice is inside or outside ; but in the latter position, as the pressure diminishes, the rate of discharge increases, till at the lowest pressure this increase amounts to 8*5 seconds, and exceeds the maximum discharge from the tube orifice A. A similar change is also noticeable in the rate of discharge through reversing the orifice C ; but as the change does not come on before the pressure is below 7 lbs., it is less marked than when the discharge is made through D. Suspecting that the phenomenal change in the rate of discharge for the same orifice was due to the varying resistances of the discharging and receiving atmospheres of pressure described in my former paper, the discharges from the orifices O, A, and D were made into a vacuum of I ’5 inch of mercury instead of into the atmosphere, and the times of discharge were recorded for each reduc- tion of I lb. of pressure. The results are shown in the Table : — MODIFIED BY THE DISCHARGING ORIFICE. 187 Table III. — Discharge into a Vacuum 1*5 inch Mercury. Lb. per Hole Plain Conoidal Conoidal Coefficient in thin tube orifice orifice for absolute plate. orifice. inside. outside. orifice. pressure. 0 A D D 0 sec. sec. sec. sec. 15 i6’o 15-0 i6‘o i6‘o •937 14 17-5 16-5 i8'o i8’o •943 13 19*0 17-5 20*0 20'0 *921 12 21*0 i9‘5 22*5 22*0 •928 II zyo 21’5 24-5 24*0 •935 10 25-5 24*0 27-5 27*0 •941 9 28-5 27*0 31-0 3°'5 ■947 8 32-5 31-0 35’5 35‘o •954 7 37'5 35'5 41*0 4o’o •947 6 45-0 42-5 49‘S 48-5 •944 5 55’o 52-5 63'o 6i’o •955 4 7o'o 67-0 8 1'o 79'° mean 3 102*0 I01‘0 I25’0 120*0 coefficient 2 i8o’o 1920 241‘0 224-0 •941 A comparison of the times of discharge through D with the conoidal orifice in both positions will show that they approach nearly to a ratio of equality. The phenomenal change in the rate of discharge from the same orifice was consequently due to the diminished resistance of the external atmosphere^ the conoidal form of the orifice in- creasing the amount of rarefaction above that obtained with a plain tube orifice. This conclusion is further evident on comparing the times of discharge from D in reversed positions from a pressure of 3 lbs. to i lb. ; for as the rarefaction in the vacuum-chamber was only reduced to I '5 inch of mercury the phenomenal change in the rate of discharge again presents itself, making a difference of 17 seconds in the times of discharge between the reversed position of the orifice for the lowest pressure. Comparing the times of discharge through the tube orifice A and the orifice O in the thin plate^ it will be seen that there is much less difference between them than for 188 EFFLUX OF AIR MODIFIED BY THE DISCHARGING ORIFICE. the same orifiees in Table II., the ratio agreeing very closely with those shown in Table I. for similar times of discharge. The approaching equality in the times of dis- charge through the tube orifice A and the orifice in the thin plate for the lower pressures is, no doubt, due to the friction of the issuing stream of air against the sides of the tube orifice. The effect of this friction for the lowest pressure, as will be seen, reduces the rate of discharge from the orifice A below that from the orifice in the thin plate. From the results of my previous experiments on the discharge of atmospheres of higher into atmospheres of lower density, the times and coefficients in Table I. and Table III. for the higher pressures may well be considered as having been obtained for discharges into a perfect vacuum, the difference in the coefficients for pressures below 10 lbs. in Table III. being entirely due to fric- tion of the issuing stream of air against the sides of the orifices. From the results shown in Tables I. and II. the maxi- mum rate of effiux is obtained from the orifices A, B, and C, and taking the efflux from these orifices as unity, the value of the coefficient for the efflux of air into a vacuum through an orifice in a thin plate is '937. These experiments also prove conclusively that the coefficients which have hitherto been applied to the efflux of air below 15 lbs. effective pressure derive nearly the whole of their value from the phenomenal changes of resistance between the discharging and receiving atmo- spheres, and not from the forms of the orifices and lengths of the adjutages, as in the discharge of inelastic fiuids. Applying the coefficient '937 to the velocity with which the atmosphere of 15 lbs. absolute pressure rushes into a vacuum, before expansion, as deduced in Table II. in my ON THE MORPHOLOGY OF PINITES OBLONGUS. 189 former paper^ we have V 633 •937 = 677 feet per seeond, or approximately one half the veloeity due to the height of the homogeneous atmosphere. The following approximate velocities with which atmo- spheres of several gases of 15 lbs. absolute pressure rush into a vacuum through an orifice of the best form, before expansion, have been calculated on the basis of Graham^s law of the velocities of efflux for equal pressures being inversely as the square roots of the specific gravities : — Air I'ooo X 677 = 677 feet per second. Oxygen o'950 X 677 = 643 „ „ Nitrogen i‘oi5 X 677 = 687 „ „ Hydrogen 3'8oo X 677 = 2572 „ „ Saturated steam... i’445 X 677 = 978 XIII. On the Morphology of Pinites oblongus (Abies oblonga of Lindley and Hutton) . By W m. Crawford Williamson, LL.D., F.R.S., Professor of Botany in Owens College. Eead April 6th, 1886. (Plate IX.) The question of the range of the Coniferse in time, and its important bearing upon the problem of evolution, sufficiently accounts for the interest attached to the dis- covery of cones belonging to that order in the various stratified rocks. Several such have already been met with, but amongst these a few objects have been obtained from the Palaeozoic and other Mesozoic rocks that are 190 PROF. W. C. WILLIAMSON ON THE either not eones of any kind^ or are those of Cycadean plants. At present the only remains which present a claim to Coniferous rank found in the Palaeozoic rocks are the Dadoxylons ; and even of these^ assuming that, as is most probable, they are Coniferous stems and not Cycadean, their affinities appear to be with the Taxinese, rather than with the more highly developed Ahietinese. Of the latter we discover no indisputable examples until we approach the base of the Cretaceous rocks *. Mr. Carruthers has expressed his conviction that no truly Coniferous cone has been found below the Kimmeridge clay. For evidence of the occurrence of true Coniferous cones in rocks of Mesozoic age, we are mainly indebted to Lindley and Hutton, Dr. Pitton, Dr. Mantell, and Mr. Carruthers. In a memoir published by the last-named author in vol. hi. p. 534 of the 'Geological Magazine,^ he reviewed those previously described by other observers, and added some new ones. Mr. Carruthers also described additional ones in vols. vi. and viii. of the same Magazine. One of the most interesting of the cones thus recorded it that figured by Lindley and Hutton in vol. ii. plate 137 of the 'Fossil Flora of Great Britain,^ under the name of Abies oblong a. The interest of this specimen resides in the fact that, in it, the large seeds are all preserved in their normal positions in the cone. A few weeks ago Professor Boyd-Dawkins showed me the half of a waterworn silicified cone, cut through longi- tudinally, which had been submitted to him by the Bev. H. H. Winwood, F.G.S., of Bath, but was the property of a Miss Flood. Mr. Winwood has since entrusted this spe- * The Timis primava of Lindley & Hutton, from the Inferior Oolite, is in all probability a Cycadean cone. MORPHOLOGY OF PINITES OBLONGUS. 191 cimen to mOj accompanied by a second half of the same specimen^ for the purpose of description and publication. The speeimen was originally obtained from the beach at Sidmouth^ where it has most probably been washed out of the Lower Greensand^ as was supposed to have been the case with Lindley and Hutton'’s specimen, found on the shore near Lyme Regis I at onee saw that the seetions placed in my hands were identical with the Abies oblonga of Lindley and Hutton ; but since they show some details of structure and morphology not mentioned by the above authors, they deserve an independent examination. Fig. I represents a vertical section through the centre of Miss Flood’s speeimen, twice its natural size. It ex- hibits a small portion of the central axis at a, the super- ficial zone of whieh is obviously woody, being traversed horizontally by numerous parallel lines, which are evi- dently medullary xylem rays; its more central portion consists of narrow, vertically elongated fibres, in which no special structure can be discerned. From this axis nu- merous lignified carpellary scales, b, c, are given oflP, as in modern cones. Sections of these seales show a difference between their superior and inferior component tissues. The former, b' , is composed of large, thiek-w ailed, sclerous parenchyma, the cells of which are generally a little elon- gated parallel to the long axis of the cone. In Lindley and Hutton’s description this tissue is vaguely deseribed by the term corky.” Cork it certainly is not. The inferior layer is much more dense, being composed of vertieally elongated and very narrow fibres. The peri- * Lindley and Hutton speak of this specimen as from “\heBresent shore.” Mr. Starkie Gardner informs me that after an exhaustive search he can find no such place, and is inclined to assume that “ Dresent ” is a misprint for some other word. ]92 PROP. W. C. WILLIAMSON ON THE pheral extremities of these earpellary seales do not become so thin as Lindley and Hutton affirmed to be the case with their example. Though rolled and waterworn, the exterior of our specimen rather suggests a slight thickening of those extremities^ resembling what is seen in Firms Strbbus and P. Cembra. In fig. 2, Plate IX., which represents portions of two earpellary scales, b and c, from the second section en- trusted to me by Mr. Winwood, the distinctions between the two woody layers are obvious at b' and b" , c and c". The several seeds, d, are borne on the upper surfaces of the basal portions of the earpellary scales, each having its micropilar extremity pointed downwards and inwards. Each seed is invested by a firm testa, fig. i, e, Plate IX., within which we have, in several of them, a thin nucellar membrane ; small fragments of this membrane are seen in the two seeds, fig. i,/, /; the almost unbroken membrane is seen in the seed, fig. i,/', and its concave half is lodged within the concavity of the testa of fig. i, e. In each of two other seeds, g,g, of fig. i, a narrow tubular structure extends from the outer end of the seed to its inner or micropilar extremity. This is obviously the emhryo-sac. The large wing of the seed is more or less conspicuous in nearly every instance. Thus it is nearly, if not wholly, coextensive with the length of the subjacent earpellary scale, as at h, h, whilst its opposite or lower portion covers the upper surface of each seed, as far as its micropile. In most cases the wing is slightly bifid where it touches the outer apex of the seed, as in h', h\ a very narrow mar- gin of it overlapping the sharply angular edge of the latter organ. These wings therefore were very large in pro- portion to the size of the seed. In fig. 2, which represents a portion of Miss Plood^s second half of the cone, enlarged six diameters, we have MORPHOLOGY OF PINITES OBLONGUS. 193 evidence that each carpellary scale bore two seeds, as is the case with the true Abietinese. Most of the features seen in fig. i are repeated in these two seeds, which are intersected in an obliquely transverse manner, the section being tangential to the surface of the entire cone. We have the testa of each seed at e. Each intersected embryo- sac appears at g, g. The wings are at h, h, extending over the entire upper surface of each seed so completely as to invest their two contiguous surfaces ; whilst the thick- ened portions, already referred to, are very obvious at h' , h'. The testa of each seed in this section is fringed at its in- ferior surface with some detached flocculent tissue. In the interior of the nucellar cavity of some of these seeds a number of small and very delicate spheres, of various sizes, are visible ; these may be products of minera- lization, but how produced is not easy to determine. As already observed, Lindley and Hutton placed their cone in the modern genus Abies in consequence of the ajDparent absence of the terminal thickening usually seen in the carpellary scales of the cones of Pinus. But the relatively large size of the seed is more suggestive of affinities with Firms than with Abies ; the more so since in such cones as those of Pinus Strobus and Cembra the terminal por- tions of these scales are only thickened in a small degree beyond what occurs in those of Abies. But apart from these facts, Mr. Carruthers, in one of the memoirs re- ferred to*, has given excellent reasons for avoiding the use of such ill-defined general terms as Pinus and Abies, hence he has placed Lindley and Huttoffis cone in the provisional genus Pinites, and I have followed his ex- ample. This name sufficiently indicates the general affinities of such specimens as the one under consideration, without * Geological Mngazine, vol. iii. p. 536. SER. III. VOL. X. O 194 MESSRS, T. BLACKBURN AND P. CAMERON ON THE suggesting closer relationsliips than can be affirmed with certainty to exist. DESCRIPTION OP THE FIGURES. Fig. I. Internal surface of one half of the cone: enlarged two diameters. a. Part of the axis of the cone. h, c. Carpellary scales. b', c', the upper; b", c", the lower tissues of these scales. d. The seeds in situ. e. The testa of the seed. /. The nu cellar membrane of the seed. g. The embryo-sac. li. The wing of the seed. Fig. 2. Transverse section of portions of two carpellary scales, enlarged six diameters, the lower bearing two ovules, as seen in a tangential section of the exterior of the cone. The reference letters as above. i. Portion of a seed belonging to a collateral cai’pellary scale. XIV. On the Hymenoptera of the Hawaiian Islands. By the Bev. T. Blackburn^ B.A., and P. Cameron. Read before the Microscopical and Natural-History Section, January i8th, 1886. The investigation of the natural history of oceanic islands is now rightly regarded 'as a subject of great interest and importance. Not only do their fauna and flora throw much light on the manner in which species have been distributed over the globe, but many of the species themselves are, from the peculiarities of their structure, of extreme value in throwing light on the origin of species. The natural history of oceanic islands ought, furthermore, to be seriously investigated without delay; for there is not the slightest doubt that the introduction HYMENOPTERA OF THE HAWAIIAN ISLANDS, 195 of cultivated plants, and the changes caused in the ground by their cultivation, as well as the introduction of Old- World weeds and insects, must, before long, lead to the extermination of many of the native species. This is the more likely to be the ease from many of them being of extreme rarity. In fact, according to Mr. Blackburn, one of the most remarkable features in connection with the insects of the Hawaiian Islands is “ the extreme rarity of specimens in comparison of the number of species, the common insects being very few indeed, and the rather common ones almost none at alP^*. We know that many of the animals of oeeanic islands have become extinet within comparatively recent times ; and in my mind there is not the slightest doubt that many more will be driven out of existence within the next generation or two. Every endeavour, therefore, ought to be made to induce resi- dents in these remote islands to collect and preserve their insect inhabitants. That good results would be obtained from their doing so can be proved by the remarkable discoveries made by the late Mr. Wollaston in St. Helena, and by Mr. Blackburn in the Hawaiian Archipelago, discoveries of the greatest morphological and biological importance. In all countries where the Coleoptera and Hymenoptera have been equally studied, it is found that the latter in numbers equal, if they do not surpass the former. Mr. Blackburn collected in the islands 428 species of beetles, whereof 352 species are at present only known from the Archipelago. As there is not one fourth of this number known of Hawaiian Hymenoptera, I think we may conelude that very many more species have yet to be discovered, even although it may ultimately be proved that they are scarcer relatively than the beetles. Scient. Trans, of the Eoy. Dubl. Soc. iii. p. 202. o 196 MESSRS. T. BLACKBURN AND P. CAMERON ON THE Dr. Sharp* divides the coleopterous fauna of the islands into three divisions : first species (chiefly cosmopolitan) introduced in stores, ballast, &c., by commerce ; secondly species introduced by natural currents in drift-wood, &c. ; and thirdly endemic or autochthonous species, the latter being distinguished from the second by structural pecu- liarities, being to all appearance forms of great antiquity, the distinction between the two groups being owing, no doubt, to the fact that the autochthonous species were introduced into the islands at a much more remote period — so remote, indeed, that their nearest allies have become extinct, or nearly so, on continents, where the struggle for existence has been much keener. My knowledge of the Hymenoptera is not sufficient to enable me to separate the species which belong to Dr. Sharpes two last categories ; yet I have no doubt at all that most of the species of Crabro, Odynerus, and Prosopis have originated in the islands by evolution from one or two species introduced at some remote period into the islands by currents on drift-wood. The aculeate species found in the Archipelago belong to genera which we might a priori expect to find there, being species which form their nests in or on wood, the genera which nidificate in the ground being absent. The following species have, I believe, been introduced by man^s agency ; — Camponotus sexguttatus, P oner a con- tracta, Monomorium specularis, Tetramorium guineense, Prenolepis longicornis, Pheidole megacephala, Sotenopsis geminata, all ants of wide range. Pelopceus cmmentarius, Polistes aurifer, P. hebraus, Xylocopa (sneipennis, Evania Icevigata, Metacoelus femoralis, and Spalangia hirta. It is possible that P. liebrneus may belong to Sharp’s second group, hut I have no doubt that P. aurifer and the * Scient. Trans, of the Eoy. Dubl. Soc. iii. p. z6i). HYMENOPTERA OF THE HAWAIIAN ISLANDS. 197 Xylocopa have been introduced in timber from America. Metaccelus and Spalangia are parasites on the house-fly. Neither of them is^ I believe, common in Europe; nor am I aware if they inhabit America. A species of Spalangia has been found in the Galapagos Archipelago. The genera Prosopis, Megachile, Odynerus, Leptogenys, Pimpla, Ophion, Limneria, Chelonus, Epitranus, Chalcis, Eupelmus, and Evania have a wide range over the earth. The genus Echthromorpha is, so far as we know, confined to oceanic islands, the five known species being from the Hawaiian Islands, St. Helena, Ascension, and Tahiti, Society Isles, in which latter island a new species has recently been discovered by Mr. J. J. Walker, R.N. The genera Sierola, Moranila, and Solindenia are only known from the Archipelago, but our knowledge of the Chalci- didse is not sufficient to enable me to say anything very definite about the affinities of the island species. Sierola and Scleroderma belong to a group of much interest, being one which is intermediate between the Terebrant and Aculeate sections of Hymenoptera. A species of Scleroderma, it may be noted, is found in St. Helena. Smith offers the opinion that the Hymenoptera are most nearly related to the American fauna. On this point I am not prepared to offer an opinion at present; and I rather think that Smith formed his conclusion on the occurrence of Xylocopa ceneipennis, Polistes aurifer, &c., which have been introduced, as I believe, by many’s agency, and consequently must not be taken into account in judging of the affinities of the endemic species. The following is the literature relating to the Hyme- noptera of the Archipelago : — Fabricius, Ent. Syst. ii. p. 269 {Odynerus radulci). F. Smith, Cat. of Hymen. Ine. i. p. 23 {Prosopis Jlavipes and P. anthra- cina). 198 MESSRS. T. BLACKBURN AND P. CAMERON ON THE F. Smith, 1. c. iv. p. 421 {Crabro unicolor and C. distinefits and Mimesa antennatd). Holmgren, Eugenics Eesa, Zool. yi. pp. 406 & 441 {Echthromorpha maculi- pennis and Bhynchium nigripenne = Odynerus mauncs, Smith). F. Smith, “ Descriptions of New Species of Aculeate Hymenoptera col- lected by the Rev. Thomas Blackburn in the Sandwich Islands,” Proc. Linn. Soc. xiv. pp. 674-685 ; also described in his ‘Description of New Species of Hymenoptera,’ 1879. Thomas Blackburn and W. F. Kirby, “Notes on Species of Aculeate Hymenoptera occurring in the Hawaiian Islands,” Ent. Month. Mag. xvii. pp. 85-89. P. Camei’on, “Notes on Hymenoptera, with Descriptions of New Species,” Trans. Ent. Soc. 1881, pp. 555-562 [Sierola (g. nov.) testaceipes, Che- loiius carinatus, Monolexis^i palliatiis, Chalets polynesialis, Crabro Polynesians'). P. Cameron, “Descriptions of New Genera and Species of Hymenoptera,” Trans. Ent. Soc. 1883, pp. 187-193 (Epitranus lacteipennis, Moranila testaceipes, Solindenia picticornis, Eupelmus jlavipes, Evania sericea, Limneria polynesialis, L. Blackburni, Ophion Imeatus, 0. nigricans). The descriptions of new species of Prosopis, Odynerus, and Crabro, and the remarks thereon are by Mr. Black- burn. All that I have done in these genera is to cata- logue and bring together the references to the species ; also I have made certain alterations in synonymy. I have likewise to thank Mr. G. F. Matthews^ B.N.^ for some specimens from the islands. — P. C. As I have in my collection of Hawaiian Hymenoptera a considerable number of undescribed species^ and made various observations of habits &c.^ at periods subsequent to the description by Messrs. F. Smithy W. F. Kirby^ and P. Cameron^ of certain new species^ I think that it will be desirable for me to put forth a paper on these insects in which I shall endeavour to include the hitherto undescribed species^ and add such remarks as may seem profitable con- cerning those that have already been described. The Hymenopterous fauna of the Hawaiian Archipelago is, I believe, a rich one. It held a claim on my ento- mological energies so decidedly second to that of the HYMENOPTERA OF THE HAWAIIAN ISLANDS. 199 Coleoptera^ that I think the fact of its being represented in my collection by considerably more than a hundred species^ to be very conclusive on the pointy that a specialist studying the group would reap a great harvest were he to visit the locality. I have published (in the Scientific Trans, of the Royal Dublin Soc. 1884^ pp. 87 et seq.) some general remarks on the climate &c. of the Hawaiian Islands in their relation to the insect-fauna, to which I will venture to refer for the generalities that might perhaps be looked for as an introduction to such a paper as the present, merely adding that (so far as I can judge) Maui is not, in respect of this group of insects, so clearly the metropolis of the islands as it is in respect of other groups. It has produced (as will appear from what follows) one or two of the most striking and specialized types, it is true ; but, nevertheless, I am inclined to think that it must yield to Hawaii the claim to be the Hymenopterous centre, as that island has yielded the most numerous and most strongly-marked forms in every family but two, viz. Apidse and Sphegidae. The species (Prosopis rugiventris, mihi) of the former, on which this remark is founded, very probably is confined to Maui (and the closely adjacent island Lanai), while the occurrence there, either solely or in much greater numbers than elsewhere, of P. Blackburni, Sm., and P. hilaris, Sm. (two of the most striking species of the genus), confirms the probability that Maui really is peculiarly rich in these insects. The occurrence in very small numbers of Mimesa antennata, Smith, of which no close ally has occurred in other localities, may possibly be due merely to insufficient observation on my part, and, therefore, will not count for much ; while, on the other hand, the fact that the Vespidfe and Crabronidse of Hawaii are so much more striking in appearance and specialized in structure than those of any 200 MESSRS, T. BLACKBURN AND P. CAMERON ON THE other island is, I feel no doubt whatever, due genuinely to the Hymenopterous wealth of the island. ANTHOPHILA. Andrenid.®. In this family the indigenous species are not improbably confined to the genera Megachile and Prosopis. Apis mellifica, Linn., is of course introduced, and it can hardly be thought likely that Xylocopa (uneipenms, De Geer, is a true native of the islands. It may fairly be questioned whether the destructiveness of the latter does not more than counterbalance the profitableness of the former. The habits of the single Hawaiian species of Megachile noticed by me have been fully reported by Mr. F. Smith. The descriptions &c. of the species of Prosopis found on the Archipelago are so scattered, and contain so many slight inaccuracies, that I think it might be well for me to review them seriatim, adding descriptions of certain additional species, and furnishing a Table of their distinctive cha- racters, as follows : — I. Prosopis fuscipennis. Prosopis fuscipennis. Smith, Proc. Linn. Soc. xiv. p. 682 ; Kirby, Ent. Month. Mag. xyii. p. 85. I have nothing to add to the excellent description of this species in Mr. P. Smithes two papers. I have never taken it elsewhere than on Oahu, and there only rarely. 2. Prosopis satellus, sp. n. Niger; confertim punctatus; clypeo (antice rotundato), antennarum articuli basalis fronte, tarsis tibiarum- que anticarum fronte, testaceis, antennarum articulo basali valde compresso ; alis fuscis. Long. 1 1 millim. HYMENOPTERA OF THE HAWAIIAN ISLANDS. 201 This species is allied to P . fuscipennis, Sm.^ from which it differs as follows : — The clypeus is yellow, the anterior margin of the thorax is not testaceous, the tegulse are paler, the punctuation throughout is finer and closer (especially so on the metathorax, which is a little rugose only in front and on the hind body). The basal joint of the antennae is much more strongly compressed, being on its flat face as wide as long, and has its front side more strongly rounded than the hinder side. I have seen only a single male of this insect, which occurred in September on Haleakala, Maui, at an elevation of about 5000 feet. 3. Prosopis BlacJcburni. Prosopis BlacTchurni, Smith, Proc. Linn. Soc. xiv. p. 682 ; Kirby, Ent. Month. Mag. xvii. p. 85. The original description of this insect was founded, I believe, on a single individual of each sex, the male being an unusually brightly coloured one. At a subsequent period I met with the species plentifully, and the exami- nation of something like a hundred specimens has satisfied me that it is subject to much variation. I think there- fore that it will be well to supplement the description with a further one, somewhat more in detail. The distinctive characters seem to be as follows : — Head un- usually elongate in both sexes, the width across and including the eyes being scarcely equal to the total length. The clypeus is abruptly truncate or even gently concave at the apex. In the male the whole space below the antennae is yellow, and this colour is produced in a trian- gular form between the base of the antennae, and also runs back as a gradually narrowing vitta adjacent to the eyes on either side of the head. The extent of this colour- ing is subject to occasional variety; I have a specimen in 202 MESSRS. T. BLACKBURN AND P. CAMERON ON THE which the small plate between the clypeus and the antennse is blacky and several specimens in whieh the lateral yellow vittae are abbreviated^ but none in which the yellow eolour- ing is confined to the space in front of the antennae. The least brightly coloured specimens^ moreover, differ from P. facilis, Sm., in having the entire space between the eyes and the clypeus yellow. The seape of the antennae is not much dilated in the male, being more than twice as long as wide, and moderately arched ; it is generally black, and rarely displays the yellow line mentioned in the original description. In both sexes the flagellum is yellow (or at least ferruginous) beneath ; in some instances the whole flagellum, and even the scape, is red, the underside of the former being then of a vivid yellow. The colouring of the legs varies, even in the male, from that described by Mr. Smith, to an almost uniform pitehy colour, save that the front of the front tibim is always pale, and the tarsi are seldom obseured. The wings have scarcely any trace of fuscous colouring in the male and not much in the female. The size of the male varies from 7—10 millim. long, that of the female from 8-1 1 millim. long. I have this species from Maui, Lanaii, and Hawaii. Specimens from Hawaii seem to be, as a rule, more obscurely coloured than those from other loealities. The brightly eoloured type occurs on Maui, near the sea-coast. 4. Prosopis facilis. Prosopis facilis, Smith, Proc. Linn. Soc. xiv. p. 683 ; Kirby, Ent. Month. Mag. xvh. p. 85. Of this insect I have examined about 50 examples. It is not very elose to any other of the genus, nor does it vary much. The original description is a good one, but may advantageously be amplified a little. P. Bluckburni, Sm., is, I think, its nearest ally. The head is moderately HYMENOPTERA OP THE HAWAIIAN ISLANDS. 203 elongate^ but decidedly less so than in P. Blackburni, the width from eye to eye in front of the base of the antennae being about the same as the length from the base of the antennae to the apex of the clypeus. The apex of the clypeus is rounded. There is a very distinct elongate depression on either side of the head close to the eyes. The clypeus and the plate between it and the antennae are yellow in the male^ as also is a narrow space on either side of the clypeus^ but the yellow colouring extends laterally to the eyes only in the extreme fronts and does not extend at all behind the antennae^ so that the head even in front of the antennae is only partially yellow. The antennae are uniformly of a blackish col our, the basal joint being not much dilated but very strongly arched in the male. The punctuation does not differ mnch from that of P. Black- burni, the upper surface of the hind body showing no distinct punctures. The legs are of a blackish colour, except the front tibiae and tarsi of the male, which are more or less testaceous in front. The size of the male varies from 6f-io millim. long, that of the female from 7-1 of millim, long. The original types of P. facilis, Sm., were from the Pauoa Valley, Oahu (not from Maui as stated by Mr. Smith). The insect, however, occurs on Maui and also on Hawaii. The only colour vars. I possess of the male have the plate between the clypeus and the antennae black. 5. Prosopis flavifrons. Prosopis Jlavifrons, Kirby, Ent. Month. Mag. xvii. p. 85 (S)- Allied (but not very closely I think) to P. Blackburni, Sm., and P. facilis, Sm. This insect may be readily iden- tified by the following characters : — The yellow mark on the face occupies the whole space in front of the antennae. 204 MESSRS. T. BLACKBURN AND P. CAMERON ON THE but does not extend behind them. The clypeus is rounded in front. The basal joint of the antennae is extremely compressed, being, on the flat faee, scarcely longer than wide, and of subcordiform shape ; the anterior margin of this joint is narrowly testaceous. Near its apex the flagellum is testaceous beneath, while the legs are of an obscure colour except the front tibiae, which are testaceous in front. The head does not differ much in shape from that of P. facilis, Sm., nor is the punctuation of the insect much different. The length is about millim. I have found this species only on Kauai, and have not seen the female. 6. Prosopis Kona, sp. nov. Niger, flavo-variegatus, hand crebre punctatus ; capite minus elongate, clypeo antice rotundato •, alls hya- linis. . Antennarum articulo basali fortiter compresso. Long. ^ 5 millim., •$ 7 millim. This is a very distinct species. In the male the face is coloured as in typical P. Blachburni. The anterior margin of the thorax and a spot under the tegulae are yellow; the tibiae are yellow with a black spot on the posterior face of the front pair, and a similar spot on each side of the others ; the first joint of each tarsus is yellow, the remainder are fuscous ; of the antennae the lower sur- face of the flagellum is testaceous, and the basal joint is much compressed (considerably more so than in P. Black- burni), but the dilated face is quite evidently not so wide as long, and its sides are strongly rounded. The hinder portion of the head is closely and very finely punctured ; the surface of the thorax is opaque with excessively miuute punctuation, and has also some larger punctures (but even these are fine), the cavities of which, under a strong lens. HYMENOPTERA OF THE HAWAIIAN ISLANDS. 205 are shining; on the postscutellum the system of larger punctures seems to fail ; the metathorax is more shining, and its sculpture seems to consist of a mixture of very fine granulation and some oblique wrinkles ; the upper surface of the hind body is not very shining, and its sculpture consists of excessively minute punctuation invisible, except under a very strong lens ; while the undersurface is simi- larly punctured with the addition of a system of much larger but very feeble shallow punctures. The female (save in the usual respects) does not differ much from the male ; it is larger, however, and the colour- ing of its head consists in a slender yellow line along the internal margin of the eyes. I obtained three specimens of this little insect on the western slopes of Manna Loa, Hawaii, at an elevation of about 6000 feet, in May. 7. Prosopis coniceps, sp. nov. Niger, flavo-variegatus, punctatus ; capite brevi pone an- tennas tumidulo; clypeo antice rotundato; alis hya- linis. ^ . Antennarum articulo basali compresso, minus elongate. Long. 6f millim. In this species the markings on the head are peculiar, — the anterior third of the clypeus is entirely yellow, the posterior quarter entirely black, the apical yellow being produced backwards in the middle of the intervening space as a broad band, while the basal black is narrowly pro- duced forwards on either side of it ; there is also a large yellow triangle on either side between the clypeus and the eye. The yellow colouring does not extend as far back- wards on the head as to the base of the antennse. The front side of the front tibiae is yellow ; the tarsi are tes- 206 MESSRS. T. BLACKBURN AND P. CAMERON ON THE taceous at the base^ becoming fuscous towards the apex ; the rest of the insect is black. I find no very noticeable difference between this species and P.facilis, Sm., in re- spect of punctuation, except that the head is rather more roughly punctured behind the antennae. The head is very short, the distance from eye to eye across the front of the base of the antennae being very considerably greater than from the base of the antennae to the base of the clypeus. The portion of the head behind the antennae is tumid, so that the ocelli seem to be placed on a rounded swelling. The apex of the clypeus is rounded. The underside of the hind body is sparingly and not strongly punctured. The basal joint of the antennae is rather strongly dilated in the male, its length being hardly twice its width. A single specimen occurred on Mauna Kea, Hawaii, at an elevation of about 7000 feet, in February. A female taken in the same neighbourhood probably belongs to this species, as its head is similarly formed, though it is less roughly punctured. It is quite black, except the legs, which are dark pitchy, and the wings are much clouded with fuscous. 8. Prosopis rugiventris, sp. nov. Niger obscure punctatus ; antennarum flagello apicem versus ferrugineo ; abdomine plus minusve rufe- scente; clypeo antice subtruncato. ^ . Fronte testacea ; tibiis anticis dilutioribus ; anten- narum articulo basali fortiter compresso, vix quam latus longiore abdominis segmentis ventralibus nitidis, insequalibus. Long. S millim., ? 7 millim. The punctuation does not appear to differ much from that of P. Blackburni, Sm., which this insect resembles also by its scarcely less elongate head and the only slightly HYMENOPTERA OP THE HAWAIIAN ISLANDS. 207 rounded apex of the clypeus. In the male the face is en- tirely (or almost entirely) yellow in front of the antennse, but the yellow colouring does not pass the antennae back- wards. The flagellum is testaceous on the underside^ in some specimens entirely ferruginous. The front tibiae of the male are testaceous in front. In both sexes the hind body is reddish (in some specimens quite red) . The basal joint of the antennae in the male is strongly compressed, its flat face being scarcely longer than broad. The hind body beneath is almost impunctate and very shining in the same sex, while across each segment runs a transverse, rounded, and sinuated ridge, more strongly developed in some specimens than in others. I possess two specimens of this insect from Maui and five from Lanai. One of them (taken in company with the males) is a female, and closely resembles the female of P. Blackburni, Sm. 9. Prosopis hilaris. Prosopis hilaris, Smith, Proc. Linn. Soc. xiv. p. 683 ; Kirby, Bnt. Month. Mag. xvii. p. 85. The male has been well described by Mr. Smith. The female closely resembles it, being, however, somewhat larger (9-9! millim. long). The colouring is precisely similar, save that bright yellow is replaced by obscure testaceous. The basal joint of the antennae is, of course, not dilated, and the apical segments of the hind body present the usual sexual differences. 10. Prosopis volatilis. Prosopis volatilis, Smith, Proc. Linn. Soc, xiv. p. 683 ; Kirby, Ent. Month, Mag. xvii. p. 85. This species (the male of which has been well described by Mr. Smith) was taken on Oahu (not Kauai, as stated in the original description). I have not seen the female. 208 MESSRS. T. BLACKBURN AND P. CAMERON ON THE Table of Species of Prosopis. 1 . Anterior margin of thorax yellow z Anterior margin of thorax not coloured yellow 3 2. Upper surface of hind body distinctly punctured fuscipennis, Sm. Upper surface of hind body not distinctly punctured. Kona, mihi. 3. Ventral segments even in both sexes 4 Ventral segments transversely ridged in the male rugiventris, mihi. 4. Upper surface of hind body not distinctly punctured 5 Upper surface of hind body with well-defined punc- tuation satelles, mihi. 5. Hind body black 6 Hind body red 9 6. Head short (i. e. distance from eye to eye in front of antennffi considerably greater than from anteniiEe to apex of clypeus) coniceps, mihi. Head elongate {i. e. the former of these distances not, or scarcely, exceeding the latter) 7 7. Apical margin of clypeus distinctly rounded 8 Apical margin of clypeus truncate Blackbiirni, Sm. 8. Basal joint of antennae not, or scarcely, longer than wide in male flavifrons, Sm. Basal joint of antennae much longer than wide facilis, Sm. 9. Yellow markings on face of male extending behind the antennae hilaris, Sm, Y'ellow markings on face of male not passing behind the antennae volatilis, Sm. The following two species have been described by Mr. P. Smith in his Cat. of Hymen. Ins. pt. i. p. 23, from the Sandwich Islands. It is more than probable that they are identical with some of the species described above^ but^ as the descriptions are not very clear, and as I have not spe- cimens of all the species for comparison, I have not been able to satisfy myself as to this. To make the descriptions of Prosopis complete, I give a copy from Smithes work of those of P. anthracina and P. flavipes. — P. C. II. Prosopis anthracina. “Female. Length 2 f lines. Entirely black, head and thorax very finely punctured, the apical joints of the an- HYMENOPTERA OF THE HAWAIIAN ISLANDS. 209 tennse testaceous beneath. Thorax, the tegulie testaceous, the wings hyaline, the nervures dark testaceous ; the en- closed portion of the metathorax longitudinally irregularly sulcate at its base. Abdomen very smooth and shining, beneath it is dark fusco-ferruginous, as well as the legs ; the claws ferruginous. ‘‘Male. The clypeus and a space on each side not touching the eyes, forming together an oval, bright yellow; the scape dilated, triangular ; the flagellum testaceous be- neath. Thorax, the anterior tibiae in front, and the claws testaceous ; otherwise as in the other sex. “ Hab. Sandwich Islands. 12. Prosopis jiavipes. “ Male. Length 2| lines. Black ; the face yellow, the colouring is continued upwards on each side nearly to the vertex of the eye ; the scape cylindrical, black, the rest of the antennae orange, yellow beneath. Thorax, the meta- thorax has no distinctly enclosed space, and is subrugose ; the wings hyaline, the nervures dark fuscous, all the tibiae and tarsi bright yellow, the former have a ferruginous stain behind. Abdomen smooth and shining, the margins of the segments narrowly rufo-testaceous. “Hab. Sandwich Islands.” ApidvE. 13. Megachile diligens. Megachile diligens. Smith, Proc. Linn. Soc. xiv. p. 684 ; Kirby, Ent. Month. Mag. xvii. p. 86. Not uncommon. “ Forming nests of leaves of a species of Acacia rolled up into cylindrical cells, which are joined one at the end of another to the length of several inches, and are placed in crevices of masonry. — T. B. SER. III. VOL. X. p 210 MESSRS. T. BLACKBURN AND P. CAMERON ON THE 14. Xylocopa (Eneipennis. Xyhcopa aneipennis, De Geer, Memoires, iii. p. 573, tab. 28. f. 8 ; St. Fargeau, Hym. ii. p. 186 ; Smith, Proc. Linn. Soc. xiv. p. 684. Very common and extremely destructive to wood by forming its nests in it^ the nests being long galleries and made in dead or living trees. FOSSORES. VeSPIDjE. 15. Polistes aurifer. Polistes aurifer, Saussure, Mon. GuSpes Soc. p. 78. Common, forming its nests in wood. 16. Polistes hebr