Sessa = eo eyes 5 ae 4 : eae. pepe ; ut it * phrtere ia bree et eer : Sarrasaies eho ode See ae sie . ee === a 2 oe oletewrace Te Big ere eee ss Sai Pat uy FN i came we TRANSACTIONS OF THE ROYAL SOCIETY OF EDINBURGH. 2 eee ae es 9 Bh. C85 tik. “At, ON Ke 7 al — Th WCRI OO acne cnt a ERANS ACTIONS OF THE mer AE, SOCIETY OF EDINBURGH. VOL. XXXV. EDINBURGH: PUBLISHED BY ROBERT GRANT & SON, 107 PRINCES STREET, AND WILLIAMS & NORGATE, 14 HENRIETTA STREET, COVENT GARDEN, LONDON. MDCCCXC. Parr I. published January 21, 1889. Part II. A : ; . March 10, 1890. Part ITI, i : . February 3, 1890. Part IV. 3 ; ‘ . April 23, 1890. CONTENTS. PART I. (1887-88.) NUMBER I. On the Number of Dust Particles in the Atmosphere. By Joun AITKEN, Esq. (With a Plate), Il. The History of Volcanic Action during the Tertiary Period in the British Isles. By ARcurpaLp GerKig, LL.D., F.R.S., Director General of the Geological Survey of the United Kingdom. (With Two Maps and Fifty-three Woodcuts), III. Mean Scottish Meteorology for the last Thirty-two Years. By C. Priazzi Smytu, /ate Astronomer-Royal for Scotland, and F.R.S.E., F.R.A.S., &c. (With Fourteen Plates), IV. Eight Years’ Observations of the New Earth Thermometers at the Royal Observatory, Edinburgh, 1879-1888. By C. Ptazzi Smytu, /ate Astronomer-Royal for Scotland, and F.R.S.E., F.R.A.S., &c. (With Four Plates), V. On Neuropteris plicata, Sternberg, and Neuropteris rectinervis, Kidston, nu. sp. By Rosert Kinston, F.R.S.E., F.G.S. (With a Plate), ; ; : VI. On the Fossil Flora of the Staffordshire Coal Fields. By Rosert Kinston, F.R.S.E., F.G.S. (With a Plate), VII. Experimental Researches in Mountain Building. By Henry M. CADELL, Esq. of Grange, B.Sc, F.R.S.E., H.M. Geological Survey of Scotland. (With Thirty-six Illustrations), . PAGE 21 315 vi NUMBER VEIL. >. TLE XIV. XV. XVI. CONTENTS. PART IL. (1887-89.) Histological Observations on the Muscular Fibre and Connective Tissue of the Uterus during Pregnancy and the Puerperium. By T. ArtHur HeEtmME, M.B. (With a Plate), On some Relations between Magnetism and Twist in Iron and Nickel. Part I. By Caramut G. Knorr, D.Sc. (Edin.), F.R.S.E., Professor of Physics, Imperial University, Tokyo, Japan, : ; ; . On the Fossil Plants in the Ravenhead Collection in the Free Library and Museum, Liverpool. By Rosert Kupsron, F.R.S.E., F.G.S. (Plates I. and IT.), . On some Fossil Plants from Teilia Quarry, Gwaenysgor, near Prestatyn, Flintshire. By Rosert Kinston, F.R.S.E., F.GS. (With Two Plates), On the Behaviour of the Hydrates and Carbonates of the Alkali- Metals, and of Barium, at High Temperatures, and on the Properties of Lithia and the Atomic Weight of Lithium. By Professor W. DirTMar, On the Determination of the Curve, on one of the Coordinate Planes, which forms the Outer Limit of the Positions of the Point of Contact of an Ellipsoid of Revolution which always touches the three Planes of Reference. By G. Puarr, Docteur és-sciences, On Ostracoda collected by H. B. Brady, Esq., LL.D., F_RS., in the South Sea Islands. By GEORGE STEWARDSON Brapy, M.D:, LED. FBS. (Plates 1.) On Benzyl Phosphines and their Derivatives. By Professor Letts and R. F. Brake, Esq., Queen’s College, Belfast. (With a Plate), On the Anatomy, Histology, and Affinities of Phreoryctes. By Frank E. Bepparp, M.A., Prosector to the Zoological Society of London, and Lecturer on Biology at the Medical School of Guy’s Hospital. (With a Plate), . PAGE 39 377 391 419 429 471 489 CONTENTS. NUMBER XVII. On the Placentation of Halicore Dugong. By Sir WILLIAM Turner, M.B., LL.D., D.C.L., F.R.SS.L. and E., Professor of Anatomy in the University of Edinburgh. (Plates [., IL., IIL), ; ; ' : XVIII. Non-Alternate + Knots, of Orders Hight and Nine. By C. N. Lirtie, of Nebraska State University. (With a Plate), PART III. (1887-89.) XIX. On the Development and Life-Histories of the Teleostean Food- and other Fishes. By Professor W. C. M‘Intosu, F.R.S., and E. E. Prince, B.A., St Andrews Marine Laboratory. (Plates I.-X X VIIL.), PART IV. (1889-1890.) XX. On the Thermal Conductivity and Specific Heat of Manganese- Steel. By A. Cricuton MirTcHELL, B.Sc., XXI. Strophanthus hispidus: its Natural History, Chemistry, and Pharmacology. By Tuomas R. Fraser, M.D., F.RS., F.R.S.E., F.R.C.P.E., Professor of Materia Medica in the University of Edinburgh. Part I. Its Natural History and Chemistry. (Plates L-VII.), : ; XXII. On the Foundations of the Kinetic Theory of Gases. III. By Professor Tarr, XXIII. On Systems of Solutions of Homogeneous and Central Equations of the nth Degree and of two or more Variables ; with a Dis- cussion of the Loci of such Equations. By the Hon. Lord M‘Laren. (Plates I-VI), Vil PAGE 641 665 947 955 1029 1045 Vili c CONTENTS. APPENDIX — The Council of the Society, Alphabetical List of the Ordinary Fellows, List of Honorary Fellows, List of Ordinary Fellows Elected during Session 1887-88, List of Ordinary Fellows Elected during Session 1888-89, Laws of the Society, The Keith, Makdougall-Brisbane, Neill, and Victoria Jubilee Prizes, Awards of the Keith, Makdougall-Brisbane, Neill, and Victoria Jubilee Prizes, Proceedings of Statutory General Meetings, List of Public Institutions and Individuals entitled to receive Copies of the Transactions and Proceedings, Index, A na ALA 11 JUL. 90 PAGE 1102 1103 1118 1120 1122 1125 1132 1135 1139 1145 1151 ’ Ls n - FEB 1889 TRANSACTIONS OF THE ROYAL SOCIETY OF EDINBURGH. VOL. XXXV. PART I.—(Nos. 1 ro 7)—FOR THE SESSION 1887-88. CONTENTS. PAGE No. I. On the Number of Dust Particles in the Atmosphere. By Joun Arrken, Esq. (With a Plate), ; ‘ : : : . 1 II, Vhe History of Volcanic Action during the Tertiary Period in the British Isles. By ArcurpaLp Guikiz, LL.D., F.R.S., Director General of the Geological Survey of the United Kingdom. (With Two Maps and Fifty-three Woodcuts), . : : : a : , ai 21 Ill. Mean Scottish Meteorology for the last Thirty-two Years. By C. Piazzt Smyru, late Astronomer-Royal for Scotland, and F.R.S.E., F.R.A.S., &e. (With Fourteen Plates), . : ; es : : d ' 185 IV. ight Years’ Observations of the New Karth Thermometers at the Royal Obser- vatory, Edinburgh, 1879-1888. By C. Piazzit Smyru, late Astronomer- 4 Royal for Scotland, and F.R.S.E., F.R.A.S., &c. (With Four Plates), . 287 V. On Neuropteris plicata, Sternberg, and Neuropteris rectinervis, Kidston, n. sp. _ By Roserr Kinsroy, F.R.S.E., F.G.S. (With a Plate), ° 313 VI. On the Fossil Flora of the Stafjordshire Coal Fields. By Roserr Kinston, F.R.S.E., F.G.S. (With a Plate), . ‘ , . A : 317 VIL = Experimental Researches in Mountain Building. By Henry M. Canetti, Esq. of Grange, B.Se., F.R.S.E., H.M. Geological Survey of Scotland. (With Thirty-six Illustrations), : : ; : ; : . 337 (Issued Janwary 21, 1889). 4 Lae | ‘ Ss 4 i - 4 * ‘ ( be - . a | ad : . ‘ io r - 4 . " = * = : a's? ; j - 2 , ‘ ~ 7 : i fi } 5 ” ; . . PS 7 ; ‘ oh AK Sy 7 ; * : a . ea* , . 4 - - a a ey. # ; pare, : Td Ate ‘ , =O » its 1% 1 Z 7 7 +: pyre 2 : f e ¢ - a + ‘ > = a f ‘ ’ a* ¢. Die af ; * , i : ‘ ‘ ‘ ‘ ‘ 7 a oes t e fi . ‘ . ’ = i i > ’ ‘ 7 mapa a ’ . ¢ + ” ‘ . TRANSACTIONS. I.—On the Number of Dust Particles in the Atmosphere. By Joun AirTKEN, Esq. (With a Plate.) (Read 6th February 1888. “ The gay motes that people the sunbeams. ”’—Wilton. The solid matter floating im our atmosphere is every day becoming of greater and greater interest as we are gradually realising the important part it plays in the economy of nature, whether viewed as to its physical, physiological, or meteorological aspects. One fundamental point on which we have at present very little information of anything like a definite character, is as to the number of solid particles present in our atmosphere. We know that they are very numerous, and it seems probable that the number varies under different conditions of weather; but what number of particles are really present under any conditions, and how the number varies, we have at present very little idea- In this field of research the physiologists are far in advance of the physicists, as they have devised means of counting the number of live germs floating in our atmosphere, and already we have a good deal of information as to how the number varies under different conditions. Part of our ignorance regarding the dead organic and inorganic matter floating in the atmosphere may no doubt be due to the apparent difficulty of an investigation of this kind, where many of the particles to be counted are so extremely small that they are not only invisible to the naked eye, but are beyond the highest powers of the microscope. But, though this may be the case, yet the real reason of our ignorance on this subject would rather appear to be, that no one has seriously set himself to the investigation of the subject ; the problem, though apparently one of considerable difficulty, has turned out to be of comparatively simple solution, when the degree of accuracy required is not very great. When we consider the numbers we have to deal with, and the conditions of the problem, perfect accuracy does not indeed seem possible. VOL. XXXV. PART 1. A 2 J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. Introduction to the Method of Counting. I shall here give an account of a method I have devised and developed for counting the number of dust particles in any sample of air; and the figures which have been obtained will, it is hoped, help to give definiteness to our ideas as to the numbers of the particles floating in the atmosphere, under both natural and artificial conditions. In approaching the solution of this problem, different ideas suggested themselves as to the manner of counting the particles, but they all depended on the fundamental prin- ciple of making them visible by supersaturating with vapour the air in which they were floating. Under these conditions, each dust particle becomes a centre of condensation, and what was invisible by itself becomes quite visible by its effects, as each invisible dust particle becomes a centre of condensation, and grows into an easily visible drop. The simplest method of carrying out this idea was to put inside a glass receiver the air to be tested along with some water, and to cause supersaturation by reducing the pressure in the receiver by means of a pump. We know that under these conditions a fogey condensation takes place, the whole receiver becoming packed with small white par- ticles, so small that, though visible to the naked eye, they float in the air. Each of the fog particles so produced has a dust particle for a nucleus. Now, it might be possible to devise some means of making an estimate of the number of these fog particles, by some sort of microscopic measurement of the average distance between their centres. But, supposing we had done this, we should by no means have solved the problem. These fog particles do not represent all the dust particles present in the air; only those having the greatest affinity for the vapour being visible, a large proportion having no vapour condensed on them. We might, after counting them, allow these visible particles to settle, and then again produce supersaturation, which would reveal some more particles. This process would, however, require to be repeated a great number of times before the last of them would become visible, and as we cannot prevent the evaporation of some of the drops, many of the particles would be counted twice ; altogether, the whole process seemed too complicated and unsatisfactory to be worth attempting. The most hopeful suggestion was to put into the receiver only a very small and measured quantity of the air to be tested, mixed with a large and known amount of per- fectly filtered dust-free air, so that the particles would be so far apart that on super- saturation being made, all of them would become centres of condensation, and thus by one treatment every particle would become visible and be counted. On trial, the first part of this plan was found to be of easy accomplishment; by simply increasing the proportion of dust-free air to the dusty air, a stage was arrived at in which every particle was made visible by one supersaturation. Turning now tothe method adopted of counting the drops. In experimenting on con- densation in supersaturated air having dust particles in it, 1 had noticed that when the particles are few, the drops are large, that is, large comparatively to what they are when the condensation takes place in ordinary air; so large are they, that they are easily seen J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. 3 showering down like fine rain. Now, it appeared to me that it might be possible to count the number of drops that fell on a given area. If this could be done, then the problem promised to be a simple one. All that would be necessary would be to fix a small stage or platform inside the receiver, at a known distance from the top, to have the surface of the stage ruled into squares of a known size, and then by simply counting the number of drops that fell on one of the little squares, it would be easy to make an estimate of the number of dust particles in the air tested. Supposing, for instance, that the platform was ruled with lines at right angles to each other, and at 1 mm. apart, and suppose the stage was fixed at 1 cm. from the top of the receiver. Then, if say one drop fell on each little square, that would give 100 drops per square centimetre, and, as there is only 1 cm. of air above the stage, there will be exactly 100 particles per cubic centimetre of the air in the receiver ; and knowing the amount to which the air was diluted with pure air, and expanded by the pump, the calculation for the number of particles in the air tested is easily made. Such was the plan which seemed to give the greatest promise of success, if the details could be successfully carried out. The first thing to which attention was directed was to find the most suitable kind of stage or platform on which to receive the drops, and on which they could be most easily seen and counted. This simple problem took long to solve ; and now that the difficulties are overcome, and the apparatus so arranged that the drops are very easily seen, and quickly counted, it is difficult to see how the time has been spent. ‘he first counting stage tried was a small piece of glass mirror, ruled on the back with fine lines, at right angles to each other, and at 1 millimetre apart. The back of the mirror was covered with black varnish to show the lines clearly. The stage was supported inside the receiver at a distance of 1 cm. from the top, and its surface was examined by means of a magnifying glass. The stage was illuminated by a gas flame placed at a short distance and slightly above it. This small mirror gave results which at first looked highly satisfactory, the drops being clearly visible on its surface with the aid of the magnifying glass. But when it came to counting the drops, the unfitness of the arrangement was evident; for over the most of its surface the drops appeared double, and the confusion produced by the reflected images caused its use to be abandoned at once. The next arrangement tried was a mirror made of very thick glass, so that the reflected image might be quite out of focus; but the result was not satisfactory, as the cross lines on this stage had to be etched on the upper surface, and these lines caused a good deal of light to be reflected from the mirror, and prevented the drops being so easily seen as on the first one. The next attempt was made with microscope glass, on which I deposited silver in the usual way; but though the thin glass brought the drop and its reflected image almost together, yet it had to be abandoned, as all the samples of this kind of glass tried were too rough and full of specks, and only the most highly finished glass is suitable for the purpose. After this, glass mirrors were abandoned, and another arrangement tried. Instead of using a mirror lighted from above, the stage was now lighted from below, and a small piece 1 J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. of thin and carefully selected glass was used instead of the mirror. The glass had fine lines etched on its surface. This arrangement gave very fair results, though not so satis- factory in some respects as the mirror, if only the double image of the latter could be got rid of. Attempts were therefore now directed to see if the mirror arrangement could not be improved. To get rid of the double reflection, a silver mirror seemed to be the best thing, if it could be got sufficiently perfect on its surface. My first attempts in this direction were made with silver deposited on highly polished glass plates, the silvered side of the glass being used. These mirrors gave highly satisfactory results, but were much too delicate, being easily destroyed by water. With some difficulty, 1 however succeeded in getting plates of solid silver with a surface sufficiently perfect for the purpose. Silver mirrors, with fine lines ruled on them at 1 millimetre apart, are now the only ones used, and are found to work very well, though they require considerable attention to keep them in working order. Before beginning work, the mirror is always polished, occasion- ally on a buff wheel with rouge, and finished off on a wool wheel. In polishing, care has to be taken that the plate is always rubbed in straight lies in one direction and along one set, and that always along the same set of ruled lines and across the other set, no cross or circular rubbings being made. The reason for this is, that, when the rubbing marks are all in one direction, it is possible so to arrange the direction of these rubbings with regard to the position of the light that the surface of the mirror will look black, and the drops shine out brightly on its surface. Over the receiver is placed a cover, blackened inside to exclude all light except what comes from the gas flame, and an opening is made in the top of it through which the stage 1s viewed by means of a lens. The mirror requires care in its adjustment with regard to the position of the light to enable the drops to be easily seen. It should be turned so that a diagonal to the little squares on its surface will point to the light. When the lighting is properly adjusted, the mirror appears black on looking through the lens, while the lines are distinctly but not brilliantly illuminated, and when the drops fall on the mirror they show as bright specks on the black surface. An interesting illustration of the spheroidal condition is often seen in these experiments. When the stage is very slightly warmer than the drops, they do not adhere to the plate, but roll on its surface, moving towards the lowest part. They glide over the little squares till they meet a boundary line into which they fall, and in which they roll down till quite evaporated. So little resistance do they meet with in their movement, that it is almost impossible to make the stage so perfectly horizontal that they will not roll one way or another. This rolling of the drops interferes much with the counting, but, as it can be easily avoided, counting should never be done while the stage is in this condition; because, in addition to the difficulty of counting, some of the drops evaporate before they can be counted. Glass plates seem to be more liable to this difficulty than the silver ones, probably owing to glass being a better absorber than silver of the radiant heat of the illuminating flame. J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. 5 Description of Apparatus. Having given a general outline of the method employed for counting the particles, I shall now describe more particularly the apparatus first used in this investigation. The general arrangement of the apparatus is shown in the Plate. All the apparatus is of the simplest kind, and can be easily obtained ready made, with the exception of the small stage on which the drops are counted. The different stages used in this investigation were ruled by myself with the aid of a simple instrument constructed for the purpose, but which need not be described here. In the figure A is the test receiver into which the air under investigation is introduced, and inside which the particles are counted. It is an ordinary glass flask with flat bottom, and supported in an inverted position. Bis an air-pump connected with A by the india-rubber tube C. It may be mentioned that the pump Bis drawn in the position shown in the sketch for the convenience of illustration. In the actual apparatus it is fixed horizontally a little above the level of the table, as this position has been found to be the most convenient for making a stroke of the pump while the eye is kept steadily applied to the magnifying glass. D is a cotton-wool filter con- nected with A by means of the pipe HE. The pipes C and E pass through an india-rubber stopper in A, and project upwards into the receiver; C stops about the middle; while EH rises to near the top, and forms the support to which the counting stage O is attached. F is a stopcock for closing the connection between the receiver A and the filter D. The air to be tested is introduced into the flask G. This flask is provided with an india-rubber stopper, through which pass the two tubes I and K. The tube I enters only a short distance into the flask, and is provided with the stopcock H. The upper branch of this stopcock communicates with the tube EH by means of the movable air-tight joint L. The other tube K attached to the flask G passes downwards to near the bottom of the flask, while outside it is connected with the small glass vessel M in the manner shown, by means of a length of india-rubber tube. The vessel M is made large enough to hold a few cubic centimetres of water, and at the lower end, at the narrow part, is an engraved index line. Above the vessel M is supported the burette N. To keep the air under examination saturated with vapour, some water is put into the receiver A, and from time to time the receiver is inverted, and the water moved about inside the flask so as to wet the imner walls. To enable this to be done easily, there is a break in the metal tube E, just below the stopcock F, which is joined by means of a short length of india-rubber tube, so that when the rimg which supports the receiver is removed, it can be turned about in any direction to bring the water inside in contact with all parts of the interior. The stage.O on which the drops are counted, as already explained, is made of a small plate of highly polished silver; it is a little over 1 cm. square, and ruled with very fine lines at right angles to each other and at 1 mm. apart. The stage is supported inside the receiver A by means of the pipe E at exactly 1 cm. below the flat top of the receiver. The object of fixing the stage to the top of the entrance pipe is that the stage often gets 6 J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. covered with a heavy deposit of dew, in which state it is quite useless, but when mounted in the manner shown, the dew is easily cleared away by heating the tube E, when the heat is carried forwards to the stage by the entering air on its passage from the filter to the receiver. It will be noticed that the stage is not placed centrally over the pipe E. This arrangement has been adopted because it has been found to keep the stage in the best working condition. If the stage is too hot, the drops roll away and quickly eva- porate ; on the other hand, if it is too cold, the surface gets wet, and counting becomes impossible. It has been noticed that the entering air tends to cool the stage, and it is found better to confine the cooling to one side of the stage, because, by this arrange- ment, thereis gene rally some part of it at the temperature most suitable for easy count- ing; and, as only one or sometimes four little squares are required, there are always plenty to select from in the hundred on the stage. The stage is viewed through the bottom of the flask, by means of the compound magnifying glass 8. A common cheap instrument, to be had from most opticians, has been found to be quite suitable for this purpose. The pipe C, connecting the pump with the receiver, terminates inside the receiver in an enlargement P, which is packed with cotton wool for a reason which will be explained later on. The stage O is illuminated by means of the gas flame R, the light from which passes through the spherical flask Q, which is filled with water. This spherical lens sifts the heat out of the rays, and concentrates the light on the stage. T is a screen enclosing the receiver A, to cut off all light except what is concentrated on the stage by the lens (), and it is blackened inside to check reflection. Suppose now the apparatus fitted up as shown in the figure, and that we wish to test a sample of air, the first thing to be done is to close the stopcock H, and open F. The pump B is now worked, and air drawn through the filter D, this is done for some time till the air begins tog etpurified; or most of the air may be pumped out and filtered air allowed to enter. After this has been done the stopcock F is closed, and a stroke of the pump made; condensation then takes place inside the flask, and if the air is nearly pure, the drops are large and soon settle down. After they have fallen, the stopcock F is again opened, and filtered air allowed to enter, when it is again closed, and another stroke is made with the pump. ‘This is repeated till all condensation stops in the flask. The air inside the receiver is now free from all dust particles. The stopcock F is then closed, the tube K disconnected from M, and the stopcock H withdrawn from its air-tight fitting L. The flask G being thus thoroughly disconnected from the apparatus, its stopper is now removed, it is filled with water, and carried to the place from which we wish to take a sample of the air to be tested. Here the water is nearly all emptied out of the flask, and the air enters to take its place. The stopper must now be tightly fitted in, the stopcock closed, and the pipe K filled with water and clamped. Returning with the flask to the apparatus, the stopcock H is carefully fitted into its place, the tube K connected with M, the lower part of M being full of water, and care taken that no air gets shut in between the water in the tube and the water in M. The stopcock H is now opened, and water J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. 7 allowed to pass from M into the flask, till the water in M falls to the index line. The air which has been displaced by this process from the flask G enters the tube E, and moves in the direction of the filter. One or two strokes of the pump and corresponding con- densations in the manner explained soon gets rid of this impure air. After all condensa- tion has ceased, some water, say 1 ¢.c., is allowed to run from the burette N into M, and one stroke of the pump is made, care being taken that both stopcocks were previously closed. The stopcock H is now opened till the water in M falls to the index line, after which it is closed. By this process 1 cc. of air is displaced from the flask G and sent into the tube E. The stopcock F is now opened, and, as we had previously made a stroke of the pump, air rushes in from the filter and carries the 1 ¢.c. of dusty air along with it into the receiver. The stage is now carefully watched through the magnifying glass, and one stroke of the pump made, the eye being steadily fixed on a selected square on the stage. At once a shower of very fine rain is seen to fall, and the drops that fall on the selected square are counted. If the stage is too hot, the drops rapidly evaporate, and the attention must be confined to one square ; but in certain conditions, difficult as yet to maintain, the drops remain visible a considerable time, so the number on a great many squares can be counted, and an average quickly got; but in most conditions of the stage the test must be repeated frequently before a satisfactory average can be obtained. The measured quantity of water must again be run into M, and its equivalent of air displaced from G into the tube E, and carried into the test receiver, condensation produced, the drops counted for say ten times, and the average taken. Too much dusty air must not be sent into the test receiver at one time, or the drops will be too close for counting ; and further, the whole of them will not be thrown down ; some of them will remain as dust, and will fall if a second expansion is made. Any error from having too many particles present need never take place, as in practice there is a constant check on the number admitted in the following manner :—After expansion has been made and the drops counted, the stopcock F is opened, and filtered air allowed to enter. A stroke of the pump is then made to prepare the receiver to draw in the air for the next test, and if, while this stroke is being made, we watch the stage, we shall see whether any drops fall or not. If none fall, then the amount of dusty air admitted has been within the correct limits ; but, if any drops appear, then too much has been used, and less water must be run into M for the next test. If no condensation took place after this stroke was made, the measured quantity of dusty air is again passed into the tube E, and carried into the receiver for another test. A complete check is thus kept on each test, ensuring that all the particles in each quantity of air tested have been thrown down. Let us now take an example to show the manner of estimating the number of particles in a sample of air by means of this apparatus. In addition to the number of drops per square millimetre, the quantities required to complete the estimate are, the capacity of the receiver A and of the pump B. In the apparatus sketched, A has a capacity of 500 c.c., but, as there are 50 c.c. of water in it, its air capacity is reduced to 450 ce If into this pure air we introduce 1 cc. of the air to be tested, the dusty air will be, 8 J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. so to speak, diluted 450 times. But the air is not only diluted, it is also expanded by the pump, which has a capacity of 150.¢.c. The dust that was in our original 1 cc. is thus expanded by the two processes into 600 c.c. The number of drops per c.c. counted on the stage must therefore be multiplied by 600 to give the number in the original cubic centimetre of dusty air. Suppose that we counted one drop per square millimetre, then, as there is 1 em. of air above the stage, this will give 100 drops per cubic centimetre in the diluted and expanded air, and this multiplied by 600 gives 60,000 dust particles per cubic centimetre of the air tested. With apparatus of the proportions shown, the described method of working is suitable for air in the condition usually found outside, but it will not do for such air as is found in rooms where gas is burning—1 cc. of air of this kind when expanded only 600 times would give such a dense shower of drops that it would be impossible to count them. We might, of course, put in less than 1 c¢.c. of the air to be tested, but it is evident that accuracy cannot be obtained if very small quantities are used, because it is difficult to measure them correctly owing to variations in temperature and pressure, and also because of the imperfections of the apparatus. The tubes connecting the stopcock H. are made of as small diameter, and as short as possible; yet, it is evident that, however small we make them, they will always hold some air, which, by the construction of the apparatus, is counted in the measured air ; but owing to the smallness of the tubes this air will not have so much dust in it, as much of it will settle out while standing. A better plan for testing very dusty air is, first to fill the flask G with water, attach it to the apparatus, and after purifying the air in the receiver, open the stopcock H and disconnect K from M; then syphon out a measured quantity of water, say 400 c.c., allow- ing filtered air to enter by H to take its place. The flask G is then disconnected from E, and 40 ¢.c. of water syphoned over, while its place is taken by the air we wish to test, which is allowed to enter by the stopcock H. ‘The rest of the testing is made as before ; and the calculations are all as in the previous example, only multiplied by 10, or whatever the proportion was in which we mixed the dusty air with pure air in the flask G. Another method of working, and the one which was principally used in the pre- liminary work, is somewhat different, and seems to possess some advantages over the one described ; the apparatus, however, ismuch larger. In this other method the flask G and the filter D are removed, the rest of the apparatus remains as shown, and in place of the flask a gasometer is used. The gasometer employed has a capacity of 20 litres; it is delicately hung, and accurately graduated, so that air can be measured in it to an accuracy of about +}o litre. The gasometer is provided with a large filter 5 inches in diameter and 5 inches deep. The manner of working is as follows :—Back weights are put on, and air drawn in through the filter till the gasometer is nearly full. A measured quantity of the air to be tested is then added to it, and the mixture stirred by means of a metal dise which can be moved up and down inside the gasometer. When testing the outside air, it is introduced into the gasometer by means of a pipe, one end of which passes to the open air, while the other is attached to the gasometer. J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. 9 The outside air is drawn through the pipe for some time just before it is connected with the gasometer. One litre of air is drawn into the gasometer which had been previously nearly filled with filtered air, and filtered air is then added to complete the 20 litres, the whole is stirred, after which the stopcock attached to the gasometer is opened, and 9 of the air allowed to escape, after which the gasometer is again filled up with filtered air. The gasometer is now connected with the test receiver by means of the tube H, the air in the test receiver having been previously purified by means of a filter. The air from the gasometer is now made to flow through the test receiver for some time to expel the pure air, the stopcock is then closed, expansion made, and the drops counted. Or, instead of passing a great quantity of air through the receiver so as to expel all pure air from it, we may allow only just as much to enter as will supply the place of what was taken out by the one stroke of the pump when the expansion was made. ‘These two ways of working, of course, give different numbers of drops per millimetre, but, when the calculations are made for the different conditions, the numbers are alike. The dusty air in the gasometer was, by the process described, first mixed with 19 times its volume of pure air, and then ;}5 was mixed with 9 times its volume; so that the original air was diluted 200 times. This proportion is found to suit some states of the outside air; but for air with more particles in it, such as the air of a room, the process has to be repeated twice or even three times, each process of emptying to 75, and filling with filtered air, requiring the number of drops to be multiplied by 10. The gasometer, however, is not always emptied to +4,; the density of the shower which appears when a trial expansion is made gives an idea of the amount of dilution required before correct counting can be done. It would save time with very dusty air to let out more than 9% before filling up with pure air, but it is not thought advisable to do so, as the measure- ments made with the lower part of the gasometer are never so accurate as those taken further up, owing to evaporation altering the level of the water. In some cases the air to be tested has been introduced by displacement, the air being contained in a large bottle and displaced by means of a measured quantity of water, attention being given to keep pressure correct. By this method of working, we can mix very small quantities of the dusty air, and make the test without emptying and fille the gasometer a number of times. On some Necessary Precautions. In developing a process of this kind, it was quite to be expected that many difficulties would present themselves. Most of these have now been overcome, but more than once the task appeared hopeless. Everything would go right for a time, then all at once it would break down. The number of particles counted in the successive tests of the same air would be fairly constant for a number of times; it would then increase to an amount far exceeding the limits of the errors of observation. Now that the road is cleared and the principal obstructions removed, it is difficult on looking back to see where the obstructions were, as their cause, and the manner of avoiding them, are now so VOL. XXXV. PART 1. B 10 J. AITKEN ON FHE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. evident. If it were not for my note-book and the interval of time which has elapsed since the preliminary trials were made with the apparatus,—time which has been spent in clearing these obstructions,—one would be unconscious that they ever existed. As, however, these same difficulties will probably occur to any one who may be induced to follow this line of investigation, it is advisable that some reference be made to them, and the manner in which they may be avoided pointed out. When the different tests of the same air gave such different results, it was at first thought that the difference might be due to imperfect filtermg. In the process described we take an amount of filtered air and mix it with a small amount of the dusty air we wish to test, and we assume that all the centres of condensation were dust particles con- tained in the dusty air. Now, it is very evident, that if the pure air is imperfectly filtered, our results will not be true, and the numbers will vary with the more or less perfect filtration of the air. As then the filtering of air lies at the very root of the matter, it was thought advisable to study this process more in detail, and determine whether it is possible by means of cotton wool to filter out all the dust particles, and, if possible, to determine the conditions under which this can be done. The apparatus used for studying this question was much the same as that represented in the Plate. The flask G was removed, and the pump and the filter connected with the receiver in the manner shown ; the connecting pipes, however, only entered the receiver to a height a little above the level of the water, so as to leave the interior of the receiver clear for observing any condensation that might take place. The gas flame was brought down to very nearly the level of the receiver, the light being allowed to pass through the opening in the screen U, the screen being painted black on the side next the receiver. By this arrangement a strong light was thrown into the receiver by means of the water lens, and by taking up a position with the eye a little above the level of the receiver, the light was not seen, while the illuminated drops were clearly observed against the black background. Some other little black screens were also introduced to cut off all light except that coming from the drops, but these need not be particularly referred to, as each operator will adjust them to suit himself. The filters consisted of cotton wool packed into glass tubes, similar to that shown at D in the figure, only of different lengths. The internal diameter of these tubes is 1 inch. A plug of wire-cloth was fitted into the bottom of each tube for the wool to rest on and prevent it pressing into the small exit tube. The filtering powers of different lengths of closely packed cotton wool were tested in the tubes, beginning with a length of 1 inch, and gradually increasing up to 12 inch (30°5 cm.). There appeared no very definite method of measuring the effect of different lengths, as, in addition to the tightness with which the wool is packed, the filtering power depends on two things. First, the thickness or length of filter; and second, the rate at which the air is passed through it. The following is the method employed for testing the filtering powers of tightly packed cotton wool, and will give an idea of the filtering power under different conditions :—The receiver employed has a J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. 11 capacity of 450 ¢.c., while the volume of the pumpis 150 c.c. In making an experiment, one stroke of the pump is made, and after the drops inside the receiver have settled, the stopcock F is opened and air allowed to enter, the air passing through the filter on its way. It was found that with a length of 1 inch (2°5 cm.) of wool in the filter, the air was very far from being freed from all its dust, as a shower always fell after expansion. But, if the rush of the air through the filter was checked, and it was made to pass slowly through, then all the dust was taken out. More and more wool was now packed into the tube, with the result, that when a length of 3 or 4 inches was attained the air might be allowed to rush unchecked through the filter, and yet be perfectly freed from all dust. Part of this better filtration is the result of the greater length of wool passed through by the air, but very much is due to the checking of the rush of air by the greater length of wool. When more wool was packed into the tube, no difference whatever was detected in its filtering power. It was, however, found that with even 12 inches of wool the filtration, though perfect under the conditions described, was imperfect if the air was made to rush through it more violently. If three strokes of the pump were made instead of one, before the stopcock F was opened, the rush of air was sufficiently violent to carry some dust through even 12 inches of tightly packed cotton wool. These results point clearly to the necessity of testing the filter connected with any apparatus, under exactly the conditions under which it will be used. When working with certain arrangements of apparatus, such as that shown in the Plate, where an air-pump is used, it does not matter how much wool we pack into the filter, the pressure employed is so great that the resistance of the filter does not practically interfere with the working of the apparatus, in which case it is advisable to have a great thickness of wool. But when working with the gasometer arrangement, the pressure available for drawing the air through the filter is very small, and a great length of wool would retard the filtering and waste much time. The filter for the gasometer was therefore made of very large area, to reduce the rate per unit of area at which the air passes through it; and after enough of wool had been packed in to give perfect filtration, when used under the pressure at which it was to be worked, a large amount more was added to give a good factor of safety. In work- ing the gasometer arrangement, it has been customary to test the action of the filter every time the gasometer is being filled with filtered air. This is necessary not only to see that the filter is acting perfectly, but also to make sure that all dusty air has been washed out before we begin to fill with filtered air, as it is difficult to get rid of the last trace of dusty air in the gasometer and its connecting pipes, and this can be done only by washing with filtered air and testing. What I have here stated definitely with regard to the filtering powers of different lengths of cotton wool was very far from being clear while the investigation was going on. At that time, what has been stated seemed to be the general conclusion, but any thing like confidence in it was destroyed by the many exceptions. For instance, tne w= inch filter seemed to do its work perfectly, filtering the air from every dust particle, so long as the rush of air through it was limited to that produced by one stroke of the pump. 12. J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. Time after time the air would be perfectly free from all traces of condensation when expansion was made, then apparently without reason it would break down, a dense shower of rain would fall, and then the next time perhaps none, but only to be followed by failure before long. As we shall see, there were many causes for the failure of the filtered air to keep free from condensation when expansion was made. These we shall consider separately. This failure, of the air to keep clear, at first seemed unaccountable with so large a factor of safety as was given by 12 inches of cotton wool, which is four times what was found to be required for perfect filtration under what appeared to be the same conditions. The first thing that was suspected was some fault in the joints of the tubes where the metal or glass joined the india-rubber. When any new failure occurred this was always the first thing suspected. Time after time were the joints taken down, and remade with a solution of india-rubber, and the stopcocks cleaned, greased, and tested; but in almost no instance were these found to be at fault, as india-rubber solution makes a perfect joint so long as it has not been severely strained. One explanation of the failure seemed to be that after all the filtermg might not be perfect, that the filter only kept back the larger particles while it passed the extremely small ones. Sir Witt1aAm THomson has concluded from certain phenomena of capillarity that the vapour pressure at a concave surface is Jess than that at a flat one; and Professor CLERK MAXWELL has extended this conclusion to convex surfaces, and has shown that the vapour pressure at a convex surface will be greater than that at a flat one, and that the smaller the body, that is the quicker its curvature, the higher will the vapour pressure be at its surface. From this we see that air which is saturated at a flat surface is not saturated at a convex one, and also that the smaller the body the higher will the super- saturation require to be to produce condensation on it. In our ignorance, it seemed from this just possible that the degree of supersaturation produced by the amount of expansion used in the experiments might just be about enough to cause condensation on these extremely small particles, so that in one test the degree might be exceeded, while in the next it might not be reached. These considerations pointed to the necessity of ree this point separately. Given a quantity of ordinary air, we have, in a previous communication, shown reasons for supposing that condensation begins before supersaturation is reached, owing to an affinity between the material of the dust particles and water vapour. When supersaturation is made in this air, these particles, owing to their affinity for water vapour, are the first to become visible by the vapour condensing on them. Suppose these are allowed to settle, then, when the next expansion and supersaturation is made, the probability is that the largest particles will take the next burden of vapour, and that the smaller ones will be left to be taken down by a subsequent supersaturation, till at last the smallest particles only are left to be brought down in a similar manner. This is theoretically what we might expect to happen, because the smaller the particle the higher will the vapour pressure be at its surface, and the higher therefore the supersaturation must be before J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. 13 condensation can take place on it; but a high degree of supersaturation is not possible while the larger particles are present, and it is not till the air is freed from them that the higher degree of supersaturation necessary to cause condensation on the smaller ones is possible. In order to determine whether the showers observed with the high degree of super- saturation used in the tests were due to the presence of extremely small particles, it was necessary for us experimentally to determine whether the size of the particles has practically any influence on the degree of supersaturation required to cause them to become centres of condensation. In order to get an answer to this question, the apparatus was arranged very much as described for testing the filtering powers of cotton wool, that is with the test receiver A, connected on the one side with the air-pump, and on the other with the tube E, through which air could be drawn either from the filter or the gasometer. ‘Through the india- rubber stopper in the receiver A was passed a third tube, to the lower end of which was attached a burette provided with a stopcock. The burette was fixed in an inverted position to the projecting end of the tube by means of a small piece of india-rubber tubing. The burette dipped into a very tall vessel full of water. This vessel was so arranged that it could be easily raised and lowered, or fixed at any desired height. The burette and vessel of water were used as an air-pump for producing small and known amounts of expansion of the air in the receiver. The ordinary air-pump could not be used for this purpose, as it is not suitable for making small and correctly measured amounts of expansion, and also because, in this experiment, the air which is taken out of the receiver at each expansion has to be returned to it, as no air from the outside can be admitted during the test. Supposing the apparatus arranged as described, the following is the manner adopted for testing the condensing powers of the different particles:—The air in the receiver and connecting tubes is first purified by pumping air through the filter. All connection is then cut off with the outside air by closing the stopcock F between the receiver and the filter. No stopcock is necessary on the exit tube, as the air-pump stops the passage of air in that direction. The burette stopcock is then opened, and the tall vessel of water is lowered till the water in the burette falls 2.¢.c. The support under the vessel is then fixed at this level, after which the vessel is again raised to its original height and kept there till the water in the burette has recovered its original level. The burette stopcock is now closed, and the vessel lowered to its previous position. The apparatus being thus adjusted, the air to be tested is drawn into the receiver through the pipe E from the gasometer. After a short time, to allow any change of volume to adjust itself, the con- nection between the receiver and the gasometer is cut off, and the testing begun by opening the burette stopcock, when the water in it at once falls, and draws out 2 cc. of air from the receiver. This expansion gives rise to condensation, the small fog particles being easily seen with the aid of a magnifying glass. After sufficient time has been given for the particles to settle, the tall vessel of water is raised, and the 2 c.c. of air are 14 J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. returned to the receiver. In a short time after, when the air is again saturated, the process is repeated, the tall vessel lowered, 2 ¢.c. of air drawn out, and a shower of fine particles produced in the receiver. ; Repeating this process a number of times, it was found that on each succeeding expansion the denseness of the condensation became less and less. At first the particles were numerous, very small, and fell very slowly, then after a few expansions they decreased in number, while they increased in size, and fell more quickly. After a considerable number of expansions had been made, condensation entirely ceased, not a drop being seen to fall. When this condition was attained, the tall vessel of water under the burette was lowered so as to cause an increased expansion. The vessel was lowered so much that on the burette stopcock being opened the water in it fell 5 ¢.c., arrangements for this having been previously made. When the stopcock was now opened, a dense shower of drops made its appearance in the receiver. An expansion of 5 c¢.c. thus produced condensation in air which had no nuclei for an expansion of 2 ¢.c. Continuing the test, the vessel of water was raised, and the 5 c.c. of air returned to the receiver, the stopcock shut, and again opened after a time, when another but less dense shower fell. After this was repeated a few times, no condensation took place with an expansion of 5¢.c. The tall vessel of water was then lowered still further, this time to an extent to cause the water in the burette to fall 10 cc. When this was done, another shower made its appearance, but not nearly so dense as the first one which fell when the expansion was increased to 5 cc. After a very few 10 cc. expansions, the condensation stopped. After this con- dition of matters was attained, an expansion of 150 ¢.c. was made by means of one stroke of the air-pump. When this was done, scarcely a drop made its appearance. We see from this experiment that a very slight degree of supersaturation will cause condensation on some of the dust particles in the air, but that the degree of supersatura- tion which is sufficient to cause some particles to become active centres, is yet insufficient to cause condensation to take place on others. An expansion of zs}, produced a super- saturation sufficient to cause condensation on more than one half of the particles, but it required a higher degree of supersaturation to produce condensation on the others, many of them requiring the supersaturation produced by an expansion of ;)5 before vapour condensed on them. It may be concluded from this experiment that we have here distinct evidence that the condensing powers of the dust particles is affected by their size. No doubt the com- position of the particles has an effect on the degree of supersaturation necessary to make even the small particles active, yet the affinity between the material of the particle and water vapour does not satisfactorily account for the different degrees of supersaturation required to make the different particles active. Though a small particle which has an affinity for vapour may have the same condensing power as a larger particle which has no affinity, yet the affinity alone does not explain the necessity for supersaturation. to make any of them active ; this, so far as we know, can be explained only by the sizes. We see from this experiment that an expansion of ;'5 is nearly, perhaps quite sufficient ai i i J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. 15 to cause condensation to take place on even the smallest particles in the air tested; from which we may conclude that the showers which unexpectedly took place from time to time in the experiments described, where high expansions were used, were not due to the presence of extremely small particles which had become active with the high degree of supersaturation. As already stated, Sir WinL14m THomson has shown that the phenomena of capillarity give experimental proof that the vapour pressure at a concave surface is less than at a flat one. In the experiment above described, we have what is, so far as I am aware, the only experimental illustration of the complement to that conclusion, as it demonstrates that the vapour tension at a convex surface is greater than that at a flat one, and also that the smaller the body, that is, the quicker the curvature, the higher is the vapour pressure at its surface. In describing the apparatus last used, it was stated that the air tested was drawn from the gasometer. The object of this was that in making an experiment of the kind described, it would have been an almost endless task to throw down all the particles in ordinary air, by successive showers, in the manner described. The gasometer was therefore used for mixing a small quantity of the ordinary air of the laboratory with a large amount of filtered air. Working in this manner, we have samples of all the different kinds of dust in the air, and a comparatively few expansions are sufficient to complete the series necessary to throw down all the particles. In making experiments of this kind there is a necessary precaution we must refer to. The air under test is kept saturated by the wet sides of the receiver. It is, however, extremely difficult to keep the air from being supersaturated, because any difference in temperature of the different parts of the receiver will cause supersaturation where the hot saturated air mixes with the colder. Great care was therefore taken to keep the temper- ature as uniform as possible, all radiation being cut off, as it is easy to see that if there is any supersaturation due to difference of temperature, then a slight expansion would have the effect of a greater expansion, and interfere with the correctness of our results. In illustration of the effect of supersaturation from inequality in the temperature of the different parts of the receiver, the following experiment may be made :—Introduce into the receiver air in which there is only a very little dust. Now place the hand on one side of the receiver to heat it slightly, and watch the result. Inside the receiver will be seen a shower of condensed particles, which will keep falling so long as there is any dust in the air and the hot side of the receiver keeps wet. After it stops we may make an expansion by means of the pump, but no condensation will take place, the condensation produced by the mixing of the hot and cold currents having previously thrown down all the particles. Having then satisfied ourselves that a very small degree of expansion is sufficient to give rise to a supersaturation great enough to cause even the finest dust particles to become centres of condensation, we may dismiss the idea that the showers which gave so much trouble by their appearance from time to time with high degrees of expansion 16 J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. were due to the imperfect action of the filter. If they were not due to the presence of dust, then we are thrown back on the conclusion that they must have been cases of con- densation without nuclei. In a previous communication* reference has been made to instances of this kind, in which other substances than water are shown to condense with- out nuclei, and experiments are also described in which water vapour seemed to condense without nuclei when the supersaturation was sufficiently great. If those troublesome condensations, which took place when high expansions were used, were really cases of condensation without nuclei, then there seemed to be a way of pre- venting them. We know that water may be cooled far below the freezing point and yet it will not become ice, if no nuclei be present ; also that water may be heated far above the boiling point without passing into steam, if no free surface be present. We also know that any violent shock will upset the unstable equilibrium, and determine the formation of ice in the one ease, and of steam in the other. Now, it is evident that in these two cases it is more the violence of the motion than the motion itself which determines the change. In both cases there must have been motion in the water due to convection currents while it was cooling or heating, but these slow movements were not sufficient to cause a break in the strained molecular condition. From this it seemed highly probable, that if we checked all violent movements of the air in the receiver, it would be possible to carry the supersaturation to a high degree without spontaneous condensation taking place ; and, on the other hand, we might, by means of violent movements and shocks, cause condensation to take place in supersaturated air though it was free from nuclei. Acting on this idea, a number of trials were made with air which had been passed through a long filter, and saturated. On drawing out the piston of the pump with a slow and steady stroke, no condensation ever took place; whereas a quick stroke generally brought down a shower, and if the piston was made to strike the cover of the cylinder with a sharp blow, the shock invariably brought down a dense shower. ‘These results point clearly to the conclusion that the condensation in the experiments took place without nuclei, as quick and slow strokes have no influence on the condensation when dust is present. It may be mentioned that the expansion was always made quick enough to prevent the air in the receiver absorbing so much heat as practically to interfere with the cooling effect of the expansion. Here then was the key to one of our difficulties, accounting for one cause of the variation in the number of particles counted in the successive tests of the same air. Many of the drops counted having no dust nucleus, as it would be inconvenient to regulate the stroke of the pump while attending to other matters, it was necessary to arrange the apparatus so as automatically to check failures of this kind. It has been found that this end can be attained by causing the air on its passage from the receiver to the pump to pass through a small opening, or, what is perhaps better, through a small cotton-wool filter. This filter is made dense enough to check the rush of air, and it also * Trans. Roy. Soc. Edin., vol. xxx. part 1. J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. 17 checks any shock being communicated from the pump to the air in the receiver. In the Plate it will be noticed that there is an enlargement P at the top of the exit tube C. The interior of P is packed with cotton wool, and a cover is put over all to keep off the showers of fine rain. This arrangement has been found to work perfectly, and it has in a simple manner removed one of our principal difficulties, keeping the air free from spontaneous condensation with even higher expansions than results from one stroke of the pump. It may be asked, Why was the use of such high degrees of expansion persisted in, when it was accompanied by so many difficulties? One reason was the very existence of these difficulties themselves. They had to be satisfactorily explained before any con- fidence could be placed in the method of working. If we had confined our attention to lower expansions, we could not, for instance, have been certain that the finest particles were thrown down and all the dust counted. But another reason was that the high degree of expansion makes the drops much larger; they therefore settle more quickly, and are more easily counted. Passing on to another necessary precaution. In making these tests, as has been already explained, it is necessary from time to time to turn the receiver upside down, and move it about in such a manner as to cause the water in it to come into contact with all parts of the interior. When using the 12-inch filter it was noticed that, after doing this, rainy condensation frequently took place on making the first expansion. It was thought this time that the failure might be due to some straining of the joints from the twisting of the tubes when moving the receiver, or that it might be due to the saturation being more perfect after the walls were newly wetted, and the air consequently more highly supersaturated on expansion, and therefore in a more favourable condition for producing condensation. This class of failures was, however, traced to the manner of wetting the inside of the flask, the particles being produced by the splashing of the water. If the wetting was roughly done, and there was much splashing, a considerable number of particles were manufactured, and a shower always took place on expansion. But if the water was quietly moved round inside the receiver, no condensation appeared. On another occasion copious showers made their appearance even when using every precaution, and the showers persisted, so that it looked as if the apparatus had broken down somewhere. At last the source of these particles was traced to a drop of water, which had got into the inlet pipe, and wet the lips of the stopcock. The air rushing over this wet surface, on its way to the receiver, had torn up the water into fine spray, which supplied active centres of condensation. A similar disturbance was also produced when the air was allowed to rush too quickly out of the gasometer into the receiver. The rush of air over the wet lip of the pipe, where it enters the gasometer, manufactured particles enough to give a good shower. There are some other precautions which require attention in working the apparatus but, as there are some developments of the apparatus at present under consideration, in which it is hoped these will be avoided, reference need not be made to them here. VOL. XXXV. PART 1. C 18 J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. Estimated Number of Particles in Air from different Sources. Having described the method of counting, the apparatus employed, and some of the precautions necessary in conducting the tests, I shall now give some of the numbers obtained by this method of counting. These numbers have all been taken with the use of the gasometer instead of the flask G shown in the Plate. Comparative tests have been made with the gasometer and flask arrangements, but not sufficiently extensive to give accurately their relative values. The numbers given by the flask method are generally less than with the gasometer, owing to the particles settling more quickly in the small flask than in the gasometer. Number of Dust Particles in Avr. Source of Air. Number perc.c. | Number per c. in. Outside (Ruining), . ? 32,000 521,000 Outside (Fair), . ; ; 130,000 119,000 Room, : : ; 1,860,000 30,318,000 Room near ceiling, . 5,420,000 88,346,000 Bunsen flame, . : : 30,000,000 489,000,000 In the first column of the above table is entered the source of the air tested. In the second column the number of particles per cubic centimetre ; and for the benefit of those who prefer English measures, there are entered in the third column the numbers per cubic inch. The experiments made on the air of our atmosphere are too few as yet to enable us to draw any conclusions from them. But, so far as they go, they indicate that there is most dust in the air durimg dry weather, and perhaps during anticyclonic con- ditions, and least during wet weather, and perhaps in cyclonic areas. The first number entered in the table for outside air was taken on the 25th January, after a wet and stormy night. The next number is an average for dry days, while we had anticyclonic weather. It is hoped that, by more extended experiments, and by the use of the improved apparatus now under construction, some interesting meteorological results may be arrived at. The air in the laboratory was tested in the first case at a height of 4 feet from the floor, and gave the third number entered in the table. Air drawn from near the ceiling gave the fourth number. ‘The reason of the greater number of particles in the room than that found outside was due to the particles produced by two gas flames burning in the room at the time. ‘The air from the Bunsen flame was collected by means of a small chimney, and drawn direct into the gasometer, where it was mixed with filtered air. So full was this air of particles that it had to be mixed with 80,000 times its volume of filtered air before the particles were separated widely enough for counting. All the numbers in the table are far from being constant; they are all found to vary much J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. 19 according to certain conditions, such as the time during which the gas has been burning in the room, manner of collecting air from the Bunsen flame, &c. Many will perhaps think that the numbers of particles as given in the table are far too high, and that there must be a mistake somewhere. It may be mentioned that the evidence in support of the correctness of our conclusions is similar to that of the chemist’s, when be puts, say, asolution of sodium chloride into a solution of silver nitrate, and from the weight of precipitated silver chloride tells the amount of silver that was in the solution. If there had been no silver in the solution, then there would have been no precipitate ; and the amount of precipitate is in proportion to the quantity of silver present. So it is in testing for dust. If there is no dust in the air, no drops are thrown down, and the number of drops is determined by the number of particles present, for each drop has a dust nucleus. I have not yet entered carefully into the consideration of the exact value of the figures in the table. While the described method of counting the particles gives a very fair estimate of the number in the air when it arrives at the test receiver, and the numbers entered in the table are the numbers calculated from the particles counted there, no allowance has been made for the dust which may have settled in the gasometer and con- necting pipes. The probability, therefore, is that the figures are rather under than over estimates of the particles in the air tested. As showing the tendency the dust has to settle in the apparatus, it may be mentioned that about one half of the dust particles settled out of the air, if it is allowed to remain in the gasometer for one hour. In the development of the apparatus for this investigation, this is one of the points to which special attention has been given, and a method has been devised by which a very short time will be given for settling before the particles are counted. It is possible the dust might settle more slowly if the vessel containing it were dry, and mercury used instead of water for displacing it. This, however, with many other points, remains for considera- tion. It may be as well to note here, that the dust settles out of the air not only on account of its weight causing it to fall, but very much is settled out by difference of tem- perature at the different parts of the vessel. Wherever the air meets a surface colder than itself it parts with some of its dust to that surface, for a reason which has been explained in a previous communication. Most of us were quite prepared to find that whenever the dust particles in our atmo- sphere were counted, the figure would be a very high one; but I imagine that the figures here given are such as few, if any expected, and they increase our admiration of the Old Testament writers’ selection of dust as a type of the infinitely small and the innumerable. Trans. Koy. DOCa duns: Volk AK J. AITKEN ON THE NUMBER OF DUST PARTICLES IN THE ATMOSPHERE. Fig. 1. = LT SS a ae A ea Se M‘Farlane & Erskine, Lith? Edin™ ( 21 ) I].—The History of Volcanic Action during the Tertiary Period in the British Isles. By ArcHipaLpD Gerxie, LL.D., F.R.S., Director General of the Geological Survey of the United Kingdom. INTRODUCTION, I. THe Basic DyKzs, . § 1. Geographical Distribution, 2. Two Types of Protrusion, 3. Nature of Component Rocks, 1. External Characters, 2. Internal Characters, 3. Chemical Characters, : 4. Petrographical Nomenclature, . Hade, . Breadth, . Interruptions of Lateral Conuaiay Length, , : periotence of Mineral Cinactrs : . Direction, 4 10. Termination pans ; 11. Known Vertical Extension, 12. Branches and Veins, , 13. Connection with Intrusive heats) 14. Intersection of Dykes—Repeated Dykes in the same Line of Fissure, 15, Contact-Metamorphism, 16. Relationof Dykes to Geological Sine. 17. Data for Estimating their Geological Age, 18. Origin and etary of the Dykes, : OnMnIA a Il. Tue Votcanic PLATEAUX, 1. Petrography, F 2. Areas of the Plateaux and saacecusiant of Rocks in them, 1. Antrim, 2. Mull, ; 3. Small Isles, 4. Skye, $3. Vents of Eruption, a. Filled with Dolerite, ihe b. Filled with aay 4. Intrusive Sheets, (Plates I., I.) (Read 21st May 1888.) CONTENTS. PAGE 21 III. Tae Bosszts AND SHEETS OF GABBRO, . 29 §1. Petrography, 39 2. Relations to the ate ‘Golem Racks 33 a. Skye, . ; : ; 35 b. Rum, . ; 35 c. Ardnamurchan, . 4l d. Mull, Aa 3. Structure Gf the Gate oon i IV. THe Acrp Rocks, 45 $1. Petrography, . é 47 1. Pitchstone and Trachyte Seniey : 48 2, Felsite, Quartz-Porphyry, Grano- 50 phyre, and Granite Series, 50 2. Types of Structure, , 2 52 1. Bosses, 55 a. Mull, . 56 b. Small Isles, . 59 c. Skye, Relation of 0 Bore to 61 other Members of the Vol- 62 canic Series, ‘ 3 63 (1) Relation to older 68 Eruptive Vents, 70 (2) Relation to the 74 Bedded Basalts of ‘a the Plateaux, . 6 16 (3) Relation to the Gab- bros, : ee (4) Relation to the aie 84 Dykes and soa : 89 d. St Kilda, 94 e. Antrim, 96 ON sillier Ghcets, m0 3. Veins and Dykes, hau 4, Superficial Lava Streams, 104 111 VY. SUMMARY, INTRODUCTION. PAGE 122 122 124 126 132 137 137 140 143 145 145 147 150 151 152 159 160 164 164 165 168 169 170 170 172 175 178 181 Among the problems for the study of which the remarkably varied geology of the British Isles offers peculiar facilities, perhaps none ranks higher in importance or in general interest than the history of volcanic action. Placed on the oceanic border of an ancient continental area, the region of Britain has lain within the limits where VOL. XXX.\", PART 2. D 22 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION hypogene activity is specially prone to manifest itself, From early geological times this activity has been displayed in various characteristic forms. Hence, within the geological records of Britain there has been preserved a more continuous and complete chronicle of volcanic phenomena than, so far as I am aware, has yet been discovered in any tract of similar size on the face of the globe. The rocks of the country have been investigated so long and so minutely that their general chronological succession has been accurately ascertained, and hence the precise herizon of each volcanic episode can be definitely fixed. The varying phases of eruptivity in different geological periods can be made out, and a large body of evidence can thus be amassed bearing on the general question of the past history of voleanism. Taking the broadest view of the subject, we find that the volcanic history of Britain naturally divides itself into two widely separated periods. The first of these embraces the vast Palzeozoic ages ; the second falls entirely within older Tertiary time. Between these two periods comes the prolonged interval marked by the whole series of Mesozoic formations in which, save at their base, in the lower Triassic rocks of Devonshire, no trace of contemporaneous volcanic action is known. It is to the records of the second of the two great volcanic eras that the present memoir is devoted. Before entering upon the detailed investigation, it may be useful to sketch briefly what has been the progress of opinion regarding the phenomena to be discussed. The basaltic cliffs of Antrim and the Inner Hebrides had attracted the notice of passing travellers, and their striking scenery had become more or less familiar to the reading public, before any attention was paid to their remarkable geological structure and history. In particular, the wonders of the Giant’s Causeway and the Isle of Staffa had already begun to draw pilgrims, even from distant countries, at a time when geology was still in its earliest infancy. The scientific tourist of those days who might care to look at rocks, was, In most cases, a mineralogist, for whom their structural relations and origin were subjects that lay outside of the range of his knowledge or habits of thought. One of the earliest traces of an intelligent appreciation of some of the geological interest of the region is to be found in Warreavurst’s Inquiry into the Original State and Formation of the Earth (2nd edit., 1786), where a good account of the basalt-cliffs of Antrim is given, and where the basaltic rocks are regarded as the results of successive outflows of lava from some centre now submerged beneath the Atlantic. More important are the observations contained in two letters of ABraHAmM Mutts, published in the Philosophical Transactions for 1790. This writer had been struck with the dykes on the north coast of Ireland, and was led to examine also those in some of the nearer Scottish islands. He believed them to be of truly volcanic origin, and spoke of them as veins of lava. A few years later, Fausas St Fonp made his well-known pilgrimage to the Western Isles. Familiar with the volcanic rocks of the Continent, he at once recognised the volcanic origin of the basalts of Mull, Staffa, and the adjoining islands. His Voyage, published in Paris in 1797, may be taken as the beginning of the voluminous geological literature which has since gathered round the subject. Three years afterwards (1800) appeared JaMEsoN’s DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 23 Outline of the Mineralogy of the Scottish Isles, Fresh from the teaching of WERNER at Freiberg, the future distinguished Professor of Natural History in the Edinburgh University naturally saw everything in the peculiar Wernerian light. He gave the first detailed enumeration of some of the eruptive rocks of the Hebrides, but of course ridiculed the idea of their igneous origin. Having heard of a reported “crater of a volcano” near Portree, he ironically expressed a hope that ‘‘ probably there may be still sufficient heat to revive the spirits of some forlorn fire-philosopher, as he wanders through this cold, bleak country.” The advent of JAmEson to Edinburgh gave a fresh impetus to the warfare of the Plutonists and Neptunists, for he brought to the ranks of the latter a mineralogical skill such as none of their Scottish opponents could boast. The igneous origin of basalt, which the Plutonists stoutly maintained, was as strongly denied by the other side. For some years one of the most telling arguments against the followers of Hurron was derived from the alleged occurrence of fossil shells in the basalt of the north coast of Ireland. Kirwan, whose Essays appeared in 1799, quoted with evident satisfaction RicHarpson’s observation of “shells in the basalt of Ballycastle,” and RicHarpson him- self, though the true explanation that the supposed basalt is only Lias shale altered by basalt, had been given in 1802, by Puayrair, in his Illustrations of the Huttonian Theory, continued for ten years afterwards to reiterate his belief in the aqueous origin of basalt. Thus the Tertiary volcanic rocks furnished effective weapons to the combatants on both sides. The dispute regarding the black fossiliferous rocks of Portrush had the effect of drawing special attention to the geology of the north of Ireland. Among the more noted geologists who were led to examine them, particular reference must be made to CONYBEARE and BuckLanpD, who, in the year 1813, studied the interesting coast-sections of Antrim. The report of their observations gives an excellent summary of the arguments for the truly igneous origin of basalt, and a statement of opinion in favour of the view that the bedded basalts are the products of submarine volcanoes. BERGER also about the same time described in fuller detail the geology of the Antrim district, and showed the rocks of the basalt-plateau to be younger than the Chalk. He likewise made a study of the basalt-dykes of the north of Ireland, and was the first to point out their prevalent north- westerly direction, These memoirs, contained in the third volume of the Transactions of the Geological Society, may justly be regarded, to quote the words of PorrLock, as “ the first effectual step made in Irish geology.” Portiock’s own Report on Londonderry, published in 1843, is still the most complete summary of information regarding the geology of that interesting region. While such advances were being made in the knowledge of the structure of the volcanic rocks of the north of Ireland, the geologist had already appeared who was the first to attempt a systematic examination of the Western Islands, and whose published descriptions are still the chief source of information regarding the geology of this extensive region. Dr MaccuLtocu seems to have made his first explorations among the Hebrides some time previous to the year 1814, for in that year there were published, in 24 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION the second volume of the Transactions of the Geological Society, some remarks by him on specimens from that district transmitted to the Society. For several years in succession he devoted himself with great energy and enthusiasm to the self-imposed task of geologically examining and mapping all the islands that he to the westward of Scotland, from the remote St Kilda even as far as the Isle of Man. From time to time, notices of parts of his work were given in the Transactions of the Geological Society. But eventually in 1819 he embodied the whole in his Description of the Western Islands of Scotland. This great classic marks a notable epoch in British geology. Properly to estimate its value, we should try to realise what was the state of the science in this country at the time of its appearance. So laborious a collection of facts, and so courageous a resolution to avoid theorismg about them, gave to his volumes an altogether unique character. His descriptions were at once adopted as part of the familiar literature of geology. His sections and sketches were reproduced in endless treatises and text-books. Few single works of descriptive geology have ever done so much to advance the progress of the science in this country. With regard to the special subject of the present memoir, MaccuLLocH showed that the basalts and other eruptive rocks of the Inner Hebrides pierce and over- lie the Secondary strata of these islands, and must therefore be of younger date. But though he distinguished the three great series of “ trap-rocks,” “ syenites” and “ hyper- sthene-rocks” or “ augite-rocks,” and indicated approximately their respective areas, he did not attempt to unravel their relations to each other. Nor did he venture upon any speculations as to the probable conditions under which these rocks were produced. He claimed that those who might follow him would find a great deal which he had not described, but little that he had not examined. Subsequent observers have noted many important facts, of which, had he observed them, he would at once have seen the meaning, and which he certainly would not have passed over in silence. But as a first broad out- line of the subject, MaccuLiocy’s work possesses a great value, which is not lessened by the subsequent discovery of details that escaped his notice, and of points of geological structure which he failed to discover. It may here be remarked, that among the earliest and ablest observations of the volcanic rocks of this country were those made by foreigners. In some cases, students who had repaired from abroad to Edinburgh for education caught the geological enthusiasm then so marked in this city, and made numerous journeys through the country in search of further knowledge of its rocks and minerals. In other instances, geologists of established reputation, attracted by the interest which the published accounts of Scottish geology had excited, were led to visit the country and to record their impressions of its rock-structure. Of the first class of observers the two most noted were Amt Bout and L. A. Necker. Bout took his degree of M.D. at Edinburgh in 1816. During his stay in Scotland he made extensive tours across the kingdom, and acquired a wide knowledge of its rocks and minerals. In the year 1820 he published his Hssaz géologique sur UEcosse. The value of this work as an original contribution to the DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 25 geology of the British Isles has probably never been adequately acknowledged. For this want of due recognition the author himself was no doubt in some measure to blame. He refers distinctly enough to various previous writers, notably to JamEson and Maccuttocu, but he modestly mingles the results of his own personal examinations with theirs in such a way that it is hardly possible to ascertain what portions are the outcome of his own original observations. Less credit has accordingly been given to him than he could fairly have claimed for solid additions to the subjects of which he treated. In the later years of his life, I had opportunities of learning personally from him how extensive had been his early peregrinations in Scotland, and how vivid were the recollections which, after the lapse of half a century, he still retained of them. Judged simply as a well-ordered summary of all the known facts regarding the geology of Scotland, his Hssaz must be regarded as a work of very great value. Especially important is his arrangement of the volcanic phenomena of Scotland, which stands far in advance of anything of the kind previously attempted. Under the head of the “Terrain Volcanique,”’ he treats of the basaltic formations, distinguishing them as sheets (nappes, coulées) and dykes; and of the felspathic or trachytic formations which he subdivides into phonolites, trachytes, porphyries (forming mountains and also sheets), and felspathic or trachytic dykes. In the details supplied under each of these sections he gives facts and deductions which were obviously the result of his own independent examination of the ground, and he likewise marshals the data accumulated by Jamuson, Maccuttocn, and others in such a way as to present a comprehensive and definite picture of the volcanic phenomena of Scotland such as no previous writer had ventured to give. L. A. Necker, as the grandson of the illustrious Dz Saussurz, had strong claims on the friendly assistance of the Edinburgh School of Geology when he went thither in 1806, at the age of twenty, to prosecute his studies. He was equally well received by the Plutonists and Neptunists, and devoted much time to the exploration of the geology, not only of the Lowlands, but of the Highlands and the Inner Hebrides. Most of his observations appear to have been made in the year 1807, but it was not until fourteen years afterwards that he published his Voyage en Ecosse et aux Iles Hebrides.* The geological part of this work must be admitted to be somewhat disappointing. The author’s caution not to commit himself to either side of the geological controversy then waging, makes his descriptions and explanations rather colourless. He adds little to what was previously known, and even as regards the true volcanic origin of the basalts of the Western Islands he could not make up his mind, contenting himself by referring them to “the trappean formation.” But these islands had so fascinated him that eventually he returned to them as his adopted home, passed the last twenty years of his life among them, and died and was buried there. Besides his Voyage, he published in French an account of the dykes of the Island of Arran which appeared in vol. xiv. of the Transactions of this Society. * See biographical notice of L. A. Necker, by Principal J. D. Forbes, Proc. Roy. Soc. Edin., v. (1862) p. 53. e 26 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION Among the foreign geologists who have been drawn to the mountains and islands of Scotland by the interest of its rocks, I have already alluded to Fausas St Fonp. Much more important, however, were the observations made some thirty years later by two German men of science, VoN OYENHAUSEN and Von Decuen. Their careful descriptions of the geology of Skye, Eigg, and Arran added new materials to the knowledge already acquired by native geologists.* To some of the more interesting parts of their work, reference will be made in later parts of this memoir. The numerous trap-dykes of Northumberland, Durham, and Northern Yorkshire at an early date attracted the attention of geologists. As far back as 1817, they had been the subject of a memoir by N. J. Wiycu, who gave an account of their effects on the adjacent rocks. More important were the subsequent papers on the same subject by Sepewroxk, who, discussing the lithological characters, probable origin, and geological age of the dykes, pointed out that while the Cleveland dyke was undoubtedly younger than a large part of the Jurassic rocks, there was no direct evidence to determine whether the dykes farther north were earlier or later than the time of the Magnesian Limestone. Subsequent accounts of the dykes of the same region were given by Buppiz,t M. Forsrur,{ N. Woop,§ H. T. M. Wrruam,|| Tarts, and others, while in more recent years important additions to our knowledge of these dykes and of their effects have been made by Sir J. Lowrnt1an Betxi** and Mr J. J. H. Tearz.tt The geological age of the great series of Tertiary volcanic rocks has only been determined, district by district, and at wide intervals. That some part of the Antrim basalts are younger than the Chalk of that region was clearly shown by BrerceEr, Cony- BEARE, and BucktanD. Porttock, however, in his Report on Londonderry, &c., referred to the occurrence of detached blocks of basalt which he supposed to be immersed in the Chalk near Portrush, and which inclined him to believe that “the basaltic flows com- menced at a remote period of the Cretaceous system.” Maccuntocy showed that the corresponding basaltic plateaux of the Inner Hebrides were certainly younger than the Oolitic rocks of that region. But no nearer approximation to their date had yet been made. In the year 1850 the Duke or ARGYLL announced the discovery of strata con- taining fossiliferous chalk-flints and dicotyledonous leaves, lying between the bedded basalts of Ardtun Head, in the Isle of Mull.t{ In the following year these fossil leaves were described by Epwarp Forsgs, who regarded them as decidedly Tertiary, and most probably Miocene. This was the first paleeontological evidence for the determination of the geological age of any portion of the basalt-plateaux, and it indicated that the basalts of the south-west of Mull were of older Tertiary date. Taken also in connection with the occurrence of lignite-beds between the basalts of Antrim, it proved that these volcanic plateaux were not due to submarine eruptions, as the earlier geologists had * Karsten’s Archi (1829), vol. i. p. 56. + Trans. Nat. Hist. Soc. Northwmberland, i. (1831) p. 9. t Op. cit., i. p. 44, § Op. cit., i. pp. 305, 306, 308, 309. || Op. cit., ii. (1838) p. 348. I Trans. Northumberland and Durham, ii. (1868) p. 30. ** Proc. Roy. Soc., xxiii, (1875) p. 543. tt Quart. Jour. Geol. Soc., xl. (1884) p. 209. tt Brit. Assoc. Report, 1850, sections, p. 70, and Quart. Jour. Geol. Soc., vii. (1851) p. 87. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES, Pai supposed, but pointed to the subzerial outpouring of lava at successive intervals, during which terrestial vegetation sprang up upon the older outflows. While Forses brought forward palzontological proofs of the Tertiary age of the voleanic rocks of the south-west of Mull, he at the same time laid before the Geological Society a paper on the Estuary Beds and the Oxford Clay of Loch Staffin, in Skye, wherein, while admitting the existence of appearances which might be regarded as favourable to the view that the intercalated basalts of that region were of much later date than the Oolitic strata between which they might have been intrusively injected, he stated his own belief that they were really contemporaneous with the associated stratified rocks, and thus marked an outbreak of volcanic energy at the close of the Middle Oolitic period.* The Duke or ARGYLL, in the paper which he on the same occasion communi- cated to the Geological Society, adopted this view of the probable age of most of the basalts of the Western Islands. He looked upon the Tertiary volcanic rocks of Mull as occupying a restricted area, the great mass of the basait of that island, like that of Skye, being regarded by him as probably not later than some part of the Secondary period. It must be granted that the appearances of contemporaneous intercalation of the basalt among the Secondary strata are singularly deceptive. When, several years after the announcement of the Tertiary age of the basalts of Ardtun, I began my geological work in the Inner Hebrides, I was led to the same conclusion as Epwarp Forpss, and expressed it in an early paper, read before this Society in 1861, on the “ Chronology of the Trap-rocks of Scotland.”t All over the north of Skye I traced what appeared to be evidence of the contemporaneous interstratification of basalts with the Jurassic rocks, and I concluded (though with some reservation) that the whole of the vast basaltic plateaux of that island were not younger than some later part of the Jurassic period. In that paper the attention of geologists was called to the probable connection of the great system of east-and-west dykes traversing Scotland and the north of England, with the basalt-plateaux of the Inner Hebrides, and as I believed the latter to be probably of the age of the Oolitic rocks, I assigned the dykes to the same period in geological history. But subsequent explorations enabled me to correct the mistake into which, with other geologists, I had fallen regarding the age of the volcanic phenomena of the Western Islands. In 1867 I showed that, instead of being confined to a mere corner of Mull, the - Tertiary basalts, with younger associated trachytic or granitic rocks, covered nearly the whole of that island, and that in all likelihood the long chain of basaltic masses, extend- ing from the north of Ireland along the west coast of Scotland to the Faroe Islands, and beyond these to Iceland, was all erupted during the Tertiary period. At the same time I drew special attention to the system of east-and-west dykes as proofs of the vigour of voleanic action at that period, and I furnished evidence that this action was prolonged through a vast interval of time, during which great subzerial denudation of the older lavas took place before the outflow of the younger.{ Later, in the same year, in * Quart. Jour. Geol, Soc., vol. vii. (1851) p, 104. + Trans. Roy. Soc. Hdin., xxii. (1861) p. 649. { Proc. Roy. Soc. Hdin., vi. (1867) p. 71. 28 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION an address to the Geological Section of the British Association, I reiterated these views, and more particularly emphasised the importance of the system of dykes, which in my opinion was possibly the most striking manifestation of the vigour of Tertiary volcanic action.* In 1871, after further explorations in the field, I gave a detailed account of the structure which had led to the mistake as to the age of the Tertiary volcanic rocks of the Western Islands; and in a description of the island of Higg, [ brought forward data to show the enormous duration of the Tertiary volcanic period in the west of Britain.t It was my intention that the paper in which these views were enunciated should be continued in a subsequent series of memoirs. Before the preparation of the second of the series was completed, Mr J. W. Jupp read before the Geological Society (21st January 1874) a paper “ On the Ancient Volcanoes of the Highlands.”{ The most novel feature of this paper was the announcement that the author had recognised the basal wrecks of five great central volcanoes in the Western Islands, among which that of Mull was inferred by him to have been at least 14,500 feet high. He was led to the conclusion that the volcanic period in these regions was divisible into three sections,—the first marked by the outburst of acid rocks (felspathic lavas and ashes, connected with deeper and more central granitic masses); the second by the extrusion of basic lavas and tuffs (the basaltic plateaux); the third by the appearance of small sporadic volcanic cones (‘‘felspathic, basaltic, or intermediate in composition”) after the great central cones had become extinct. It will be seen from the present communication that the views adopted by Professor Jupp are not those to which my study of the subject has led me. I have not been able to discover evidence of any great central volcanoes, and have found the order of outflow of the successive eroups of rocks to have been the reverse of what he believed it to be. The appearance of his memoir, however, led me to postpone the continuation of the series of papers which I had begun. The conviction that, in some way or other, as yet wholly inexplicable to me, the dykes, which at so early a period of my researches arrested my attention, had played a leading part in the volcanic phenomena of the Tertiary period, became every year stronger. At last, in the year 1879, during a traverse of some portions of the volcanic region of Wyoming, Montana, and Utah, I was led to perceive the meaning of what had hitherto been so puzzling. Riding over those great plains of basalt, and looking at the sections cut by the rivers through the thick series of horizontal basalt-beds underlying them, I appreciated for the first time the significance of RicHTHOFEN’s views regarding “massive” or “ fissure-eruptions,” as contradistinguished from those of central volcanoes like Etna or Vesuvius, and I saw how completely the structure and history of these tracts of Western America explain those of the basalt-plateaux of Britain.§ Since that year, at such intervals of leisure as I could command, I have renewed the investigation, and now at last, after a quarter of a century of more or less continuous labour in the * Brit. Assoc. Report (Dundee), 1867, sects. p. 49. + Quart. Jour. Geol. Soc., xxvii. (1871) p. 279. t Quart. Jour. Geol. Soc., xxx. (1874) p. 220. § Geological Essays at Home and Abroad, pp. 271, 274; Nature, November 1880. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 29 subject, I offer my results to the Royal Society of Edinburgh, which honoured and encouraged me by printing in its Transactions my first essay on the volcanic rocks of this country. In describing the geological history of a great series of rocks, chronological order is usually the most convenient method of treatment. Where, however, the rocks are of volcanic origin, and do not always precisely indicate their relative age, and where more- over the same kinds of rock may appear on widely separated geological horizons, it is not always possible or desirable to adhere to the strict order of sequence. With this necessary latitude, I propose to follow the chronological succession from the older to the newer portions of the series. I shall treat first of the system of basic dykes, by which so large a part of Scotland and of the north of England and Ireland is traversed. Many of the dykes are undoubtedly among the youngest members of the volcanic series, and in no case can their age be determined except relatively to the antiquity of the rocks which they traverse. They must, of course, be posterior to these rocks, and hence it would be quite logical to reserve them for discussion at the very end of the whole volcanic phenomena. My reason for taking them at the beginning will be apparent in the sequel. After the dykes, I shall describe the great volcanic plateaux which, in spite of vast denudation, still survive in extensive fragments in Antrim and the Inner Hebrides. The eruptive bosses of basic rocks that have broken through the plateaux will next be discussed. An account will then be given of the protrusions of acid rocks which mark the latest phase of eruption in the region. The last section of the memoir will contain a summary of the history of Tertiary volcanic action in Britain. I. THE BASIC DYKES. If a geologist were asked to select that feature in the volcanic geology of the British Isles which more than any other marks this region off from the rest of the European area, he would probably choose the remarkable system of wall-like masses of erupted igneous rock to which the old Saxon word “dykes” has been affixed. From the moors of eastern Yorkshire to the Perthshire Highlands, and from the basins of the Forth and Tay to the west of Donegal and the far headlands of the Hebrides, the country is ribbed across with these singular protrusions to such an extent that it may be regarded as a typical region for the study of the phenomena of dykes. That all the dykes in this wide tract of country are of Tertiary age, I am far from believing. Some of them are of the era of the Old Red Sandstone, others are undoubtedly Carboniferous, while some, though later than the Coal Measures, may be older than the Permian, or at least the Trias formations. As illustrations of these older dykes, I may refer to the remarkable series which traverses the Carboniferous rocks of Northumberland and Durham, and which includes the well-known Whin Sill. That this series belongs to a totally different and greatly more ancient period of extrusion was indicated many years ago by Sepewick,* who referred to the previous * Trans. Cambridge Phil. Soc. (1822), vol. ii. p. 28; Winch, Geol. Trans., iv. (1814) p. 25. VOL. XXXV. PART 2. E 30 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION observations of Wr1ncH that these dykes, though they ascend through the Coal Measures, never enter the Magnesian Limestone. They differ also in direction from the younger dykes, their general trend being south-westerly. They are further distinguished by petro- graphical characters. But when these and all other dykes which can reasonably be referred to older geological periods are excluded, there remains a large majority which cannot be so referred, but which are connected together by various kinds of evidence into one great system that must be of late geological date, and can be assigned to no other than the Tertiary period in the volcanic history of Britam. In my original memoir, “On the Chronology of the Trap-rocks of Scotland,’ where I first drew attention to this great system of dykes in connection with the progress of volcanic action in the country, I pointed out the grounds on which it seemed to me that these rocks belonged to a com- paratively late geological date. My own subsequent experience and the full details of structure collected by my colleagues of the Geological Survey in all parts of the country, have amply confirmed this view, though, as already stated, instead of placing the era of eruption in the Jurassic, I now put it in the older part of the Tertiary period. The characters which link this great series of dykes together as one connected system of late geological date are briefly enumerated in the following list, and will be more fully discussed in later pages. 1, The prevalent tendency of the dykes to take a north-westerly or westerly course. There are exceptions to this normal trend, especially where the dykes are small and locally numerous ; but it remains singularly characteristic over the whole region. 2. The increasing abundance of the dykes as they are traced to the west coast and the line of the great Tertiary volcanic plateaux of Antrim and the Inner Hebrides. 3. The rectilinear direction so characteristic of them and so different from the tortuous course of other groups of dykes. The exceptions to this normal feature are as a rule confined to the same localities where departures from the prevalent westerly trend occur. 4, The great breadth of the larger dykes of the system and their persistence for long distances. This is one of their most remarkable and distinctive characters. 5. The posteriority of the dykes to the rest of the geological structure of the regions which they traverse. They are not only younger than the other rocks, but younger than nearly all the folds and faults by which the rocks are affected. 6. The manner in which they cut the Jurassic, Cretaceous, and older Tertiary strata in the districts through which they run. At the south-eastern end of the region they rise through the Lias and Oolite formations, in the west they intersect the Chalk and the Tertiary volcanic plateaux with their later eruptive bosses. 7. Their petrographical characters, among which perhaps the most distinctive is the frequent appearance of the original glassy magma of the plagioclase-pyroxene- magnetite (olivine) rock, of which they essentially consist. This glass, or its more or less completely devitrified representative, often still recognisable with the microscope among the individualised microlites and crystals throughout the body of a dyke, is also not DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 31 infrequent as a black vitreous varnish-like coating on the outer walls, and occasionally appears in strings and veins even in the centre. It is the assemblage of dykes presenting these features which I propose to describe. Obviously, the age of each particular dyke can only be fixed relatively for itself. But when this remarkable community of characters is considered, and when the Tertiary age of at least a very large number of the dykes can be demonstrated, the inference is reason- able that the whole assemblage constitutes one great system, extravasated during a time of great volcanic disturbance, which could not have been earlier than the beginning of the Tertiary period. And this inference may be maintained even when we frankly admit that every dyke within the region is by no means claimed as belonging to the Tertiary series. — ——— = ———_ W.WATSON.- SC= Fie. 1,—Dyke on the south-east coast of the Island of Mull. In spite of their number and the extraordinary voleanic activity to which they bear witness, the basic dykes form a much less prominent feature in the landscape than might have been anticipated. In the lowlands of the interior, they have for the most part been concealed under a cover of superficial accumulations, though in the water-courses they not infrequently project as hard rocky barriers across the channels, and occasionally form picturesque waterfalls. On the barer uplands, they protrude in lines of broken crag and scattered boulders, which by their decay give rise to a better soil covered by a greener vegetation than that of the surrounding brown moorland. Among the Highland hills, they are often traceable from a distance as long black ribs that project from the naked faces of crag and corry. Along the sea coast, their peculiarities of scenery are effectively displayed. Where they consist of a close-grained rock, they often rise from the beach as 32 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION straight walls which, with a strangely artificial look, mount into the face of the cliffs on the one side, and project in long black reefs into the sea on the other (fig. 1). Every visitor to the islands of the Clyde will remember how conspicuous such features are there. But it is among the Inner Hebrides that this kind of scenery is to be found in greatest perfection. The soft dark Lias shales of the island of Pabba, for example, are ribbed across with scores of dykes which strike boldly out to sea. Where, on the other hand, the material of the dykes is coarse in grain, or is otherwise more susceptible to the disintegrating influences of the weather, it has rotted away and left yawning clefts behind, the vertical walls of which are those of the fissures up which the molten rock ascended. Some good instances of this kind are well known to summer visitors on the eastern shores of Arran. Others, on a large scale, may be seen in the interior of the same island along the crests of the granite ridges, and still more conspicuously on the jagged summits of Blath Beinn and the Cuillin Hills of Skye. § 1. GrocRrapHIcAL DisTRIBUTION. The limits of the region within which the dykes occur cannot be very precisely fixed. There can be no doubt, however, that on their southern side they reach to the Cleveland Hills of Yorkshire and the southern borders of Lancashire, and on the northern side to the farther shores of the island of Lewis—a direct distance of 360 miles. They stretch across the basin of the North Sea, including the Isle of Man, and appear in the north of Ireland north of a line drawn from Dundalk Bay to the Bays of Sligo and Donegal. Dykes are of frequent occurrence over the north of England and south of Scotland, at least as far north as a line drawn from the coast of Kincardineshire along the southern flank of the Grampian Hills by the head of Glen Shee and Loch Tay to the north-western coast of Argyleshire. They abound all along the line of the Inner Hebrides and the adjacent coasts of the mainland from the remoter headlands of Skye to the shores of county Louth. They traverse also the chain of the Long Island in the Outer Hebrides. So far as I am aware, they are either absent or extremely rare in the Highlands north of the line I have indicated. But a good many have been found by my colleagues in the course of the Geological Survey of the northern lowlands of Aberdeenshire and Banffshire. The longest of these has been traced by Mr L. HinxmAn for rather more than two miles running in a nearly east and west direction through the Old Red Sandstone of Strathbogie, with an average width of about 35 feet. Another in the same district has a width of from 45 to 90 feet, and has been followed for a third of a mile. But far beyond these northern examples, I have found a number of narrow basalt-veins traversing the Old Red flagstones of the Mainland of Orkney, which I have little doubt are also a prolongation of the same late series. Taking, however, only those western and southern districts in which the younger dykes form a notable feature in the geology, we find that the dyke-region embraces an area of upwards of 40,000 square miles—that is, a territory greater than either Scotland or Ireland, and equal to more than a third of the total land-surface of the British Isles (Plate I.). DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 33 Of this extensive region the greater portion has now been mapped in detail by the Geological Survey. Every known dyke has been traced, and the appearances it presents at the surface have been recorded. We are accordingly now in possession of a larger body of evidence than has ever before been available for the discussion of this remarkable feature in the geology of the British Isles. I have made use of this detailed information, and besides the data accumulated in my own note-books, I have availed myself of those of my colleagues in the Survey, for which due acknowledgment is made where they are cited. § 2. Two Types or Protrosion. The dykes are far from being equally distributed over the wide region within which they occur. In certain limited areas they are crowded together, a score or more occurring in a single square mile, while elsewhere they appear only at intervals of several miles. Viewed in a broad way, they may be conveniently grouped in two types, which, though no hard line can be drawn between them, nevertheless probably point to two more or less distinct phases of volcanic action. In the first, which for the sake of distinction we may term the Solitary type, there is either a single dyke separated from its nearest neighbours by miles of intervening and entirely dykeless ground, or a group of two , or more running parallel to each other, but sometimes a mile or more apart. The rock of which they consist is, on the whole, less basic than in the second type; it includes the andesitic varieties. It is to this type that the great dykes of the north of England and the south and centre of Scotland belong. The Cleveland dyke, for example, at its eastern end has no known dyke near it for many miles. The coal-field of Scotland is traversed by five main dykes, which run in a general sense parallel to each other, with intervals of from half a mile to nearly five miles between them. Dykes of this type display most conspicuously the essential characters of the dyke-structure, in particular the vertical marginal walls, the parallelism of their sides, their great length, and their persistence in the same line. In the second, or what for brevity may be called the Gregarious type, the dykes occur in great abundance within a particular district. They are on the whole narrower, shorter, less strikingly rectilinear, more frequently tortuous and vein-like, and, on the whole, more basic in composition than those of the first type. They include the true basalts and dolerites. [Illustrative districts for dykes of this class are the islands of Arran, Mull, Eige, and Skye. The great single or solitary dykes may be observed to increase in number, though very irregularly, from south to north, and also in central Scotland from east to west. They are specially abundant in the tract from the Firth of Clyde along a belt of country some thirty miles broad on either side of the Highland line, as far at least as the valley of the Tay. They form also a prominent feature in the islands of Jura and Islay. Those of the gregarious type are abundantly and characteristically displayed in the basin of the Firth of Clyde. Their development in Arran formed the subject of an 34 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION interesting paper by NEcKEr, who catalogued and described 149 of them, and estimated their total number in the whole island to be about 1500.* As the area of Arran is 165 square miles, there would be, according to this computation, about nine dykes to every square mile. But they are far from being uniformly distributed. While appearing only rarely in many inland tracts, they are crowded together along the shore, particularly at the south end of the island, where the number in each square mile must far exceed the average just given, The portion of Argyleshire, between the hollow of Loch Long and the Firth of Clyde on the east and Loch Fyne on the west, has recently been found by my colleague, Mr C. T. CLoueu, to contain an extraordinary number of dykes (see fig. 17). The coast line of Renfrewshire and Ayrshire shows that the same feature is prolonged into the eastern side of the basin of the Clyde estuary. But immediately to the westward of this area the crowded dykes disappear from the basin of Loch Fyne. In Cantire their scarcity is as remarkable as their abundance in Cowal. Both in the north of Ireland and through the Inner Hebrides, dykes are singularly abundant in and around, but particularly beneath, the great plateaux of basalt. Their profusion in Skye was described early in this century by Maccuocs#, who called attention more especially to their extraordinary development in the district of Strathaird. ‘‘ They nearly equal in some places,” he says, “when collectively measured, the stratified rock through which they pass. I have counted six or eight in the space of fifty yards, of which the collective dimensions could not be less than sixty or seventy feet.” He supposed that it would not be an excessive estimate to regard the igneous rock as amounting to one-tenth of the breadth of the strata which it cuts.t Among the districts where dykes of the gregarious type abound at a distance from any of the basalt-plateaux, reference should be made to the curious isolated tract of the central granite core of Western Donegal. In that area a considerable number of dykes rises through the granite, to which they are almost wholly confined. Again, far to the east another limited district, where dykes are crowded together, lies among the Mourne Mountains. These granite hills are probably to be classed with those of Arran, as portions of a series of granite protrusions belonging to a far more recent period than that to which the youngest granitic masses of the Highlands are to be assigned. Though the dykes may be conveniently grouped in two series or types, which on the whole are tolerably well marked, it is not always practicable to draw any line between them, or to say to which group a particular dyke should beassigned. In some districts, however, in which they are both developed, we can separate them without difficulty. In the Argyleshire region above referred to, for example, which Mr CLoveH has mapped, he finds that the abundant dykes belonging to the gregarious type run in a general N.W. or N.N.W. direction, and distinctly intersect the much scarcer and less basic dykes of the solitary type, which here run nearly E. and W. (fig. 17). Hence, besides their com- position, distinction in number, breadth, rectilinearity, and persistence, the two series demonstrably belong to distinct periods of eruption. * Trans. Roy. Soc. Edin., xiv. (1840) p. 677. t Trans. Geol, Soc., iii. (1815) p. 79. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES, 30 § 3. Nature or Component Rocks. The Tertiary dykes of Britain include representatives of two very distinct groups of igneous rocks. The vast majority of them are basic compounds, belonging to the family of the pyroxenic lavas, which, where the percentage of silica is relatively high, are known as andesites, and where it is relatively low, have been variously styled basalts, dolerites, melaphyres, or diabases. It is to these basic dykes that the general descriptions of the present section exclusively refer. The second class is composed of an acid rock, either more or less crystalline, such as felsite, quartz-porphyry, rhyolite or trachyte; or vitreous, in the form of pitchstone. These acid dykes or veins, though extremely abundant at a few localities, are on the whole rare. They will be described by themselves in subsequent pages (p. 175). To the field geologist, who has merely their external features to guide him, the ordinary Tertiary basic dykes present a striking uniformity in general petrographical character. They vary indeed in fineness or coarseness of texture, in the presence or absence of porphyritic crystals, amygdules, glassy portions, and other points of structure. But there is seldom any difficulty in perceiving that they are basic rocks belonging to one or other of the types of the basalts, dolerites, diabases, or andesites. This sameness of composition, traceable from Yorkshire to Skye and from Donegal to Perthshire, is one of the strongest arguments for referring this system of dykes to one geological period. At the same time, there are enough of minor variations and local peculiarities to afford abundant exercise for the observing faculties alike in the field and in the study, and to offer materials for arriving at some positive conclusions regarding the geological processes involved in the uprise of the dykes. 1. External Characters.—As regards the grain of the rock, every gradation may be found, from a coarsely crystalline mass, in which the component minerals are distinctly traceable with the naked eye, to a black lustrous basalt-glass. Hach dyke generally preserves the. same character throughout its extent. As a rule, broad and long dykes are coarser in grain than narrow and short ones. For the most part, there runs alongside each side of a dyke a selvage of finer grain than the rest of the mass. This marginal strip varies in breadth from an inch or less up to a foot or more, and obviously owes its origin to the more rapid chilling of the molten rock along the walls of the fissure. It usually shades away imperceptibly into the larger-grained inner portion. Even with the naked eye, its component materials can be seen to be more finely crystalline than the rest of the dyke, though where dispersed porphyritic felspars occur they are usually as large in the marginal strip as in any other part of a dyke. This finer-grained external band, so distinctive of an eruptive and injected rock, is of great service in enabling us to trace dykes when they traverse other dykes or masses of igneous rock of similar characters to their own. When one dyke crosses another, that which has its marginal band of finer grain unbroken must obviously be the younger of the two. 36 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION But in many examples in the south of Scotland, Argyleshire, and the Inner Hebrides, the fineness of grain of the outer band culminates in a perfect volcanic glass. Where this occurs, the glass is usually jet black, more rarely greenish or bluish black in tint, and varies in thickness from about half an inch to a mere varnish-like film on the outer face of the dyke, the average width being probably less than a quarter of an inch. On their weathered surface, these external glassy layers, generally present a pattern of rounded or polygonal prominences, varying up to four or five lines or even more in diameter, and separated by depressions or narrow ribs that remind us of the lines seen in perlitic structure. The transition from the glass to the crystalline part of the marginal fine- grained strip is usually somewhat abrupt, insomuch that on weathered faces it is often difficult to get good specimens, owing to the tendency of the vitreous portion to fly off when struck with the hammer. The glass doubtless represents the original condition of the rock of the dyke. It was suddenly chilled and solidified by contact with the walls of the fissure. Inside this external glassy coating, the molten material had time to assume a more or less completely crystalline condition before solidification. Not infrequently the glass shows spherulitic forms, visible to the naked eye, and likewise a more or less distinctly developed perlitic structure. These features, however, are best studied in thin sections of the rock with the aid of the microscope, as will be subsequently referred to. In some dykes, the glass is not confined to the edges, but runs in strings or broader bands along the central portions. I have found several examples of this peculiarity. The most remarkable of them occurs in the well-known dyke of Eskdale, which runs for so many miles across the southern uplands of Scotland.* This dyke throughout most of its course is a crystalline rock of the less basic type. At Wat Carrick, in Eskdale, it presents an arrangement into three parallel bands. On either side lies a zone about eight feet broad of the usual crystalline material. Between these two marginal portions there is an intercalated mass sixteen to eighteen feet broad, of a very compact and more or less vitreous rock. The demarcation between this central band and the more crystalline zones of the outside is quite sharp, and the two kinds of rock show a totally distinct system of jointing. There can, therefore, be little doubt that the glassy centre belongs to a later uprise than the outer portions, though possibly it may still have been included in the long process of solidification of one originally injected mass of molten material. Mr C. T. Crovex, while mapping for the Geological Survey the extraordinarily numerous dykes in the eastern part of Argyleshire between the Firth of Clyde and Upper Loch Fyne, has observed six or seven examples of dykes showing glassy bands in their centres, with characters similar to those of the Eskdale dyke. He informs me, that he has found an absence of definite and regular joints in the central glassy band, and on the other hand, an irregular set of divisional planes by which the rock is traversed, and which he compares to those seen in true perlitic structure. * See Proc. Roy. Phys. Soc. Hdin., v. (1880) p. 241. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. O7 While, as a general rule, the external portions of a dyke are closer-grained than the centre, rare cases occur where the middle is the most finely crystalline part. I am disposed to regard these cases and the glassy centres as forming in reality no true exceptions to the rule, that the outer portions of a dyke consolidated first, and are there- fore finest in texture. For the most part, each dyke appears to be due to a single uprise of molten matter, though considerable movements may have taken place within its mass before the whole stiffened into stone. But where, after more or less complete consolidation had taken place, the fissure opened again, or from any other cause the dyke was split along its centre, any lava which rose up the rent would tend to take a finer grain than the material of the rest of the dyke, and might even solidify as glass. Large scattered crystals of felspar, of an earlier consolidation than that of the minuter forms of the same mineral in the general ground-mass of the rock, give a porphyritic structure and andesitic character to many dykes. Occasionally such crystals attain a considerable size. Mr Croven has observed them in some of the Argyleshire dykes reaching a length of between three and four inches, with a thickness of two inches. Some- times they are distributed with tolerable uniformity through the substance of the dyke. But not infrequently they may be observed in more or less definite bands parallel with the boundary walls. Unlike the younger lath-shaped and much smaller felspars of the eround-mass, they show no diminution either in size or abundance towards the edge of the dyke. On. the contrary, they are often conspicuous in the close-grained marginal strip, and they may be found even in the glassy selvage, and touching the very wall of the fissure. Indeed, they are sometimes more abundant in the outer than in the inner portions of a dyke. Mr CLoveH has given me the details of an interesting case of this kind observed by him in Glen Tarsan, HKastern Argyleshire :—“ For an inch or so from the edge of this dyke,” he remarks, “ porphyritic felspars giving squarish sections, and ranging up to one- third of an inch in length, are so abundant as nearly to equal in bulk the surrounding eround-mass. For the next inch and a half, they are decidedly fewer, occupying perhaps hardly an eighth of the area exposed. Then for a breadth of three inches they come in again nearly as abundantly as at the sides; after which they diminish through a band 27 inches broad, where they may form from } to 5}, of the rock.” He found another case where, in a dyke several yards wide, porphyritic felspars, sometimes an inch long, are common along the eastern margin of the dyke in a band about two inches broad, but are nearly absent from the rest of the rock. Elsewhere the crystals are grouped rather in patches than in bands. Not only are these porphyritic felspars apt to occur in bands parallel with the outer margins of the dykes, but they tend to range themselves with their longer axis in the same direction, thus even on a large scale, visible at some distance, showing the flow- structure, which is so often erroneously regarded as essentially a microscopic arrange- ment. | Another macroscopic character of the material composing the dykes is the frequent VOL. XXXV. PART 2. F 38 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION presence of amygdules. It has sometimes been supposed that the amygdaloidal structure may be relied upon as a test to distinguish a mass of molten rock which has reached the surface, from one which has consolidated under considerable pressure below ground. That this supposition, however, is erroneous, is demonstrated by hundreds of dykes in the great system which | am now describing. But the amygdules of a dyke offer certain peculiarities which serve in a general way to mark them off from those of an outflowing lava. They are usually smaller, and more uniform in size, than in the latter rock. They are also more regularly spherical and less frequently elongated in the direction of flow. Moreover, they are not usually distributed through the whole breadth of a dyke, but tend to arrange themselves in lines especially towards its centre (fig. 2). In these central bands the cavities are largest and depart farthest from the regular spherical form, so that for short spaces they may equal in bulk the mass of en- closing rock. In some rare instances, a whole dyke is composed of cellular basalt, like one of the sheets in the plateaux, as may be seen on the north flank of Beinn Suardal, Skye. Besides the common arrangement of fine- grained edges and a more coarsely crystalline centre, instances are found where one of the contrasted portions of a dyke traverses the other in the form of veins. Of these, I think, there are two distinct kinds, probably originating in entirely different conditions. In the first place, they may be of coarser grain than the rest of the rock; but such a structure appears to be of extremely rare occurrence. I have noticed some examples on the coast of Renfrewshire, where strings of « more coarsely crystalline texture traverse the finer-grained body of the rock. Veins of this kind are probably of the same nature as the segregation-veins, to be afterwards referred to as a frequent occurrence among the thicker intrusive sheets. They consist of the same minerals as the rest of the rock, but in a different and more developed crystalline arrangement, and they contain no glassy or devitrified material, except such portions of that of the surrounding ground-mass as may have been caught between their crystalline constituents. | Fic, 2.—Arrangement of lines of Amygdules in a Dyke, Strathmore, Skye. The second kind of veins, which though not common, is of much more frequent oceur- rence than the first, is more particularly to be met with among the broader dykes, and is distinguished by a remarkable fineness of grain, sometimes approaching the texture of felsite or jasper, and occasionally taking the form of actual glass. Such veins vary from half an inch or less, up to four or five inches in breadth. They run sometimes parallel with the walls of the dyke, but often irregularly in all directions, and for the most part avoid the marginal portions, though now and then coming up to the edge. They never extend beyond the body of the dyke itself into the surrounding rock. Though they have DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 39 obviously been injected after the solidification of the rock which they traverse, they may quite possibly be extrusions of a deeper unconsolidated portion of the same rock into rents of the already stiffened overlying parts. The field-geologist cannot fail to be struck with the much greater hardness of these fine-grained veins and strings that ramify through the coarsely crystalline dolerite, andesite, or other variety of the broader dykes. He can readily perceive in many cases their more siliceous composition, and the inferences he deduces from the rough observations he can make in the field are confirmed by the results of chemical analysis (see p. 44). In connection with veins of finer material, that may belong to a late stage of the con- solidation of the general body of a dyke, reference may be made here to the occasional occurrence of patches of an exceedingly compact or homogeneous texture immersed in the usual finely crystalline marginal material. They look like angular and subangular portions of the more rapidly cooled outer edge, which have been broken off and carried upward by the still moving mass in the fissure.* In general, each dyke is composed of one kind of rock, and retains its chemical and mineralogical characters with singular persistence. The difference of texture between the fine-grained chilled margin, with its occasional glassy coating, and the more coarsely crystalline centre is obviously due to the effects of different rates of cooling in what was no doubt originally one uniform molten mass. The glassy central bands, too, though they seem to indicate a rupture of the dyke up the middle, may at the same time quite conceivably be, as I have said, extrusions from a lower portion of the dyke before the final solidification of the whole. The ramifying veins of finer grain that now and then traverse one of the large dykes are likewise explicable as parts of the same stage towards entire consolidation. All these vitreous portions, whether still remaining as glass or having undergone devitrification, are more acid than the surrounding crystalline parts of the rock. They represent the siliceous ‘‘ mother-liquor,” so to speak, which was left after the separation from it of the crystallised minerals, and which, perhaps entangled here and there in vesicles of the slowly cooling and consolidating rock, was ready to be forced up into cracks of the overlying mass during any renewal of terrestrial disturbance. But examples occur where a dyke, instead of consisting of one rock, is made up of two or more bands of rock which, even if they resemble each other closely, can be shown to be the results of separate eruptions. These, which are obviously not exceptions to the general rule of the homogeneity of dykes, I will consider in a later section of this paper. Among the petrographical varieties observable in the field is the occasional envelopment of portions of the surrounding rocks in the body of a dyke. Angular fragments torn off from the fissure-walls have been carried upwards in the ascending lava, and now appear more or less metamorphosed, the amount of alteration seeming to depend chiefly upon the susceptibility of the enclosed rock to change from the effects of heat. Cases of such entanglement of foreign substances, however, are of less common occurrence than might have been expected. Occasionally, where the enclosed fragments are oblong, * See J. J. H. Teall, Quart. Jour. Geol. Soc., xl. (1884) p. 214. 40 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION they are arranged with their longer axes parallel to the walls of the dyke, showing flow-structure on a large scale. Mr Ciouen has lately found some dykes near Dunoon which enclose fragments of schist nearly three feet in length. One of the most interesting of the macroscropic features of the dykes, is the joints by which they are traversed. These divisional planes are no doubt to be regarded as con- sequences of the contraction of the original molten rock during cooling and consolidation between its fissure-walls. They are of considerable interest and importance, inasmuch as they furnish a ready means of tracing a dyke when it runs through rock of the same nature as itself, and also help to throw some light on the stages in the consolidation of the material of the dyke. Two distinct systems of joints are recognisable (fig. 3). Though sometimes combined in the same dyke, they are most conspicuously displayed when each occurs, as it generally does, by itself. The first and less frequent system of joints (a) has been deter- mined by lines of retreat, which are parallel to the walls of the dyke. The joints are then closest together at the margin, and may be few or altogether absent in the centre. They are a sometimes so numerous, parallel and defined |H- | towards the borders of the dyke, as to split the a ou le rock up into thin flags. Where transverse joints Fic, 3.—Systems of Joints in the Basie Dykes. dere 3 a, parallel ; b, transverse. are also present, these flags are divided into irregular tessere. In the second or transverse system of joints (b), which is the more usual, the divisional lines pass across the breadth of the dyke, either completely from side to side or from one wall for a longer or shorter distance towards the other. Where this series of joints is most completely developed the dyke appears to be built up of prisms piled horizontally, or nearly so, one above another. ‘These prisms, in rare instances, are as regular as the columns of a basalt-sheet. Usually, however, they have irregularly defined faces, and merge into each other. Where the prismatic structure is not displayed, the joints starting sharply at the wall of the dyke strike inwards in irregular curving lines. It is such transverse joints that enable the eye, even from a distance, to distinguish readily the course of a dyke up the face of a cliff of basalt-beds, for they belong to the dyke itself, are often at right angles to those of the adjacent basalt, and by their alternate projecting and re-entering angles are banded across with parallel bars of light and shade. Where they traverse not only the general mass of a dyke, but also the ‘‘ contemporaneous veins” which cross it, it may be plausibly inferred that these veins were injected before the final solidification and contraction of the whole dyke. One of the most remarkable exhibitions of joint-structure hitherto noticed among these dykes, is that which occurs in the central vitreous band of the Eskdale dyke already referred to. The rock is divided into nearly horizontal prisms, each of which DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 41 consists of a central more vitreous core and an outer more lithoid sheath. By the coherence of their polygonal and irregular faces, and the greater durability of their material, these sheaths project on the weathered wall of the vitreous centre of the dyke in a curiously reticulated grouping of prominent ribs each about two inches broad (fig. 4), while the vitreous cores, being more readily acted on by the weather, are hollowed out into little cup-shaped depressions. Hach rib is thus composed of the sheaths or outer lithoid portions of two prisms, the line of separation being marked by a suture along the centre (fig. 4,8). Between this median suture and the inner glassy core the rib is further cut into small segments by a set of close joints, which are placed generally at right angles to the course of the rib (fig. 4, c). Examined with a lens, the lithoid substance of these sheaths has a dull finely granular aspect, like that of felsitic rocks, with scattered felspars. It is obviously a more devitrified condition of the material which forms the core of each prism. This material presents on a fresh fracture a deep iron-black colour, dull resinous A. B. C. Fic. 4.—Joint-Structures in the central vitreous portion of the Eskdale Dyke (B. N. Peach). A. View of a square yard of the outer wall of the vitreous central band, showing the polygonal arrangement of the prisms and their investing sheath of ribs. B. View of a smaller portion of the same wall to show the detailed structure of the ribs (a, a) and their vitreous cores (8, b). c. Profile of a part of the weathered face of the wall, showing the way in which the hard ribs or sheaths project at the surface, lustre, and vitreous texture. It at once recalls the aspect of many pitchstones, and in the early days of petrography was naturally mistaken for that rock. Through its substance numerous kernels of more glassy lustre are dispersed, each of which usually contains one or more amygdules of dull white chalcedony, but sometimes only an empty black cavity. These black glistening kernels of glass, of all sizes up to that of a small bean, scattered through the dull resinous matrix, form with the white amygdules the most prominent feature in the cores; but crystals of felspars may also be observed. Some details of the microscopic characters of this remarkable structure will be given in a subsequent page. The relation of the cores and sheaths to the prismatic jointing of the rock seems to show that devitrification had not been completed when these joints were established, and that it proceeded from the faces of each prism inwards. 2. Internal Characters.—Much information has in recent years been obtained regarding the microscopic structure of some of the basic dykes. The crystalline characters of those 42 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION in the north of England have been studied by Mr Tratt,* and some of those from the west of Scotland have been investigated by Professor Jupp and Mr Corz.t Taken as a whole, the rocks composing the dykes are found, when examined microscopically, to consist essentially of mixtures of a plagioclase felspar, pyroxene, an iron oxide, and sometimes olivine, usually with more or less interstitial matter. The felspar appears to be in some cases labradorite, in others anorthite, but there may be a mingling of several species in many of the dykes, as in the augite-andesite of the Santorin eruption in 1866, wherein Fouqu# found the larger porphyritic felspars were mainly labradorite, but included also anorthite, while those of the ground-mass were microliths of albite and oligoclase.{ The large felspars scattered porphyritically through the ground-mass are evidently the result of an early consolidation. They are often cracked, and penetrated by the ground-mass, or even broken into fragments. They also include portions of the ground-mass, and present the zonal growth structure in great perfection, The small felspars of the ground-mass, on the other hand, are as obviously the result of a later crystallisation, for they vary in size and crystallographic development according to their position in the dyke. Those from the centre are often in well-formed crystals, which sometimes pass round their borders into acicular microliths. Those in the marginal parts of the dyke occur chiefly in the form of these microliths. Curious skeleton forms, composed of aggregates of microliths, connect the latter with the more completely developed crystals, and illustrate the mode of crystallisation of the felspathic constituents of the dykes.§ The pyroxene is probably in most cases monoclinic (black or common augite), but is sometimes rhombic (usually enstatite, less frequently perhaps hypersthene). It occurs in (a) well-developed crystals, (>) crystalline masses with some of the faces of the crystals developed, (c) granular aggregates which polarise in one plane, (d) separate granules and microscopic microliths, which may be spherical (globulites) or oblong (longulites). The black iron oxide is sometimes magnetite, sometimes ilmenite, or other titaniferous ore. Apatite not infrequently occurs among the original constituents. Olivine is entirely absent from many of the dykes, and no serpentinous matter remains to indicate that it was ever present in them. But it is also to be met with in numerous cases, either in sparsely scattered or in tolerably abundant crystals. Biotite occasionally appears. Among the secondary products, calcite and pyrites are doubtless the most common. To these must be added quartz, chalcedony, and various zeolitic substances, besides the “viridite” and “ opacite,” which result from the decomposition of the ferro-magnesian constituents and the oxidation of the ferrous oxides. In many dykes there is little or no interstitial matter between the crystalline constituents of the ground-mass. In others this matter amounts to a half or more of the whole composition, and from such cases we may trace a series of gradations until * Quart. Jour. Geol. Soc., vol. xl. (1884). + Op. cit., vol. xxxix. (1883) p. 444 (basalt-glass) ; xlii. (1886) p. 49, where Professor Jupp discusses the gabbros, dolerites, and basalts as a whole. See postea, p. 77, note. t Santorin et ses Lruptions, 1879 p. 203. § See Mr Traxt’s excellent description of the Cleveland dyke, in the paper above cited. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 43 we arrive at a complete glass containing only the rudimentary forms of crystals (globulites, longulites, &c.), with scattered porphyritic crystals of an earlier consolida- tion. The process of the disappearance of this original glass may be admirably studied in many dykes. At the outer wall, the glass remains nearly as it was when contact with the cold walls of the fissure solidified it. From that external vitreous layer the successive devitrification products and crystalline growths may be followed inwards until in the central parts of the dyke little trace of the interstitial matter may be left. The most instructive example of the process of devitrification which has come under my observation occurs in the Eskdale dyke. The central “cores” already referred to present a true glass, which in thin sections is perfectly transparent and almost colourless, but by streaks and curving lines of darker tint shows beautiful flow-structure. The devitrification of this glass has been accomplished by the development of crystallites and crystals, which increase in number until all the vitreous part of the rock disappears. What appears under a low power to be a structureless or slightly dusty glass can be resolved with a higher objective into an aggregate of minute globules or granules (globulites), which average perhaps zo,oo0 Of an inch in diameter. ,,, Pe Wironapin, Senctae of the Some of these bodies are elongated and even dichotomous vitreous part of the Eskdale Dyke. at the ends. These granules are especially crowded upon au acetate ek ieaaiaa or clear yellow dart-shaped rods, which in turn are especially _ with microliths, each of which consists of a central pale yellow rod crusted with pale yellow isotropic globulites. prominent upon crystals and crystalline grains of augite which bristle with them, while the immediately surround- The glass around this aggregation is : clear, but at a little distance globulites ing glass has become clear. There can be little doubt — (many of them elongated and dicho- that these rudimentary bodies are stages in the arrested mous) abound, with here and there scattered microliths, some of which are development of augite crystals. There occur also opaque curved and spiral. (800 diameters. )* grains, rods, and trichites, which no doubt consist in whole of magnetite (or other iron oxide), or are crusted over with that mineral. At least two broad types of microscopic structure may be recognised among the basic dykes. (1) Holocrystalline, or with only a trifling proportion of interstitial matter. This type includes the dolerites and basalts, as well as rocks which German , petrographers would class as diabases or diabase-porphyrites. The rocks are very generally characterised by what is known as the ophitic structure, where the lath-shaped felspars penetrate the augite, and are therefore of an earlier consolidation. In such cases there is a general absence of any true interstitial matter. The rocks of this type are often rich in olivine, and appear to be on the whole considerably more basic than those of the second group. It is observable that they increase in numbers from the centre of Scotland westwards, and throughout the region of the basalt-plateaux they form the prevailing * Proc. Roy. Phys. Soc. Edin., v. (1880) p. 255. 44 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION type. (2) In this type there is a marked proportion of interstitial substance, which is inserted in wedge-shaped portions among the crystallised constituents (‘“intersertal structure” of Rosrnpuscu). The ophitic structure appears to be absent, and olivine is either extremely rare or does not occur at all. The rocks of this group are obviously less basic than those of the other. They form the large dykes that rise so conspicuously through the south of Scotland and north of England, and their general characters are well described by Mr Teatu in the paper already cited. In some instances they enclose abundant porphyritic felspars of earlier consolidation, and then present most of the characters of andesites. Professor RosENBuscH has recently extended the name of “ Tholeiites” to rocks of this group in the north of England.* The vitreous condition is found in both types, but is perhaps more frequent in the second. The glass of the basalts, however, even in thin slices, is characteristically opaque from its crowded inclusions ; while that of the andesitic forms, though black in hand specimens, appears perfectly transparent and sometimes even colourless in thin slices. 3. Chemical Characters.—The only one of these to which reference will be made here is the varying proportion of silica. While the dykes as a whole are basic, some of them contain so high a percentage of silica as to link them with the acid rocks. The pro- portion of this ingredient ranges from less than 50 to nearly 60 per cent. The rocks with the lower percentage of acid are richer in the heavy bases, and have a specific gravity which sometimes rises above 3°0. They include the true dolerites and basalts. Those, on the other hand, with the higher ratio of silica, are poorer in the heavy bases, and have a specific gravity from 2°76 to 2°96. They comprise the “tholeiites,” “‘andesites,” and other more coarsely crystalline rocks of the great eastern and south- eastern dykes.t Not only do the dykes differ considerably from each other in their relative proportions of silica, but even the same dyke may be found to present a similar diversity in different parts of its mass. It has long been a familiar fact that the glassy parts of such basic rocks are more acid than the surrounding crystalline portions. The original magma may be regarded as a natural glass or fused silicate, in which all the elements of the rock were dissolved, and which necessarily became more acid as the various basic minerals crystal- lised out of it.{ In the Eskdale dyke the silica percentage of this glassy portion is 58°67, that of the little kernels of black glass dispersed through the rock as much as 65°49.§ In the Dunoon dyke observed by Mr Cuoves the siliceous or jaspideous veins contain no less than 68°05 per cent. of silica, while the mass of the dyke itself shows on analysis only 47°36 per cent.|| * Mikroskopische Phystographie, 2nd edition, 504 et seq. + For analyses of dykes, see I. L. Bell, Proc. Roy. Soc., xxiii. p. 546; J. S. Grant Wilson, Proc. Roy. Phys. Soc. Edin., v. p. 253 ; Teall, Quart. Jour. Geol, Soc., xl. p. 209; Judd and Cole, Quart. Jour. Geol. Soc., xxxix. p. 444. t On this subject see a paper by Dr A. Lagorio, “ Uber die Natur der Glasbasis sowie der Krystallisationsvorginge im eruptiven Magma,” Tschermak’s Mineralog. Mittheil., viii. (1887) p. 421. §J.S. Grant Wilson, Proc. Roy. Soc. Phys. Edin., v. (1880) p. 253. || Unpublished analyses made by Prof. Dirrmar of Glasgow, and communicated to me by Mr Croven. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 45 4, Petrographical Nomenclature.—It is obvious that no one term will suffice to describe a series of rocks presenting such variety of mineralogical and chemical composi- tion as those that form the system of dykes now under discussion. Basalt, dolerite, melaphyre, diabase, augite-porphyrite, diabase-porphyrite, augite-andesite, and doubtless other names might be appropriately applied to different dykes; sometimes, indeed, more than one of these terms might be given to different parts of the same dyke. When the geological history of the dykes, and their connection with the rest of the volcanic phenomena are the subject of inquiry, rather than their petrographical characters, it becomes convenient to adopt some general term which may appropriately describe the whole. The word “basalt” has been so employed, but it is obviously so inapplicable to the more acid and andesitic rocks that its use as a general epithet is objectionable. None of the other specific names are free from the same defect. The old term “trap” would be useful, but it has become obsolete, and its revival might be attended with grave dis- advantages. In referring to the dykes of this great system, therefore, I shall speak of them as “the basic dykes,” reserving specific names for such individual cases as may require them. § 4. Have. In the great majority of cases the dykes are nearly or quite vertical. This position is more particularly exhibited by the great single dykes. But occasionally, where one of these crosses a deep valley, a slight hade is perceptible by the deviation of the line of the dyke from its normal course. SeDGwick long ago noticed that the Cleveland dyke has, in places, an inclination of at least 80° to its N.E. side.* In the coal-workings, also, a trifling inclination is sometimes perceptible, especially where a dyke has found its way along a previously existing line of fault, as in several examples in Stirlingshire. But in those districts where the dykes are gregarious, departures from the vertical position are not infrequent, more particularly near the great basalt-plateaux. It was long ago noticed by Necker, that even in such a dyke-filled region as Arran, almost all of the dykes are vertical, though sometimes deviating from that position to the extent of 20°. BrrcEr found that the angle of deviation among those of the north of Ireland ranges from 9° to 20°, with a mean of 13°.{ The most oblique examples are probably those which occur in the basalt-plateaux of the Inner Hebrides, where the same dyke in some parts of its course runs horizontally between two beds, across which it also ascends vertically (see fig. 41). But with these minor exceptions, the verticality of the great system of dykes, pointing to the perpendicular fissure-walls between which the molten rock ascended, is one of the most notable features in their geological structure. § 5. BREADTH. An obvious characteristic of most dykes is the apparent uniformity of their breadth. Many of them, as exposed along shore-sections, vary as little in dimensions as well- * Cambridge Phil. Trans., ii. p. 28. + Trans. Roy. Soc, Edin., xiv. p. 677. £ Trans. Geol. Soc., iii. p. 227. VOL. XXXV. PART 2. G 46 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION built walls of masonry do. Departures from such uniformity may often indeed be noted, whether a dyke is followed laterally or vertically. The largest amount of varia- tion is, of course, to be found among the dykes of the gregarious type, the thinner examples of which may diminish to a width of only one inch or less, while their average breadth is greatly less than in the case of the great solitary dykes. In the district of Strathaird, in Skye, MaccuttocH estimated the remarkably abundant dykes there developed to vary from 5 to 20 feet in breadth, but with an average breadth of not more than 10 feet.* In the isle of Arran, according to NEcKER’s careful measurements, most of the dykes range from 2 or 3 to 10 or 15 feet, but some diminish to a few inches, while others reach a width of 20,30 or even 50 feet.t In the north of Ireland, Bercer observed that the average breadth of thirty-eight dykes traversing primitive rocks (schist, granites, &c.) was 9 feet; and of twenty-four in Secondary rocks, 24 feet.t But when we pass to the great solitary dykes, that run so far and so continuously across the country, we encounter much thicker masses of igneous rock. Most of the measurements of these dykes have been made at the surface, and the variations noted in their breadth occur along their horizontal extension. The Cleveland dyke, which is the longest in Britain, varies from 15 to more than 100 feet, with perhaps an average width of between 70 and 90 feet.§ Some of the great dykes that cross Scotland are of larger dimensions. Most of them, however, like that of Cleveland, are liable to considerable variations in breadth when followed along their length. The dyke which runs from the eastern coast across the Cheviot Hills and Teviotdale to the head of the Ale Water, is in some places only 10 feet broad, but at its widest parts is probably about 100 feet. The Eskdale and Moffat dyke is in parts of its course 180 feet wide, but elsewhere it diminishes to not more than 40 feet. These variations are repeated at irregular intervals, so that the dyke alternately widens and contracts as we trace its course across the hills. Some of the dykes further to the north and west attain yet more gigantic proportions. That which crosses Cantyre opposite Ardlamont Point has been measured by Mr J. B. Hint of the Geological Survey, who finds it to be from 150 to 180 feet broad on the shore of Loch Fyne, and to swell out beyond the west side of Loch Tarbert to a breadth of 240 to 270 feet. A dyke near Strathmiglo, in Fife, is about 400 feet wide. The broadest dyke known to me is one which I traced near Beith, in Ayrshire, traversing the Carboni- ferous Limestone. Its maximum width is 640 feet. Unfortunately, it is much less easy to get evidence of the width of dykes at different levels in their vertical extension. Yet this is obviously an important point in the theoretical discussion of their origin. Two means are available of obtaining information on the subject—(a) from mining operations, and (b) from observations at precipices and between hill-crests and valley-bottoms. * Trans, Geol. Soc., ili. p. 80. + Trans. Roy. Soc. Hdin., xiv. p. 690 et seq. t Trans. Geol. Soc., iii. p. 226. He believed that dykes in Secondary rocks reach a much greater thickness than in other formations. My own observations do not confirm this generalisation. § At Cockfield, where it has long been quarried, it varies from 15 to 66 feet ; at Armathwaite, in the vale of the Eden, it is about 54 feet (J. J. H. Teall, Quart. Jour. Geol. Soc., xl. p. 211). DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 47 (a) In the central Scottish coal-field and in that of Ayrshire some large dykes have been cut through at depths of two or three hundred feet beneath the surface. But there does not appear to be any well-ascertained variation between their width so far below ground and at the surface. In not a few cases, indeed, dykes are met with in the lower workings of the coal-pits which do not reach the surface or even the workings in the higher coals. Such upward terminations of dykes will be afterwards considered, and it will be shown that towards its upper limit a dyke may rapidly diminish in width. (b) More definite information, and often from a wider vertical range, is to be gathered on coast-cliffs and in hilly districts, where the same dyke can be followed through a vertical range of several hundred feet. But so far as my own observations go, no general rule can be established that dykes sensibly vary in width as they are traced upward. Hvery one who has visited the basalt precipices of Antrim or the Inner Hebrides, where dykes are so numerous, will remember how uniform is their breadth as they run like ribbons up the faces of the escarpments.* Now and then one of them may be observed to die out, but in such cases (which are far from common among true dykes) the normal width is usually maintained up to within a few feet of the termination. All over the southern half of Scotland, where the dykes run along the crests of the hills and also cross the valleys, a difference of level amounting to several hundred feet may often be obtained between adjacent parts of the same dyke. But the breadth of igneous rock is not perceptibly greater in the valleys than on the ridges. The depth of boulder clay and other superficial deposits on the valley bottoms, however, too frequently conceals the dykes at their lowest levels. Perhaps the best sections in the country for the study of this interesting part of dyke-structure are to be found among the higher hills of the Inner Hebrides, such as the quartzites of Jura and the granophyres and gabbros of Skye. On these bare rocky declivities, numerous dykes may be followed from almost the sea- level up to the rugged and splintered crests, a vertical distance of between 2000 and 3000 feet. The dykes are certainly not as a rule sensibly less in width on the hill tops than in the glens. So far, therefore, as I have been able to gather the evidence, there does not appear to me to be, as a general rule, any appreciable variation in the width of dykes for at least 2000 or 3000 feet of their descent. The fissures which they filled must obviously have had nearly parallel walls for a long way down. § 6. INTERRUPTIONS oF LATERAL CoNTINUITY. In tracing the great single dykes across the country, the geologist is often surprised to meet with gaps, varying in extent from a few hundred feet to several miles, in which no trace whatever of the igneous rock can be detected at the surface. This dis- appearance is not always explicable by the depth of the cover of superficial accumulations; * This point did not escape the attention of that excellent observer, BERGER, in his examination of the dykes in the north of Ireland. We find him expressing himself thus :—“The depth to which the dykes descend is unknown; and after having observed the sections of a great many along the coast in cliffs from 50 to 400 feet in height, I have not been able to ascertain (except in one or two cases) that their sides converge or have a wedgeform tendency” (Trans. Geol. Soc., iii. p. 227). 48 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION for it may be observed over ground where the naked rocks come almost everywhere to the surface, and where, therefore, if the conspicuous material of-the dykes existed, it could not fail to be found. No dyke supplies better illustrations of this discontinuity than that of Cleveland. Traced north-westward across the Carboniferous tracts that lie between the mouth of the Tees and the Vale of the Eden, this dyke disappears some- times for a distance of six or eight miles. In the mining ground round the head of the South Tyne the rocks are bare, so that the absence of the dyke among them can only be accounted for by its not reaching the surface. Yet there can be no doubt that the various separated exposures, which have the same distinctive lithological characters and occur on the same persistent line, are all portions of one dyke which is continuous at some depth below ground. We have thus an indication of the exceedingly irregular upward limit of the dykes, as will be more particularly discussed further on. But there are also instances where the continuity is interrupted and then resumed on a different line. One of the best illustrations of this character is supplied by the large dyke which rises through the hills about a mile south of Linlithgow and runs westward across the coal-field. At Blackbraes it ends off in a point, and is not found again to the westward in any of the coal-workings. But little more than quarter of a mile to the south a precisely similar dyke begins, and strikes westward parallel to the line of the first one. The two separated strips of igneous rock overlap each other for about three-quarters of a mile. But that they are merely interrupted portions of what is really a single dyke can hardly be questioned. A second example is furnished by another of the great dykes of the same district, which after running for about 12 miles in a nearly east and west direction suddenly stops at Chryston, and begins again in the same direction, but on a line about a third of a mile further north. Such examples serve to mark out irregularities in the great fissures up which the materials of the dykes rose. § 7. Leneru. In those districts where the small and crowded dykes of the gregarious type are developed, one cannot usually trace them for more than a short distance. The longest examples known to me are those which have recently been mapped with much patience and skill by Mr CroveH in Eastern Argyleshire. Some of them he has been able to track over hill and valley for four or five miles, though the great majority are much shorter. In Arran and in the Inner Hebrides, it is seldom possible to follow what we can be sure is the same dyke for more than a few hundred yards. This difficulty arises partly, no doubt, from the frequent spread of peat or other superficial accumulation which conceals the rocks, and partly also from the great number of dykes and the want of sufficiently distinct lithological characters for the identification of any particular one. But making every allowance for these obstacles, we are compelled, I think, to regard the gregarious dykes as essentially short as well as relatively irregular. In striking contrast to these, come the great solitary dykes. In estimating their DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 49 length, as I have already remarked, we must bear in mind the fact that they occasionally undergo interruptions of continuity owing to the local failure of the igneous material to rise to the level of what is now the surface of the ground. A narrow wall-like mass of augite-andesite, dolerite, or basalt which sinks beneath the surface for a few hundred yards, or for several miles, and. reappears on the same line with the same petrographical characters, while there may be no similar rock for miles to right and left, can only be one dyke prolonged underneath in the same great line of fissure. But even if we restrict our measurements of length to those dykes or parts of dykes where no serious interruption of continuity takes place, we cannot fail to be astonished at the persistence of these strips of igneous rock through the most diverse kinds of geological structure. A few illustrative examples of this feature may be selected. It will be observed that the longest and broadest dykes are found furthest from the basalt-plateaux, while the shortest and narrowest are most abundant near these plateaux. Not far from what I have taken provisionally as the northern boundary of the dyke region, two dykes occur which have been mapped from the head of Loch Goil by Arrochar across Lochs Lomond and Katrine by Ben Ledi to Glen Artney, whence they strike into the Old Red Sandstone of Strathmore, and run on to the Tay near Perth—a total distance of about 60 miles. If the dyke which continues in the same line on the other side of the estuary of the Tay beyond Newburgh, is a prolongation of one of these, then its entire length exceeds 70 miles. A few miles further south, one of a group of dykes can be followed from the heart of Dumbartonshire by Callander across the Braes of Doune to Auchterarder—a distance of 47 miles, with an average breadth of more than 100 feet. In the district between the Forth and Clyde a number of long parallel dykes can be traced for many miles across hill and plain, and through the coal-fields. One of these is continuous for 25 miles from the heart of Linlithgowshire into Lanarkshire. Still longer is the dyke which runs from the Firth of Forth at Grangemouth westward to the Clyde, opposite Greenock—a distance of about 36 miles. Coming southward, we encounter a striking series of single dykes on the uplands between the counties of Lanark and Ayr, whence they strike into the Silurian hills of the southern counties. One of these runs across the crest of the Haughshaw Hills, and can be followed for some 30 miles. But if, as is probable, it is prolonged in one of the dykes that traverse the moorlands of the north of Ayrshire and south of Renfrewshire to the Clyde, its actual length must be at least twice that distance. The great Moffat and Eskdale dyke strikes for more than 50 miles across the south of Scotland and north of England. The Hawick and Cheviot dyke runs for 26 miles in Scotland and for 32 miles in Northumberland. But the most remarkable instance of persistence is furnished by the Cleveland dyke. From where it is first seen near the coast-cliffs of Yorkshire it can be followed, with frequent interruptions, during which for sometimes several miles no trace of it appears at the surface, across the north of England and as far as Dalston Hall south of Carlisle, beyond which the ground onwards to the Solway Firth is deeply covered with superficial deposits. The total distance through which this dyke can be recognised is about 110 miles. But 50 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION it probably goes much further still. On the opposite side of the Solway, a dyke which runs in the same line, rises through the Permian strata a little to the east of the mouth of the Nith. Some miles further to the north-west, near Moniaive, Mr J. Horne, in the progress of the Geological Survey, traced a dark compact dyke with kernels of basalt-glass near its margin, running in the same north-westerly direction. Still further on in the same line, another similar rock is found high on the flanks of the lofty hill known as Windy Standard. And lastly, in the Ayrshire coal-field, a dyke still continuing the same trend, runs for several miles, and strikes out to sea near Prestwick. It cannot, of course, be proved that these detached Scottish protrusions belong to one great dyke, or that if such a continuous dyke exists, it is a prolongation of that from Cleveland. At the same time, I am on the whole inclined to connect the various outcrops together as those of one prolonged subterranean wall of igneous rock. The distance from the last visible portion of the Cleveland dyke near Carlisle to the dyke that runs out into the Firth of Clyde near Prestwick, is about 80 miles. If we consider this extension as a part of the great north of England dyke, then the total length of this remarkable geological feature will be about 190 miles. § 8. Persistence or MinERAL CHARACTERS. Not less remarkable than their length is the preservation of their normal petrographical characters by some dykes for long distances. In this respect the Cleveland dyke may again be cited as a typical example. The macroscopic and microscopic structures of the rock of this dyke distinguish it among the’ other eruptive rocks of the north of England. And these peculiarities it maintains throughout its course.* Similar though less prominent uniformity may be traced among the long solitary dykes of the south of Scotland, the chief variations in these arising from the greater or less extent to which the original glassy magma has been retained. The same dyke will at one part of its course show abundant glassy matter even to the naked eye, while at a short distance the vitreous ground-mass has been devitrified, and its former presence can only be detected with the aid of the microscope. § 9. Direction. Another characteristic feature of the dykes is their generally rectilinear course. So true are they to their normal trend that, in spite of varying inequalities of surface and wide diversities of geological structure in the districts which they traverse, they run over hill and dale almost with the straightness of lines of Roman road. In the districts where they assume the gregarious type, and depart most widely from the character of the great solitary dykes, they still tend to run in straight or approximately straight lines, or, if wavy in their course, to preserve a general parallelism of direction. Yet even among the great persistent dykes instances may be cited where the recti- linear trend is exchanged for a succession of zig-zags, though the normal direction is * See the careful examination of this dyke by Mr Teall, Quart. Jour. Geol. Soc., xl. p. 209. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 51 on the whole maintained. In such cases, it is evident that the fissures were not long straight dislocations like the larger lines of fault in the earth’s crust, but were rather notched rents or cracks which, though keeping on the whole one dominant direction, were continually being deflected for short distances to either side. As a good illustration of this character, reference may be made to the Cheviot and Hawick dyke. In Teviotdale this dyke can be followed continuously among the rocky knolls, so that its deviations can be seen and mapped. From the median line of average trend the salient angles sometimes retire fully a quarter of a mile on either side. Some examples of the same feature may be noticed in the Eskdale dyke. The large dyke which runs westward from Dunoon has been observed by Mr Ciovex to change sharply in direction three times in four miles, running sometimes for a short distance at a right angle to its general direction (see fig. 17). Among these solitary dykes also, though the persistence of their trend is so pre- dominant, there occur instances where the general direction undergoes great change. Some of the most remarkable cases of this kind have been mapped by Mr B. N. Praca and Mr R. L. Jack, in the course of the Geological Survey of Perthshire. Several important dykes strike across the Old Red Sandstone plain for many miles in a direction shghtly south of west. But when they approach the rocks of the Highland border in Glen Artney, they bend round to south-west, and continue their course along that new line. In my early paper on the “Chronology of the Trap-Rocks of Scotland,” * I called attention to the dominant trend of the dykes from N.W. to 8.E. Subsequent research has shown this to be on the whole the prevalent direction throughout the whole region of dykes. But the detailed mapping, carried on by my colleagues and myself in the Geological Survey, has brought to light some curious and interesting variations from the normal trend: In the districts where dykes of the gregarious type abound there is sometimes no one prevalent direction, but the dykes strike to almost all points of the compass. Of the Arran dykes, so carefully catalogued by NEcKER, only about a third have a general north-westerly course. But in Eastern Argyleshire the abundant dykes mapped by Mr Ciovues trend almost without exception towards N.N.W. In the north of Ireland BercEr found the direction of thirty-one dykes to vary from 17° to 71° W. of N., giving a mean of N. 36° W.t In Islay, Jura, Higg, Mull, and Skye the mean of several hundred observations has given me similar results. It appears therefore that though there is sometimes extraordinary local diversity in the direction of the dykes in those districts where they present the gregarious type, the general north-westerly trend can usually still be recognised. But when we turn to the long massive solitary dykes, we soon perceive a remarkable change in their direction as we follow them northward into Scotland. In the paper just referred to, I pointed out how the general north-westerly trend becomes east and west in the Lothians, with a tendency to veer a little to the south of west and north of east. This departure from the normal direction is now seen to be part of a remarkable radial arrangement of the dykes. * Trans. Roy. Soc. Hdin., xx. p. 650. + Trans. Geol. Soc., iii. p. 225. 52 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION Beginning at the southern margin of the dyke-region, we have the notable example of the Cleveland dyke, which in its course from Cleveland to Carlisle runs nearly W. 15° N. The Eskdale dyke has an average trend of W. 32° N., and the same general direction is maintained by the group of dykes which run from the Southern Uplands across the south- west of Lanarkshire and north-east of Ayrshire. But as we proceed northwards we observe the trend to turn gradually round towards the west. ‘The dyke that runs from near the mouth of the Coquet across the Cheviot Hills to beyond Hawick has a general course of W. 8° N. In the great central coal-field of Scotland the average direction may be taken to be nearly E. and W., the same dyke running sometimes to the north, and sometimes to the south of that line. But immediately to the north a decided tendency to veer round southwards makes its appearance. Thus the long dyke which runs from the Carse of Stirling through the Campsie Fells to the Clyde west of Leven, has a mean direction of W. 5° S. This continues to be the prevalent trend of the remarkable series of dykes which crosses the Old Red Sandstone plains, though some of these revert in whole or in part to the more usual direction by keeping a little to the north of west. Even as far as Loch Tay and the head of Strathardle, the course of the dykes continues to be to the south of west. Tracing these lines upon a map of the country we perceive that they radiate from an area lying along the eastern part of Argyleshire and the head of the Firth of Clyde (see Plate I.). § 10. Termination Upwarps. It was pointed out many years ago by WinoH that some of the dykes which traverse the Northumberland coal-field do not cut the overlying Magnesian Limestone. The Hett dyke, south of Durham, which no doubt belongs to the ancient series of igneous protrusions already referred to, is said to end off abruptly against the floor of the limestone.* Here and there, among the precipices of the Inner Hebrides, a dyke may be seen to die out before it reaches the top of the cliff. But in the vast majority of Fie. 6.—Section along the line of the Cleveland Dyke at Cliff Ridge, Guisbrough (G. Barrow), scale, 12 inches to 1 mile. cases, no evidence remains as to how the dykes terminated upwards. I have referred to the occasional interruptions of the continuity of a dyke, where, though the rock does not reach the surface, it must be present in the fissure underneath. Such interruptions show that, in some places at least, there was no rise of the rock even up to the level of what is now the surface of the ground, and that the upward limit of the dykes must have been exceedingly irregular. * This is expressed in the Geological Survey map, Sheet 93, N.E. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 53 Excellent illustrations of this feature are supplied by sections on the line of the Cleveland dyke. Towards its south-eastern extremity this ereat band of igneous rock ascends from the low Triassic plain of the Tees into the high uplands of Cleveland. Its (ee > i) 6 ° io ° = i) ° a BN o m7) ¢ k y Qy CO) eee eae op eee eee | course across the ridges and valleys there has been carefully traced for the Geological Survey by Mr G. Barrow, who has shown that over certain parts of its course it does not reach the surface, but remains concealed under the Jurassic rocks, which it never succeeded in penetrating. But that in places it comes within a few feet of the soil is shown by the baked shale at the surface, for the alteration which it has induced on the surrounding rocks only extends a few feet from its margin. These interruptions of continuity show how uneven is the upper limit of the dyke. The characteristic porphyritic rock may be observed running up one side of a hill to the crest, but never reaching the surface on the other side. At Cliff Ridge, for example, about three miles south-west of Guisbrough, Mr Barrow has followed it up to the summit on the west side; but has found that on the east side it does e not pierce the shales, which there form the declivity. This BAK structure is represented in fig. 6. The vertical distance e between the summit to the left, where the dyke (b) disappears, Lee and the point to the right, where the Lias shale (a) of the [ Ba hill-side is concealed by drift (c), amounts to 250 feet, the Nt, horizontal distance being a little more than 900 feet. But as the shale when last seen at the foot of the slope is quite unaltered, the dyke must there be still some little distance beneath the surface, so that the vertical extension of this upward tongue of the dyke must be more than 250 feet. Mr Barrow, to whom I am indebted for these particulars, has also drawn the accompanying section (fig. 7) along the course of the dyke for a distance of nearly 11 miles eastward from the locality represented in fig. 6. From this section, it will be observed that in that space there are at least three tongues Burnt Shale. a, Liassic shales, sandstones, and ironstones ; b, The Dyke. Burnt Shale. the Geol. Survey, Geology of Cleveland, p. 61). Burnt Shale. Fic. 7.—Section along the course of the Cleveland Dyke, at the head of Lonsdale, Yorkshire (G. Barrow, in Memoirs of or upward projections of the upper limit of the dyke. Several additional examples of the same structure are to be seen further east towards the last visible outcrop of the dyke. Another feature connected with the upward termination of the dyke is well seen in some parts of the ground through which the two foregoing sections are taken. Mr Barrow ci informs me that at Ayton a level course has been driven into the hill for mining VOL. XXXV. PART 2. H DATUM LINE 400 FY AROVE SEA LEVEL Main Seam of Iron- stone burnt by Dyke. 54 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION operations, at a height of 400 feet above sea-level, and the dyke has there been ascer- tained to be 80 feet broad. Higher on the hill, close to the 750 feet contour-line, its breadth is only 20 feet, so that it narrows upward as much as 60 feet in a vertical height of 350 feet. Its contraction in width during the last twenty feet is still more rapid, and in the last few yards it diminishes to two or three feet, and has a rounded top over which the strata are bent upward. The accompanying section (fig. 8) across the upper part of the dyke will make these features clearer. Further to the west an exposure of the upper limit of the dyke has been described and figured by Mr Teatt. In 1882, at one of the Cockfield quarries (fig. 9), the dyke a b Fic. 8,—Section across the extreme upper limit of the Cleveland Fic. 9.—Upper limit of the Cleveland Dyke in Dyke, Ayton, on the scale of 20 feet to one inch (G. Barrow). quarry near Cockfield (after J. J. H. Teall). a, Jurassic shales, &c. ; b, Dyke. a, a, Carboniferous shales ; b, Dyke. was “seen to terminate upwards very abruptly in the form of a low and somewhat irregular dome, over which the Coal Measure shales passed without any fracture, and only with a slight upward arching.” * Near the other or north-western termination of this great dyke, similar evidence is found of an uneven upper limit. After an interrupted course through the Alston moors, the dyke reaches the ground that slopes eastward from the edge of the Cross Fell escarpment. Its highest visible outcrop is at a height of 1700 feet. But westwards from that point the dyke disappears under the Carboniferous rocks, and does not emerge along the front of the great escarpment that descends upon the valley of the Eden, where among the naked scarps of rock it would unquestionably be visible if it reached the surface. Its upper edge must rapidly descend somewhere behind the face of the escarpment, for the igneous rock crops out a little to the west of the foot of the cliff, at a height of about 1000 feet below the point where it is last seen on the hills above. Here the top of the dyke has a vertical drop of not less than 1000 feet, in a horizontal distance of five miles, as shown in fig. 10, which has been drawn for me by Mr J. G. Goopcutzp. * Quart. Jour. Geol. Soc., xl, p. 210. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. It will be observed that in these sections (figs. 7 and 10) there is a curiously approximate coincidence between the inequalities in the upper surface of the dyke and those in the form of the overlying ground. The coincidence is too marked and too often repeated to be merely accidental. Whether the ancient topographical features had any influence in determining, by cooling or otherwise, the limit of the upward rise of the lava, or whether the dyke, even though concealed, has affected the progress of the denudation of the ground overlying it, is a question worthy of fuller investigation. § 11. Known VerticaL Extension. Closely connected with the determination of the upper limit reached by the dykes, is the total vertical depth to which they can be traced. Of course, the depth of the original reservoir of molten rock which supplied them remains unknown, and probably undiscoverable. But it is possible in many cases to determine at least the inferior limit of the thickness of rock through which the molten material of the dykes has ascended. In the dark gabbro hills of Skye, numerous dykes may be seen climbing from the glens right up the steep rugged acclivities and over the crests. In these and similar cases, we can actually trace the dykes through a vertical thickness of more than 3000 feet of rock. The dykes which cross Loch Lomond and ascend the hills on either side of that deep depression must rise through at least as great a thickness. But where a knowledge of the geological structure of the ground enables us to estimate the bulk of the successive rock-formations which underlie the surface, it can be shown that the lava ascended through a much greater depth of rock. Measurements of this kind can best be made towards the eastern end of the Cleveland dyke, where the different sedimentary groups have not been seriously disturbed, and where from natural sections and artificial borings their thicknesses are capable of satisfactory computation. The highest bed of the Jurassic series anywhere touched by the dyke is the Cornbrash. It is certain, therefore, that the igneous rock rises through all the subjacent members of the Jurassic series up to that horizon. There can be no doubt also that the Trias and Magnesian Limestone continue in their normal thickness underneath the Jurassic strata. To what extent the Coal- Measures exist under Cleveland has not been ascertained ; possibly they have been entirely denuded from that area, as from the ground to the west. But the Millstone Grit and Carboniferous Limestone pro- bably extend over the district in full development; and below them there must lie a vast depth of Upper and Lower Silurian strata, Smittergill. Cross Fell Escarpment. Eden Valley. 5D The shaded part shows the position of the dyke, le of 1 inch to 1 mile). the unshaded part overlying it marks where the dyke does not reach the surface (sca Section along the course of the Cleveland Dyke across the Cross Fell escarpment (J. G. Goodchild). Fic. 10. 56 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION probably also of still older Palseozoic rocks, and beneath all the thick Archzean platform. Tabulating these successive geological formations, and taking only the ascertained thickness of each in the district, we find that they give the results shown in the subjoined table.* Strata Cut by the Cleveland Dyke. Feet. Cornbrash— Lower Oolite and Upper Lias, as proved by bore-hole on Gerrick Moor, 5 : . 950 Middle and Lower Lias, ascertained from measurement of cliff-sections and from mining operations to be more than : : . 850 New Red Sandstone and Marl, found by borin AES to the Tees to sroned 5 . 1,600 Magnesian Limestone, at least : ; : : ° 3 - . 500 Coal-Measures, possibly absent : : : : , . : ‘ 0 Millstone Grit, not less than : ; A : F : : . 500 Carboniferous Limestone series, at least : : . . c ‘ . 3,000 Silurian rocks, probably not less than : . : : 5 : . 10,000 17,400 There is thus evidence that this dyke has risen through probably more than three miles of stratified rocks. How much deeper still lay the original reservoir of molten material that supplied the dyke we have at present no means of computing. § 12. BrancHEs AND VEINS. It might have been anticipated that the uprise of such abundant masses of molten rock in so many long and wide fissures would generally be attended with the intrusion of the same material into lateral rents and irregular openings, so that each dyke would have a kind of fringe of offshoots or processes striking from it into the surrounding ground. It might have been expected also that dykes would often branch, and that the arms would come together again and enclose portions of the rocks through which they rise. But in reality such excrescences and bifurcations are of comparatively rare occurrence. As a rule, each dyke is a mere wall of igneous rock, with little more projection or ramification than may be seen in a stone field-fence. Among the short, narrow, and irregular dykes of the gregarious type branchings are occasionally seen, and in some districts are extraordinarily abundant. But among the great single dykes such irregularities are far less common than might have been looked for. A few characteristic examples from each type of dyke may here be given. The Cleveland dyke, which in many respects is typical of the great solitary dykes of the country, has been traced for many miles without the appearance of a single offshoot of any kind. Yet here and there along its course it departs from its usual regularity. As it crosses the Carboniferous tracts of Durham and Cumberland, there appear near its course lateral masses of eruptive rock, most of which doubtless belong to the much older “Whin Sill.” But there is at least one locality, at Bolam near Cockfield, in the county * Drawn up for me by Mr Barrow. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 57 of Durham, where the dyke, crossing the Millstone Grit, suddenly expands into a boss, and immediately contracts to its usual dimensions. Around this knot several short dykes or veins seem to radiate from it. The dyke has been quarried here, and its relations to the surrounding strata have been laid bare, as will be again referred to a little further on.* Among the great persistent dykes of Scotland the absence of bifurcation and lateral offshoots offers a striking contrast to the behaviour of the dykes in those districts where they are small in size and many in number. But exceptions to the general rule may be gathered. Thus the Eskdale dyke is flanked at West Carrick with a large lateral vein, which is almost certainly connected with the main fissure. The Hawick and Cheviot dyke splits up on the hill immediately to the east of the town of Hawick, sends off some branches, and then resumes its normal course (fig. 11). Again, one of the two nearly parallel dykes which run from Loch Goil Head across Ben Ledi into Glen Artney bifurcates at the foot of that valley, its northern limb (about two miles long) speedily rs Fig. 11.—Branching portion of the great Dyke near Fic, 12,—Branching Dyke at foot of Glen Artney (length Hawick (length about 1 mile). about 4 miles). dying out, and its southern branch throwing off another lateral vein, and then continuing eastward as the main dyke (fig. 12). In the districts of gregarious dykes, however, abundant instances may be found of dykes that branch, and of others that lose the parallelism of their walls, become irregular in breadth, direction, and inclination, so as to pass into those intrusive forms that are more properly classed as veins. Excellent illustrations of bifurcatng dykes may be observed along the shores of the Firth of Clyde, particularly on the eastern coast line of the isle of Arran. The venous character has been familiar to geologists from the sketches given by Maccutitocs from the lower parts of the cliffs of Trotternish in Skyet But still more striking examples are to be seen in the breaker-beaten cliffs of Ardnamurchan. The pale Secondary limestones and calcareous sandstones of that locality are traversed by a series of dark basic veins, and the contrast of tint between the two kinds of rock is so marked as even to catch the eye of casual tourists in the passing steamboats. The * This locality was well described by SEDGWICK, in his early paper on Trap-Dykes in Yorkshire and Durham, Trans. Cambridge Phil. Soc., i. p. 27. + Western Islands, plate xvii. 58 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION veins vary in width from less than an inch to several feet or yards. They run in all directions and intersect each other, forming such a confused medley as requires some patience on the part of the geologist who would follow out each independent ribbon of injected material in its course up the cliffs, or still more, would sketch their ramifications in his note-book. A good, though perhaps somewhat exaggerated, illustration of their general character was given by Maccuntocu.* The accompanying figure (fig. 13) is less sensational, but represents with as much accuracy as I could reach, the network of veins near the foot of the cliffs. One conspicuous group of veins, which seen from a distance looks like a rude sketch of a lug-sail traced in black outline upon a pale ground, is known to the boatmen as ‘*‘ M‘Niven’s Sail.” As a general rule, the narrower the vein the finer in grain is the rock of which it consists. This compact dark homogeneous material has commonly passed by the name Fic, 13.—Basic Veins traversing Secondary Limestone and Sandstone on the coast cliffs, Ardnamurchan, of “basalt,” but its minuteness of texture probably in most cases arises from local rapidity of cooling, and it may be the same substance which, where in larger mass in the immediate neighbourhood, has solidified as one of the other pyroxene-plagioclase- magnetite rocks. With regard to the places where such abundant tortuous veins are more especially developed, I may remark that they are particularly prominent under a thick overlying mass of erupted rock, such as a great intrusive sheet, or the bedded basalts of the plateaux, or where there is good reason to believe that such a deep cover, though now removed by denudation, once overspread the area in which they appear. It will be shown in the sequel that such horizons have been peculiarly liable to intrusions of igneous material of various kinds, and at many different intervals, during the volcanic period. A thick cake * Op. cit., plate xxxiii. fig, 1. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 59 of crystalline rock seems to have offered such resistance to the uprise of molten material through it, that when the subterranean energy was not sufficient to rend it open by great fissures, and thus give rise to dykes, the lavas were forced into such irregular cracks as were made partly in the softer rocks underneath and partly in the cake itself, or found escape along pre-existing divisional planes. In Ardnamurchan, round the Cuillin Hills of Skye, and in Rum, the overlying resisting cover now consists mainly of gabbro sheets. In the east of Skye, in Higg, and in Antrim, it is made up of the thick mass of the plateau- basalts. § 13. Connection or Dykes witH InrRusiveE SHEETS. Every field-geologist is aware how seldom he can actually find the vent or pipe up which rose the igneous rock that now forms those massive beds which he denominates intrusive sheets. He might well be pardoned were he to anticipate that, in a district much traversed by dykes, there should be many examples of intrusive sheets and frequent opportunities of tracing their connection with the fissures from which their material might be supposed to have been supplied. But such an expectation is singularly disappomted by an actual examination of the Tertiary volcanic region of Britain. That there are many intrusive sheets belonging to the great volcanic period with which I am now dealing, I shall endeavour to show in the sequel. But it is quite certain that though these sheets have of course each had its subterannean pipe or fissure of supply, they can only in very rare instances be directly traced to the system of dykes. On the other hand, the districts where great single dykes are most conspicuous, are for the most part free from mtrusive sheets, except those of much older date, like the Carboniferous Whin Sill of Durham and the diabases of Linlithgowshire. Yet a few interesting examples of the relation of dykes to sheets have been noticed. The earliest observed instances were those figured and described by Maccuttocu in his Western Islands of Scotland. Among them one has been familiar to geologists from having done duty in text-books of the science for more than half a century. I allude to the diagram of ‘‘ Trap and Sandstone near Suishnish.”* In that drawing seven dykes are shown as rising vertically through the horizontal sandstone, and merging into a thick overlying mass of “trap.” The author in his explanation leaves it an open question “whether the intruding material has ascended from below and overflowed the strata, or has descended from the mass,” though from the language he uses in his text we may infer that he was inclined to regard the overlying body as the source of the veins below it.t The section given by Maccuttoca, however, does not quite accurately represent the facts. The narrow dykes there drawn have no connection with the overlying sheet, but are part of the abundant series of basaltic dykes found all over Skye. The feeder of the sheet was undoubtedly the thick dyke which descends the steep bank immediately on the * Op. cit., pl. xiv. fig. 4. + Vol. i. pp. 384, 385. 60 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION southern front of Carn Dearg (636 feet high). The accompanying figure (fig. 14) shows what I believe to be the true geological structure of the locality, but the actual junction of the dyke and sheet is concealed under the talus of the slope. I shall have occasion in a later part of this paper to refer again to this section in connection with the history of intrusive sheets. SEDGWIOK, in the paper already quoted, gave an account and figure of the expansion of the Cleveland dyke at Bolam, to which allusion has already been made. He showed that from a part of the dyke which is unusually contracted a great lateral extension of the igneous rock takes place on either side over beds of shale and coal. While in the dyke the prisms are as usual directed horizontally inward from the two walls, those in the connected sheet are vertical, and descend upon the surface of highly indurated strata on which the sheet rests. But by far the most important examples known to me are those which occur in the coal-field of Stirlingshire. In that part of the country, the remarkable group of dykes already referred to, lying nearly parallel to each other and from half a mile to about JS XN g Rery Ly (NR y WN | , es (| l LD Cum WEA Saas Z = f poaee aL! ECO rm rer rm ema TE OE D> ma renter e Fic. 14.—Section showing the connection of a Dyke with an Intrusive Sheet, Point of Suisnish, Skye. g, Granophyre of Carn Dearg; f, similar rock, which appears eastward under the ‘‘sill” (d); e, intrusive sheet of fine-grained ‘‘ basalt” ; d, intrusive sheet or ‘‘sill” of coarse dolerite, 200 feet thick at its maximum, and rapidly thinning out ; c, dyke or pipe of finer grain than d; 6, yellowish-brown shaly sandstones, and a, dark sandy shales (Lias). three miles apart, runs in a general east and west direction. From one of these dykes no fewer than four sheets or “sills” strike off into the surrounding Coal-Measures. The largest of them stretches southwards for three miles, but the same rock is probably con- tinued in a succession of detached areas which spread westwards through the coal-field and circle round to near the two western sheets that proceed from the same dyke. Another thick mass of similar rock extends on the north side of the dyke for two and a half miles down the valley of the river Avon. These various processes, attached to or diverging from the dyke, are unquestionably intrusive sheets, which occupy different horizons in the Carboniferous series. The one on the north side has inserted itself a little above the top of the Carboniferous Limestone series. Those on the south side lie on different levels in the Coal-Measures, or rather they pass transgressively from one platform to another in that group of strata. No essential difference can be detected by the naked eye between the material of the dyke and that of the sheets. If a series of specimens from the different exposures were mixed up it would be impossible to separate those of the dyke from those of the sheets. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 61 A microscopical examination of the specimens likewise shows that they are perfectly identical in composition and structure, chiefly referable to rocks of the dolerite type, but partly to the tholeiite type. I have therefore no doubt that these remarkable appendages to this dyke are truly offshoots from it, and are not to be classed with the general mass of the diabases of central Scotland, which are Lower Carboniferous. The accompanying diagrammatic section (fig. 15) explains what appears to me to be the structure of the ground. An interesting and important fact remains to be stated in connection with these sheets. They are traversed by some of the other east and west dykes. This is particu- larly observable in the case of the sheet which extends northwards from the dyke through Fic. 15.—Section to show the connection of a Dyke with an Intrusive Sheet, Stirlingshire Coal-field. a, Dyke in line of fault ; b, intrusive sheet traversing and altering the coals ; 7, Slaty-band Ironstone. the parish of Torphichen. Two well-marked dykes can be seen running westwards among the ridges of the sheet. It is obvious, therefore, that these particular dykes are younger than the sheet. But, as will be shown in the sequel, there is abundant evidence that all the dykes of a district are not of one eruption. The intersection of one eruptive mass by another does not necessarily imply any long interval of time between them. They mark successive, but it may be rapidly successive, manifestations of volcanic action. Hence the cutting of the sheets by other dykes does not seem to me to invalidate the identification of these sheets as extravasations from the great dyke by which they are bounded. § 14. Ivrersections or Dykes—RepraTED DyKEs IN THE SAME LINE oF Fissure, Innumerable instances may becited, where one dyke or one set of dykes cuts across another. To some of these I shall refer in discussing the data for estimating the relative age of dykes. In considering the intersection from the point of view of geological structure, we are struck with the clean sharp way in which it so generally takes place. The rents into which the younger dykes have been injected seem, as a rule, not to have been sensibly influenced in width or direction by the older dykes, but go right across them. Hence the younger dykes retain their usual breadth and trend (fig. 16). The most interesting examples are those in which one dyke runs along another, as may occasionally be observed in the west of Scotland.* In these cases, which are to be distinguished from those where the whole may be really a portion of one original slowly cooling mass, the central dyke differs sufficiently in texture and structure to be discrimin- * Maccuxiocs figured an example from Strathaird, Western Islands, pl. xviii. fig. 1. Mr CioueH has found some good instances in south-eastern Argyleshire. VOL, XXXV, PART 2. I 62 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION ated from that which it has invaded. Its rock is generally rather fine-grained, some- times decidedly porphyritic, and in many cases is a true basalt. Where it is broad enough to show the difference between margin and q i — “a. centre, its outer edges present the usual finer grain. f Fe i “4 ty 4 There can be no doubt that the older dyke has been i | actually split open, and fresh eruptive material has risen along the fissure. If the subterranean movements were energetic enough to split up an already consolidated dyke, so as to allow of the renewed uprise of molten material between the separated portions, we may believe that much more frequently the opening would be effected not along the middle of the dyke, but between the dyke and one of its fissure walls. I have observed examples of this structure in the Western Islands, and Mr Cioven has recently found a numberin Argyleshire. If the section is limited a Tn in extent, we may be unable to determine which is the tie re Gt aa ae 7 a bedded older of the two parallel bands of igneous rock, though the fact that they present to each other the usual fine- grained edge due to more rapid cooling, shows that they are not one but two dykes belonging to distinct eruptions. So far as I have noticed, where one of the dykes can be continuously traced for a considerable distance, the other is short, and cannot be recognised at other exposures of the more continuous one. I infer that the shorter one is the younger of the two. § 15. Conract-METAMORPHISM OF THE DykEs. Another anticipation which a geologist might naturally entertain is, that these abundant intrusions of igneous rock should be accompanied with plentiful evidence of contact-metamorphism along their flanks. But in actual fact, evidence of any serious amount of alteration is singularly scarce. A slight induration of the rocks on either side of a dyke is generally all the change that can be detected. Some of the larger dykes, however, show more marked metamorphism, the nature of which is chiefly determined by the chemical composition of the rock affected. The most pronounced alteration is that which has been superinduced on carbonaceous strata, and particularly on seams of coal. In the Ayrshire coal-field the alteration of the coal extends sometimes 150 feet from the dyke, the extent of the change depending not merely on the mass of the igneous rock, but on the nature of the coal, and possibly on other causes. Close to a dyke, coal passes into a kind of soot or cinder, but sometimes assumes the. form of a finely columnar coke.* Shales are converted into a hard flinty substance that breaks with a conchoidal fracture and rings under the hammer. Fire-clay is baked into a * Explanation of Sheet 22, Geol. Survey Scotland, p. 26. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 63 porcelain-like material. Limestone is changed for a few inches into marble. Sandstones are indurated into a kind of quartzite, sometimes assume a columnar structure (the columns being directed away from the dyke-walls), and for several feet or yards have their yellow or red colours bleached out of them. The granite of Ben Cruachan where quarried on Loch Awe, as I am informed by Mr J. 8. Grant Witson of the Geological Survey, is traversed by a basic dyke, and for a distance of about 20 feet is rendered darker in colour, becomes granular, and cannot be polished and made saleable. These, however, are the extremes of contact-metamorphism by the Tertiary basic dykes. Let any geologist visit the Lias district of Skye, and he will not fail to be surprised at the almost entire absence of alteration in circumstances where he would have expected to find it. The dark shales, though ribbed across with hundreds of dykes, are sometimes hardly even hardened, and the limestones are not rendered in any appreciable degree more crystal- line even up to the very margin of the intrusive rock. Where the igneous material has been thrust between the strata in sheets, it has produced far more general and serious metamorphism than when it occurs in the form of dykes. The famous rock of Portrush, which was once gravely cited as an example of fossiliferous basalt, is a good illustration of the way in which Lias shale is porcellanised when the intruded igneous material has been thrust between its planes of bedding. In connection with the metamorphism superinduced by dykes, reference may be made to the curious alteration which they themselves have sometimes undergone where they have invaded a carbonaceous shale or coal. The igneous rock loses its dark colour and obviously crystalline structure, and becomes the pale-yellow or white, dull, earthy substance known to geologists as “ white trap.” The chemical changes involved in this alteration have been described by Sir I. Lowrntan Betz.* Dr Srecuer has also discussed the the alterations traceable by the aid of the microscope.t § 16. Rexation or Dykes To THE GroLocicaL STRUCTURE OF THE DisTRICTS WHICH THEY TRAVERSE. In no respect do the Tertiary basic dykes stand more distinguished from all the other rocks of this country than in their extraordinary independence of geological structure. The successive groups of Palaeozoic and Mesozoic strata follow each other in approximately parallel bands, which run obliquely across the island from south-west to north-east. The most important lines of fault take the same general line. The contemporaneously included igneous rocks follow, of course, the trend of the stratified deposits among which they lie, and even the intrusive eruptive rocks tend to group themselves along the general strike of the whole country. But the Tertiary dykes have their own independent direction, to which they adhere amid the extremest diversities of geological arrangement. * Proc. Roy. Soc., xxiii. (1875)*p. 543. t Tschermak’s Mineralogische Mittheilungen, ix. (1887) p. 145; Proc. Roy. Soc. Edin., 1888. Dr SrecuEr’s investigation is based upon a series of specimens from the intrusive (Carboniferous) rocks of the basin of the Firth of Forth, and has reference both to the phenomena of contact-metamorphism and the alteration of the eruptive rock ; but these changes belong to the Carboniferous period. 64 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION In the first place, the dykes intersect nearly the whole range of the geological formations of the British Islands. In the Outer Hebrides and north-west Highlands, they rise through the most ancient Archean gneisses, and through the red (Torridon) sandstones, which may be older than any of the Cambrian rocks of Wales. In the south of Scotland and north of England, they traverse the various subdivisions of the Lower and Upper Silurian system. In the southern Highlands, they pursue their course across the gnarled and twisted schists of the younger crystalline series. In the basins of the Tay, Forth, and Clyde they cross the plains and ridges of the Old Red Sandstone, with its deep pile of intercalated volcanic rocks. In central Scotland, and the northern English counties, they occur abundantly in the Carboniferous system, and have destroyed the seams of coal. In Cumberland and Durham, they traverse the Permian and Trias groups. In Yorkshire, and along the west of Scotland, they are found running through Jurassic strata. In Antrim, they intersect the Chalk. Both in the north of Ireland, and all through the chain of the Inner Hebrides, they abound in the great sheets and bosses of Tertiary volcanic rocks. These are the youngest formations through which they rise. But it is deserving of note, that they intersect every great group of these Tertiary volcanic products, so that they include in their number some of the latest known manifestations of eruptive action in the geological history of Britain. 7 In the second place, in ranging across groups of rock belonging to such widely diverse periods, the dykes must necessarily often pass abruptly from one kind of material and geological structure to another. But, as a rule, they do so without any sensible deviation from their usual trend, or any alteration of their average width. Here and there, indeed, we may observe a dyke to follow a more wavy or more rapidly sinuous or zig-zag course in one group of rocks than in another. Yet, so far as I have myself been able to observe, such sinuosities may occur in almost any kind of material, and are not satisfactorily explicable by any difference of texture or arrangement in the rocks at the surface. No dyke traverses a greater variety of sedimentary forma- tions than that of Cleveland. In the eastern part of its course, it rises through all the Mesozoic beds up to the Cornbrash. Further west it cuts across each of the different subdivisions of the Carboniferous system ; and, of course, it must traverse all the older formations which underlie these. But the occasional rapid changes noticeable in its width and direction cannot be referred to any corresponding structure in the surrounding rocks. The Cheviot dyke crosses from the Carboniferous area of Northumberland into the Upper Silurian rocks and Lower Old Red Sandstone voleanic tract of the Cheviot Hills. It then strikes across the Upper Old Red Sandstone of Roxburghshire, and still maintain- ing the same persistent trend, sweeps westward into the Lower Silurian rocks of the Southern Uplands. Though liable to occasional deviations, these do not seem to have reference to any visible change of structure in the adjacent formations. Again, some of the great dykes at the head of Clydesdale furnish striking illustrations of entire indifference to the nature of the rock through which they run. Quitting the Lower DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 65 Silurian uplands, they keep their line across Upper Silurian, Old Red Sandstone and Carboniferous rocks, and through large masses of eruptive material. In the third place, not only are the dykes not deflected by great diversities in the lithological character of the rocks which they traverse, they even cross without deviation some of the most important geological features in the general framework of the country. Some of the Scottish examples are singularly impressive in this respect. Those which strike north-westward from the uplands of Clydesdale cross without deflection the great boundary-fault which, by a throw of several thousand feet, brings the Lower Old Red Sand- stone against the Lower Silurian rocks. They traverse some large faults in the valley of the Douglas coal-field, pass completely across the axis of the Haughshaw Hills, where the Upper Silurian rocks are once more brought up to the surface, and also the long felsite ridge of Priesthill. The dykes in the centre of the kingdom maintain their line across some of the large masses of igneous rock that protrude through the Carboniferous system. Further north, the dykes of Perthshire cut across the great sheets of volcanic material that form the Ochil Hills, as well as through the piles of sandstone and conglomerate of the Lower Old Red Sandstone, and then go right across the boundary-fault of the Highlands, to pursue their way in the same independent manner through grit, quartzite, or mica-schist, and across glen and lake, moor and mountain. No one can contemplate these repeated examples of an entire want of connection between the dykes and the nature and arrangement of the rocks which they traverse without being convinced that the lines of vent up which the material of the dykes rose were not, as a rule, old fractures in the earth’s crust, but were fresh fissures, opened across the course of the older dislocations and strike of the country by the same series of subterranean operations to which the uprise of the molten material of the dykes was also due. In the fourth place, the dykes for the most part are not coincident with lines of fault. After the examination of hundreds of dykes in all parts of the country, and with all the help which bare hill-sides and well-exposed coast sections can afford, I can almost reckon on my fingers the number of instances where dykes have availed themselves of lines of fault. Some of these will be immediately cited. To whatever cause we may ascribe the rupture of the solid crust of the earth, which allowed of the rise of molten rock to form the dykes, there can be no doubt that it was not generally attended with that displacement of level on one or both sides of the dislocation, which we associate with the idea of a fault. Nowhere can this important part of dyke-structure be more clearly illustrated than along the Cleveland dyke, where the igneous rock rises through almost horizontal Jurassic strata and gently inclined Coal Measures (figs. 7 and 8). Besides the localities already cited, mining operations both for coal and for the Liassic ironstone have proved over a wide area that the dyke has not risen along a line of fault. Again, in Skye, Raasay, Higg, and other parts of the west coast, where Jurassic strata and the horizontal basalts of the plateaux are plentifully cut through by dykes, the same beds may be seen on the same level on either side of them. In the fifth place, while complete indifference to geological structure is the general 66 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION rule among the dykes, instances do occur in which the molten material has found its way upward along old lines of rupture. Most of such instances are to be found in districts where previously existing faults happened to run in the same general direction as that followed by the dykes. These lines of fracture would naturally be reopened by any great earth-movements acting in their direction, and would afford ready channels for the ascent of the lava. Yet it is curious that, even when their trend would have suited the line of the dykes, they have not been more largely made use of for the purpose of relief. Some of the best examples of the coincidence of dykes with pre-existing faults in the same direction are to be found in the Stirlingshire coal-field. The dyke that runs from Torphichen for 23 miles to Cadder oecupies a line of fault which at Slamannan has a down-throw of more than 70 fathoms. The next dyke further south has also risen along an E. and W. fault. But other examples may be observed where pre-existing fissures have served to deflect dykes from their usual line of trend. Thus the Cleveland dyke, after crossing several faults in the Coal-Measures, at last encounters one near Cockfield Fell, which hes obliquely across its path. Instead of crossing this fault it bends sharply round a few points south of west, and after keeping along the southern flank of the fault for about a mile, sinks out of reach. Some of the Scottish examples are more remarkable. One of the best of them occurs in the Sanquhar coal-field, where a dyke runs for two miles and a half along the large fault that here brings down the Coal-Measures against the Lower Silurian rocks. At the north-western end of the basin, this fault makes an abrupt bend of 60° to W.S.W., and the dyke turns round with it, keeping this altered course for a mile and a half, when it strikes away from the fault, crosses a narrow belt of Lower Silurian rocks, and finds its way into the parallel boundary fault which defines the north-western margin of the Silurian rocks of the Southern Uplands. Some of the Perthshire dykes, where they reach the great boundary-fault of the Highlands, present specially interesting features. There can be no doubt that this dislocation is one of the most important in the general framework of the British Isles. We have not yet been able to ascertain definitely how much rock has been actually displaced by it. But the fact that in one place the beds of Old Red Sandstone are thrown on end for some two miles back from it, shows that it must be a very powerful fracture. Here, therefore, if anywhere, we might confidently anticipate either an entire cessation of the dykes, or at least a complete deflection of their course. It would require, we might suppose, a singularly potent dislocation to open a way for the ascent of the lava through such crushed and compressed rocks, and still more to prolong the general line of fracture on either side of the old fault. Two great dykes, about half a mile apart, run in a direction a little 8. of W. across the plain of Strathearn. Passing to the south of the village of Crieff, they hold on their way until they reach the highly-inclined beds of sandstone and conglomerate which here lean against the Highland fault in Glen Artney. They then turn round towards §.W., and run up the glen along the strike of the beds, keeping approximately parallel to the fault for about three miles, when they both strike. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 67 across the fault, and pursue a W.S.W. line through the contorted crystalline rocks of the Highlands. About two miles south, another dyke continues its normal course across the belt of upturned Old Red Sandstone; but when it reaches the fault it bends round and follows the line of dislocation, sometimes coinciding with, sometimes crossing or running parallel with that line at a short distance (see fig. 12). Mr Croveu has supplied me with notes of some remarkable examples recently observed _———— REDDON» ————\ il Zand slips S‘cale: oncinch=one mile SO Fic. 17.—Map of the chief Basic Dykes between Lochs Riddon and Striven (C. T. CLoven). The large E. and W. dyke is a continuation of that which reaches the shore of the Firth of Clyde at Dunoon. by him in eastern Argyleshire, where broad bands of basalt or other allied rock run in a N. and §. direction, and are formed by the confluence of N.W. and 8.E. or N.N.W. and 8.S.E. dykes, where they are drawn into a line of fault. These broad bands, he says, are not usually traceable for more than a mile or so, for the dykes of which they are made up will not be diverted from their regular paths for more than a certain distance, so that one by one the dykes leave the compound band to pursue their normal course. He adds, that the occasional great thickness of those compound bands depends partly on the size 68 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION and partly on the number of separate dykes that are diverted into the line of transverse fissure ; for, where the fissure crosses an area with fewer N.W. dykes, the band becomes thinner or ceases altogether. In some rare cases, the dykes have been shifted by more recent faults. I shall have occasion to show that faults of several hundred feet have taken place since the Tertiary basalt-plateaux were formed. There is therefore no reason why here and there a fault with a low hade should not have shifted the outcrop of a dyke. But the fact remains that, as a general rule, the dykes run independently of faults even where they approach closely to them. Mr Croven has observed some interesting cases in south-eastern Argyleshire, where the apparent shifting of a dyke by faults proves to be deceptive, and where the dyke has for short distances merely availed itself of old lines of fracture. One of the most remarkable of these is presented by the large dyke which runs westward from Dunoon. No fewer than three times, in the course of four miles between Lochs Striven and Riddon, Mr Crover has found this dyke to make sharp changes of trend nearly at right angles to its usual direction, where it encounters N. and 8. faults (fig. 17). It would be natural to conclude that these changes are actual dislocations due to the faults. But this careful observer has been able to trace the dyke in a very attenuated and uncrushed form along some of these cross faults, and thus to prove that the faults are of older date, but that they have modified the line of the long E. and W. fissure up which the material of the dyke ascended. § 17. Data For Estimatine THE GroLocicaL AGE OF THE DYKES. I have already assigned reasons for regarding the system of E. and W. or 8.E. and N.W. dykes as belonging to the Tertiary volcanic period in the geological history of the British Islands. But I have no evidence that they were restricted to any part of that period. On the contrary, there is every reason to consider the uprise of the earliest and latest dykes to have been separated by a protracted interval. That they do not all belong to one epoch I shall now proceed to prove. The intersection of one dyke by another furnishes an obvious criterion of relative age. Maccuxtocu# drew attention to this test, and stated that it had enabled him to make out two distinct sets of dykes in Skye and Rum. But he confessed that it failed to afford any information as to the length of the interval of time between them.* It is not always so easy as might be thought to make sure which of two intersecting dykes is the older. We have to look for the finer-grained marginal strip at the edge of a dyke, which, where traceable across another dyke, marks at once their relative age. The cross joints of the two dykes also run in different directions. It is obvious that in the case of two such dykes, no longer interval need have elapsed between their successive production than was needed for the solidification and assumption of a joint-structure by the older one before the younger broke through it. They may both belong to one brief period of volcanic activity. But when we pass to a series of dykes traversing a considerable district of country, and * Trans. Geol. Soc., iii. p. 75. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. find that those which run in one direction are invariably cut by those which run in another, the inference can hardly be resisted that they do not belong to the same eruption, but mark successive epochs of volcanic energy. An excellent example of this kind of evidence is furnished by Mr CLoveu from eastern Argyleshire. The east and west dykes in that district are undoubtedly older than those which run in a N.N.W. direction (fig. 17). The latter are by far the most abundant, and are on the whole much narrower, less per- sistent, and finer in grain. On the opposite coast of the Clyde, a similar double set of dykes may be traced through Renfrewshire, those in an east and west direction being com- paratively few, while the younger N.N.W. series is well developed. The great sheets or “sills” connected with one of the Stirlingshire dykes, already described, appear to me to furnish similar evidence in the younger: dykes which run through them. And this evidence is peculiarly valuable, for it shows a succession even among adjacent dykes which all run in the same general direction. But in all these cases it is obvious that we have little indication of the length of time that intervened between the successive uprise of the dykes. In Skye, however, we meet with more definite evidence that the interval must have been in some cases a protracted one. In a paper published as far back as the year 1857,* I showed that the basic dykes of Strath in Skye were of two ages; that one set had been erupted before the appearance of the so-called “syenite” of that district, and was cut off by the latter rock; and that the other had arisen after the “‘syenite” which it intersected. Recent re-examination has enabled me to confirm and extend this observation. The granitoid eruptions of the Inner Hebrides are marked by so varied a series of rocks, and so complex a geological structure, that they may, with some confidence, be regarded as having occupied a considerable interval of geological time. Yet we find that this episode in the volcanic history was both preceded and followed by the extravasation of basic dykes. I have been unable to make out any appreciable petrographical difference between the two sets of dykes. But for the evidence of the granophyre, they would unquestionably be all classed together as one series. Let me add one further piece of evidence to prove that some of the dykes go back to a remote part of the volcanic history of Tertiary time in Britain. The Scuir of Hige, to which fuller reference will be made in a later part of this memoir, is formed of a mass of pitchstone, which has filled up an ancient valley eroded out of the terraced basalts of the plateaux. At both ends of the ridge, these basalts are seen to be traversed by dykes that are abruptly cut off by the shingle of the old river-bed which the pitchstone has occupied (fig. 63). It is thus evident that, though these dykes are younger than the plateau-basalts, they are much older than the excavation of the valley out of these basalts, and still older than the eruption of pitchstone. The latter rock probably belongs to the close of the period of acid eruptions just referred to, and we have seen that abundant dykes were extruded after most of the acid rocks had appeared. It is certain, therefore, that the dykes which in Britain form part of the great Tertiary * Quart. Jour. Geol. Soc., xiv. p. 1. VOL. XXXV. PART 92. K 70 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION voleanic series, were not all produced at one epoch, but belong to at least two (and possibly to many more) episodes in one long volcanic history. As they rise through every member of that series of rocks (save the pitchstones), some of them must be among the very latest records of the prolonged volcanic activity. But, on the other hand, some may go back to the beginning of the Tertiary volcanic period. § 18. Origin AND History oF THE DYKES. Reference has already been made to the doubt expressed by Maccuttocu whether the dykes of Skye had been filled in from above or from below. That the dykes of the country as a whole were supplied from above, was the view entertained and enforced by Bout. He introduces the subject with the following remarks :—“ Scot- land is renowned for the number of its basaltic veins, which gave Hutton his ideas regarding the injection of lava from below; but, as the greatest genius is not infallible, and as volcanic countries present us with examples of such veins arising evidently from accidental fissures that were filled up by currents of lava which moved over them, and as the Scottish instances are of the same kind, we regard it as infinitely probable that all these veins have been formed in the same way, notwithstanding the enormous denudation which this supposition involves; and that only rarely do cases occur where they have been filled laterally or in some other irregular manner.”* I need not say that this view, which, except among Wernerians, had never many supporters, has long ago been abandoned and forgotten. There is no longer any question that the molten material came from below. 1. In discussing the history of the dykes, we are first confronted with the problem of the formation of the fissures up which the molten material rose. From what has been said above regarding the usual want of relation between dykes and the nature and arrangement of the rocks which they traverse, it is, I think, manifest that the fissures could not have been caused by any superficial action, such as that which produces cracks of the ground during earthquake-shocks. The fact that they traverse rocks of the most extreme diversities of elasticity, structure, and resistance, and yet maintain the same persistent trend through them all, shows that they originated far below the limits to which the known rocks of the surface descend. We have seen that in the case of the Cleveland dyke, the fissure can be proved to be at least some three miles deep. But the seat of origin of the rents no doubt lay much deeper down within the earth’s crust. It is also evident that the cause which gave rise to these abundant fissures must have been quite distinct from the movements that produced the prevalent strike and the main faults of this country. From early geological time, as is well known, the movements of the earth’s crust, beneath the area of Britain, have been directed in such a manner as to give the different stratified formations a general north-east and south-west strike, and to dislocate them by great faults with the same average trend. But the fissures of the Tertiary dykes run obliquely and even at a right angle across this prevalent older series * Kessai Ceologique sur V Ecosse, p. 272. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 71 of lines, and are distinct from any other architectonic feature in the geology of the country. They did not arise therefore by a mere renewal of some previous order of disturbances, but were brought about by a new set of movements to which it is difficult to find any parallel in the earlier records of the region.* We have further to remember that the fissures were not produced merely by one great disturbance. The evidence of the dykes proves beyond question that some of them are earlier than others, and hence that the cause to which the fissures owed their origin came into operation more than once during the protracted Tertiary volcanic period. One of the most instructive lessons in this respect is furnished by the huge eruptive masses of gabbro and granitoid rocks in Skye. These materials have been erupted through the plateau-basalts. The granitoid bosses are the younger protrusions, for they send veins into the gabbros; but their appearance was later than that of some of the dykes and older than that of others. Nevertheless, the latest dykes maintain the usual north-westerly trend across the thickest masses both of the gabbro and the granophyre. Thus we learn that, even after the extrusion of thousands of feet of such solid crystalline igneous rocks, covering areas of many square miles, the fissuring of the ground was renewed, and rents were opened through these new piles of material. From the evidence of the dykes also, we learn that the general direction of the fissures remained from first to last tolerably uniform. Here and there indeed, where one set of dykes traverses another, as in the basin of the Clyde, we meet with proofs of a deviation from the normal trend. But it is remarkable that the very youngest dykes which pierce the eruptive bosses of the Inner Hebrides rose in fissures that were opened in the normal north-westerly line through these great protrusions of basic and acid rock. Such a gigantic system of parallel fissures points to great horizontal tension of the terrestrial crust over the area in which they were developed. Hopxins, many years ago, discussed from the mathematical side the cause of the production of such fissures.t He assumed the existence of some elevatory force acting under considerable areas of the earth’s crust at any assignable depth, either with uniform intensity at every point, or with a somewhat greater intensity at particular points. He did not assign to this force any definite origin, but supposed it “to act upon the lower surface of the uplifted mass through the medium of some fluid, which may be conceived to be an elastic vapour, or, in other cases, a mass of matter in a state of fusion from heat.” { He showed that such an upheaving force would produce in the affected territory a system of parallel longi- tudinal fissures, which, when not far distant from each other, could only have been formed simultaneously, and not successively ; that each fissure would begin not at the surface, but at some depth below it, and would be propagated with great velocity ; that there would be more fissures at greater than at lesser depths, many of them never reaching the surface ; that they would be of approximately uniform width, the mean width tending * The only other known example of such a dyke-structure is that of the Pre-Cambrian series of dykes in the Archeean gneiss of Sutherland, + Cambridge Phil. Trans., vi. (1835) p. 1. Oper. p10, 72 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION to increase downwards ; that continued elevation might increase these fissures, but that new fissures in the same direction would not arise in the separated blocks which would now be more or less independent of each other; that subsequent subsidences would give rise to transverse fissures, and by allowing the separated blocks to settle down would cause irregularities in the width of the great parallel fissures. He considered also the problem presented by those cases where the ruptures of the terrestrial crust have been filled with igneous matter, and now appear as dykes. ‘‘The results above obtained,” he says, “will manifestly hold equally, whether we suppose the uplifted mass acted upon immediately through the medium of an elastic vapour or by matter in a state of fusion in immediate contact with its lower surface. In the latter case, however, this fused matter will necessarily ascend into the fissures, and if maintained there till it cools and solidifies, will present such phenomena as we now recognise in dykes and veins of trap.” * The existence of a vast lake or reservoir of molten rock under the fissure-region of Britain is demonstrated by the dykes. But, if we inquire further what terrestrial opera- tion led to the uprise of so vast a body of lava towards the surface in older Tertiary time, we find that as yet no satisfactory answer can be given. 2. The rise of molten rock in thousands of fissures over so wide a region is to my mind by far the most wonderful feature in the history of volcanic action in Britain. The great plateaux of basalt, and the mountainous bosses of rock by which they have been disrupted, are undoubtedly the most obvious memorials of Tertiary volcanism. But, after all, they are merely fragments restricted to limited districts. The dykes, however, reveal to us the extraordinary fact that, at a period so recent as older Tertiary time, there lay underneath the area of Britain a reservoir or series of reservoirs of lava, the united extent of which must have exceeded 40,000 square miles. That the material of the dykes rose in general directly from below, and was not injected laterally along the open fissures, cannot be doubted. ‘The narrowness of these rents, and their enormous relative length, make it physically impossible that molten rock could have moved along them for more than a short distance. The homogeneous character of the rock, the remarkable scarcity of any broken-up consolidated fragments of it immersed in a matrix of different grain, the general uniformity of composition and structure from one end of a long dyke to another, the spherical form of the amygdules, the usual paucity of fragments from the fissure walls—all point to a quiet welling of the lava upward. Over the whole of the region traversed by the dykes, from the hills of Yorkshire and Lancashire to the remotest Hebrides, molten rock must have lain at a depth, which, in one case, we know to have exceeded three miles, and which was probably everywhere considerably greater than that limit. Forced upwards, partly perhaps by pressure due to. terrestrial contraction and partly by the enormous expansive force of the gases and vapours absorbed within it, the lava rose in the thousands of fissures that had been opened for it in the solid overlying crust. That in most cases its asgent terminated short of the surface of the ground may reasonably * Op. cit., p. 69. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 73 be inferred. At least, we know, that many dykes do not reach the present surface, and that those which do have shared in the enormous denudation of the surrounding country. That even in the same dyke the lava rose hundreds of feet higher in one place than at another is abundantly proved. When, however, we consider the vast number of dykes that now come to the light of day, and reflect that the visible portions of some of them differ more than 3000 feet from each other in altitude, we can hardly escape the conviction that it would be incredible that nowhere should the lava have flowed out at the surface. Subsequent denudation has undoubtedly removed a great thickness of rock from what was the surface of the ground during older Tertiary time, and hundreds of dykes are now exposed that originally lay deeply buried beneath the overlying part of the earth’s crust through which they failed to rise. But some relics, at least, of the outflow of lava might be expected to have survived. I believe that such relics remain to us in the great basalt-plateaux of Antrim and the Inner Hebrides. These deep piles of almost horizontal sheets of basalt, emanating from no great central volcanoes, but with evidence of many small local vents, appear to me to have proceeded from dykes that reached the highest level, and from which orifices, communicating with the surface of the ground, allowed the molten material to flow out in successive streams with occasional accompaniments of fragmentary ejections. The structure of the basalt-plateaux, and their mode of origin, will form the subject of the next division of this paper. . We can hardly suppose, however, that the lava flowed out only in the western region of the plateaux. Probably it was most frequently emitted and accumulated to the greatest depth in that area. But over the centre of Scotland and north of England there may well have been many places where dykes actually communicated with the outer air, and allowed their molten material to stream out over the surrounding country. The disappearance of such outflows need cause no surprise, when we consider the extent of the denudation which many dykes demonstrate. I have elsewhere shown that all over Scot- land there is abundant proof that hundreds and even thousands of feet of rock have been removed from parts of the surface of the land since the time of the uprise of the dykes.* The evidence of this denudation is singularly striking in such districts as that of Loch Lomond, where the difference of level between the outcrop of the dykes on the crest of the ridges and in the bottom of the valley exceeds 3000 feet. It is quite obvious that, had the deep hollow of Loch Lomond lain as it now does in the pathway of these dykes, the molten rock, instead of ascending to the summits of the hills, would have burst out on the floor of the valley. We are, therefore, forced to admit that a deep glen and lake- basin have been in great measure hollowed out since the time of the dyke. Ifa depth of many hundreds of feet of hard crystalline schists could have been removed in the interval there need be no difficulty in understanding that by the same process of waste, many sheets of solid basalt have been gradually stripped off the face of central Scotland and northern England. * Scenery of Scotland, 2d edit. (1887), p. 149. But see the remarks already made (p. 55) on the curious coincidence sometimes observable between the upper limit of a dyke and the overlying inequalities of surface. 74 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION This association of dykes with the out-welling of lava and with the accumulation of deep and extensive volcanic plateaux, is paralleled in other parts of the world. The description by Mr G. T. Ciarx of the dykes connected with the vast basaltic sheets of the Bombay Presidency corresponds almost exactly with that which I have given of those of this country. The Indian, like the British, examples occur in great numbers, rising through every rock in the district up to the crests of the Ghauts, 4000 feet above the sea. They vary from one or two to 10, 20, 40, and even occasionally 100 or 150 feet in width, and are often many miles in length. They observe a general parallelism in one average direction, and show no perceptible difference in character even when traced up to elevations of 3000 and 4000 feet.* To this and other areas, where horizontal sheets of basalt cover enormous tracts of country with no great central voleanic cones from which the material could have come, fuller reference will be made in the next division of this paper, which treats of the basalt- plateaux of the British Islands.t II]. THE VOLCANIC PLATEAUX. We have now to consider the structure and history of those volcanic masses which, during Tertiary time, were ejected to the surface within the area of the British Islands, and now remain as extensive basalt-plateaux. Short though the interval has been in a geological sense since these rocks were erupted, it has been long enough to allow of very considerable movements of the ground and of enormous denudation. Hence the superficial records of Tertiary volcanic action have been reduced to a series of broken and isolated fragments. I have already stated that no evidence now remains to show to what extent there were actual superficial outbursts of volcanic material over the rest of the dyke-region of Britain, and the subsequent waste of the surface has been so enormous that various lava-fields may quite possibly have stretched across parts of England and Scotland, from which they have since been wholly stripped off, leaving behind them only that wonderful system of dykes from which their molten materials were supplied. There can be little doubt, however, that whether or not other Phlegrean fields extended over portions of the country whence they have since been worn away, the chief volcanic tract lay to the west in a broad and long depression that stretched from the south of Antrim to the Minch. From the southern to the northern limit of the fragmentary lava-fields that remain in this depression is a distance of some 250 miles, and the average breadth of ground within which these lava-fields are preserved may be taken to range from 20 to 50 miles. If, therefore, the sheets of basalt and layers of tuff * Quart. Jour, Geol. Soc., xxv. (1869) p. 163. + It isinteresting to note that in the great paper on Physical Geology already cited, HopKrns considered the question of the outflow of lava from the fissures which he discussed. “If the quantity of fluid matter forced into these fissures,” he says, “ be more than they can contain, it will, of course, be ejected over the surface; and if this ejection take place from a considerable number of fissures, and over a tolerably even surface, it is easy to conceive the formation of a bed of the ejected matter of moderate and tolerably uniform thickness, and of any extent” (op. cit., p. 71). DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 75 extended over the whole of this strip of country, they covered a space of some 7000 or 8000 square miles. But they were not confined to the area of the British Islands. Similar rocks rise into plateaux in the Faroe Islands, and it may reasonably be conjectured that the remarkable submarine ridge which extends thence to the north-west of Scotland, and separates the basin of the Atlantic from that of the Arctic Ocean, is partly at least of volcanic origin. And still further north come the extensive Tertiary basaltic plateaux of Iceland, while others of like aspect and age cover a vast area in southern Greenland. Without contending that one continuous belt of lava-streams stretched from Ireland to Iceland and Greenland, we can have no doubt that in older Tertiary time the north-west of Europe was the scene of more widely-extended volcanic activity than showed itself at any other period in the geological history of the whole continent. Possibly, as I have already suggested, the present active vents of Iceland and Jan Mayen are the descendants in uninterrupted succession of those that supplied the materials of the Tertiary basaltic plateaux, the volcanic fires slowly dying out from south to north. But so continuous and stupendous has been the work of denudation in these northern regions, where winds and waves, rain and frost, floe-ice and glaciers reach their highest level of energy, that the present extensive sheets of igneous rock can be regarded only as magnificent relics, the erandeur of which furnishes some measure of that which characterised the last episode in the extended volcanic records of Britain. The long and wide western valley in which the basalt-plateaux of this country were accumulated seems, from a remote antiquity, to have been a theatre of considerable geological activity. There are traces of some such valley or depression even back in the period of the Torridon sandstone of the north-west which was laid down in it between the great ridge of the Outer Hebrides and some other land to the east. The Lower Old Red Sandstone of Lorne may represent the site of one of its lakes. The Carboniferous rocks, which run through the north of Ireland, cross into Cantyre, and are found even as far north as the Sound of Mull, mark how, in later Paleozoic time, the same strip of country was a region of subsidence and sedimentation. During the Mesozoic ages, similar operations were continued ; the hollow sank several thousand feet, and Jurassic strata to that depth filled it up. Before the Cretaceous period, underground movements had disrupted and irregularly upheaved the Jurassic deposits, and prolonged denudation had worn them away, so that when the Cretaceous formations came to be laid down on the once more subsiding depression, they were spread out with a strong unconformability on everything older than themselves, resting on many successive horizons of the Jurassic system, and passing from these over to the submerged hill-sides of the crystalline schists. Yet again, after the accumulation of the Chalk, the sea-floor along the same line was ridged up into land, and the Chalk, exposed to denudation, was deeply trenched by valleys, and entirely removed from wide tracts which it once covered. It was in this long broad hollow, with its memorials of repeated subsidences and upheavals, sedimentation and denudation, that the vigour of subterranean energy at last showed itself in volcanic outbreaks, and in the gradual piling up of the materials of the 76 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION basalt-plateaux. So far as we know, these outbursts were subeerial. At least no trace of any marine deposit has yet been found even at the base of the pile of volcanic rocks. Sheet after sheet of lava was poured out, until several thousand feet had accumulated, so as perhaps to fill up the whole depression, and once more to change entirely the aspect of the region. But the Volcanic period, long and important as it was in the geological history of the country, came to an end. It too was merely an episode during which denudation still continued active, and since which subterranean disturbance and superficial erosion have again transformed the topography. In wandering over these ancient lava- fields, we see on every hand the most stupendous evidence of change. They have been dislocated by faults, sometimes with a displacement of hundreds of feet, and have been hollowed out into deep and wide valleys and arms of the sea. Their piles of solid rock, thousands of feet thick, have been totally stripped off from wide tracts of ground which were once undoubtedly buried under them. Hence, late though the volcanic events are in the history of the land, they are already separated from us by so vast an interval that there has been time for cutting down the wide plateaux of basalt into a series of mere scattered fragments. But the process of land-sculpture has been of the utmost service to geology, for, by laying bare the inner structure of these plateaux, it has provided materials of almost unequalled value and extent for the study of one type of volcanic action. § 1. PerroGRAPRy. The superficial outbursts of volcanic action during Tertiary time in Britaim are represented by a comparatively small variety of rocks. By far the largest area and thickest mass consist of dark basic lavas. In only one locality (Isle of Higg) has any outflow of acid lava been detected. Between the lava-sheets occasional layers of volcanic and even non-volcanic fragmental rocks occur. The general lithological characters of the whole group of plateau-rocks may here be briefly enumerated. 1. Lavas.—In external characters these rocks range from coarsely crystalline varieties, in which the constituent minerals may be more or less readily detected with the naked eye or a field-lens, to dense black compounds in which only a few porphyritic crystals may be microscopically visible. They are easily recognised as pertaining in the vast majority of cases to the great group of the dolerites and basalts. One of their characteristic features is the presence of the ophitic structure, sometimes only feebly developed, some- times showing itself in great perfection. Many of the rocks are holo-crystalline, but usually show more or less interstitial matter (dolerites) ; in others the texture is finer, and the interstitial matter more developed (basalts) ; in no case, so far as I have observed, are there any glassy varieties, which are restricted to the dykes, though in some of the basalts there is a considerable proportion of glassy or incompletely devitrified substance. The felspars are of the characteristic lath-shaped forms, and are usually quite clear and fresh. The augite resembles that of the dykes, occurring sometimes in large plates that enclose the felspars, at other times in a finely granular form. Olivine is frequently not a DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. ta to be detected, even by green alteration products. Magnetite is sometimes present in such quantity as to affect the compass of the field-geologist. Porphyritic varieties occur with larger crystals of a different form from the laths of the base; but such varieties are, I think, less frequent among the plateau-rocks than among the dykes. In a few localities, there are found intercalated with the ordinary dark heavy dolerites and basalts certain pale rocks of much lower specific gravity (2°71-2°74). Externally these sheets are dull in texture, sometimes strongly amygdaloidal, sometimes with a remarkable platy structure, which, in the process of weathering, causes them to split up like stratified rocks. Examined with the microscope, they are found to consist almost wholly of felspar in minute laths or microliths, but in none of my specimens sufficiently definite for satisfactory determination. In one of the best slides Dr F. Harton, in whose hands I placed it, finds that “each lath of this abnormal felspar passes imperceptibly into those adjacent to it; the double refraction being very weak, and the twin-striation, if present, not being traceable.” He suggests whether the rock “ originally consolidated as a glass, poor in iron and magnesia, the development of the felspar being due to devitrification.”* Some of the varieties are amygdaloidal, the cells being filled with epidote, which also appears in the fissures, and sometimes even as a constituent of the rock. To such compounds I do not know that any existing petrographical name is applicable. As they form the upper portion of Ben More, and the tops of some of its neighbours in Mull, I have been in the habit of speaking of them as the “ felspathic lavas” or “pale-group” of Ben More, and it will be preferable to use some such vague definition until their true chemical and mineralogical characters have been worked out. Passing now to the occurrence of the lavas as beds of rock in the plateaux, we find them to present three well-marked types, all of which, however, pass into each other. 1st, Massive and amorphous ; 2d, Prismatic; 3d, Amygdaloidal and slagey. 1. The more coarsely crystalline varieties (dolerites) are apt to occur in thick massive beds, with no definite structure except the usual somewhat irregular joints placed perpendicularly to the upper and under surfaces. In their general aspect, such beds cannot readily be separated from intrusive sheets. But where they are not intrusive, they will generally be found somewhat cellular towards their upper and lower surfaces; while, where intrusive, they are generally more close-grained there than anywhere else. Rocks of this character are less frequent than those of the other two varieties. 2. Prismatic structures are typical of the more compact heavy basalts. A considerable variety is observable in the degree of perfection of their development. Where they are * Jn the course of my investigations I have had many hundreds of thin slices cut from the Tertiary volcanic rocks for microscopic determination. These I have myself studied in so far as their microscopic structure appeared likely to aid in the investigation of those larger questions of geological structure in which I was more specially interested. But for their detailed examination I have placed them with Dr Hatcu, in whose hands, together with the large series of specimens accumulated by the Geological Survey, they will form the subject of a future memoir on the microscopic petrography of this most interesting group of rocks. He has submitted to me the results of his preliminary examina- tion, and where these offered points of geological import I have availed myself of them by citations in the course of this memoir. Professor JUDD, in a series of valuable papers, has discussed the general petrography of the Tertiary volcanic rocks; Quart. Jour. Geog. Soc., vols, xxxix., xli., xlii. VOL. XXXV. PART 2. L 78 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION least definite, the rock is traversed by vertical joints, somewhat more regular and close- set than those in the dolerites, by the intersection of which it is separated into rude quadrangular or polygonal columns. The true prismatic structure is shown in two chief forms. (a) The rock is divided into close-fitting parallel, usually six-sided, columns ; the number of sides varying, however, from three up to nine. The columns run the whole thickness of the bed, and vary thus from 8 or 10 to 40 or even 80 feet in length. They are segmented by cross joints which sometimes, as at the Giant’s Causeway, take the ball and socket form. Occasionally they are curved, as at the well-known Clam-shell cave of Staffa. (b) The prisms are much smaller, and diverge in wavy groups crowded confusedly over each other, but with a general tendency upwards. ‘This starch-like agoregation may be observed superposed directly upon the more regular columnar form, as at the Giant’s Causeway and also at Staffa. 3. It may often be noticed that, even where the basalt is most perfectly prismatic, it presents a cellular and even slaggy structure at the bottom. The rock that forms the Giant’s Causeway, for instance, is distinctly vesicular, the vesicles being drawn out in a general E. and W. direction. The beautifully columnar bed of Staffa is likewise slaggy and amygdaloidal for a foot or so upwards from its base, and portions of this lower layer have here and there been caught up and involved in the more compact material above it. Even the bottom of the confusedly prismatic bed above the columnar one on that island also presents a cellular texture. A similar rock at Ardtun, in Mull, passes upward into a rugged slag and confused mass of basalt blocks, over which the leaf-beds lie. At Loch-na-Mna, in the island of Eigg, one of the basalts presents in places a remarkable streaky structure, due, doubtless, to the arrangement of its component materials during the flow of the still molten rock. Amyegdaloidal structure is more or less well developed throughout the whole series of basalts. But it is especially marked in certain abundant sheets, which, for the sake of distinction, are called amygdaloids. These beds, which form a considerable proportion of the materials of every one of the plateaux, are distinguished by the abundance and large size of their vesicles. In some places, these cavities occupy at least as much of the rock as the solid matrix in which they lie. They have generally been filled up with some infiltrated mineral—calcite, chalcedony, zeolites, &e. The amygdules of the west of Skye and of Antrim have long been noted for their zeolitic enclosures. As a consequence of their cellular texture and the action of infiltrating water upon them, these amygdaloidal beds are always more or less decomposed. ‘Their dull, lumpy, amorphous beds contrast well with the prismatic sheets above and below them, and as they crumble down they are apt to be covered over with vegetation. Hence, on a sea-cliff or escarpment, the green declivities between the prominent columnar basalts usually mark the place of these less durable bands. Exceedingly slag-lke lavas are to be seen among the amygdaloids, immediately preceded and followed by beds of compact black basalt with few or no vesicles. From the manner in which such rocks yield to the weather, they often assume a singularly DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 79 deceptive resemblance to agglomerates. One of the best examples of this resemblance which have come under my notice is that of the rock on which stands Dunluce Castle, on the north coast of Antrim. Huge rounded blocks of a harder consistency than the rest of the rock project from the surface of the cliffs, ike the bombs of a true volcanic agolomerate, while the matrix in which they are wrapped has decayed from around them. But an examination of this matrix will soon convince the observer that it is strongly amyedaloidal, and that the apparent “bombs” are only harder and less cellular portions of it. The contrast between the weathering of the two parts of the rock seems to have arisen from an original variety in the relative abundance of steam-cavities. Another singular instance occurs at the foot of the outlier of Fionn Chro (fig. 51), in the island of Rum. A conspicuous band underlying the basalts there might readily be taken for a basalt-conglomerate. But in this case, also, the apparent matrix is found to be amyedaloidal, and the rounded blocks are really amygdules, sometimes a foot in length, filled or lined with quartz, chalcedony, &c. A somewhat different structure, in which, however, the appearance of volcanic breccia or agglomerate due to explosion from a vent is simulated, may be alluded to here. The best instance which I have observed of it occurs at the south end of Loch-na-Mna, in the island of Hige. The basalt above referred to as occurring at this locality shows on its weathered surfaces a remarkable streaky structure that gives rise to prominent thin nearly parallel ribs comcident with the direction of bedding. This arrangement, probably due, as I have said, to the flow of the basalt while still unconsolidated, can hardly be traced with the naked eye on a fresh fracture of the rock, the whole appearing as a black compact basalt. On the weathered faces, the streaky layers may be observed to have been broken up, and their disconnected fragments have been involved in ordinary basalt wherein this flow-structure is not developed, while large blocks and irregular masses are wrapped round in a more decomposing matrix. There can be no doubt that in such cases we see the effects of the disruption of chilled crusts, and the entanglement of the broken pieces in the still fluid lava. Great variety is to be found in the thickness of different sheets of lava in the plateaux. Some of them are not more than 6 or 8 feet; others reach to 80 or 100 feet, and some- times, though rarely, to even greater dimensions. In Antrim, the average thickness of the flows is probably from 15 to 20 feet.* In the fine coast-sections at the Giant’s Causeway, however, some bands may be seen far in excess of that measurement. The bed that forms the Causeway, for instance, is about 60 or 70 feet thick, and seems to become even thicker further east. Along the great escarpment, 700 feet high, which rises from the shores of Gribon, on the west coast of Mull, there are twenty separate beds, which gives an average of 35 feet for the thickness of each flow. On the great range of sea-precipices, on the west coast of Skye, which present the most stupendous section of the basalts anywhere to be seen within the limits of the British Islands, the average thickness of the beds can be conveniently measured. At the Talisker cliffs some of the * See Explanation of Sheet 20, Geol. Survey, Ireland, p. 11. 80 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION flows are not more than 6 or 8 feet; others are 30 or 40 feet. In the vast walls that form the seaward margin of the tableland of Macleod’s Tables (fig. 21), fourteen successive beds of basalt can be counted in a vertical section of 400 feet, which is equal to an average thickness of about 28 feet. But some of the basalts are only about 6 feet thick, while others are 50 or 60. Each bed appears, on a cursory inspection, to retain its average thickness, and to be continuous for a long distance. But I believe that this persistence is in great measure deceptive. It is not often that we can follow the same bed with absolutely unbroken continuity for more than a mile or two. Even in the most favourable conditions, such as are afforded by a bare sea-cliff on which every bed can be seen, there occur small faults, gullies where the rocks are for the time concealed, slopes of débris, and other failures of continuity ; while the rocks are generally so like each other, that on the further side of any such interruption, it is not always possible to make sure that we are still tracing the same bed of basalt which we may have been previously following. On the other hand, a careful examination of one of these great natural sections will usually supply us with proofs that, while the bedded character may continue well marked, the Fic. 18.—Termination of Basalt-beds, Carsaig, Mull. individual beds die out, and are replaced by others of similar character. On the south coast of Mull, for instance, cases may be observed where the basalt of one sheet abruptly wedges out, and is replaced by that of another. Where both are of the same variety of rock, it requires close inspection to make out the difference between them; but where one is a green, dull, earthy, amorphous amygdaloid, and the other is a compact, black, prismatic basalt, the contrast between the two beds can be recognised from a distance (fig. 18). Again, along the west coast of Skye, the really lenticular character of the beds can be well seen. In Antrim also, where similar proofs may be obtained, remarkable evidence is presented of the rapid attenuation not of single beds only, but of a whole series of basalts. Thus, at Ballycastle, the group of lavas known as the Lower Basalts, which underlie the well-known horizon of iron-ore, are at least 350 feet thick. But, as we trace them west- wards, bed after bed thins out until, a little to the west of Ballintoy, a distance of only about 6 miles, the whole depth of the group has diminished to somewhere about 40 feet. A decrease of more than 300 feet in six miles or 50 feet per mile points to considerable DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 81 inequalities in the accumulation of the lavas. If the next series of flows came from another vent and accumulated against such a gentle slope, it would be marked by a slight unconformability. Structures of this kind are much rarer than we should expect them to be, considering the great extent to which the plateaux have been dissected and laid open in cliff sections. Near the west end of Glen More, in Mull, I observed a hillside where, as seen from a little distance, one series of basaits appears to be banked up against the edges of another. A common feature in all the plateaux is the intervention of a red layer between successive sheets of basalt. These red streaks form a striking feature on many sea-cliffs, and emphasise the bedded character of the volcanic series. Examined more closely, the thin red line is found to be a layer of clay or bole which shades into the decomposed top of the bed whereon it lies, and is usually somewhat sharply marked off from that which covers it. This layer has long, and I think correctly, been regarded as due to the atmospheric disintegration of the surface of the basalt on which it occurs, before the eruption of the overlying flow. It varies in thickness from a mere line up to a foot or more, and it passes into the tuffs and clays which are sometimes interposed between the sheets of basalt. 2. Fragmental Rocks.—While the plateaux are built up mainly of successive flows of basaltic lavas, they include various intercalations of fragmental materials, which, though of trifling thickness, are of great interest and importance in regard to the light which they cast on the history of the different regions during the volcanic period. I shall enumerate the chief varieties of these rocks here, and give fuller details regarding their stratigraphical relations and mode of occurrence in connection with the succession of beds in each of the plateaux. a. Volcanic Agglomerates.—Under this name are included all the tumultuous unstratified masses of fragmentary materials which fill eruptive vents in and around the plateaux. The stones vary in size up to blocks several feet in diameter. They consist for the most part of basalts, often highly slaggy and scoriaceous, also fragments of different acid eruptive rocks (generally felsitic in texture), with pieces of the non-volcanic rocks through which the volcanic pipes have been drilled. The paste is granular, dirty-green or brown in colour, and seems generally to consist chiefly of comminuted basalt. b. Voleame Conglomerates and Breccias in beds intercalated between the flows of Basalt.—These are of at least three kinds. (a) Basalt-conglomerates, composed mainly of rounded and subangular blocks of basalt (or allied basic lava), sometimes a yard or more in diameter, not unfrequently in the form of pieces of rough slag or even of true bombs, embedded in a granular matrix of comminuted basalt-débris. In some cases, the stones form by far the most abundant constituents of the rock, which then resembles some of the coarse agglomerates just described. On the east side of Mull, for example, the slaggy basalts of Beinn Chreagach Mhor are occasionally separated by materials of this character. But such intercalations are seldom more than a few feet or yards in 82 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION thickness. ‘Their coarseness and repetition on successive horizons show that they accumulated in the near neighbourhood of one or more small vents, from which discharges of fragmentary materials took place at the beginning or at the close of an outflow of lava. More commonly, however, the dirty-green or dark-brown granular matrix exceeds in bulk the stones embedded in it. It has obviously been derived mainly from the trituration of already cooled basalt-masses, and probably also from explosions of the still molten rock in the vents. As in the case of the agglomerates of the vents, pieces of older acid lavas, and still more of the non-volcanic rocks that underlie the plateaux, are found in these bedded conglomerates and breccias. In Antrim and Mull, for instance, fragments of flint and chalk are of common occurrence. A characteristic example of this kind of rock is to be seen forming the platform of the remarkable columnar bed out of which Fingal’s Cave, Staffa, has been excavated. (8) Felsitic Breccia and Conglomerate-—This variety is of rare occurrence, but it is to be seen in a number of localities in the island of Mull. It is composed in great measure of angular fragments of a close-grained flinty felsitic rock, with pieces of quartzite and amygdaloidal basalt, the dull dirty-green matrix appearing to be made up chiefly of basalt-dust. (vy) Breccias of Non-Voleanic Materials—These, the most exceptional of all the fragmentary intercalations in the plateaux, consist almost wholly of angular blocks of rocks which are known to underlie the basalts, but with a variable admixture of basalt fragments. They are due to volcanic explosions which shattered the subjacent older crust of rocks, and discharged fragments of these from the vents or allowed them to be borne upwards on an ascending column of basiclava. Pieces of the non-volcanic platform are of common occurrence among the fragmentary accumulations, especially in the lower parts of the plateaux-basalts. But I have never seen so remarkable an example of a breccia of this kind as that which occurs near the summit of Sgurr Dearg, in the east of Mull. The bedded basalt encloses a lenticular band of exceedingly coarse breccia, consisting mainly of angular pieces of quartzite, with fragments of amygdaloidal basalt. In the midst of the breccia lies a huge mass or cake of erupted mica-schist, at least 100 yards long by 30 yards wide, as measured across the strike up the slope of the hill. To the west, owing to the thinning out of the breccia, this piece of schist comes to he between two beds of basalt. A little higher up, other smaller but still large blocks of similar schist are involved in the basalt, as shown in fig. 19. As the huge cake of mica-schist plunges into the hill, its whole dimensions cannot be seen; but there are visible, at least, 15,000 cubic yards, which must weigh more than 30,000 tons. Blocks of quartzite of less dimensions occur in the basalts on Loch Spelve. There can be no doubt, I think, that these enormous fragments were torn off from the underlying crystalline schists which form the framework of the western Highlands, and were floated upward in an ascending flow of molten basalt. Had the largest mass occurred at or near the base of the volcanic series, its size and position would have been less remarkable. But it lies more than 2000 feet up in the basalts, and hence must have been borne upward for more than that height. A similar DURING THE TERTIARY PERIOD IN THE BRITISH ISLES, 83 but less striking breccia occurs on the south coast of the same island, near Carsaig, made up chiefly of pieces of quartzite and quartz.* ce. Tuffs—So far as I am aware, all the tuffs intercalated in the basalt-plateaux consist essentially of basic materials, derived from the destruction of different varieties of basalt-rocks, though also containing occasional fragments of older felsitic rocks, as well as pieces of chalk, flint, quartz, and other non-volcanic materials. They are generally dull, dirty-green in colour, but become red, lilac, brown, and yellow, according to the amount and state of combination and oxidation of their ferruginous constituents. They usually contain abundant fragments of amygdaloidal and other basalts. As a rule, they are distinctly stratified, and occur in bands from a few inches to 50 feet or more in thick- ness. The matrix being soft and much decomposed, these bands crumble. away under the action of the weather, and contribute to the abruptness of the basalt-escarpments that so often overlie them. Where the tuffs become fine-grained and free from embedded stones, they pass into variously-coloured clays. Among these are the “ beauxite” and “lithomarge” of Antrim. Fie. 19.—Breccia and Blocks of mica-schist, quartzite, &c., lying between bedded Basalts, Isle of Mull. a,a, Bedded basalts ; 6, Breccia; d, Basic dyke. Associated with these deposits in the same district, is a pisolitic hematite, which has been proved to occur over a considerable area on the same horizon. Many of the clays are highly ferruginous. The red streaks that intervene between successive sheets of basalt are of this nature (bole, plinthite, &c.). The source of the iron-oxide is doubtless to be traced to the decomposition of the basic lavas during the volcanic period. d. There occur also grey and black clays and shales, of ordinary sedimentary materials, not infrequently containing leaves of terrestrial plants and remains of insects (leaf-beds), sometimes associated with impure limestones, but more frequently with sand- stones and indurated gravels or conglomerates containing pieces of fossil wood. These intercalated bands undoubtedly indicate the action of running water and the accumulation of sediment in hollows of the exposed flows of basalt at intervals during the piling up of the successive lava-sheets that form the plateaux. The vegetable matter has in some places gathered into lenticular seams of lignite, and * This is noticed by Mr STarKIE GARDNER, Quart. Jour. Geol. Soc., xliii. (1887) p. 283, note. 84 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION even occasionally of black glossy coal. Amber also has been found in the lignite. Where the vegetation has been exposed to the action of intrusive dykes or sheets, it has some- times passed into the state of graphite. The remarkable terrestrial flora found in the leaf-beds, and in association with the lignites, was first made known by the descriptions of Epwarp Fores already referred to, and has more recently been studied and described by Herr, Mr Batty, and Mr Stsrxre GARDNER.* It was regarded by Fores as of Miocene age, and this view has generally been adopted by geologists. Mr Srarkre GARDNER, however, contends that it indicates a much wider range of geological time. He believes that a succession of floras may be recognised, the oldest belonging to an early part of the Hocene period. Terrestrial plants, it must be admitted, are not always a reliable test of geological age, and I am not yet satisfied that in this instance they afford evidence of such a chronological sequence as Mr GARDNER claims, though I am convinced that the Tertiary volcanic period was long enough to have allowed of the development of considerable changes in the character of the vegetation. For the purpose of the present paper, however, the precise stage in the geological record, which this flora indicates, is of less consequence than the broad fact that the plants prove beyond all question that the basalts among which they le were erupted on land during the older part of the long succession of Tertiary periods. ‘Their value in this respect cannot’ be overestimated. Stratigraphical evidence shows that the eruptions must be later than the Upper Chalk; but the embedded plants definitely limit them to the earlier half of Tertiary time. § 2. AREAS OF THE PLATEAUX AND SucCESSION oF ROCKS IN THEM. There are four districts in which the original widespread lava-fields have been less extensively eroded than elsewhere, or at least where they have survived in larger and thicker masses. Whether or not each of them was an isolated area of volcanic activity cannot now be determined. ‘Their several outflows of lava may have united into one continuous volcanic tract, and their present isolation may be due entirely to subterranean movements and denudation. ‘There is a certain convenience, however, in treating them separately. They are—1. Antrim; 2. Mull; 3. Small Isles; 4. Skye. To these might be added the Shiant Isles and St Kilda. 1. Antrim.t—The largest of the basalt-plateaux of Britain is that which forms so prominent a feature in the scenery and geology of the north of Ireland, stretching from Lough Foyle to Belfast Lough, and from Rathlin Island to beyond the southern margin | of Lough Neagh. Its area may be roughly computed at about 2000 square miles. But, * Mr GarpNeR is now describing and illustrating the flora fully for the Palzontographical Society; see vols. XXXVIll., XXXix, ef seq. + The basalts of Antrim are the subject of an abundant literature. I may refer particularly to the papers of BerGer and ConyBeare (Trans. Geol. Soc., iii.), the Geological Report of Portiock, and the Explanations of the Sheets of the Geological Survey of Ireland. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 85 as its truncated strata rise high along its border, and look far over the low grounds on every side, it must be regarded as a mere fragment of the original volcanic plain. It may be described as an undulating tableland, which almost everywhere terminates in a range of bold cliffs, but which, towards the centre and south, sinks gently into the basin of Lough Neagh. The marginal line of escarpment, however, presents considerable irregularity both in height and form, besides being liable to frequent local interruptions. It is highest on the west side, one of its crests reaching at Mullaghmore, in county Londonderry, a height of 1825 feet. On the north, it sinks down into the valley of the Bann, east of which it gradually ascends, forming the well-known range of cliffs from the Giant’s Causeway and Bengore Head to Ballycastle. It then strikes inland, and making a wide curve in which it reaches a height of more than 1300 feet, comes to the sea again at Garron Point. From that headland the cliffs of basalt form a belt of picturesque ground southwards beyond Belfast, interrupted only by valleys that convey the drainage of the interior of the plateau to the North Channel. Above the valley of the Lagan the erest of the plateau rises to a height of more than 1500 feet. Throughout most of its extent the basalt-escarpment rests on the white limestone or Chalk of Antrim, beneath which lie soft Lias shales and Triassic marls. Here and there, where the substratum of Chalk is thin, the action of underground water in the crumbling shales and marls below it has given rise to landslips. The slopes beneath the base of the basalt are strewn with slipped masses of that rock, almost all the way from Cushendall to Larne, some of the detached portions being so large as to be readily taken for parts of the unmoved rock. On the west side also, a group of huge landslips cumbers the declivities beneath the mural front of Benevenagh. [I have found some difficulty in the attempt to ascertain what' was the probable form of surface over which the volcanic rocks of this plateau began to be poured out. The Chalk sinks below the sea-level on the north coast, but, in the outlier of Slieve Gallion, three miles beyond the western base of the escarpment, it rises to a height of 1500 feet above the sea. On the east side also, it shows remarkable differences of level. Thus, below the White Head at the mouth of Belfast Lough, it passes under the sea-level, but only 16 miles to the south, where it crops out from under the basalt, its surface is about 1000 feet above that level. If these variations in height existed at the time of the out- pouring of the basalt, the surface of the ground over which the eruptions took place was so irregular that some hundreds of feet of lava must have accumulated before the higher chalk hills were buried under the voleanic discharges. But it seems to me that much of this mequality in the height of the upper surface of the Chalk is to be attributed to unequal movements since the volcanic period, which involved the basalt in their effects, as well as the platform of Chalk below it. Had the present undulations of that platform been older than the volcanic discharges, it is obvious that upper portions of the basalt- series would have overlapped lower, and would have come to rest directly on the Chalk. But this arrangement, so far as I am aware, never occurs, except on a trifling scale. Wherever the Chalk appears, it is covered by sheets of the lower and not of the upper of VOL. XXXV. PART 2, M 86 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION the two groups into which the Antrim basalts are divisible. We have actual proof of considerable terrestrial disturbance, subsequent to the date of the formation of the volcanic plateau. Thus, near Ballycastle, a fault lets down the basalt and its Chalk platform against the crystalline schists of that district. On the east side of the fault, the Chalk is found far up the slope, and circling round the base of the beautiful cone of Knocklayd—an outher of the basalt which reaches a height of 1695 feet. The amount of vertical displacement of the volcanic sheets is here 700 feet.* Many other displace- ments, as shown by the mapping of my colleagues in the Geological Survey, have shifted the base of the escarpment from a few inches up to several hundred feet. It is evident, therefore, that the present position of the Chalk platform is far from agreeing with that which it presented to the outflow of the sheets of basalt. But, on the other hand, there can be no doubt that its surface at the beginning of th evolcanic out- bursts was not a level plain. It was probably a rolling country of low bare chalk-downs, like parts of the south-east of England. ‘The Chalk attains its maximum thickness of perhaps 250 feet at Ballintoy. But it is liable to rapid diminution. On the shore at Ballycastle, about 150 feet of it can be seen, its base being concealed ; but only 24 miles to the south, on the outlier of Knocklayd, the thickness is not quite half so much. On the west side of the plateau also, there are rapid changes in the thickness of Chalk. Such variations appear to be mainly attributable to unequal erosion before the outflow of the basalts. So great indeed had been the denudation of the Cretaceous and underlying Secondary formations previous to the beginning of the volcanic outbursts, that in some places the whole of these strata had been stripped off the country, so that the older platform of Paleozoic or still more ancient masses was laid bare. Thus, on the west side of the escarpment, the basalt steals across the Chalk and comes to rest directly upon Lower Carboniferous rocks, The authors who have described the junction of the Chalk and basalt in Antrim have generally referred to the uneven surface of the former rock as exposed in any given section. The floor on which the basalt lies is remarkably irregular, rising into ridges and sinking into hollows or trenches, but almost everywhere presenting a layer of earthy rubbish made of brown ferruginous clays, mixed with pieces of flint, chalk, and even basalt.t The flints are generally reddened and shattery. The chalk itself has been described as indurated, and its flints as partially burnt by the influence of the overlying basalt. But I have not noticed, at any locality, evidence of alteration of the solid chalk, except where dykes or intrusive sheets have penetrated it.{ There can be no doubt that the hardness of the rock is an original peculiarity, due to the circumstances of its formation. The irregular earthy rubble, that almost always intervenes between the chalk and the base of the basalt, like the ‘‘ clay with flints” so general over the Chalk of southern England, no * Explanatory Memoir of Sheets 7 and 8, Geological Survey, Ireland, by Messrs Symes, Eoan, and M‘HEnry (1888), p. 37. + Portiock, Report on Geology of Londonderry, &c. (Geological Survey), p. 117. ~ See PortTLocK, op. cit., p. 116. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES, 87 doubt represents long-continued subzerial weathering previous to the outflow of the basalt. Even, therefore, if there were no other evidence, we might infer with some con- fidence from this layer of rubble, that the surface over which the lavas were poured was a terrestrial one. The Antrim plateau is not only the largest in the British Islands, it is also the most continuous and regular. It may be regarded, indeed, as one unbroken sheet of volcanic material, with no such mountainous masses of eruptive rock as in the other plateaux disturb the continuity of the horizontal or gently inclined sheets of basalt. Around its margin, indeed, a few outliers tower above the plains, and serve as impressive memorials of its losses by denudation. Of these, by much the most picturesque and imposing, though not the loftiest, is Knocklayd already referred to, which forms so striking a feature in the north-east of Antrim. The total thickness of volcanic rocks in the Antrim plateau exceeds 1000 feet; but, as the upper part of the series has been removed by denudation, the whole depth of lava originally poured out cannot now be told. A well-marked group of tuffs and clays, traceable throughout a large part of Antrim, forms a good horizon in the midst of the basalts, which are thus divisible into a lower and upper group. The Lower Basalts have a thickness of from 400 to 500 feet. But, as already mentioned (p. 80), they rapidly die out in about six miles to no more than 40 feet at Ballintoy. They are distinguished by their general cellular and amyedaloidal character, and less frequently columnar structure. The successive flows, each averaging perhaps about 15 feet in thickness, are often separated by thin red ferruginous clayey partings, sometimes by bands of green or brown fine gravelly tuff. The most extensive sheet of tuff is one which occurs in the lower part of the group at Ballintoy, and can be traced along the coast for about five miles. In the middle of its course, near the picturesque Carrick-a-raide, it reaches a maximum thickness of about 100 feet, and gradually dies out to east and west. The neck of coarse agglomerate at Carrick-a-raide, already referred to, is doubtless the vent from which this mass of tuff was discharged (see fig. 29). Owing to the thinning out of the sheets of basalt, as they approach the vent, the tuff comes to rest directly on the Chalk, and for some distance westwards forms the actual base of the volcanic series.* Occasional seams of carbonaceous clays, or even of lignite, appear on different horizons. Beneath the whole mass of basalt, indeed, remains of terrestrial vegetation here and there occur. Thus, near Banbridge, county Down, a patch of lignite, 4 feet 10 inches thick, underlies the basalt, and rests directly on Silurian rocks. Such fragmentary records are an interesting memorial of the wooded land-surface over which the earliest outflows of basalt spread. The central zone of tuffs, clays, and iron-ore is generally from 30 to 40 and sometimes as much as 70 feet thick. From the occurrence of the ore in it, this zone has been explored more diligently in recent years than any other group of rocks in Antrim, and its outcrop is now known over most of the district in which it occurs. The iron-ore bed * See Explanation of Sheets 7 and 8 of the Geological Survey of Ireland (1888), p. 23. 88 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION varies from less than an inch up to 18 inches in thickness, and consists of pisolitic concretions of hematite, from the size of a pea to that of a hazel nut, wrapped up in a soft ochreous clayey matrix. Where it is absent, its place is sometimes taken by an aluminous clay, worked as “ beauxite,” which has yielded stumps of trees and numerous leaves and cones. Beneath the iron-ore, or its representative, lies what is called the ‘“ pavement,”—a ferruginous tuff, 8 to 10 feet thick, resting on “ lithomarge,’”—a lilac or violet mottled aluminous earth sometimes full of rounded blocks or bombs of basalt. The well-known horizon for fossil plants at Ballypallidy is a red tuff in this zone. This intercalated band of ferruginous deposits forms one of the most persistent and interesting features in the Antrim plateau. The actual area now occupied by it has been so reduced by denudation into mere scattered patches that it probably does not exceed 170 square miles. But the zone can be traced from Divis Hill, near Belfast, to Rathlin Island, a distance of 50 miles, and from the valley of the Bann to the coast above Glenarm, more than 20 miles. There can be little doubt that it was once continuous over all that area, and that it probably extended some way further on all sides. Hence, the original area over which the iron-ore and its accompanying tuffs and clays were laid down can hardly have been less than 1000 square miles. This extensive tract was evidently the site of a lake during the volcanic period, formed by a subsidence of the floor of lower basalts. The salts of iron contained in solution in the water, whether derived from the decay of the surrounding lavas or from the discharges of chalybeate springs, were precipitated as peroxide in pisolitic form, as similar ores are now being formed on lake-bottoms in Sweden. For a long interval, quiet sedimentation went on in this lake, the only sign of volcanic energy during that time being the dust and stones that were thrown out and fell over the water-basin, or were washed into it by rains from the slopes around, Immediately above the iron-ore, or separated from it in places by only a few inches of tuff, comes the group of Upper Basalts, which varies up to 600 feet in thickness, though, as the upper portion has been everywhere removed by denudation, no measure remains of what may have been the original depth of the group. The general character of these basalts is more frequently columnar, black and compact, and with fewer examples of the strongly amygdaloidal structure so conspicuous in the lower group. But this distinction is less marked in the south than in the north of Antrim, so that where the intervening zone of tuffs and iron-ore disappears, no satisfactory line of division can be traced between the two groups of basalt. The occurrence of that zone, however, by giving rise to a hollow or slope, from which the upper basalts rise as a steep bank or cliff, furnishes a convenient topographical feature for mapping the boundary of these rocks. Among the upper basalts, also, there is perhaps a less frequent occurrence of those thin red partings of bole between the successive flows, so conspicuous in the lower croup. But the flows are not less distinctly marked off from each other. Nowhere can their characteristic features be better seen than along the magnificent range of cliffs from the Giant’s Causeway eastwards. The columnar bed that forms the Causeway is the DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 89 lowest sheet of the upper group, and may be seen resting directly on the zone of grey and red tuffs. It is about 60 or 70 feet thick; and, while perfectly regular in its columnar structure at the Causeway and the “Organ,” assumes further eastward the confusedly starch-like arrangement of prisms already referred to. But, in the great cliff section of the ‘‘ Amphitheatre,” the more regular structure is resumed, the bed swells out to about 80 feet in thickness, and columns of that length run up the face of the precipice, weathering out at the top into separate pillars, which, perched on the crest of an outstanding ridge, are known as the “Chimneys.” ‘The basalt-beds that succeed the lowest one are each only about 15 to 20 feet thick. Between the successive sheets of the upper basalts thin seams of red ferruginous clay, though, as I have said, less frequent perhaps than in the lower group, continue to show that the intervals between successive eruptions were of sufficient duration to admit of considerable subzerial decay of the surface of a lava before the outflow of the next bed. Occasional thin layers of tuff also, and even of pisolitic iron-ore, have been observed among these higher basalts. But the most interesting and important intercalations are inconstant seams of lignite. One of the most conspicuous of these lies immediately above the basalt of the ‘“‘ Causeway,” where it was long worked for fuel, and was found to be more than 6 feet thick. But it is quite local, as may be seen at the ‘‘ Organ” over which it lies, with a thickness of only 12 inches, rapidly dying out so as to allow the basalts above and below it to come together. The removal of the upper portion of the basalts prevents us from carrying the volcanic history of the Irish plateau further. It is obvious that nowhere in Antrim does any trace exist of a central vent or cone from which the volcanic materials were discharged. There is no perceptible thickening of the individual basalt sheets, nor of the whole series in one general direction, in such a manner as to point to the site of some chief focus of eruption. Nor can we place reliance on the inclination of the several parts of the plateau. I have pointed out that the varying dip of the beds must be attributed mainly to post-voleanic movements, or at least to movements which, if not later than all the phases of volcanic action, must have succeeded the outpouring of the plateau-basalts. There has been a general subsidence towards the central and southern portions of the plateau, and this movement has no doubt given rise to the hollow that is now occupied by Lough Neagh. But nowhere in the depression is there any trace of the ruins of a central cone or focus of discharge. The Antrim plateau, in these respects, resembles the others. But it differs from them in one important particular. It has nowhere been disrupted by huge eruptive bosses of younger rocks, such as have broken up the continuity of the old lava-fields further north. Yet it is not without its memorials also of these younger protrusions. It has some feeble representatives of the great acid bosses of the Inner Hebrides, and it contains not a few excellent examples of true volcanic vents. To these fuller reference will be made in later pages. . 2. Mull.—This plateau, besides the island of Mull, embraces a portion of Morven, 90 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION and, stretching across Loch Sunart, includes the western part of the peninsula of Ardna- murchan. That it formerly extended far beyond its present limits is impressively indicated by its margin of cliffs and fringe of scattered islands and outliers. It went west, at least, as far as the ‘T'reshnish Isles, which are composed of basalt. On its eastern border, a capping of basalt on the top of Ben Iadain (1873 feet) in Morven, and others further north, prove that its volcanic sheets once spread far into the interior of Argyle- shire (fig. 20). On the south, its fine range of lofty cliffs, with their horizontal bars of basalt, bear witness to the diminution which it has undergone on that side ; while, on the north, similar sea-walls tell the same tale. Not only has it suffered by waste along its margin, it has also been deeply trenched by the excavation of glens and arms of the sea. The Sound of Mull cuts it in two, and the mainland portion is further bisected by Loch Sunart, and again by Loch Aline. The island of Mull is so penetrated by sea-lochs that a comparatively slight depression would turn it into a group of islands. But, besides its enormous denudation, the Mull plateau has been subjected to great disruption from Fic. 20.—Basalt-Capping on top of Ben Jadain, Morven. subterranean movements. In the southern portion of the island, it has been broken up by the intrusion of large bosses and sheets of gabbro, and by masses as well as innumer- able veins of various granitoid and felsitic rocks. In Ardnamurchan, it has suffered so much disturbance from the same cause that its original structure has been almost obliterated over a considerable area. Moreover, it has been dislocated by many faults, by which different portions have been greatly shifted in level. The most important of these breaks is one noticed by Professor Jupp, and visible to every tourist who sails up the Sound of Mull. It traverses the cliffs on the Morven side, opposite Craignure, bringing the basalts against the crystalline schists, and strikes thence inland, wheeling round into the long valley in which Lochs Arienas and Teacus lie. On its western side, the base of the basalt-series is almost at the sea-level ; on its eastern side, that platform rises high into the outliers of Beinn na h-Uamha (1521 feet) and Beinn Jadain. The amount of displacement here is probably not much less than 1500 feet. Many other DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 91 minor faults in the same district show how much the crust of the earth has been fractured here since older Tertiary time.* Nevertheless, in spite of the extent to which the Mull plateau has suffered from denudation and subterranean disturbance, and indeed in consequence thereof, this plateau presents clear sections of many features in the history of the basalt-outflows and of the subsequent phases of Tertiary volcanic action which cannot be seen in the more regular and continuous tableland of Antrim. Moreover, it still possesses in its highest mountain, Ben More (3169 feet), a greater thickness and a higher series of lavas than can now be seen in any other of the plateaux. It will be readily understood that, in the case of this plateau, the difficulties already referred to in regard to that of Antrim, of tracing the probable form of ground on which the volcanic eruptions began, are considerably increased. We can dimly perceive that the depression in the crystalline rocks of the Highlands which had, from at least the older part of the Jurassic period, stretched in a N.N.W. direction along what is now the western margin of Argyleshire, lay beneath the sea in Jurassic time, and was then more or less filled up with sedimentary deposits. The hollow appears thereafter to have become a land-valley, whence much of the Jurassic strata was cleared out by denudation before its subsequent submergence under the sea in which the upper Cretaceous deposits accumulated. Professor Jupp has shown how relics of these Cretaceous strata appear on both sides of the plateau from under the protecting cover of basalt-sheets. But, before the volcanic eruptions began, the area had once again been raised into land, and the youngest Secondary formations had been extensively eroded. In their general aspect the basalts of Mull agree with those of Antrim, and the circumstances under which they were erupted were no doubt essentially the same. But considerable differences in detail are observable between the succession of rocks in the two areas. The total depth of basalt-sheets in Mull is greater than in any other of the plateaux. When I first visited the island in 1866, the only available maps, with any pretensions to accuracy, were the Admiralty charts; but, as these do not give the interior except in a generalised way, it was difficult to plot sections from them, and to arrive at satisfactory conclusions as to the thickness of different groups of rock. Accordingly, as the successive nearly flat flows of basalt can be traced from the sea-level up to the top of Ben More, I contented myself with the fact that the total depth of lava-beds in Mull was at least equal to the height of that mountain, or 3169 feet. The publication of the Ordnance Survey Maps now enables us to make a nearer approximation to the truth. From the western base of the magnificent headland of Gribon, the basalts in almost horizontal beds rise in one vast sweep of precipice and terraced slope to a height of over 1600 feet, and then stretch eastwards to pass under the higher part of Ben More, at a distance of some 8 miles. They have aslight easterly inclination, so that the basement * There are no fewer than three faults in the basalt-capping on the summit of Ben Iadain. By bringing the basalts and schists into juxtaposition, they have given rise to topographical features that can be seen even from a distance. See fig. 20, 92 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION beds seen at the sea-level, at the mouth of Loch Scridain, gradually sink below that level as they go eastward. It is not easy to get a measurement of dip among these basalts, except from a distance. If we take the inclination at only 1°, the beds which are at the base of the cliff on the west, must be about 700 feet below the sea on the line of Ben More, which would give a total thickness of nearly 3900 feet of bedded lava below the top of that mountain. We shall not probably overestimate the thickness of the Mull . plateau if we put it at 3500 feet. The base of the volcanic series of Mull can best be seen on the south coast at Carsaig, and at the foot of the precipices of Gribon. As already stated, it is there found resting above Cretaceous and Jurassic rocks. The lowest beds are basalt-tuffs, of the usual dull- green colour. They are in places much intermingled with sandy and gravelly sediment, as if the volcanic débris had fallen into water where such sediment was in course of deposition. One of the most interesting features, indeed, in this basement part of the series, is the oczurrence of bands of non-volcanic. material which accumulated after the tuffs and some of the lavas had been erupted, but before the main mass of basalts. Those at Carsaig include a lenticular bed, 25 feet thick, of rolled flints, which, with some associated sandy bands, lies between sheets of basalt. On the opposite side of the promontory is the well-known locality of Ardtun, from which the first land-plants in the voleanic series were determined. The actual base of the basalts is not there seen, being covered by the sea. The “ leaf-beds,” with their accompanying sandstones, gravels, and limestone, lie upon a sheet of basalt, which in some parts is exceedingly slagey on the top, passing down into a black compact basalt, and assuming at the base of the cliff a columnar arrangement, with the prisms curved and built up endways towards each other. Some of the gravels exceed 30 feet in thickness, and consist of rolled flints, bits of chalk, and pieces of basalt, and of other basic igneous rocks. But some of their most interest- ing ingredients are pebbles of sanidine lavas, which have been recognised in them by Mr G. Cotz.* No known protrusions of such lavas occur anywhere beneath or interstratified with the plateau-basalts. As will be afterwards shown, all the visible acid rocks, the geological relations of which can be ascertained, are of younger date than these basalts. I am disposed to regard the fragments found in the Ardtun conglomerates as probably derived from some of the basalt-conglomerates of the plateau, in which fragments of siliceous igneous rocks do occur. Though there is no evidence that any lavas of that nature were poured out at the surface before or during the emission of the basalts, the contents of these fragmental volcanic accumulations prove that such lavas, already consolidated, lay at some depth beneath the surface, and that fragments were torn off from them during the explosions that threw out the materials of the basalt-conglomerates to the surface. Mr Srarkie GARDNER has called attention to the extraordinarily fresh condition of the vegetation in some of the layers of the Ardtun section. One of the leaf-beds he has found to be made up for an inch or two of a pressed mass of leaves, lying layer upon * Quart. Jour. Geol. Soc., xliii. (1887) p. 277. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 95 layer, and retaining almost the colours of dead vegetation. Among the plants represented is a large purple Ginkgo and a fine Platanites, one leaf measuring 153 inches long by 104 broad. The characteristic dicotyledonous leaves at this locality possessed relatively large foliage.* To the early observations of MaccuLLoce we are indebted for the record of an interesting fact in connection with the vegetation of the land-surface over which the first lava-flows spread. He figured a vertical tree trunk, imbedded in prismatic basalt, and rightly referred it to some species of fir.t This relic may still be seen under the basalt- precipices of Gribon. Mr Garpner found it to be “a large trunk of a coniferous tree, five feet in diameter, perhaps Podocarpus, which has been enveloped, as it stood, in one of the flows of trap to the height of 40 feet. Its solidity and girth evidently enabled it to resist the fire, but it had decayed before the next flow passed over it, for its trunk is a hollow cylinder filled with débris, and led with the charred wood. A limb of another, or perhaps the same tree, is in a fissure not far off.” f At different levels in the volcanic series of Mull, beds of lignite and even true coal are observable. These seem to be always mere lenticular patches, only a few square yards in extent. The best example I have met with is among the basalts near Carsaig. It is in part a black glossy coal, and partly dull and shaly. Some years ago it was between two and three feet thick, but now, owing to its having been dug away by the shepherds, only some six or eight inches are to be seen. It lies between two basalt-flows, and rapidly disappears on either side. More frequent than these inconstant layers of fossil vegetation are the thin partings of tuff and layers of red clay, sometimes containing iron-ore, which occur at intervals throughout the series between different flows of basalt. But even such intercalations are of trifling thickness, and only of limited extent. The magnificent precipices of M‘Gorry’s Head and Gribon expose a succession of beds of columnar amorphous and amygdaloidal basalt, which must attain a thickness of at least 2500 feet, before they are overlain by the higher group of lavas in Ben More. On the east side of the island, thin tuffs and bands of basalt-conglomerate occur on different horizons among the bedded basalts, from near the sea-level up to the summit of the ridge which culminates in Beinn Meadhon (2087 feet), Dun-da-Ghaoithe (2512 feet), and Mainnir-nam-Fiadh (2483 feet). Above the ordinary compact and amygdaloidal basalt comes the higher pale group already referred to as forming the uppermost part of Ben More, whence it stretches continuously along the pointed ridge of A’Chioch, and thence northwards into Beinn Fhada. The same felspathic lavas are likewise found in two outliers, capping Beinn a’ Chraig, a mile further north, and I have found fragments of them on some of the loftier ridges to the south-east. This highest and youngest group of lavas in the plateaux has been reduced to mere isolated patches, and a little further denudation will remove it * For fuller local details regarding the Ardtun leaf-heds, I may refer to the original paper by the DUKE or ARGYLL (Quart. Jour. Geol. Soc., vii. p. 89), and to the recent memoir by Mr SrarKrE-GARDNER (op. cit., xliii., 1887, p. 270). + Western Islands, vol. i. p. 568, and plate xxi. fig. 1. £ Quart. Jour. Geol. Soc., xliii. p. 283. VOL. XXXV. PART 2. N 94 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION altogether. Yet it is not less than about 800 feet thick, and consists of bedded lavas, which alternate with and follow continuously and conformably upon the top of the ordinary plateau-basalts. I have described these rocks as dull, finely crystalline or compact, light-grey in colour, and weathering with a characteristic platy form, which has been mistaken for the bedding of tuffs. The fissility, however, has none of the regularity or parallelism of true bedding, and may be observed to run sometimes parallel with the bed- ding of the sheets, sometimes obliquely or even at right angles to it. Hven where this structure is best developed, the truly crystalline nature of the rocks can readily be detected. Some of them are porphyritic and amyedaloidal, the very topmost bed of the mountain being a coarse amygdaloid. Intercalated with these curious rocks there are others in which the ordinary characters of the dolerites and basalts of the plateaux can be recognised. The amygdaloids are often full of delicate prisms of epidote. In Mull, as in the other areas of terraced basalts, we everywhere meet with gently inclined sheets, which do not thicken out individually or collectively in any given direction, except as the result of unequal denudation. So far as I have been able to discover, they afford no evidence of any great volcanic cone from which they proceeded. Their present inclinations are unquestionably due, as in Ireland, to movements subsequent to the formation of the plateau. In Loch-na-keal they dip gently to the E.N.E.; in Ulva and the north-west coast to N.N.E.; near Salen to W.S.W. on the one side, and N.W. on the other. Round the southern and eastern margins of the mountainous tract of the island, they dip generally inwards to the high grounds. The Mull plateau presents a striking contrast to that of Antrim, in the extraordinary extent to which it has been disrupted by later protrusions of massive basic and acid rocks over a rudely circular area, extending from the head of Loch Scridain to the Sound of Mull, and from Loch-na-keal to Loch Buy. The bedded basalts have been invaded by masses of dolerite, gabbro, and granophyre, with various allied kinds of rock. They have not only been disturbed in their continuity, but have undergone considerable metamorphism. Again, further to the north, in the promontory of Ardnamurchan, the plateau has been disrupted in a similar way, and only a few recognisable fragments of it have been left. These changes will be more appropriately discussed in connection with similar phenomena in the other plateaux further north. 3. Small Isles—This plateau, the smallest and most discontinuous of the four, includes the islands of Higg, Rum, Canna, and Muck, which form the parish of Small Isles. That the fragments of the bedded volcanic masses, preserved on each of these islands, were once connected can hardly be doubted. Indeed, as already stated, they were not improbably united with the plateau of Skye on the north, and with that of Ardnamurchan and Mull on the south. Taking the whole space of land and sea within which the basalt of Small Isles is now confined, we may compute it at not much less than 200 square miles. In Eigg, Muck, and Canna, the basalts retain their almost horizontal position, and from underneath them emerge the Jurassic strata on which they lie. The DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 95 central part of the plateau, forming the island of Rum, is, however, much less regular. Four small outliers of the basalts le at levels of 1200 feet and upwards, on the western slope of that island. They are underlain by a thick mass of red (Cambrian or Torridon) sandstones, which form the northern half of the island, and which southwards are connected with a confused series of gneisses and schists. These rocks are doubtless a continuation of the red sandstones and schists of Sleat, in Skye, and like them have been subjected to those post-Silurian convolutions and metamorphism whereby Archean gneisses have been brought above younger rocks, and the whole have been crushed and rolled out so as to assume a new schistose arrangement. Before the time when volcanic action began, a mass of high ground, consisting of these ancient rocks, stood where the island of Rum is now situated. The streams of basalt spread around it, not only covering the surrounding low tracts of Jurassic rocks, but gradually accumulating against the hills, and thus reducing them both in area and in height above the plain.* The plateau has been obliterated over the centre and south of Rum by the extrusion of enormous masses of gabbro, and some later granitoid rocks. The most extensive of its fragmentary portions is that of Eigg, where the sheets of basalt, resting on Jurassic beds and dipping gently southwards, can be studied all round the island in a continuous range of precipices (see fig. 62). The general aspect and succession of volcanic sheets in the area of Small Isles agree with those of Antrim and of the older part of the plateau of Mull. The basalts in Eigg, Canna, and Muck rise into ranges of fine sea-walls, sometimes five or six hundred feet high. The thickest mass of them occurs in Higg, where, lying unconformably upon different platforms of the Jurassic rocks, they attain a thickness of about 1100 feet. They consist of the usual types—black, fine-grained, columnar and amorphous basalts, more coarsely crystalline dolerites, and dull earthy amygdaloids with red partings, and occasional thin bands of basalt-conglomerate or tuff. The individual beds range in thickness from 20 to 50 or 60 feet. Though they seem quite continuous when looked at from the sea, yet, on closer examination, they are found not unfrequently to die out, the place of one bed being taken by another, or even by more than one, in continuation of the same horizon. The only marked petrographical variety which occurs among them is a light-coloured band which stands out conspicuously among the darker ordinary sheets of the escarpment on the east side of theisland. The microscopic characters of this rock show it to belong to the same series of highly felspathic lavas as the “pale group” of Ben More, in Mull. It is strongly vesicular, and the cells are in some parts so flattened and elongated as to impart a kind of fissile texture to the bed.t This plateau has suffered even more than that of Mull from the combined influence * That the lava-fields did not completely bury this nucleus of older rock has been supposed to be shown by the fragments of red sandstone found in the ancient river-bed of Eigg, which was scooped out of the basalt-plateau and sealed up under pitchstone. But I am disposed to think that these fragments, together with those of Jurassic sandstone, came, not from Rum, but from some district more to the north and east, as will be adverted to in a later part of this paper. t+ For further details regarding this plateau in Eigg, see my paper, Quart. Jowr. Geol. Soc. xxvii. (1871) p. 290. 96 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION of later intrusive bosses and of prolonged denudation. That it once extended over the site of the whole of Rum can hardly be doubted. The edges of the beds that form the outliers would, if prolonged, cover the northern or lower half of the island, where the ancient Paleozoic and Archean rocks form the surface. In the southern half, the continuity of the basalts has been partly obscured and partly destroyed by the protrusion of the great masses of gabbro that form the singularly picturesque mountain group to which this island owes its prominence as a land-mark far and wide along the west coast of Scotland. 4. Skye.—This is the largest and geologically most important of all the Scottish plateaux. Comprising the island of Skye, at least as far south as Loch Hishort, the west side of Scalpa and the southern half of Raasay, and probably extending to the Shiant Isles, it may be reckoned to embrace an area of not less than 800 square miles. The evidence that its limits are now greatly less than they originally were is, like that of Mull, abundant and impressive. Its truncated edges, rising here and there for a thousand feet as a great sea-wall above the breakers at their base, and presenting everywhere their succession of level or gently inclined bars of basalt-beds, are among the most stupendous Fie. 21.—Terraced Hills of Basalt Plateau (Macleod’s Tables), Skye. monuments of denudation in this country. But still more striking to the geologist is the proof, furnished along the eastern margin of the plateau, that the Jurassic and other older rocks there visible were originally buried deep under the basalt-sheets, which have thus been entirely stripped off that part of the country. Throughout most of the district, wherever the base of the basalts can be seen, it is found to rest upon some member of the Jurassic series, but with a complete unconforma- bility. The underlying sedimentary strata had been dislocated and extensively denuded before the volcanic period began. On the southern margin, however, the red (Cambrian or Torridon) sandstones emerge from under the basalts of Loch Scavaig, and extending into the island of Soay are no doubt prolonged under the sea into Rum. This ridge probably represents the range of the ancient high ground of the latter island already referred to. Nowhere are the distinctive topographical features and geological structure of the basalt-plateaux more impressively displayed than in the northern half of the island of Skye. The green terraced slopes, with their parallel bands of brown rock formed by the DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 97 outcrop of the nearly flat basalt-beds, rise from the bottoms of the valleys into flat-topped ridges and truncated cones (fig. 21). The hills everywhere present a curiously tabular form that bears witness to the horizontal sheets of rock of which they are composed.* And along the stupendous sea-precipices, each successive sheet of basalt can be counted from base to summit, and followed from promontory to promontory (fig. 22). In the district of Trotternish, the basalt hills reach a height of 2360 feet. Further west, the singular flat-topped eminences, called ‘‘Macleod’s Tables” (fig. 21), ascend to 1600 feet. Along the western side of Skye, the basalts descend beneath the level of the Atlantic. Along the eastern side their base runs on the top of the great Jurassic escarpment, whose white and yellow sandstones form there, and on the east side of Raasay, so prominent a feature in the landscape. To the south-east, the reeularity of the volcanic plateau is effaced, as in Mull and Ardnamurchan, by the protrusion of the extensive mass of eruptive rocks constituting the Cuillin and Red Hills, east of which the basalts have been almost Fic. 22.—‘‘ Macleod’s Maidens” and part of Basalt Cliffs of Skye. entirely removed by denudation, so as to expose the older rocks which they once covered, and through which the later eruptive bosses made their way. ‘This is undoubtedly the most instructive district for the study of that later phase in the volcanic history of Britain comprised in the eruptive bosses of basic and acid rocks. , The magnificent plateau of this island has been so profoundly cut down into glens and arms of the sea, and its component layers are exposed along so many leagues of noble precipice, that its structure is perhaps more completely laid open than that of any of the other areas. Itis built up of a succession of basalts and dolerites of the usual types, which probably reach a thickness of more than 2000 feet, though in their instance, also, denudation has left only a portion of them, without any evidence by which to reckon what their total original depth may have been. In rambling over Skye, the geologist is more than ever struck with the remarkable scarcity and insignificance of the interstrati- fications of tuff or of any other kind of sedimentary deposit between the successive lava- * These features are more fully described in my Scenery of Scotland, 2d edit. (1887), pp. 74, 145, 216. 98 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION sheets. In many places, indeed, bands of dirty-green tuff or basalt-conglomerate may be observed, sometimes, as at Portree harbour, associated with lenticular seams of coal, from a few inches to three feet in thickness. Sheets of finer tuff of brighter colours, violet, bluish, and red, like those of Antrim, form conspicuous features in some of the western sea-cliffs, as at Talisker. But compared with the enormous area and thickness of the basalts, these fragmentary ejections are of the most trifling extent. In no part of the Tertiary volcanic area of Britain can the characters of the lavas and the structure of the plateaux be so impressively seen as along the west side of Skye, north of Loch Bracadale. The precipices rise sheer out of the sea, to heights of some- times 1000 feet, and from base to summit every individual bed may be counted. As an illustration of the general succession of beds, I give here a diagrammatic view of the Fic. 238.—Section of the largest of Macleod’s Maidens. largest of M‘Leod’s Maidens—the three wierd sea-stacks that rise so grandly in front of the storm-swept precipice at the mouth of Loch Bracadale. The height of the stack must be at least 150 feet (figs. 22 and 23). About ten distinct sheets of igneous rock can be counted in it, which gives an average thickness of 15 feet for the individual beds. It will be observed that there is a kind of alternation between the compact, prismatic basalts and the more earthy amygdaloids, but that the former are generally thickest.* These features, * A striking and illustrative contrast between the relative thickness of the beds of the two kinds of rock is supplied by the fine sections of this district. The amygdaloids range from perhaps 6 or 8 to 25 or 30 feet; but the prismatic basalts, while never so thin as the others, sometimes enormously exceed them in bulk. In the island of Wiay, for example, a bed of compact black basalt, with the confused starch-like grouping of columns, reaches a thickness of no less than 170 feet. Its bottom rests upon a red parting on the top of a dull greenish earthy amygdaloid. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 99 which are repeated on cliff after cliff, may be considered typical for all the plateaux. Another characteristic point, well displayed here, is the intervening red parting between the successive beds. If the occurrence and thickness of this layer could be assumed as an indication of the relative lapse of time between the different flows of lava, it would furnish us with a rude kind of chronometer for estimating the proportionate duration of the intervals between the eruptions. It is to be noticed on the top both of the compact prismatic and of the earthy amygdaloidal sheets; but is more frequent and generally thicker on the latter than on the former, which may only mean that the surfaces of the cellular lavas were more prone to subzerial decay than those of the compact varieties. Nevertheless, I am disposed to attach some value to it, as an index of time. In the present instance, for example, it seems to me probable that the lavas in the lower half of M‘Leod’s Maiden, where the red layers are very prominent, were poured out at longer intervals than those that form the upper half. Another characteristic plateau-feature is admirably displayed in Skye—the flatness of the basalts and the continuity of their level terraces (though not of individual sheets) from cliff to cliff and hill-side to hill-side. This feature may be followed with almost tiresome monotony over the whole of the island, north of a line drawn from Loch Brittle to Loch Sligachan. Throughout that wide region, the regularity of the basalt-plateau is unbroken, except by minor protrusions of eruptive rock, which, so far as I have noticed, do not seriously affect the topography. But south of the line just indicated, the plateau undergoes the same remarkable change as in Rum, Ardnamurchan, and Mull. Portions of it which have survived indicate with sufficient clearness that it once spread south- wards and eastwards over the mountainous district, and even farther south into the low parts of the island. Its removal from that tract has been of the utmost value to geological research, for some of the subterranean aspects of volcanism have thereby been revealed, which would otherwise have remained buried under the thick cover of basalt. Denudation has likewise cut deeply into the eruptive bosses, and has carved out of them the groups of the Red Hills and the Cuillins, to whose picturesque forms Skye owes so much of its charm. In this, as in each of the other plateaux, there is no trace of any thickening out of the basalts towards a supposed central vent of eruption. The nearly level sheets may be followed up to the very edge of the great mountainous tract of eruptive rocks, retaining all the way their usual characters ; they do not become thicker there either collectively or individually, nor are they more abundantly interstratified with tuffs or volcanic conglomerates. On the contrary, their very base is exposed around the mountain ground, and the thickest interstratifications of fragmentary materials are found at a distance from that area. So far as regards the structure of the remaining part of the plateau, the eruption of the gabbros and granitoid rocks might apparently have taken place as well anywhere further north, 100 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION § 3. Vents oF ERuprion. In the approximate horizontality and regularly stratified arrangement of their component beds of lava, the plateaux of Britain resemble those of older Tertiary and still earlier date in other volcanic tracts, both in the Old and the New World, where the absence of any obvious vents from which the molten material flowed long presented a difficulty to geological students. I have stated that in no one in- stance have I been able to discover a trace of any central voleano, whence the sheets of basalt in the British plateaux could have proceeded. On the contrary, the uniformity of the beds in petrographical character, thickness, and persistent flatness point, I think, unmistakably to the occurrence not of a few great volcanoes, but of many minor vents breaking out one after another and shifting from district to district. Only by some such distribution of the foci of discharge can we account for the continuity and horizontality of the basalts that have gradually built up the plateaux. It is one of the most interesting points in this volcanic history that, in spite of the enormous geological revolutions that have passed since they became extinct, the sites of many scattered vents can still be recognised. A far greater number must lie buried under the basalts, and of others the positions are concealed by the sea, which now covers so large an area of the old lava- fields. Nevertheless, partly on the surface of the plateaux, but still more on the surrounding tracts from which the basalts have been removed by denudation, the stumps of unmistakable vents of discharge stand out prominently amid the general wreck. Obviously it may be difficult to connect these vents directly with the plateau- lavas. On the one hand, those which project from the surface of the plateaux must, of course, be younger than the basalts through which they rise; how much younger we cannot tell. They may possibly be later than any of the plateau-sheets; they may even belong to a subsequent and waning condition of volcanic action. On the other hand, the vents which can now be traced outside of the present limits of the edges of the plateaux may, like those just mentioned, be younger than the basalt-sheets, or, on the contrary, they may be records of a period of eruptivity anterior to the emission of any of the rocks of the plateaux, and may have been deeply buried under a mass of basalt-beds subsequently removed. Positive demonstration is, from the nature of the case, impossible, unless we could find at the foot of the basalt-escarpment a volcanic vent immediately connected with some of the beds of the plateau above it.* When, however, we reflect that the vents which exist are precisely such as the structure of the plateaux would have led us to expect, we may not unreasonably look on them as part of the phenomena of this section of the volcanic period. Besides, in some cases, their connection with the rocks of the plateaux is as nearly proved as many facts in geology which nobody would now dispute. The most convenient classification of these vents is according to the nature of the * The instance of Carrick-a-raide, to be immediately referred to, is as near such a positive demonstration as could be looked for. DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 101 material that now fills them. They are either occupied by (a) some form of crystalline eruptive rock, or by (b) volcanic agglomerate. (a) Vents filled with Dolerite, Basalt, &c.—These are by far the most numerous, and as this is what the composition of the plateaux would lead us to anticipate, the fact may be held to confirm the justice of the assumption that these vents were really sources for the plateau-lavas. They are perhaps most conspicuously visible in Antrim, both on the tableland and on the underlying rocks round its edges. The finest example in that district is undoubtedly furnished by the lofty eminence called Slemish, which rises above the surrounding basalt-terraces to a height of 1437 feet above the sea (fig. 24). It is elliptical in ground-plan, measuring some 4000 feet in length by 1000 in breadth. Seen from the north, it appears as a nearly perfect cone. The material of which it consists is a coarsely crystalline olivine-dolerite, presenting under the microscope a nearly holocrystalline aggregate, in which the lath-shaped felspars penetrate the augite, with abundant fresh olivine, and wedge-shaped patches of interstitial matter. The rock is Fie. 24.—Slemish, a Volcanic Neck or Vent on the Antrim Plateau, seen from the north. massive and amorphous, except that it is divided by parallel joints into large quadrangular blocks like a granitic rock, and wholly different from the character of the surrounding basalts. The latter, which possess the ordinary characters of the rocks of the plateaux, can be followed to within 80 yards of this neck, which rises steeply from them, but their actual junction with it can nowhere be seen, owing to the depth of talus. At the nearest point to which the two rocks are traceable, the basalts appear somewhat indurated, break with a peculiar splintery fracture, and weather with a white crust. These characters are still better shown on abundant fragments which may be picked up among the débris further up the slope. There can be no doubt, I think, that a ring of flinty basalt, differing considerably in texture from the usual aspect of that rock in the district, surrounds the neck. The meaning of this ring will be more clearly seen from the description of another example in Mull. About four miles to the.north-east of Slemish, a smaller and less conspicuous neck rises out of the plateau-basalts. The rock of which it consists is less coarsely crystalline than that of Slemish, but its relations to the VOL. XXXV. PART 2. 0) 102 DR GEIKIE ON THE HISTORY OF VOLCANIC ACTION surrounding volcanic rocks is obviously the same. On the west side of Belfast Lough a boss of similar rock, about 1200 feet in diameter, rises at the very edge of the basalt escarpment into the eminence known as Carnmony Hill (fig. 25). On its northern side it presents along its wall a mass of interposed volcanic agglomerate.* Of the other doleritie necks scattered over the surface of the Antrim plateau, I will refer to only one which occurs on the hill slopes between Glenarm and Larne. It forms a prominence known as the Scawt Hill, and consists of a boss of basalt, which, in rising through a vent rua lh ie aK tesa ny | SET , 3 Meas speee ae py caee. op Fig. 25.—Section of Voleanic Vent at Carnmony Hill (E. Hull). T, Lower basalt ; C, Cretaceous beds ; L, Lower Lias ; M, Triassic marls. in the plateau-sheets, has carried up with it and converted into marble a large mass of chalk which is now exposed along its eastern wall (fig. 26). As examples of the similar necks which have been exposed by denudation outside the present limits of the plateau, I may allude to those which rise through the Cretaceous and other Secondary strata on the northern coast near Ballintoy. One of the most striking of these may be seen at Bendoo, where a plug of basalt, measuring about 1400 feet in one diameter and 800 feet in another, rises through the Chalk, and alters it around Fic. 26.—Section of the east side of Scawt Hill, near Glenarm. a, bedded basalt; b, mass of chalk; c, basalt neck. the line of contact (fig. 27). Another remarkably picturesque example is to be seen near Cushendall, where a prominent doleritic cone rises out of the platform of Old Red Sand- stone, some distance to the north of the present edge of the volcanic escarpment. The greater coarseness of grain of the material filling these pipes, compared with that of the sheets in the terraces, is only what the very different conditions of cooling and consolidation would lead us to expect. There is no essential difference of composition * This neck was recognised by Du Noymr in 1868 as “one of the great pipes or feeders of the basaltic flows.” See Prof. Hull, Explanation of Sheets 21, 28, and 29, Geol. Survey of Ireland (1876), p. 30. 1 DURING THE TERTIARY PERIOD IN THE BRITISH ISLES. 103 between the two rocks; but we find that where the erupted material has been poured out at the surface, it has assumed a finely crystalline texture, while, where it has slowly solidified within a volcanic pipe at some depth beneath the surface, and where con- sequently its component crystals have had more time for development, the resulting structure is much more largely crystalline, with a more complete development of the ophitic structure. In the island of Mull, another instance of the same kind of vent has been observed and described by Professor Jupp.* ' It rises in the conspicuous hill, ’S Airde Beinne (Sarta Beinn), about two miles south-west from Tobermory, and consists of a coarsely Su fo meets 2, 4 eX ON FN TT ok (qt een SE Fic. 27.—Section of Neck of Basalt, Bendoo, Ballintoy. aa, Chalk ; 6, Neck. crystalline dolerite, which becomes rather finer in grain towards the outer margin (fig. 28). No bedding or structure of any kind beyond jointing is perceptible in it. Examined in thin sections under the microscope, this rock is found to be another typical ophitie dolerite, consisting of lath-shaped felspars, embedded in augite masses, with here and there wedge-shaped portions of interstitial matter and grains of olivine. Dr Hatcu observes that the felspars contain spherical inclusions of devitrified glass, filled with black eranules and trichites and that, under a high power, the interstitial matter is seen to consist mainly of greenish-brown isotropic matter, in which are inclosed small crystals of ne DUD) Dog ‘ \ IT oe Pea aT mO, auqmq Prteoat fodpoos oy ST: Sa Trans -Roy- Soc. Edim® i z a ‘$3/NDyj-.—-—- — “WIS ¥ Sex4G o/spg == . (URHGUDD)'2UOZSPUDSDEL) RA ene bey, 2/UD2/Of FEY oC |) ZONE «(OY Sz/Pseg POPPA SEY (SD/N{G 4EM07,) 2U028 91/7, at a] SUH FI4I129D pleqiyoiy Ag S3AMS 43O ANVTS! SHL 40 LYUWd JO dVW IVOIDOIOAD HOLAWS P ayo Y epee 99/12/07 0/9977) a DIDS A/SSPINL (He) 2p ashy douDIg ‘ie. | DappTg) UD-ON AV spUa7D = = Kad ( Lg s = eee payed mypoasy a iis i oy fe ee v i t +) r Beis ee c a (i acu, 1 Rupapey/ TEP Some TY é P: pe 2 : (eA? >. i Es D Oy 3 Z 5 [TPL aD =| ave. ef OLIV Py : if ie : Whiz IP San’ f, y 25 ‘Pay = bo j513.L;RUSDO - + od Lo oe aad 3 i 4 BWAy? a ; ; 7 Pa) JATOMN (oats : Witt al sth Br a ar . 3 ey = wa POU PPN UTE Ave an: Sperone SS acy spuds vu > =x UD. PINT Meu (PUP MT “* . or . ba aur A ae ' a! tw MEAN SCOTTISH METEOROLOGY FOR THE LAST THIRTY-TWO YEARS, DISCUSSED FOR ANNUAL CYCLES, AS WELL AS SUPER-ANNUAL CURVES; ON THE BASIS OF THE OBSERVATIONS OF THE SCOTTISH METEOROLOGICAL SOCIETY; AS FURNISHED TO, AND PUBLISHED BY, THE REGISTRAR-GENERAL OF BIRTHS, DEATHS, &c., IN SCOTLAND; AFTER BEING COMPUTED FOR THAT OFFICER AT THE ROYAL OBSERVATORY, EDINBURGH. IN THREE PARTS. By Cs PIAZAT “SMYTH, LATE ASTRONOMER-ROYAL FOR SCOTLAND AND FE.R.S.E., F.R.A.S., &c. This paper has been passed through the Press under the careful revision of Mr Thomas Heath, first Assistant Astronomer, and in full charge of the Royal Observatory, Edinburgh, since Mr C. Piazzi Smyth’s retirement on August 15, 1888. March 1888. VOL. XXXV. PART 3. , 2B Table I, = II - III 3 IV Se RE DE Wee e-e00? SLY: tO, XXVL ORV. XX Vill. XX VILL OSC she eo. ORT Plate 1, represents Table L., ( 186 ) CO Nn: MEAN SCOTTISH METEOROLOGY. Part I.—LIST OF TABLES. Barometric Pressure (reduced to 32° and to the Sea-Level), . Mean Barometric Range, . Mean Temperature, . - Mean Daily Range of Peewee, Mean of Black Bulb in the Sun, . Mean of Black Bulb during Night, . Humidity, . Number of Days on -aigh Raia F ell, . Depth of Rain in Inches, . . Mean Force of the Wind ; lbs. Neots on Sq. Foot, . Winds— Northern Quarter, 4 + N.W., N., and $ N.E, . Winds—Eastern Quarter, $ N.E., E., andl 3 SE, . Winds—Southern Quarter, $ 8.E., S., and $58.W., . Winds—Western Quarter, $S.W., W., and $ N.W., . Mean Number of Hours of Sunshine, . : . Mean Amount of Cloud, . Lightning—Mean Number of Days, . Lightning—Number of Stations, . Aurora—Mean Number of Days, . Aurora—Number of Stations, Mean Maxima of Shade Temperature, . Mean Minima of Shade Temperature, . Accumulated Rainfall, Useful Plant-Growth Toenean) Progressive Accumulations of each kind of Useful Plant: Growth iTesperabmeet Final Accumulations of Useful Plant-Growth Temperature, . Black-Bulb Thermometers, Maxima and Minima Extremes, . “ Frost,” in Depressions below the Freezing Point, “Fire,” in Elevations above the Freezing Point, . Wind Force per Month, Wind Force, Accumulated Quantinees Monruty ELEMents oF ALL ScorrisH Misrzonozocy, REDUCED TO ONE Cuma GerocGRAPHICAL Point, viz.: LatituDE=56° 30’ N.; LoneitrupE=3° 40’ W.; AND HeicHT=256 Ferrer (sucH POINT BEING FURTHER DisTANT FROM THE GENERAL SHA-Coast, on THE East, 40 Mixes ; on THE West, 90; ON THE Nortu, 120; anp on THE SoutH, 120 Mites) ;—anp ror THE MBEAN OF THE Years 1856 to 1887 INcLUSIVE, Part IJ.—LIST OF PLATES. or Barometric Pressure; and Table IL., Barometric Pressure, » %, represents Composite Table I., vz., Mean of Barometric Pressure and Barometric Monthly Range x 3. or Monthly Range of PAGE 188 190 192 194 196 198 200 201 202 204 206 207 208 209 210 211 212 213 214 215 216 218 220 222 224 226 228 256 258 260 262 COONAN why — i=) CONTENTS. Plate 3, represents Table III., or Mean Temperature in Shade; and Table IV., or Daily Range of Shade Temperature. , 4, represents Table V., or Black Bulb by Day; and Table VI., or Black Bulb by Night. », 9, represents Composite Table II., or Mean Shade Temperature+ Mean Maxima of Shade Temp., + Mean of Black Bulb by Day. ,, 6, represents Table VII., or Humidity ; and Table VII’., or Elastic Force of Vapour, due to both Humidity and Shade Temperature. , 7@, represents Table VIII., or Days of Rainfall; and Table IX., or Annual Depth of Rainfall. ,, 8, represents Table X., or Strength of Wind. Table XI., or Days of North Wind. Table XII., or Days of East Wind. Table XIII., or Days of South Wind ; and Table XIV., or Days of West Wind. represents Table XV., or Hours of Sunshine ; and Table XVI., or Percentage of Cloud. represents Table XVIII., or Occurrences of Lightning ; and Table XX., or Occurrences of Aurora. ,, 11, represents Composite Table III., or Sum of Lightning and Aurora occurrences, and Composite Table IV., or Sum of Lightning taken two years beforehand, and Aurora in eal i its own year. represents Composite Table IV., or Lightning two years beforehand+ three times the occurrences of Aurora in its own years. represents Table XXI., or Mean Maxima of Shade Temperature ; and Table XXII., or Mean Minima of Shade Temperature. 14, represents Table XXVII., or ‘Frost,’ in Depressions below the Freezing Point; and Table XXVIIL., or “ Fire,” in Elevations above the Freezing Point. = Cc) — & 29 Part III.—EXPLANATIONS OF THIRTY-ONE CHRONOLOGICAL TABLES. . Historic Origin of the Data, Of the Old Tables newly continued to the Piesene ‘aie . Newly prepared Tables for New Derivations from the Old oueeratonl istdovoloy . Frost and Fire, , . Wind Force ; and ital Gres : Be: Annual Cycles of Weather and Solar Phenorienas . Temperature, Barometric Range, and Sun-Spots, . Details of Sun-Spot Cycles, . Aurora, Lightning, and Sun-Spots, . Of an unfinished Paper on the individual Bie iorsinea ae every Sciation snplley ee. 187 Year, MEAN SCOTTISH METEOROLOGY. PART I. Tabur —SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. January. Barometric PressvrE (Repucep To 32° anp To THE SeA-LEvEL). February. Obsd. Means, 29°618 29°767 29°791 29°739 29°789 29°774 29°739 29°769 29°734 29°716 29°709 29°71 29°715 29°723 29°722 29°701 29°688 29°691 29°690 29711 29°707 29'720 29°733 29°752 29°758 29°771 29°769 29.769 29°770 29°763 29°764 Accumeg. Obsd, 29°891 29°840 29998 29°709 29°932 29°681 30°052 30°013 29°886 29°801 29°514 29°816 29°799 29°67 29°856 29°811 29664 307106 29°867 30°090 29663 29°712 30°099 29-512 29°553 29°801 29-998 29°834 29°750 29°462 30°075 30°143 Accumg, Means. 29°866 29°910 29°860 29°874 29°842 29°872 29°8g90 29°889 29°880 29°847 29°844 29°841 29°829 29°831 29°830 29°820 29°836 29°838 29°850 29°841 29°835 29°847 29°833 29°822 29°821 29°827 29°828 29°825 29'813 29821 29°831 March, Obsd. 30°195 29°804 29°852 29°707 29°639 29°507 29°698 29°758 29°634 29°886 29673 29°875 29°749 29°890 30°052 29-878 29-715 29°818 29-988 30°151 29°394 29-674 29°977 29°899 30°030 29°766 29°767 29°959 29°798 29°997 29°890 30021 April. Obsd. 29°785 29°767 29°942 29°751 29978 30177 29°881 29°819 30°022 30°112 29°935 29°591 29°852 29°992 29°993 29°781 29°874 307046 29°741 30°026 29°816 29°819 29°861 29°748 29°815 30°010 29°77 29 992 29°872 29°778 29870 29°982 Acenmg. Means, May. Obsd. 29°862 29°959 29°823 30°046 29°831 30070 29°810 29°945 29°995 29°836 29°975 29°938 29-882 29°899 29°906. 30°063 29°848 29°919 30°001 29°884 30°158 29°860 -29°712 29-983 30°084 30°035 30°011 29909 29°867 29°719 29°888 30°036 June, Obsd. 29-900 30°020 30°032 29-934 29°674 29°961 29°733 29°78 29°802 307188 29°881 30°050 30:034 30039 30031 29:968 29°781 29°894 30°075 29°807 29°922 29°897 29-911 29-709 29-920 29°876 29°818 29-949 30°013 29°992 29-929 30°174 Aecumg. Means, 29°960 29°984 29°972 29912 29920 29°893 29°879 29°870 29'902 29"900 29°913 29922 29930 29°937 29'939 29930 29°928 29°936 29°929 29°929 29°927 29°927 29'918 29°918 29'916 29912 29°914 29°917 29°920 29°920 29°928 July. Obsd. 29°893 29°832 29°887 30°050 29°988 29°619 29°735 30-076 29°934 29849 29°911 29861 30-058 29-962 29°945 29692 29°927 29°795 29°890 29°985 29-951 29°762 30008 29°698 29°835 29°834 29°701 29°73 29°869 30°099 29°804 29°911 Aceung. Means. MEAN SCOTTISH METEOROLOGY. 189 Taste I. continued.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. BaRoMETRIC PRESSURE (REDUCED To 32° aND TO THE SEA-LEVEL). August, September, October. November, December. Mean Month Successive of Observed Means of the Accumg, ap Accumg, Accumg. Accumg. Accumg, panpittes ia zeonnulating OP | Means, | °P8 | Means, | CP Means. | 9°84 | Means. | 98% | Means. oro be 29-888 29°766 30°084 30002 29°628 29°869 30-014 29°882 29-803 307115 29-989 29894 29°951 29°824. 29°944 30°058 29°808 29'882 29943 29898 29°892 29°956 29°703 29°916 29°948 29°849 29°926 30°024 29°773 29°893 29°850 29°722 29667 29°855 29°651 29°817 29°924 29°817 29°862 29°982 29°743 29°874 29°575 29°868 29°784 29°919 29-709 29°786 29°854 29'827 29°846 29°969 29°736 29°856 29°74 29-723 29936 29°544 30-020 29°838 29°841 29°810 29°861 29°898 29°783 29°853 29°885 29-979 29°620 29897 29°767 29-812 29°847 29°834. 29°827 29°898 29°781 29°847 29°779 29°613 29°657 29°825 29°840 29°800 29°838 29°806 29°805 29°889 29°788 29°842 30018 29-731 29°914 29°681 29°921 29879 29°858 29°798 29°817 29°866 29°803 29°846 29°796 30°131 29-641 29-787 30°015 29-371 29°852 29°830 29°800 29°858 29°824. 29°848 29-687 29°555 30°047 29°753 29°672 29-761 29°837 29°806 29°822 29°848 29°810 29°840 29856 29-931 29°765 30°230 29°919 29-872 29°839 29°817 29°818 29°880 29°820 29°843 29°808 29-903 29°72 29°955 29312 29°822 29°836 29°823 29°814 29°886 29°780 29°841 30°015 29°590 29°969 29°730 29-693 29°852 29°849 29°807 29°825 29°875 29°74 29°842 80°014 29-937 29°614 29-725 23937 29-904 29°860 29°815 29°811 29°865 29°785 29°846 29-908 29°930 29-822 29-991 29°906 29°871 29°863 29°822 29°812 29°873 29°793 29°848 29°944 29°682 29587 29-530 29-464 29-698 29°868 29°814 29°798 29°853 29°773 29°839 29°779 29839 29°682 29°829 29-984 29°846 29°863 29'816 29°792 29°851 29°831 29°839 29-782 29°717 29°670 29°850 29°781 29°842 29'859 29°8r0 29°786 29°851 29°789 29°840 29-968 29-981 29°752 29-826 29-958 29°926 29°864 29°819 29°784. 29°850 29°793 29°844 29°868 29°753 29°856 29°858 29-409 29°814 29°864. 29°816 29°787 29°850 29°775 29°842 29°807 30-030 29-802 29°386 29°823 29°767 29°862 29°826 29°788 29°829 29°777 29°839 29°758 29°818 29°615 29°812 29°674 29°853 29°857 29°825 29°780 29°828 29°77 29°840 29°703 29802 30-050 30°219 30°116 4 29:°873 29°851 29°824 29°792 29°845 29°787 29°841 30-037 29°896 29-968 29°72 29-740 29905 1880 29°858 29°827 29°799 29°842 29°785 29°844 29°733 29-986 30°023 29°623 29°765 29°863 1881 29°853 29°83 29°807 29°8 29°784 29°844 29-805 29°818 3 29-820 29541 a 29°618 29°815 1882 29'852 29°833 29°808 29°82 29°778 29°843 29°859 29°783 29821 29°593 : 29:997 29°850 1883 29°852 29°831 29°808 29814 29°786 29°843 29931 29-905 29-929 30°062 29°661 29°869 1884 29°855 29°833 29°812 29°823 29°782 29°844 29:977 29-706 29683 29-829 30010 29°837 1885 29°859 29°829 29°808 29°823 29°789 29°344 29°874 29 932 29°793 : 29°777 29°545 29827 ‘ 1886 29°859 29°832 29°808 29822 29'782 29°844 29°918 29°864 80°025 29°660 29-688 29°934 1887 29°861 29°833 29°814 29°817 29°779 29°846 VOL. XXXV. PART 3. 2C 190 PROFESSOR C. PIAZZI SMYTH ON Taste I.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Mean Barometric RANGE. Year, January. February, March, April, May, June, Accumeg,. Accumg. Accumg, Accumg. Accumg. Accumg, Ops. Means, peait Means, het. arene ve. Means, pied. Means, Obsa Means, 1:897 1512 0-803 1185 1:061 0737 1534 1:289 2021 1142 0°890 1:039 1716 1400 I'412 r'r64 0'976 0888 1:241 1-427 1587 1:434 1°339 0°702 pe 1°557 T*409 1°470 1254 1'097 0°62 1:855 1375 1:270 1:289 0498 0°653 1°632 I‘4O1 I'420 1'262 0'947 0°783 1°810 2:079 1/931 1°860 1-228 1:102 1°667 1°536 I'522 1°382 1003 0°847 1:026 1:670 1:430 0°734 0937 0694 ; 1°560 1'559 I'507 1'274 0"992 0°82 1°451 1402 1°322 1:204 0°845 1-074 1°545 1°536 1°481 1'264 0971 0'856 1°882 1°385 1:227 1:090 1:108 0°809 1°587 I‘517 I°449 1'242 0988 o'851 1:298 1:479 1123 1032 0669 0°731 E555 1513 1°413 I'219 0'953 0838 1-710 1:715 1175 0°679 0°884 0850 5 157° 1°533 1°38 I'165 0'946 0°839 1771 1:348 1:601 ee 1218 1131 0°883 1'589 1°516 1408 1'I70 0°963 0°843 1:521 é 1:972 1:957 1:326 0°810 1:203 1°583 I°554 I°454 1183 0°950 0°873 1°885 1-889 1°824 1°541 1105 0°833 1606 1580 1482 I'210 0'962 0870 1:723 1°452 1°420 1:503 1121 0919 I°615 I‘571 1'478 I'231 0'973 0°874 2024 1540 1°420° 1:197 1:404 1-088 1°642 1'569 I'474 1'229 I ‘002 0888 1:940 i 1:098 1°421 1:065 0°931 0'893 as 1°660 1539 I'471 I'219 07998 Oo; 1:709 1004 1:084 oy, 1:016 1:335 0950 1°663 1°508 1°448 1'207 I‘O17 0892 2:023 1°737 1°234 0°881 1:042 0°934 1684 1‘520 1°436 1'189 I‘O19 0°894 1466 1663 1°525 1°754 0°866 1:027 1672 1*528 I"441 r'218 I‘OIL oO*9OI 1778 Bie 0869 1:264 1°548 1:033 1:256 1'67 I°495 I°432 I'235 L‘Or2 o"919 1-184 1:260 1:917 hi 1:397 0-969 0°848 1°654 1°484 ung I'°243 smo} Ke) o'9I5 1:663 5 1191 0996 ie 1'388 1°652 1046 1°055 I°470 1°434 I'249 I'039 o'921 1-446 -~ 1:007 1:569 1°427 0'943 0°865 1'64 I*450 I°440 I'257 I'035 o’919 1:074 1°381 1:160 1:249 0°968 0-751 1622 I°447 1428 I'257 I'032 O'9I2 1°262 E 1°603 1°772 1451 1:000 0981 1°607 1°454 I'442 1264. I'O3I o'9I5 1°855 - 1°757 1:416 0786 1:542 1:008 3 1617 1°465 1°441 1'246 r'o50 o'91 1993 . 1°758 1526 1:447 1317 1:088 1°631 1°476 1°444 I'253 r*060 0°925 1-716 : 1°635 1°734 1:337 0°997 0°848 1634 1482 1°455 1'256 r'058 o'922 2952 1:497 1:265 1:053 1:474 0°807 1°679 1'482 1°448 I'249 r'072 o'918 1°929 1:387 1:382 aliaty(e( 0969 11380 1688 1479 1°446 1'247 1'069 0°925 1°254 1508 1°460 1573 1157 0°842 1674 1480 1446 1'258 1072 0"922 1575 1:463 1°432 1:467 1:223 0°833 1°671 1°480 1°446 1°264 1'076 0'919 MEAN SCOTTISH METEOROLOGY. 191 TasieE II. continued—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Mean Barometric Rance. August, September. October. November, December. Accung. Accumg, Accumg, Accumg, Accumg, Obsd. Means, Obsd: Means, Obst Means, Obsd. Means, Obsd. Means, 0°812 1:204 1:070 1:033 1636 0°661 1101 1:246 1719 1:338 1°736 I°m52 I'158 1°376 1°487 1:003 0°997 1°687 1°872 1-297 0°825 I°IOI 1°334 I'541 I'°424 1:167 1-063 1:236 27129 1°853 o'9II I‘Ogr I°310 1688 I°531 1-080 1165 1:261 1°641 1°426 0°945 I'r06 I°300 1'679 I‘510 0°797 1172 1-201 1-295 1459 0'920 ie inity/ 1'°284 T'6I5 I’502 0944 0:993 1°872 1513 1:204 0°923 I*099 1°368 I’600 I°459 0°816 1°442 1660 1347 1:421 o'910 I'I42 I"404. 1569 I'454 1-037 1:094 1776 2:056 1-264 0924. 1°137 1°445 1°623 1°433 0811 0887 1:571 1°789 2013 0'913 I'112 1458 I°639 1°49 1:057 1:165 1-042 0941 1511 0'926 ninaaiy I°420 1‘576 1493 0°650 1:059 1:286 1381 1371 0°903 I'lI2 I°409 I°560 1483 0989 1411 1:002 1793 1°704 o'9I0 1°35 1°378 1°578 I*500 0923 1:563 1181 1:150 2212 o'9I0 I°165 1°364 1'547 I'551 0°854 1:598 2°114 1631 1°818 0°907 I‘Ig4 I*414 I°553 1*568 1/263 1:090 1:295 0°972 1:287 0'929 I°188 1°406 1°516 I°551 0°826 1101 1-258 1°810 1262 0923 1°183 1°398 1°534 1°534 0°702 1172 1622 1:949 1:450 O’9QII I°182 I'410 1649 I*529 1-254 1:049 1711 1545 1°621 0929 I'175 1°426 1'556 1°534 0°714 1-295 1071 1383 1:°444 0'918 I'rs1 1°408 I'547 I°530 1/199 1:148 1612 1:055 1596 0°93 I°179 1°418 1524 1'533 0°890 1105 1616 1908 1°525 0'930 r'176 1427 I'542 1532 1:088 1232 1438 1:284 1456 0°936 I°I79 I°427 I°530 I°529 1:223 1-215 1:501 1:072 1512 0°948 I'180 I°430 I'512 1528 0°947 1013 1-143 1612 1:574 0°948 1'173 1'419 I'515 1'530 1:343 0:944 1°903 2008 1°782 0°963 T°165 1°438 1°534 1°540 1:124 1341 1:567 1-478 1154 0'969 I'17i I'442 I'532 1'526 1:187 1:365 1548 1-679 ievalat 0977 1°178 "446 1°537 1°532 0°747 1:231 1°721 1°412 1°450 0"969 I'180 I°456 1°533 I°529 1151 1:124 1618 1°524 1613 0°975 I'r78 1°46 I'533 1532 0°791 1-217 1°654 j 1523 2636 0'969 I'I79 I°467 I'532 1°568 1:106 1:472 1:441 1'760 1-416 0°974 1188 1°466 I'539 I'563 Mean Month of Observed 1152 1'236 1:294 1:289 1444 1:099 1/218 1:254 1207 1:246 1/234 1/299 1°415 1:330 1:458 1175 1156 1:282 1:350 1-221 1:270 1:326 1-206 1-180 1:269 1422 1:418 1:401 1:370 1°318 1°392 1:357 Successive Means of the Quantities in | Accumulating | repeated. each Year, Years. Year 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 192 Taste III.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. PROFESSOR C., PIAZZI SMYTH ON Mean TEMPERATURE. January. February. April. May. June. Accumg. Accumg. Accumg, Accumg. Accumg, Obsd. Means, Means, Obsd. Means, Obsd. Means, Bak Means, oe rah on orn! Dia oR, oR, or | OR, 34:3 443 46°7 53:3 35°7 42:7 49:8 57°4 . 35°0 39°4 43'5 48'2 55°4 39:3 43°8 49:5 58:9 36°4 38'2 43°6 48°7 56°5 39°6 41:9 51:9 566 37°2 38'8 43°2 49°5 56°5 35°5 41:5 50:2 53:0 36'9 37°8 42°8 49°6 558 36:3 45:4 49-1 57-2 36°8 38°I 43°3 49°5 56°1 38°4 44:6 51-1 524 37°0 38°4 43°5 49°8 55°5 38:5 44-4 48:6 54:0 37°2 38°8 43°6 49°6 55°4 36-2 46:1 50-0 534 371 382 43°9 49°7 551 34:6 46°5 50°9 571 36°8 B77 44°1 49°8 55°3 39:4 44:0 479 56:1 371 37°6 44°1 49°6 55°4 31:8 453 475 543 36°6 38'0 44°2 49°4 55°3 37°5 46:0 51-4 556 36°7 38'2 44°4 49°6 See 40:4 469 451 53-1 370 38°5 44°5 49°3 55°2 35°9 469 50°5 556 36°9 38°3 44°7 49°4 55°2 33°8 42:5 50°3 53-4 36°7 38°4 44°6 49°4 551 39:0 45:2 47-4 551 36'8 38°6 44°6 49°3 551 39:2 44:8 46°9 55:9 37°0 384 44°6 49°2 551 40°5 46°7 471 54:8 37°2 38'5 44°7 49'0 551 39:7 46°5 517 54:0 37°3 38°3 44°8 49°2 551 39-2 43°7 489 55:0 37°4 38°3 44°7 49°2 551 37°6 41-4 459 55:1 37°4 38°3 446 49°0 551 38:0 45:5 503 555 37°4 38°5 44°6 490 551 31:0 41:0 462 53-2 371 38°3 44°5 49°0 55'0 36:8 44:7 49-0 549 37°I 38°4 44°5 48°9 55°0 28:2 422 50:4 529 36°8 38°3 44°4 49°0 54°9 41:3 43-1 49°7 58:5 37'0 38°4 44°4 49'0 54°9 38:3 44:6 47°8 53°5 7 "0 38'5 44°4 49° 54°8 40°3 ‘ 433 48°6 54:2 371 38'5 44°3 490 54°8 35°9 439 452 53°6 37°! 38'5 44°3 48°9 54°8 34-1 43°1 47:0 52:9 Z 37°0 38°4 44°3 48°8 54°7 37°5 423 48:9 57°6 37°0 38"4 44°2 48°8 54°8 July. Accumg. Obed, Means, 56°4 58:0 57°2 . 56:0 56'8 59:0 57°4 573 57°3 56°8 57°2 53°8 56°38 56°1 56°7 56°7 56°7 584 56°38 56°9 56°9 54:8 56°7 60:4 57'0 59°3 57° 59°6 57°3 577 57° 59°3 3 57°4 58°5 7°5 59:4 5 57°6 57°1 57°6 58:4 576 563 576 59°5 6 54°8 . 575 567 7°5 56°7 5 57°5 57°3 7" 559 ad 57'4 573 574 57°5 57°4 56+4 57°4 59°3 57°4 > = MEAN SCOTTISH METEOROLOGY. 193 Tasie III. continued.-SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF, August, Accumg. Obsd, Means. by (cal 60:0 58°6 57°9 58°3 57°8 582 54:4 57°4 57°4 57°4 56:0 572 55:7 57°0 54:4 56°7 561 56°7 55:0 56'5 57°4 56°6 58°5 56'8 56:1 56°7 580 56°8 58°9 56°9 56°5 56°9 56:4 56°9 55:9 56°8 58°1 56°9 57°8 6"9 55:1 , 6°8 58°6 3 (ob 56°0 oP 56°9 59°4 570 53°5 56°8 57°3 6" 56:2 ee 6°8 58:4 e 56°9 53°6 6°8 56:2 : 6°8 56°4 : 56°38 September, Obsd, ed 50°9 56:1 54:5 52°3 50:2 53°7 53°4 50°1 524 58:0 51°4 534 53°2 53°7 53°6 52:2 515 51°4 52°8 54:4 518 50°5 54:3 51:5 55'2 52°4 51°8 52°8 54:2 50°8 52:2 515 Accumg, Means. on 53°5 53°8 53°4 52°8 53°0 53°0 52°6 52°6 53°2 53°0 5310 53° 53° 53°1 53°1 53°0 52°9 529 5370 52°9 52°8 52°9 52°8 529 52°9 52°8 52°8 52°9 52°8 52°8 52°8 VOL. XXXV. PART 3. October, Accumg, Onsd, Means, 48-8 49°6 49°2 44-9 47°8 45°8 47°3 46:0 47°0 49°5 47°4 471 47°4 46°8 47°3 45°8 47°1 46:0 47°0 48:6 47°2 464 47°1 44:8 46°9 47°3 47°0 46°3 46°9 47:2 46°9 45°8 46°9 44:3 46°7 46:5 46°7 47:0 46°7 49:8 46°9 46-7 46°9 48:9 46°9 46-0 46°9 42:4 46°7 44:8 46°7 48:0 46°7 46°4 46°7 46°9 46°7 42-4 466 49°5 46°7 44-1 46°6 Mean TEMPERATURE. November. Accumg, Obst. Means. oF, SK, 39°7 43°7 41°7 39°4 40°9 39°4 40°6 391 40°3 38°5 400 371 39°6 43°1 40°0 409 40°L 41°4 40°2 41:2 40°3 41°6 40°4 392 40°3 40-4 40°3 39°1 40°2 386 40°2 413 40°2 41°2’ 40°3 41-1 40°3 39:2 40°3 40°7 40°3 42:5. 40°4 380 40°3 40°5 40°3 38'5 40°2 45:0 40°4 39°1 40°4 40-4 40°4 40:2 40°3 40°3 40°3 42°8 40°4 39°6 40°4. December. Mean Month of Observed Oy 45-7 48°0 466 46°8 44-5 46°9 46°1 46°8 45°5 46°9 46°3 45:7 47°6 46°4 46:1 46-4 46°9 46°4 46°5 46-9 466 45-7 46°8 43-9 46°4 44:7 46:7 46-0 46°7 44-9 44-9 46-0 Successive Means of the a 46°8 46°8 46°38 46°3 46°4 46°4 46°4 46°3 464 46"4 46°3 46°4 46°4 46°4. 46°4 46"4 46°4 46°4 46°4 46°5 46°4 46°4 46°3 46°3 46°3 46°3 46°3 46°3 46°2 46'2 46'2 2 1D) 194 : PROFESSOR C. PIAZZI SMYTH ON Taste IV.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Mean Datty Rance or TEMPERATURE. January, February, March, April, July. Accumg, Accumg. Accumg, Accumg, Accumg. Accumg, Opa. Means, aise Means. a Means, bed Means, Ohad. Means, Ce Means, or. °F, or, Fad ale os: °F, oF | °F. nas onK. oR, 73 13°2 }13°3 14:2 14:4 16°7 8-2 3 9°5 12:0 14°4 172 14:1 Re II'4 12'6 14°3 15'8 154 9°4 11°9 15:3 14°8 16°4 147 It’s 13'5 I4'5 16'0 152 9°6 10°9 13°5 19°7 161 14:3 , 114 13'5 15'8 16'0 I5'0 8-1 11°5 14°9 15:0 13°3 145 II‘4 13°8 15°6 I5'5 14°9 8:2 11°4 14-1 15°6 13°6 13°6 8'5 Ir"4 13°8 15°6 I5'2 14°6 71 9°3 13°7 14-1 12°6 13°1 8°3 IL'l 13'8 15°4 14°8 14°4 87 11:2 13°4 14:1 13°2 16°8 8°3 II‘r 13'8 15'2 14'6 14'7 9:1 11:0 145 16:1 13°7 14:7 I1°l 13°9 15°3 14'5 14°7 9-2 10°8 16:1 14:0 173 15°7 8°5 I'l 14‘I I5'2 14'8 14°8 8-9 11°4 13°1 179 15°8 14:0 8°5 II'r I4'0 I5"4 14'9 14'7 9°7 11-4 11°5 12°2 13°9 12:9 II’ 13°8 I5‘2 14'8 14'7 9:0 12:0 12°9 14°9 16°3 18-2 I1'2 13'7 I5°2 14'9 14°9 8-1 120 15°8 14°7 15°8 15°8 Ir'2 13'9 I5‘1 I5'0 14'9 8:2 12°3 15°6 14:2 149 15°5 II’3 14'0 I5‘I I5'0 150 89 12:9 131 175 15°3 13°9 Ir” 13" 152 I5‘0 14°9 85 10°9 ‘ 12°6 ig 13°5 13°8 14:8 Ir’ 13'8 I5‘I 14°9 14'9 9:0 11:2 ‘ 14:7 2 146 15°6 15°1 II'4 13'9 I5‘I I5'0 14'9 9°9 12°0 15°4 14:2 18°8 157 II‘4 139 15‘0 15'2 15'0 97 115 17:3 15°3 15°9 16'9 8°7 1I‘4 14°I 15'0 152 15'0 9°7 10°6 13‘1 16°6 177 16:0 II’ 14’ I5'I 153 I5‘I 9°6 12°5 4 11:9 ‘ 14:1 14'9 12°4 Ir’ I4'0 I5‘r 153 I5'0 12°4 4 13°9 14:5 16°5 16:0 Ir* I4’0 150 I5°3 I5'0 110 : 12°4 16:2 13°6 11°9 114 13°9 I5‘L 15°3 14°9 146 14:1 16°5- 172 14°4 11'6 13'9 152 I5°4 14'9 12°7 15°8 4 18:0 16°3 14:0 a 1r'6 I4’0 153 154 14 12:3 13°6 18°3 15°8 146 11r'6 140 I5°4 I5"4 14'8 125 14:7 15°7 16:2 145 - i I4’0 15 "4 15°4 14 11°5 : 14°6 4 16:1 16:0 14*4 Il'7 140 15°4 I5‘5 14'8 132 14°6 14:2 16'6 175 it’ 140 154 15'5 |. 14°9 11:2 4 14'8 14°5 16°4 15°6 II’ I4q°I 153 15'5 14'9 13°5 4 159 16°4 19°0 16°4 118 I4'I 154 15°6 I5‘0 MEAN SCOTTISH METEOROLOGY. 195 TaBLE IV. continued.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Mean Dairy Rance or TEMPERATURE. September, October. November. December. Mean Month of Observed | Quantities in | Accumulating | repeated, Successive Means of the} Year Accumg Accumg. Accumg, Accumg, Be Means Obed Means, CREB Means, Va Means, pecans’: meee op, °F oR) on, on °F, °F, Rs a pak ors 13°2 10°9 10°0 93 12°2 1856 12°8 11°4 syal 85 118 1857 130 Ir‘2 96 8°9 12'0 146 12°4 9°7, 83 12°8 1858 13'5 116 9°6 8°7 12°3 13°6 12:0 10°4 87 12°8 1859 13°5 IL'7 9'8 8°7 12"4 13°8 : 10°9 81 8-1 11°8 1860 13" rr*s 9'°5 8°6 12°3 11:0 116 10:9 95 11°6 1861 13°2 II's 97 8°7 I2‘2 14:1 12‘7 11:0 8:7 11°5 1862 13°3 Il'7 ‘9 8°7 I2'r 12:2 10°6 9°8 4 9°8 1271 1863 132 I1'6 9'9 8°9 I2°I 13°8 113 10°6 Ua’ 12°5 1864 13'2 II'5 Io'o 8'°7 I2‘I 15°9 122 10°9 84 12°8 1865 13°5 1r'6 I0'0 87 12'2 12°7 11°3 101 95 12:1 1866 13°4 Ir'6 10'0 8°38 12°2 11°7 11°9 10°4 92 11°5 1867 13°3 rr°6 Io‘'r 8°8 I2°I 12°6 12°8 9°3 8°8 12°6 1868 I3°2 II'7 I0'o 8°8 I2°2 2:0 11-1 10°3 9-9 12°6 1869 13'1 1r'6 I0‘o 8'9 12°2 15°5 12°9 10°7 9:7 130 1870 13°3 I1'7 Io'L 89 I2'2 13:2 119 9°8 10:1 12°6 1871 13°3 Il'7 Io'L xe) 7 11:3 11:3 9°6 8-4 : 115 Z 1872 13°2 II'7 I0'0 9'0 I2'2 14:3 12°9 102 9°6 11°9 1873 132 11'8 10'0 9'0 I2'2 132 13°2 9°5 11°4 13°3 1874 13'2 II'9 Boke) QI I2°3 14°4 10°2 102 9:3 12°8 1875 13°3 118 10'0 Q'L 12°3 12°4 9°6 O37, 74 124 1876 13°3 I1'7 100 91 12°3 14°6 12°5 10°1 9-4 12-1 1877 13°3 I1l'7 10'0 g'I re 13°3 10°9 10:1 10°9 127 : 1878 13°3 Il'7 10'0 QI I2°3 13°6 14:3 10°3 iler/ 12°4 1879 13°3 11'8 I0’0 9°3 12°3 15°6 14'2 12:7 105 13°8 1880 13°4 Ir‘ I0°L ; re 12°8 11°8 4 112 10°1 hi 13°2 ‘ 1881 13°4 Ir’ 102 s 12" 14°6 11:7 ‘ 11:0 9-9 a: 131 : 1882 13°4 Ir’ 10'2 9°4 12"4 13°9 13°4 4 10°8 10-2 12°9 1883 13'5 Ir" 102 9°4 12"4 15:0 12°4 ? 11-2 9-4 13°0 1884 13°5 II'9 10°3 9°4 12'5 14:4 11:7 10:2 10°3 131 1885 nee Tr” - 5 ae 14°6 a 10°8 : 106 7 10°6 ." 12°8 % 1886 13°6 Ir‘ Io' 9°5 12'5 14-1 131 e 9°7 4 101 13°8 1887 13°6 II'9 10°3 9°5 ue) 196 ; PROFESSOR C. PIAZZI SMYTH ON TaBL—E V.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Mean or Brack Bus In THE SuN, oR By Day. January. February, March, April, May. June. July, Yer oo oo le SS ea a aa a Accumg. Accumg. Accumg, Accumg. Accumg. Accumg. Accumg Obsd. Means, Obsd. Means, Obsd. Means, Obed. Means, ObsA. Means. Obed. Means, Obsd. Means, PR. pt oF oR: oF om oR PR. 30) Oe on. i oR, ae: sai ON 1856 1857 | 56°7 62°0 58°5 70:2 81:0 98:0 92°5 1858 | 52°6 59°3 68°6 775 81:3 97°4 89°8 54°6 60°6 63°6 738 812 97'°7 gr'2 1859 | 54°6 59°3 65:1 71:0 91'8 95°3 92:0 54°6 60°2 64°E 72°9 84°7 96'9 91"4 1860 | 48-4 57°0 66°5 76°7 81°5 80°8 90°8 53°I 59°4 64°7 73°8 83°9 92°9 91°3 1861 | 46°6 55°4 62°1 73°7 79:9 89:0 86°3 51°8 58°6 64°2 73°8 83° g2°I 90°3 1862 | 47°9 57°5 56°2 707 77°8 78°4 80°8 Srl 58°4 62°8 733 82°2 89'8 88°7 1863 | 47°6 56:3 63°6 67°6 74°8 82°8 89-2 50°6 58°r 62°9 72'5 812 88°38 88°8 1864 | 48-0 54:0 589 72'9 826 82:7 89°3 50°3 57°6 62°4 72°5 81°3 88'0 88'8 1865 | 46°8 49°5 61:3 75°6 791 916 90:7 49°9 56'°7 62°3 72°9 81° 88'5 89'0 1866 | 50°6 56°6 63°4 70°4 81°6 89°8 88-1 50°0 56°7 62°4 72°6 81°r 88°6 89'0 1867 | 46°5 58°6 62°6 68°6 74:1 85°8 85°6 49°7 56°9 62°4 72°3 80°5 88°3 88°6 1868 | 47:8 56°2 65:1 72:2 815 88°5 97°5 49°5 56'8 62° 72°83 80°6 88°3 89°4 1869 | 48-9 57°3 wo | | 776 773 87-7 92-4 49°5 56°38 62°8 G27, 80°3 88°3 89°6 1870 | 47:1 52°1 66-2 771 81°5 91°2 956 49°3 56'5 63°1 73°0 80°4 88°5 go"o 1871 | 45:2 55°0 67°8 72°'5 89°8 92°8 94°8 490 564 63° 730 810 88°38 90°4. 1872 | 48:8 56°7 65°4 " 15°7 81°7 89°3 97:0 490 564 63° 73°1 81'1 88°8 90'8 1873 | 48°8 56°4 63°2 a 76°9 83°2 91°0 92°9 49'0 56°4 63° 73° 81'2 88°9 90°9 1874 | 50°6 56°3 64°5 e4 74:8 3 81:0 93°8 94°2 49°I 56°4 63°6 73°4 812 89'2 QI'r 1875 | 49°5 51°2 62°6 78:7 80°4 92°2 92°4 49°I 56°r 63° 73'7 8r'2 89°4 g1'2 1876 | 50°4 55°3 58°1 on 726 86:3 92°4 93°8 49°2 561 63°2 73°6 81°4 89'5 91°3 1877 | 48-4 56°2 64:9 65°7 78°6 89°3 85°3 49°1 561 63° 7333 81'3 89°5 gto 1878 | 50°7 57°3 66:2 24 72°2 82°4 92°0 96°5 49°2 56°2 63" 73°2 81°3 89°6 91°3 1879 | 45°0 49:1 61:0 a4 71:2 79°5 853 83°7 490 55°9 63°3 73°E 81'2 89°4 90°9 1880 | 48°7 60°5 70°7 76°3 85°8 94°6 95:0 49'0 56'0 63°6 73°3 814 89'7 Ql'r 1881 | 47°1 ‘ §2°4 64-1 : 76°8 % 86°4 90°7 87°8 48°9 559 63° 4 81° 89°7 gro 1882 | 51°4 58°8 66:1 24 722 4 87°4 89°6 92°3 49°0 56'0 63°8 734 81'9 89°7 gto 1883 | 48°6 56:0 65:2 72'9 81°0 899 92°5 49°0 56'0 63°8 aha 81°38 89°7 gI'r 1884 | 48:7 554 61°9 74°5 va 81:2 89°7 89°7 49°0 56'0 63°7 73°4 81°8 89°7 gr'0 1885 | 43°7 571 664 73°5 76°5 90°2 92°9 48°8 6'0 63'8 . 816 89'7 (oh me) 1886 | 45:2 54°2 : 62°9 : 773 fan 782 93°2 91°8 48°7 56'0 63'8 73'5 81'S 89'8 gI'r 1887 | 47°6 60°3 69°1 77'8 86'0 971 99°6 MEAN SCOTTISH METEOROLOGY. 197 TaBLE V. continued.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Mean oF Brack Bus IN THE Sun, oR BY Day August, September. October. November, December, Mean Month Successive of Observed } Means of the Year Resa aceane Race ‘Aeoaey Wartne Quantities in | Accumulating | repeated, Obs: Means, IES Means, Ds Means, siete Means. ; ae Means. each: Meaty se ee | or | on | ck | cr | on Rear fee °F oR, oF, 1856 97-1 83°6 73°6 59:2 55°3 74:0 1857 93°7 88:0 67°7 59:1 50°6 73°8 1858 95°4 85°8 70°6 59°2 53'0 73°9 91-1 83°4 70°1 5671 46°4 73:0 94°0 85'0 70'S 58'1 50°8 736 1859 84°6 81:7 68:1 532 45:0 69°5 1860 916 84°2 69°9 56°9 49°3 72°6 81:3 796 70°4 55°3 51:4 69°2 1861 89°6 83°3 7o'O 56°6 49°7 719 82:2 82°3 68:4 53°4 49-4 67:1 1862 88°3 83°1 69°7 56°0 49°7 qu 83°7 739 65:0 55°7 48°8 67°4 1863 87°7 81°8 69'0 56'0 49°6 70°6 87°7 80:2 66:0 55°3 46°7 68°8 1864 87°7 81°6 68°7 55°9 49°2 70°4 82°6 89:0 66°2 57°5 52°6 70°2 1865 87°1 82"4 68°4. 56'r 49°6 70°3 82°8 774 68-4 58:2 49°8 69°8 1866 86°7 819 68°4 56°3 49°6 70°3 86°8 778 67:1 57°3 49°8 68°4 1867 86°7 81'5 68°3 56°4 49°6 70'L 85:1 76:9 65°3 51:9 49-4 69°8 1868 ; 86°6 812 68'0 56'0 49°6 7O'L 90°4 HED 65:7 53°6 45°9 69°9 1869 86°8 80°9 67°8 55'8 49°3 7o'L 98°8 865 69°8 56:2 43-4 721 1870 87'7 81°3 68'0 559 48°9 70°2 95:0 84:9 69°5 55:2 48°8 726 1871 88'2 81°5 68° 8 48°9 70"4 91:2 76°1 68°7 54:9 = 46°8 71:0 1872 88°4 81'2 68°r 55°8 48°8 70'4 86°9 83:0 66:0 52°6 49°8 70°9 1873 88°3 81°3 68°0 552 48°3 70'4. 87°0 78°9 65°8 §2°3 41:4 70:0 1874 88°2 81°2 67°9 55°4 48°4 70°4 87:1 5 80:1 62:9 51°6 47°4 69°7 1875 82 81'r 67°6 2 48°4 70°4 93:0 81-4 67°7 55°2 = 46:0 71:0 1876 88"4 81'r 67°6 55°2 48°2 70°4 81-4 e: 81:7 67°8 57°9 48-1 68°38 1877 Gr 81'r 67°6 5° 48°2 70°3 os | | ss 68-2 fo es ale ee 75 1878 Bi 81°3 67° ; 48'0 70°4 89°83 83°1 74:6 zi 585 a 46-4 68°9 1879 88'2 814 68'0 55°4 47°9 79°3 96-1 A 89°9 70:2 56:2 473 74:3 1880 : 88°5 81°7 68°0 55°4 479 70°5 86°5 x OSM 68-2 57:0 476 70°4 1881 , “5 817 68°r : 47°9 79'S 92°5 a 80°5 67°5 53°6 a 41-9 71-2 1882 6 81°6 68'0 : 47°7 Woes 88°8 ae: 82:2 72:5 56°4 rel 48°6 71-2 1883 8" 8r°6 68°2 : 47°7 70'S 92:9 86-7 68°3 Fld ean eal ce 70°7 1884 88°8 8x'8 68'2 554 47°6 7O'5 85:5 82:0 67:4 52:2 49-3 69:7 1885 88°7 81°8 68'2 : 47°7 70°'5 91°6 ae 82°7 69-1 60°8 ae 46°8 71:2 1886 ’ : 81'°8 682 : 47°6 795 93°3 84-7 734 etiee | ts 74-2 1887 oe) 819 68°4 55°4 47°6 70°7 2: VOL. XXXV. PART 3. 198 TasLtE VI.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. January. Accumg. Oba. Means, wk. nai. 28°8 30°9 29'8 30°3 30°0 26°7 29°2 28°7 29°! 31°6 29°5 30°4 29°6 27:1 29°3 26°4 29'0 31'2 29'2 22°3 28°6 28°3 28°6 33'0 28'9 28:0 28°83 252 28°6 29°6 28°7 30°5 28°83 31°0 28'9 30°3 29'°0 29°7 29°0 28°5 29'0 28-4 28'9 20°4 28°6 26°5 28°5 171 28'0 32°7 28'2 30°2 28°3 323 28°4 27°2 28°4 24°8 28°3 29°5 28°3 PROFESSOR C. PIAZZI SMYTH ON February. Accumg. Obed. Means. Sate or. 31°7 24-7 28°2 30°8 29°I 24:1 27'8 31:0 28'5 32°0 29°0 32'1 29°5 23'3 28'7 25°6 28"4 27°6 28°3 32'3 28°7 32°4 290 32°7 29°3 25°4 290 33°3 29°3 32°0 29°4 254 29°2 282 29'1 26°9 290 27°1 28'9 30°5 290 32°5 29'2 25°5 29'0 31°5 29°I 26°5 29'0 329 29'2 31°8 29°3 30°5 29°3 28°6 29°3 257 29'2 30°0 29'2 Mean or Buack Burs purine Nicut. Obsd. _ 31°5 29:2 32°9 27°4 31°6 29-4 33°7 28:3 27°5 27°7 25°9 32°1 27:2 28°1 32:0 31°6 29°8 32°5 29°6 28°2 27°8 29:1 281 28°6 271 330 26:0 31°3 28°0 28°3 27°7 Accumg. Means, be 30°4 312 30°2 305 30°3 30°8 30°5 30°2 29°9 31°3 317 31°9 32'2 32°3 32°3 32°6 32°8 32°8 32°9 32°8 32°9 329 32°9 yr 37°2 37°1 37°I 37°3 36'8 36°9 37°0 36°7 36'°8 36°8 36°7 36'5 36°4 36°4 36°4 448 4570 45'2 45°2 44°3 MEAN SCOTTISH METEOROLOGY. 199 TaBLE VI. continued.—-SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Mean oF Brack Bus purine NIGHT. September, October, November. December, Obed. |“yreans, | O% |stemne, | OP | “ateana, | O%- | “afeans ets. termes I gears |p nd | oe 43°7 39°3 34:2 36°1 411 33°8 29°3 31:0 38°4 ia" 35°0 ae 27°8 ae 24°3 oe 411 36'0 30°4 30°5 380 35°2 30'5 26:0 43°1 ae 38°5 - 288 ae 28°8 ay 41:1 ? 35°6 eS 27:2 4 33°6 oT 38°5 aig 36°6 ot 336 313 aT 40-2 oi 350 i 50°0 a 31°6 4 40°5 36°1 302 30°3 45-4 33°7 30°3 343 39°7 a} 38°5 ae 30°8 ij 30°9 oF 41°6 a 35°4 - 31:0 7 30°1 or 41-4 ee 02°8 ie 29°4 ae 31°9 a | 40°8 c 36'2 ~ 29°8 o 25°0 a 41'0 358 30°2 30°4 40°2 34:2 28°7 24:0 39°3 ea oo'2 We 28°0 a6 27:0 Br 39°4 em 336 ow 31°3 it 29°3 oe 88°5 ne 331 a2 31°0 * 33°1 re 40°9 - 33°6 sa 31:0 Pog 20:0 ze 40°6 350 30°2 29°4 41°4 371 29-1 29:2 41-1 Ee 40°4 ae 31:2 ie 32°3 Sy 375 acd 85°7 - 32°6 - 29°9 F 42°8 yee 38°5 ee 27°4 6 19*7 ny 39°4 =P 334 os 29:2 a 23°1 ot 40°6 aor7: 30° 28°8 40:7 29°1 27°3 27°5 40°8 ‘sd 33°1 2" 34:4 ie 2971 =f 39'2 ‘a 375 oe 28°5 a 24°5 A 41°7 a 35°5 = 31:0 ig 30°8 ey 420 es 35°4 ae 29°2 7) 27°7 ine 40°6 35°4 30°1 28°6 38°2 32:2 31:0 29:1 40°7 a 39°77 eS 33°4 7" 23°8 ay 39°8 ce 32°7 ce 30:2 aa 26°4 =e 40'S 35°3 30°2 28°4 Mean Month of Observed Successive Means of the Year Quantities in | Accumulating | repeated. each Year, 1% 38°0 35°1 34°6 33°8 36°5 35°9 36°0 34°6 35°5 35°3 35°4 36°3 34:9 34°6 34°9 385°5 35°0 3474 35°0 35°7 35°0 35°3 82°6 33°8 33°'2 35°4 35'5 35°8 33°9 34°5 34°7 Years. oR. 200 PROFESSOR C. PIAZZI SMYTH ON Taste VII.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Humoopiry. January, July. | August, [September] October, [November.|December.JMean Mont Successive | of Observed Means of Year. ——— = — Quantities | the Accu- Ac. i Ac, Ac, Ac, Ac, Ac. Ac, in each mulating Oh. | Mn, Ob. Mn, Ob. Mn, Ob. Mn, Ob. Mn. Ob. Mn, Ob: Mn. Year, Years, 1856 } 85 7 81 83 90 89 89 82 1857 | 87 80 85 87 90 90 88 86 86 78 83 85 go go 88 | 1858 | 86 83 81 84 87 89 90 84 86 80 82 85 89 89 89 1859 | 87 81 80 82 89 89 88 83 86 80 82 84 89 89 89 1860 | 89 83 85 87 87 90 90 86 87 80 82 85 89 89 89 1861 } 90 84 86 88 90 87 90 86 87 81 83 85 89 89 89 1862 | 90 83 87 88 88 90 89 87 88 82 84 86 89 89 89 1863 § 90 80 85 86 89 89 88 86 88 8r 84 86 89 89 89 1864 | 89 83 81 86 89 91 89 86 88 82 83 86 89 89 89 1865 | 87 82 87 86 88 89 87 86 88 82 84. 86 89 89 89 1866 | 89 83 86 87 90 87 89 86 88 82 84. 86 89 89 89 1867 } 86 84 86 87 89 87 89 86 88 82 84 86 89 89 89 | 1868 } 89 78 83 86 87 87 90 84 88 82 84 86 89 89 89 1869 § 90 82 82 86 88 87 88 85 88 82 84 86 89 89 89 1870 } 89 83 82 87 88 89 87 86 88 82 84 86 89 89 89 | 1871 | 88 83 84 86 89 88 89 85 88 82 84 86 89 89 89 | 1872 | 90 84 86 87 88 90 90 87 88 82 84 86 89 89 89 | 1873 | 89 84 86 85 88 89 88 86 | 88 82 84. 86 88 89 89 1874 | 88 82 84. 86 87 89 84 85 | 88 82 84 86 88 89 89 | 1875 | 92 82 86 87 88 89 90 86 88 82 84 86 88 89 89 1876 | 90 80 81 87 88 90 91 86 89 82 84 86 88 89 89 | 1877 } 89 84 88 86 88 88 90 86 89 82 84 86 88 89 89 1878 } 90 82 86 86 88 88 88 86 89 82 84 86 88 89 89 | 1879 | 86 85 86 86 88 86 88 86 | 89 82 84 86 88 89 89 1880 | 88 84 85 86 85 88 88 85 89 82 84 86 88 89 89 | 1881 | 85 83 83 88 86 88 89 85 88 82 84 86 88 89 89 | 1882 | 88 84 84 87 90 88 89 86 88 82 84 86 88 89 89 | 1883 | 88 83 84 87 88 89 89 85 88 82 84 86 88 89 89 1884 } 89 85 83 87 87 87 88 85 88 82 84 86 88 89 89 1885 | 88 81 83 84. 85 88 89 84 88 82 84 86 88 89 89 1886 | 87 80 83 84 89 88 86 84 hose 88 82 84 86 88 | | 89 89 1887 | 87 78 79 85 83 87 86 82 88 82 84 86 88 88 89 MEAN SCOTTISH METEOROLOGY. 201 Taste VIII.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. NumpBer or Days on wHicH Rain FELL. January. } February.| Mar ch, April, May. June. August. |September) October. |November.|December,|!ean Month of Observed |) Means of ‘Ob. Ac, Mn, Ob, Ac, Mn, Ac, “| Mn, Ac, "| Mn, Ob. Ac, Mn. Ob, Ac, Mn. Ob. Ac, Mn, 14 I2 13 12 12 12 13 ue I2 I2 13 13 13 rs us) a) 73 13 13 13 13 us) 3 13 us) us) aS) 3 I2 uS) I2 VOL. XXXV. PART 3. 13 13 16 | 4 13 14 I2 I2 I2 13 13 13 13 a3 tS x3 us) 13 13 13 13 13 14 13 13 13 13 3) 8} 3) us) U8) 13 a3 13 12 us) 13 14. 16 16 16 16 16 16 16 16 16 5 us ™ 15 16 16 15 16 16 16 16 16 16 16 15 15 15 15 16 15 16 15 16 16 16 17 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 14 15 15 16 16 16 17 16 16 16 16 16 16 16 16 16 16 16 17 17 17 17 17 16 16 16 16 16 16 17 16 [2 I2 12 13 14 14 14 14 14 14 14 14 14 14 14 14 14 15 15 15 15 15 15 T5 15 IS 16 15 15 15 16 15 16 16 16 15 16 16 16 16 17 17 17 17 16 16 17 16 16 17 17 17 17 16 16 16 16 16 16 16 16 16 Quantities in each Year, Successive the Accu- mulating Years, 202 PROFESSOR C. PIAZZI SMYTH ON TaBL—E [X.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. DertH or Rain 1n INCHES. January, February. March, April, June, Year, : Accumg, Accumg. Accumg. Accumg, Accumg. Accumg, Accumg. Ohad: Means, Obed. Means. Obs0 Means, bad. Means, pet: Means, hee: Means, Means. 1856 | 2:38 3°30 _ 0:26 2°44 3°71 1857 | 2°77 1:54 2°94 2:38 2-79 e 2°58 2°42 1°60 2°41 3°25 2°3 1858 | 2-98 1:13 ; 1:95 1°86 2°36 ze 2°71 1°99 1°72 2'2 2°95 3°01 1859 | 4:21 3°38 418 3°20 2°04 3°08 2°34 2°33 2°47 2°72 2°95 1860} 4:56 2°69 3°52 1:18 4°34 ; 3°38 2°41 2°57 2°21 3°05 2°72 1861] 3:09 3°32 510 1:04 2°35 3°33 2°56 2°99 2°02 2°93 2°92 1862 | 5:32 1°88 3°63 2:99 3°99 : 3°62 2°46 3°08 2'16 3°08 3°06 1863 | 6:20 2°40 2:08 3:27 3°24 . 3°94 2°46 2°96 2°30 3°t0 2°77 1864 | 2-84 3°75 3°96 1:57 2°57 3°82 2°60 3°07 2°21 3°04 2°72 1865 | 3°73 3 2°91 2°05 0-94 0°75 5 Z 4 3°81 2°63 2°97 2'0 . 2°81 271 1366 | 5-31 451 3-15 163 | 1:85 3°94 2°80 2°98 2°05 2°73 2°79 1867 | 4:74 3:09 2:26 4:43 211 4°01 282 2"92 2°25 2°68 2°93 1868 | 5°53 4:75 4:22 3°31 1:14 ‘ i 4°13 2°97 3°02 2° 2°5 27. 1869 | 4:85 4:05 1°33 i)!) 4 2°15 4°18 3°05 2°90 2°31 2°53 2°67 1870 | 3:08 3°89 1:24 1:58 191 6 4°II Eyes 2°79 2°26 2°49 2°62 1871 | 2:74 4:40 2°50 4:08 2:07 4 4°02 ‘19 2°77 2°37 2°4 2°72 1872 | 6:48 4:28 ? 3°26 214 7 5:16 : ul 4°17 3°25 2°80 2°36 2°62 2°77 1873 | 5:37 1°45 2°32 0°70 174 8 ‘ 4°23 apis 2°78 2°27 2°57 2°07 1874 | 4-02 ileal 282 2:27 1-42 4°22 3°08 2°78 2'27 2°51 2°88 1875 | 5°63 1:72 1:68 1:41 3°14 BB 4°29 ‘or 2°72 2'22 2°54 25 1876 | 2°84 433 | > 5-10 311 312 4°22 3°07 2°84 2°27 2°57 2185 1877 | 6:96 4:12 2°58 2:96 3°72 4°35 3°12 282 2°30 2°62 2°92 1878 | 4:01 1:92 2:09 171 2°78 5 4°33 ‘07 2°79 2'2 2°63 2°84. 1879 | 1°84 ase | > 3°20 1°89 4 4:24 4°23 3/04 2°81 2°26 2°69 2°93 1880 | 2:02 3°98 2°32 3°37 2:09 6 6 4°14 *08 2°79 2°30 2°07 2°9 1881 | 1°30 3°79 3 3°49 1:16 : 3°23 4'03 3°11 2°82 2'26 2°69 3 Or 1882 | 3°41 3-20 4°17 3°09 3°68 4°01 Br 2°87 Bee 2°73 3°07 1883 | 4:48 4-14 2°36 188 j 2°34 4°02 "LS 2°85 2°27 2°72 3°10 1884 } 5:80 ae | > 3°24 1°31 0°87 4°09 3°17 2°86 2°24 2°65 3°15 1885 | 2°93 4°35 2°53 2°56 1-45 4°05 3°21 2'8 2'2 2°61 3°10 1886 | 4°42 1°81 3°14 ; 1:98 4 158 3 4°06 “7 2°86 2'2 25 3°11 1887 | 3-25 ous | 77 | rag 2°05 . 0:96 4'03 3°I4 2°83 2°24 2°53 3°11 MEAN SCOTTISH METEOROLOGY. 2038 TaBLE IX. continued.-SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. DeptH or Rain in Incues. Suecessive Successive December, oa Teeensios Yearly Means of é Sums of Sums of Year August, September. October, November, ae SE EE ee uantities {Months of » ama. ene ona, Paramel ona, smal oma, Faramel ona, camel ee [enaerl gus | meine |" 3°46 4-64 1:43 2°12 4-09 2°75 1856 1:87 3°82 2°36 2°89 3:37 2°55 1857 2°61 En 200| 7° 4-72 se oe. | lean | 272 2:83 a 1858 2-27 Me 321 | 37> | 4-60 abs 3°37 oo 3°66 atte 3°10 ce 1859 2°55 3°62 3°28 2°69 3°78 33°66 3-79 1-92 5-14 2°83 3-91 3°16 1860 6-44 a 5-27 SNE 3°34 oe 663 |” | 298 ae 3°76 a 1861 pa | >" 2°44 ae 6°32 ae any | 297 | 5-29 aa 3°77 af 1862 mo Meee Uae |) 7 Wensae | oo thea a 3°51 ie 1863 fas | °°" 4-61 ie 547 | 7° | 409 377 | 71 i 3°22 ee 1864 3°33 3°71 4°17 3°36 3°99 38°17 3°89 114 5-ll 3-29 3°65 2°83 1865 3°99 hl 4°34 a6 2°86 a 393 | °° | 5-29 ae 3°45 eee 1866 ep | > 3:17 a3 TecaNNaie | Gtor™ Walaee ar a 3-21 Se 1867 fig | °° eee | 3-71 ne Vag, | >> | 6-00 Te 3°59 ae 1868 132 | 3° poz | Paco | aes as 4:66 a 3-04 ay 1869 3°37 3°69 4°03 3°26 4°19 38°35 1°55 3°32 4-63 2:58 3°54 2°65 1870 ag2 | 2° 2:57 a ee fo) ee ea 3°76 a 3°10 wee 1871 39 | 273 5:94 apt a Wein | Woes By 4-51 a 1872 an | 377 msg. | 5-47 a4 332 | 2°? | 343 ote 3°28 og 1873 ee | °° Me| 97° cesuliaiaea (e ees 2°69 ek 3°35 oe 1874 3°43 3°77 4°26 3°44 4°06 38°93 2:97 4°34 4-72 4-87 3°67 3-26 1875 373 | >" 3°56 ope 4-77 a 368 | >> | 757 es 3-74 3 1876 6a |°* pia | >” pa 6:07 mad ii 4°32 aA 1877 3-96 oes cp |? eae ie lesan ye sok 3-02 Ae, 1878 4-48 ae oo 1:97 oo 2:27 = 2°70 pe 3:04 an 1879 AGE ae 4:25 3°56 4°Ir 39°51 0°86 3°68 2:53 5-03 3:96 2:89 1880 meg | 9° 3-01 ag6 3°51 oe 5-21 a? 3°87 mk 3°30 a 1881 am | 363 | >” 3°62 pe 5-42 ate pag la 3°74 ae 1882 a | °> 326 | 373 4-04 va 4:59 ge) 3°56 ae 3:36 eae 1883, gay | 353 a7 | 37" 346 | * > | 3-40 a og 3129 5 1884 3°49 3°68 4°1r 3°76 4°13 39°56 2°70 5-32 3-28 2°54 2°89 2:95 1885 aoe | 24° 396 | 373 3-99 er 3°87 aoe eaten 3°16 ee 1886 am | >” 363 | 974 2°39 376 | >? | 3:30 as 2°58 24 1887 340 3°74 4°03 3°73 4°07 39°12 204 PROFESSOR C. PIAZZI SMYTH ON Taste X.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Mean Force or tHE Winp; ups. Avorn. on Square Foor, January, February. March, April, May. July. Year. > a Aecumeg. i Accumg, E Accumeg, Accumeg, . Accumg. Accumg, Accumg. Obsd Means. Obsd. Means, poe Means. Obsd. nike Obsd. Means, Obsd. Means, Obsd. Means, 1856 | 1°22 2°20 1:65 0-98 0:97 1:90 1:34 1857 ] 1°25 177 1°88 118 0°79 0°65 1°55 I'24 1°98 1°76 108 0°88 r'28 I"44. 1858 | 2°36 1:80 1°89 1°45 1:34 1:36 111 r'6r I'92 18x I'20 I'03 1°30 133 1859 | 2°95 2°67 3°19 2°33 0°84 1°66 1:44 1'94 2°11 ats 1°48 0°98 1°39 1°36 1860 } 1°78 2°33 1:95 1°55 1:42 1:28 0:87 r'or 2°15 eau I’*50 I'07 1°37 1°26 1861} 1°33 2°22 2°64 1:18 1:18 0°88 1:41 1°82 2°16 2°20 1°44 I‘09 1'29 1'209 1862 | 1°68 1:36 1:36 1:57 1:27 1:67 1°76 1°80 2°05 2°08 r°46 I'I2 1°34 1°35 ( 1863 }] 1:98 1:90 1:54 1:87 114 1:05 1:03 1°82 2°03 2°O1 I'5I Tee I°3r 1°31 1864 } 1°54 1°31 1:47 1:02 113 1:46 115 . 1°79 195 1°95 r'45 I°12 1°32 1°30 1865 {| 1:97 1:28 1°62 1:22 1:48 Ei 0:98 r'8r 1°88 I'92 1°43 r'16 1°30 1°26 . 1866 | 2°18 1:89 1:48 1:54 1:05 0°86 0:90 1°84 1°88 188 r'44 IIS 126 I'23 1867 | 1:43 2°13 1:63 1°84 131 0:98 1:04 1°81 I'90 1°86 I'47 r'16 I'24 I'22 1868 | 1:92 3°21 2°18 156 1:49 1:58 0:94 1°82 2°00 1°88 r'48 I'Ig 1°26 I‘19 1869 | 1°83 2°05 1:43 1°40 1:44 1:08 1:28 1°82 2°01 1°85 I'47 I'20 1'25 1"20 1870 | 1:04 1:70 131 1°66 1:47 112 1:05 1°76 1°99 185 I'49 I'22 124 I'Ig 1871 | 1°36 2°12 1°87 1:36 1-12 1:07 111 1°74 2°00 182 r'48 I'22 I'23 r'18 1872 | 2:18 1:93 1-80 2°14 1:59 1:18 1:15 1°76 1°99 1°81 I'52 I'24 1°23 r'18 1873 | 2:06 1:36 1:30 1:47 1:23 1°32 1:09 . 1°78 1°96 I'79 I'52 r'24 1'23 opie 1874 | 2°24 1:30 2°30 1:66 : 1°32 151 1:18 1°80 I'92 1°81 m52 124 1°25 I'r8 1875 | 1°75 1°39 1:46 1:02 115 1:10 1:09 1°80 1°90 1°80 I'50 1°24 I'24 I'I7 e 1876 |} 2°37 1°84 3°01 1:97 1:46 1°72 2:07 1°83 1°89 1°85 I'52 1'25 1°26 r'21 1877 | 3°01 2°97 2°20 2°73 2°37 2°03 1°85 1°88 1°94 1°87 1°58 I°30 1°30 1°24 1878 | 1:92 171 2°42 1:59 2 1°81 1:27 1:27 1°88 1°93 1°89 r'58 1°32 I°30 1'24 1879 | 1°74 1:68 2°98 177 . 1:68 1°35 2:00 1°88 I'92 1'94 r'58 1°34. I°30 1°28 1880 | 1°82 3°00 1:39 2:06 2-02 1:52 SOE 1°87 1°96 1'92 1°60 1°36 1°31 1'27 1881 | 1:27 1°94 2°87 1°87 1:90 2°01 2:03 1°85 1°96 T'95 1°61 1°38 1°34 1°30 1882 | 2°92 2°83 3°65 2°47 1°63 iva 1:49 1°89 1°99 2°02 16 1°39 1°35 1°31 1883 J 2°91 3°99 2°99 2°16 P 2°53 1:58 1:56 1°93 2'07 2'0 r'66 I*4 1°36 1°31 1884 | 3°92 3°19 2°32 : 1°47 211 : 1:59 1:20 2°00 2°11 2°06 1°66 1°46 1°37 S73e 1885 | 2°35 2°70 2°89 2°33 2:28 1°64 1°35 2'O1 2°T3 2°09 1°68 1°48 1°37 r’3I 1886 | 2°99 151 2°59 2°62 2°08 2°19 2:28 2°04 201 2°10 rer I'50 I'40 1°34 1887 | 2°76 2°38 1:81 1:96 1:98 1:37 1°73 2°06 2°11 2°09 1'72 I'52 1°40 1°35 MEAN SCOTTISH METEOROLOGY. 205 TaBLE X. continued.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Mean Force or tae Wind; ups. Avorn. on Square Foor. August. September, October, November, December, Accumg. Accumg. Accumg. Accumg. Accumg. esd, Means, OKs Means, i )ek Means. Ce Means, Chee Means, 1:01 1-69 0°88 0:97 1:87 1:04 1:38 1:29 1:10 2°32 I‘02 1°54 I'08 I'04 2°10 0-99 1:68 1:90 1:09 1:80 IOI 1°58 1°36 IOS 2°00 1:58 1:80 1:63 1:31 1:67 I'16 1°64 I'42 I'I2 I*92 115 1:09 2°34 1:09 1:37 I'Is I'53 r‘6r I‘Ir 1°81 1:92 1:38 1:28 2°36 1:20 1'28 1°50 1°55 1°32 1°70 0°82 0°92 2:07 0°80 2°15 I’21 I'42 1°63 I'25 77, 114 1:69 1:46 1:37 2°39 I'20 I"45 r'61 I'26 r'85, 1:09 1:50 1:25 1:13 1°31 I‘I9 1°46 I°57 I'25 1°79 0°88 1:25 1°73 1:06 2°50 I'r6 1°44 1°58 tae 1°86 1:16 1:36 1:06 1:78 2 1:80 r'r6 1°43 1°54 1°28 1°85, 0:97 1:46 1:37 1:03 1:60 I'I4 1°43 I'52 1°26 1°83 1°60. 1:21 1:64 1:37 1:69 r'18 I"42 Ey I'27 1°82 1:16 1:90 1:62 3 1:92 1°85 Irs 1°45 1°54 I°31 1°82 0°84 1-13 1:50 1:04 1°28 r'r6 1°43 I'53 I'29 1°79 1:26 1:04 1:42 1°36 164 1'16 I'40 I 1°30 1°78 0°93 1:52 : 1°82 2 1:92 ; 1:90 IIs I"4I 1°54 1°34 1°78 1:24 1:34 1°31 1:65 1°96 1°16 1°41 I'53 I°30 1°74 1:39 1-65 1:81 1°31 1°30 I'I7 I"42 I'55 1°35 1°72 1:27 1-24 2°61 1°56 181 I'I7 1°41 1‘60 1°36 1°77 1:82 1:36 2-03 1:70 ; 2°64 1'20 I'41 I'62 1°38 r'8r 1-46 1-69 2°69 2°61 2°23 I'2r I'42 1°67 14: 1°83 1-41 2°40 2°85 191 1 39 I'22 1°46 72 1"45 1°81 161 2°04 1:38 2°29 2:03 1'24 I°49 I'71I 1°49 1°82 0°83 1-47 1:92 2°82 2°45 1'22 1°49 I'71I I" 1°85 2°01 1:50 3°37 3°71 ¥ 2°45 I'25 1°49 1°78 1°63 1°87 1:91 1°72 2:07 2°73 1:96 1'28 I'50 I'79 1°67 1°87 2°00 1:89 2°47 2:43 2°57 1°30 I'°5r r'8r r'69 I*go 1:40 191 3°03 2°38 257 I°3r I'52 1°86 1°72 1°92 1:70 2°46 2°47 1:90 2°85 1°32 1°56 1°88 1°72 1°95 1°70 1:99 177 2°25 2:23 1°33 I'57 1°87 1°74 1°96 1:25 1°75 2°24 2:06 2:08 1°33 1°58 1°88 1°75 1°96 VOL. XXXV. PART 3. Mean Month of Observed Quantities in each Year, 1:39 1:35 1:56 1:92 1°52 1:58 1°45 1°55 1:28 1:42 1:42 1:40 1°70 1:58 1:26 1°39 1°67 1°44 1°58 1°45 2°00 2°32 1°83 1°88 1°87 2:24 2°26 2°42 2°26 2°24 2°18 1:95 Successive Means of the Accumulating Years, ms ( Year repeated, PIAZZI SMYTH ON PROFESSOR C. 206 Taste XI.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Winps—NorrHern Quarter, $ N.W., N., anp § N.E. oO Saw. B@,agia Sada Ss sats goo Fh Baga Bua = Ci ae iis wee Sosa s Pier © aos gh ou Co as | ie) — I sH © wm OH s wm bo) ID sH xo o O © Oo 1h to) mo WO Oo 0 Oo 1 iD ae) mo Oo © o 2 I Oo 9 vo (2) B | ga nN nN © oo Oo mM wH nM Mm mM Oo 0 0 0 0 © o © © 0 © o © © 0 oO 0 © 0 8 o° - = So Z s | oa m + 12 IQ SER SE SE Se SE re Naps SSP + + 1 wm WH Ge Se Se Se Ge mM mM mM wm WwW nm wm Ww 2 So Nee aS +H ANN AN CO co 0 OH OH OO ow © oO 4 A Oo + 19 © Nn Oo * © © oe 0 © a ~ . a’ | 4g sh Se Sr Ne SP Se SP GY GP NR Se So oosp SP GROG + +t WM 1D Ww + + 0 HM WH mot 1 I o a|g|[ «an mo 0m Om HAN aat © © © oO © Se OC) pe a + & a ) —] = & al : 2 i) x —_ ee Gg t[e|/nnrmt ao nat wwa oOo a oo WN + Ht Om N at tH Oo + co OO © 1» 0 OO aN |, —_ ~~ 106 2 & : Oo ey) be ote om ona m x 16D Oo ~ Oo OD oun A 3 Se e68 Sete e gee ee SEES S SE GEE £2eS 2 2 3 8 ~ a — oe | eof ft a or qa Ff A An A = | a er a ee 5 cater a ES a» 207 MEAN SCOTTISH METEOROLOGY. Taste XII.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Winps—EasTern Quarter, $ N.E., E., anp $ S.E. Years 6 6 6 6 6 6 5 5 6 5 6 5 5 5 5 5 5 5 5 5 6 OF i] 6a “lof Means of the Accu- mulating nth} Successive in each Yeu Quantities November.\December, |Mean Mo . [September] October, Ac Mn June. ee Ip See o Oo = 23 o Cy Yee ey ico SS TS i LS Seis aS Woy iss ik ESOS Nn WN N N © ao o o oO oo o co 0 a = Sh We Sr Sy ee) ee) aoa ao tn €& PS Sey ey en) SS re (Oo co co oOo 6 KN HH ~ ma a - a FH Sete ee ee ae | g & a BE) ge +O 1M t+ + g | <5 Set 9) no nm mM + + 2D) kn) un) a nD nM WH WwW no Mo MY) MH WwW no mW WM E 5 ; ie) SS SSS > | 8a 4 | <5 ope “Atoy Sy Soph Sag ey ape Yn) wn St LO ani any mo wWMWowMno wn WwW iYoy Voy = \Vol Ye) Vo} Vo) Voy Avo) Way Vo} Woy oy ¥o) 3 [=| - eleas|tece eon ~ 10) 10 H+ 19 oS So ow SL vn) DW OO O BH a Sos oe Sih SS ao ~~ NN Me ao Oo © een SSS SSS B Oo mr CO D So FN ow OSH 3 1D 1 10 So 6S & S oS 5 8 8 SiS? Se os et ey SS Sess Bn S 8 2 o o& S Cy Ey eH CO) 500s GO) G05 ico Co 0 © O © Os S60) ) 5G) Gon on oO) GO) GO; 60 co Con een are Wee aes) co © re At we os A ne | a et et Se A a et fe St A a oft et eS SS a we 208 PROFESSOR C. PIAZZI SMYTH ON Taste XITI.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Winps—SovuTHern Quarter, 4 S.E., S., anv } S.W. January. | February.}| March, Ac, Ac, Ac, “| Mn, Mn, Ob. Mn. 8 4 12 8 6 Io 6 8 4 7 9 5 8 6 8 9 6 4 if 8 8 6 10 8 8 8 6 8 6 8 8 6 8 9 8 8 6 6 6 9 8 6 6 6 8 8 6 5 7 9 8 6 if 5 8 8 6 7 9 8 7 7 8 5 8 8 7 6 5 9 7 6 8 8 9 7 6 12 8 9 8 7 4 6 9 8 6 ll 8 9 8 7 5 4 9 8 6 6 6 9 7 6 4 6 9 7 6 8 4 9 . 6 6 6 9 of 6 10 8 9 7 6 6 6 9) _ 4 6 7 6 9 7 6 9 4 9 7 6 10 12 9 7 6 9 6 9 8 6 7 9 9 8 7 8 6 9 8 6 April. Ob. CO SOG Oa OO m OO OG Oo 10 Ot. CO. OG) 1, 3 orn’ Oo wn | 399 52°7 1869 63°7 59°7 52°8 45°3 43°6 52°5 66°9 61-4 52-7 44:5 38°3 52:7 1870 63°9 59'8 52°8 45°3 43°3 52°5 66:8 58:8 53-2 435 43-0 526 1871 64°1 59°7 52°8 452 43°3 52°5 63:5 57-1 51-4 46:1 42:5 526 1872 64°1 59°6 52°7 45°2 43°2 52°5 63°0 58°6 50°7 46°3 47°3 52°7 1873 64'0 59°5 52°6 45°3 43°4 52°6 63-2 59-4 53-1 459 366 531 1874 64"0 59°5 52°6 45°3 43°1 52°6 64:9 61°6 521 443 43-5 53:3 1875 64°0 59°6 52°6 45°3 43°1 52°6 66-2 58:0 54-6 455 43°7 52°9 1876 64°r 59°5 52°7 45° 43°1 52°6 61-2 578 52:9 475 2 Neo 517 1877 640 59°5 52°7 45°4 43°2 52°6 65°8 60:9 54:3 43-0 36°1 531 1878 64°1 59°5 52°8 : 42°9 52°6 62°6 583 53-2 45-7 ee 40°5 50:0 1879 64°0 59°5 52°8 45°3 42°8 52°5 67°5 ‘ 63:0 49-5 44-9 41:8 533 1880 4° 59°6 52°7 : 42°7 52°5 60:5 58:8 50-7 50°6 ee 43°3 51°3 1881 64"0 59°6 52°6 : 42°8 52°5 64:9 59-1 53°8 44-6 Bae 38:6 53-2 1882 64'0 59°6 52°6 H 42°6 52°5 63-4 59°8 53-1 45°8 ee 44-5 524 1883 64°0 59°6 52°6 ; 42°7 525 66°5 61:7 53-1 458 hag 41-4 53-2 1884 64°1 59°6 52°6 45°5 42°6 52°5 61:2 58-0 48:2 45:4 43-4 51-4 1885 640 59°6 52° 45°5 42°6 52°5 63:5 59-5 54-9 : 48-1 38:3 51°3 1886 64°0 59°6 52°6 456 42°5 5255 64:8 586 50:6 44-4 41-2 52°9 1887 640 59°6 52°5 45°6 42°5 5 VOL. XXXV. PART 3. 2K 218 PROFESSOR ©. PIAZZI SMYTH ON Taste XXIIL—SCOTTISH COUNTRY ANT TOWN STATIONS, METEOROLOGY OF. Mean Minima or TEMPERATURE. January March June, July, Year, Obsd. | eans Hae, Opsd. | Sfeane, | OP | Steams, | O%4 | Steams 1856 | 30°7 46-1 48-0 1857 | 31°6 48-8 51:0 1358] s46 | > a EN Seer: 27> Te eee i859 | 343 | > _ ae 4 | 436 po mee |e 32°9 34°6 41°6 48°6 49°8 1860 | 31°5 46-4 50-1 1861 | 32:2 = ae a 50-4 pr oe eae 1862 | 34:8 soa a TN ae we 47-2 Be iaaleeah to” a 42) joy | 49? eee 1864 | 31:6 cole a #° | 48-6 pee 458 ule pe 32'9 34°3 42°0 47°9 49°3 1865 | 30:0 48-5 50°5 1866 | 35:0 age iss v1 432 ee 95 Wen elite 32°8 33°9 41°9 are 48°0 see 49°5 1868 | 33-0 | > 9 EN 49 | eg | CO ree ee 1869 | 36-4 ae ae | ape: | 2 serene 32°7 33°7 41°7 47°7 49°7 1870 | 31:8 48-2 51°8 Me on 32°6 33°7 41°8 45-8 47°7 50:7 49°8 vee Nee 324 33°8 418 48-9 47°6 51D 49°9 1873 | 24:7 oo o OT a3 yoo 505 eae 1874 | 35:5 ms 7 a apa | “7 oie ieee 32'8 34°2 41°5 47-5 50°L 1875 | 34:9 460 48-7 1876 | 34-4 oe ‘a 7 1 ea 7 > | coe eee 1877 | 328 | > iad 40 1 ary 1-44 soe is78 | 332 | 2° a 7S | ars | 7S ie ee 1879 | 25-8 | °° i 1 apa | 4 eee eee 32°7 33°9 414 47°4 50°I 1880 | 32:0 46:3 49°5 eal eto 32°7 33°9 441 ise | 473 op (Pons 1882 | 36-7 es =. 4 | ae | 7" I coos ‘sat Fb 32°4 33°9 aP4 4) Ges, | | 472 Pi 50°0 iss4 | 95:3 | >? ae 31 apo | “7? 1 epee 32°6 33°8 41°3 471 50°0 1885 | 31°6 45°3 48-7 1886 | 29:1 ae a ee Lae | 7° TE eee 1887 | 33:0 re di ea od sia ae 32'5 33°7 4U'z 470 50°0 MEAN SCOTTISH METEOROLOGY. 219 Taste XXIL continued—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Mean Minima of TEMPERATURE, August. Obsd, Succes, Means. 59°9 50°2 50°5 50°4 50°2 49°8 49°7 49°6 49°7 49°8 49°7 49°7 49°8 49°7 49°7 49°7 49°8 49°7 49°7 49°8 49°8 49°8 49'7 49°7 49°7 49°7 49°6 49°6 49°6 45°6 45°9 44-2 46:2 47-2 45°6 43°2 47-7 44-7 47°+4 46:0 44°5 45°8 46:7 43°6 44:9 44°5 September, 46'5 46°4 46°4 46°3 46°3 46°3 46°3 46° 46'2 461 46'2 46°2 461 46°I 46°1 46°0 46'0 46'0 Obsd. 43°4 43°9 387 39°8 40°6 43°7 40°7 41°5 40°2 39°9 43:0 40°4 38°4 41:7 39°9 41-2 40°2 87°9 39°9 41°9 45:0 40°5 43°5 38°8 35'3 389 42-2 39°7 40°7 36°6 44-1 375 October. Succes, Means, 43°6 42°0 41°3 44°7 412 41'I 41'I 41'I 410 40°8 410 410 41'I 40°8 4°°7 40°8 40°7 40°7 November, December, Succes, Succes, ts Means, cE Means, 34:7 33'3 391 40-7 36°9 37°0 34°6 35°7 30°1 36°6 34°2 29°6 35°6 34°8 35°1 30°1 35'5 4 33°1 33°2 Be id 35°1 33°8 316 37°4 34°6 34°3 38°2 35°9 35°71 34°75 35°6 35°6 35° 34°6 360 38°7 3572 35°0 36°2 35°8 35°3 351 36°4 B42 354 35°70 34°6 36°2 35°3 3571 35°2 29-9 35°3 34°7 33°7 28°7 35°2 34°3 33°7 33°0 B52 342 36°5 341 35°2 3472 36-1 37°7 35°3 3474 36°3 25°2 35°3 33°9 34-1 34°3 35°2 34°0 35°9 36°3 35°3 34° 375 34°6 35°4 34° 33°0 25°3 35°3 BBIY/ 35°3 28°9 B53 33°5 32°1 31°4 35°2 33°4 39°4 33°3 35°3 33°4 33°6 28°6 35°3 33°2 35°0 34:3 35°2 33°3 34°6 320 35°2 33°2 35°2 33°1 35°2 33°2 37°5 27-7 5. 33°I 34°8 23 311 3573 33°0 Mean Month of Observed | Means of the Successive Year Quantities in | Accumulating | repeated. each Year, 39°6 42-2 Years, 40°9 40°7 40°6 40'2 40°4 40"4 40°4 40°3 40°3 40°3 40°3 40°4 40°4 40°3 40°3 40°3 40°3 40°3 40°3 40°3 40°3 40°3 40°2 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 220 January. F PROFESSOR C. PIAZZI SMYTH ON ACCUMULATED RAINFALL. May. Taste XXIII.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. June. Means, 2°38 2°77 2°98 ft 4°21 Se 3°08 4°56 3°09 ae 32 3°33 6:20 ee 2-84 3°94 3°82 3°73 5°31 he 4-74 3°94 5°53 ie 4°85 ae 4°18 3°08 2°74 a 6°48 tae par |b 4:02 nae 4°22 5°63 84 4°29 6°96 Ae 4-01 4°35 1°84 4°33 4°23 2°02 1:30 os 3°41 eu 4°48 sae a 4'02 4/09 2°93 4°42 ie 3°25 ay 4°03 Obsd. ebruary. March, Successive Successive Means, Obsd. Means. 5:94 7°25 500 6°60 6:06 4°70 6"42 11°77 5°42 7°76 10°77 : 8°36 5°79 1151 3} 5°89 8°88 10°83 6°08 9°16 10°68 6°39 9°35 10°55 6°42 9°48 8°69 6° "40 PAGS; dae 67 97 S 10°09 % 68 "76 : 14°50 ; 7°10 Io‘'I2 10°23 7°23 10°13 8:21 7°21 I0"00 9°64 2x 98 g 14:02 a3 “42 10'22 Ae 9°14 38 10°16 13 8°55 7°30 10'07 9:03 7°30 I0"02 12:27 7°29 10°13 13°66 7°46 10°29 8:02 7°40 10°19 7°56 7°27 10'08 8:32 7 22 I0‘O1 8°58 7°14. 9°96 10°78 712 9°99 10°98 ary 10'02 12°88 7°26 Io'I2 9°81 7°26 Io'1L 9°37 Z 10'O! 7 23 7-59 9 717 10’00 April. Successive Obsd, Means, 8°38 9°63 9'00 792 8°64 14:97 10°22 11°95 10°57 12°55 I0"90 13°82 II‘32 13°95 Ir‘65 12°12 IL'7O 9°63 II"49 14°65 11°78 14°52 I2'Or 17°81 12°45 12°22 12°44 9°79 12°26 13°72 12°35 16°16 12°58 9°84 12°42 10°82 12°34 10°44 12°24 15°38 12°39 16°62 12°59 9°73 12°46 9°45 12°34 11°69 12°31 9°74 I2‘21 13°87 I2"27 12°86 12°29 14:19 12°36 12°37 12°36 11°35 12°33 9°64 3 12°24 Means, Obsd. 14°71 14:08 13°09 17°30 18°47 16°47 21°70 19°53 16°67 13°74 17:86 19°46 21°46 15°74 14:31 16°91 24°64 14:27 14:06 15°61 19°41 23°09 15:90 15:99 14:98 15°45 19°71 17:04 18:07 17:04 16°50 11°99 Successive Means, MEAN SCOTTISH METEOROLOGY. 221 Taste XXIII.‘ continued—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. ACCUMULATED RAINFALL. July. August, September. October, November, December. Year ee repeated, oma. | Ssetenr*| oma. |Sisseir=) oma, |Sseemire| ons. |Sueie] ones, [Suzemire] ome, |Syzer® 17:26 20°72 25°36 26°79 28°91 33°00 1856 16°25 18:12 21°94 24°30 27°19 30°56 1857 17-40 i: 20°01 ag 22°81 ee 27°53 ae 29°91 a 33°91 aT 1858 20-06 ta 22°33 oy 25°54 Fda 30°14 —- 33°51 sa 3717 Ay 1859 17°74. 20°30 23°91 27°19 29°88 33°66 20°29 24:08 26°00 31:14 33°97 37°88 1860 20°41 eg 26°85 ay 82°12 ae 35°46 2? 42:09 ao 45 ‘07 Sart 1861 1861 22°02 25°63 29°23 32°60 36°26 25°57 28°92 31°36 37°68 40:09 45-29 1862 20°25 a 24°75 i 29°47 ae 33°58 aoe 37°10 oo 42°11 ae; 1863 19-04 Oe 20°70 ‘ae 25°31 ae 30°78 sie 34°87 rie 38°58 ae 1864 19°61 22°94 26°66 30°82 34°18 38°17 16°83 20°72 21°86 26°97 30°26 33°91 1865 ree) | aco | asa | son] 2 | ope | 87? fae | 7791 secs 23°84 ie 26°66 ca 29°83 es 34°12 aon 35°37 aye 38°52 a 1867 22°16 ig 27°34 ey 30°68 a 34°39 Sr 37°01 at 43°03 a 1868 17°36 he 18°68 ey 24°60 oo 27°60 ee 31°88 et 36°54 sat 1869 19°84 23°20 26°87 30°90 34°16 38°36 16:19 17:74 21°06 25°69 28°27 31°81 1870 21°07 “i 23°99 ri 26°56 F tag 30°02 a 33°43 aie! 37°19 ag 1871 28:23 Oe 32°12 at 38°06 7 42°81 ie 48°82 ee 54°15 a 1872 18°84 ig 23°05 c. 27°41 : ie 82°88 as 36°20 a 39°33 oak 1873 17-17 . 22°71 ce 26°89 ain 32°94 seh 37°43 one 40°17 a3 1874 19°96 23°39 27°17 31°42 34°87 38°93 18°51 21°48 25°82 30°54 35°41 39°08 1875 21°67 ei 25°40 at i 28°96 ges 33°73 a 87°31 oe 44°88 ce 1876 27°40 oe 33°75 or 35°87 F aie 41°19 Se 47°26 pao 51°83 se 1877 17:02 a 20°98 a 25°60 . 30-06 ae 33-97 Sat 36°28 aks 1878 21:02 “oa 25°50 ne 29°49 ce 31°46 oat 33°73 oe 36°43 ce: 1879 20°20 23°82 27°58 31°83 35°39 39°51 18°67 19°53 23°21 25°74 30°77 34°73 1880 19°61 aa 23°94 ‘oh 26°95 aie 30°46 a 35°67 a 39°54 ae 1881 24°38 | 27-09 er 30°72 . 34°34 sis 39°76 a: 44-92 re 1882 20°82 eo 24°93 Pe 28°19 a 32:23 ae 36°82 Bae 40°38 oe 1883 22°81 aa | 25°28 a 28°00 Gs 31°46 ou 34°86 ae 39°44 is 1884 20°38 23°87 27°55 31°66 35°42 39°56 18.69 21:39 26°71 29°99 32:53 35°42 1885 19-89 ai 21°95 ak 25:91 rhe 29:90 ee 33°77 Bees 37°93 SB 1886 14:96 om 17°68 ae 21°51 <7 23°90 no 27°66 ie 30°96 de 1887 20°15 23°55 27°29 31°32 35°05 39/12 VOL. XXXV. PART 3. 21 222 PROFESSOR C, PIAZZI SMYTH ON Taste XXIV.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Usrerunt PLant-GrowtH TEMPERATURE IN EACH MoNTH BEING THE Excess OF MEAN TEMPERATURE ABOVE 42°-0 F. x 1vto Number or Days In nAcH MONTH (TO EVEN DEGREES ONLY), January, February, March, Succes. Succes, Succes, Obsd. Acbaris, Obsd. chen Obsd, MGRtN) — 239 - 70 —195 - 76 — 84 -174 — 42 MEAN SCOTTISH METEOROLOGY. 223 TABLE XXIV. continued.cSCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Ussrut Puant-GrowtH TEMPERATURE IN EACH MontH BEING THE Excess oF Mean TEMPERATURE ABOVE 42°-0 F.x1nto Numper or Days in Each MontTH (TO EVEN DEGREES ONLY). August, Succes, Obsd. Means, +468 +558 +51 +493 +506 +490 +502 +384 +479 +477 +478 mee | +472 +425 rf +466 +384 +457 + 437 + 4.403 455 +450 +477 +452 a | + +437 7 +456 +496 +458 +524 2 +462 +450 +462 +446 +461 +431 +459 +499 +461 +490 +46 mage | +460 +515 +462 +434 +461 +539 +46 pane | +460 +474 +461 +440 +460 +508 +462 +360 +458 ag | +458 +446 sf +457 September, Succes, pent Means, +267 +423 +345 +375 +355 +309 +344 +246 + 32. +351 aes +328 +342 +330 +248 3 +320 +312 +319 +480 +335 + 282 2 +330 +342 2 +331 +336 +33£ +351 +333 +348 +334 +306 +332 +285 +329 +282 +327 +324 +327 +372 +329 +294 +327 +255 +324 +369 +326 +285 +324 +396 +327 +312 +326 +294 +325 +324 +325 +366 +327 +264 +324 +306 +324 +285 +323 October. Obsd. +211 +236 + 90 +118 +124 +232 +158 +149 +118 +124 +205 +136 + 87 +164 +133 +161 +118 + 71 +140 +155 +242 +146 +214 +124 + 12 + 87 +186 +136 +152 + 12 +232 + 65 Succes, Means. November. December, Succes, Succes, Obed Means. ERS Means, — 69 —127 + 51 + 90 = %) - 18 — 78 — 65 = 32 — 34 — 78 — 248 — 44 — 88 — 8&7 — 245 — 52 —119 —105 —124 — 61 — 120 —147 6 fa — 104 + 33 37 — 60 -— 95 — 33 81 ai SY/ — 94 - 18 + 28 = 253 — 82 — 24 43 — 50 — 78 - 12 99 SA, — 80 — 84 43 = Go) EH. 2x48 : — 220 = Ee) = 87 — 87 — 264 — 2 = —102 > —124 ie - 56 — 100 — 21 -—115 - 3 — 101 — 24 22 + 16 = 52 = 95 = Oy : —344 — 51 — 108 — 84 — 96 — 52 —107 — Bye : — 62 = Fe — 105 + 15 — 84 = —10 sig | (| 850, : -— 52 -II — 45 — 226 ; — 51 — 120 —105 —167 — 54 — 121 seg! ee | ets — 48 —12I — 87 — 260 - 49 —126 = oAg — 81 - —125 — 54 us —164 - 50 —126 — 51 -118 = 50 —126 + 24 —279 — 47 — 131 — 72 —183 — 48 — 133 Mean Month of Observed Quantities in each Year, +113 +185 +142 +148 ar Cd +149 +127 +149 +109 +152 +133 +114 +172 +134 +128 +134 +149 +134 +138 +151 +143 +118 +146 + 58 +185 + 82 +148 +121 +144 + 88 + 90 +122 Mean Month’s Successive Means of the Accumulating Years, +149 +147 +147 +133 +136 +134 +136 +133 +135 +135 +133 +136 +136 +135 +135 +136 +136 +136 +137 +137 +136 +137 +133 +133 +131 +132 +131 +132 +130 +129 +129 1880 1881 1882 1883 1884 1885 1886 1887 224 PROFESSOR C. PIAZZI SMYTH ON Taste XXV.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. PROGRESSIVE ACCUMULATIONS OF EACH KIND OF USEFUL PLANT-GROWTH TEMPERATURE, BOTH ABOVE AND BELOW 42°, FROM THE BEGINNING TO THE END OF THE YEAR CONTINUOUSLY. | Year.) Below 42°. Ob. 1856 | — 239 1857 |—195 1858 | — 1859]-— 74 1860 | — 202 1861 ]-177 1862 }—112 1863 |— 108 1864 ]-180 1865 | — 229 1866}— 81 1867 }— 316 1868 | — 140 1869}— 50 1870 |—189 1871 | — 254 1872}— 93 1873 |- 1874}— 46 1875}- 71 1876}|-— 87 1877 | -—136 1878 }—124 1879 |—341 1880 j-161 1881 | — 428 1882}— 22 1883 |—115 1884}— 53 1885 |— 189 1886 |— 245 1887 |— 140 January. — 159 — 162 = 155 — 149 —152 — 160 — 153 — 166 — 164 —156 —158 — 164 — 160 —156 —150 — 146 — 143 —142 —I5r —I51 — 162 —157 —155 — 152 — 153 — 156 Above 42°, February, Below 42°. Su. Mn. — 290 —279 — 238 —278 — 272 = 257) — 241 — 262 — 281 —276 — 281 —271 —256 — 264 — 265 —256 = 257) —251 — 250) —249 — 247 — 242 —256 — 252 — 267 —258 = 255 —250 —252 —258 — 257, Aboye 42°. March, Below 42°. | Above 42°, Su. Su. Ob. | wm, | 9+ | on. en Bey oe a mee — 358 - — 74 i — 336 3 - = 361 = -—116 +31 — 300} +8 — 546 - — 349 +6 —275 are ae — 337 + _ 995 33 f 5 = I + =ygd\e > 4:28) — 306 3f | ea (Me = 318)5) sage — 602 - — 361 +6 — 353 - — 361 at —513 3 - ° - + “year 2A lyon) 3 — 356 +6 —183 se - — 344 +6 — 457 - — 351 +6 — 282 a +19 - - +6 _129 347 2 = — 334 +6 — 343 33 - + — 334 +6 — 186 33 40 = — 324 +8 — 293 - = — 322 dt “a7 ee = — 25 + —318 8 - 4 = — 324 +6 —191 3 - ~ — 319 +6 —705 - os 330 +6 —195 - = — 329 +6 —793 - * — 347 +6 — 22 +39 ° Sih Te —349 wen ° — 335 +6 —165 - co) — 330 +6 — 389 - ° — 332 +6 —601 2 - ° — 340 +6 — 309 - ° — 339 +6 Above 42°, June. Below 42°, 374 Aboy +554 +725 +793 61 +776 e 42°, MEAN SCOTTISH METEOROLOGY. 225 Tasne XXV. continued.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Procressive ACCUMULATIONS OF EACH KIND OF UseFuL PLant-GrowtH TEMPERATURE, BOTH ABOVE AND BELOW 42°, FROM THE BEGINNING TO THE END OF THE YEAR CONTINUOUSLY. August. September. October, November. December. Below 42°. | Above 42°. | Below 42°. | Above 42°, ] Below 42°. | Above 42°, | Below 42°. | Above 42°. | Below 42°, | Above 42°, | Below 42°. Above 42°, Suc Suc, Suc, Sue, Suc Suc, Suc. Suc. Sue, Suc, Suc, 0b. | iin Ob. | ym. | OP | ae. | OP | am. | OP Mn. Ob. | ym. | OD- Mn, Ob. | yn. | OP: | wn. | OP | ym. | OP: Mn. —390 +1000 —390 +1468 —390 i +1735 — 390 +1946 —459 +1946 — 586 +1946 —358 +1221 — 358 +1779 —358 +2202 — 358 +2438 —358 +2489 — 358 +2579 — 374) +1110 — 374 +1624) — 374 +1968 — 374 +2192) — 408 +2218 —472 +2262 — 336) : +1227 —336 : +1720 — 336 +2095 — 336 +2185 — 414 +2185 479 : +218 — 361 +1149 — 361 +1656 — 361 +2011, = 36n +2190 — 410 +2207] — 47. +22 -119 " +1303 -119 +1793 —119 +2102 —119 +2220 —197 +2220 445 is 22) a — 301 +1188) — 301 +1690 — 301 +203 — 301 +2197 — 357 +2210 — 467 +2232) -561 +1058 —561 +1442 —561 +1688 —561 +1812 — 648 +1812 893 +1812 —353 +1162 — 353 +1640 — 353 +196 — 353 +2120) — 415 +2130 —552 +2148) -275 +1237 —275 +171 —275 +2065 —275 +2297 —380 +2297 504 +2297 : — 340) DL, — 34 +1653 — 340 +1981 — 340 +2150) — 409 +2159) - +21 —295 +1038 — 295 +1472 — 295 +1814 — 295 +1972 — 442 +1972 448 a +1972 a wees) +1155 > 333 +1627 mess) +1957 w333 +2124 Sau +2132 = 589 +21 -130 +1102 —130 4 +1527 2 — 130 +1770 —130 +1919 —130 +1952 167 7 +1952 ay — 308 +1148) — 30 +1614 — 308 aa! — 308 — 378 +210 — 48 +2120 — 566 : +1169 — 566 +1553 — 566 2 +1865 sy — 566 : +1983 — 599 : +1983 7 680) +3 +1983 EE +IISt = SEY +1608 = 337 + 1926 = BEY) +2086 — 403 +2095 — 507 +2105 — 602 +1372 — 602 Ss +1809 — 602 +2289 — 602 +2413 — 620 +2413 620 +2441 — 363 +1173 — 363 +1628 — 363 + 1962) — 363 +2118 — 425 +2127 —518 +21 —353 2 +1128 — 353 EB +1531 : — 353 +1813 — 353 +2018 -377 +2018 420 +2018 a — 362 + 1169) — 362 +1619 — 36: +1949 — 362 +2109 — 420 +2117 —50 +2128 -513 +1035 —513 +1512 —513 +1854 —513 +199 — 525 +1990 624 +1990 —375 +1158 — 375 +1610 —375 +1941 =375 +2099) — 429 +2106 —519 +2116 -152 +1414 — 152 +1926 ze — 152 +2262 —152 +2349 —236 +2349 279 +2349 — 358 oF 8 + 1634 —35 + 1966 — 358 +2119 Saray +2125 — 500 +21 ~183 +1112 ad — 183 +1900 — 183 +206 —231 +2064 451 +2064 H — 345 +162 — 345 +1961 — 345 +2115 — 401 +2121 — 497 +2129) — 457 +1365 ; — 457 +2209 — 457 +2342 — 544 +2342 808 +2342 — 353 I — 353 +1978 — 353 +2130 —4I1 +2135 —517 +21 299] | t1120 «| 282___ 2960), [282] °” [+2 7-384 1 50s) 421) — 34 apes — 348 +1976) — 348 +2129 — 409 +213 —517 +2141 -122 +1192 Z — 122 +1927 —122 +2045 —148 5 258 +2045 me a55 + 164. — 33 +1973 = 335 +2124 — 393 +2129 — 502 +2136 — 343 +1165 : —343 +1893 — 348 +1964 — 367 1964 367 +1980 3 — 335 +1642 —33 +1968 = 81815) +2115 — 39 +2120 — 494. +212 -136 +1262 — 136 +2017 —136 +2157 —163 2 507 +2157 di |-325 +1645) — 325 +1971 — 325 +2117] — 380 +2122 — 495 +2129 — 293 +1264 — 293 +2135 — 298 +2290 =377 +2290 473 +2290 =323 +1650) —323 +1979 — 323 +2126) — 380 +2130 — 494 +2137 -3871 : +1163 is -371 +1947 —371 +2189 — 410 472 +2189 ‘ — 32 +1651 — 326 +1978 — 326 +2129 — 381 +2133 — 493 +2139) —336 - + 957 Z — 336 +1618 —336 +1764 — 336 +1779 420 +1779 — 32 1638) — 326 +1961 — 326 +2112) — 379 +2117 —489 +212 =191) +1309 —191 +2193 —191 +2407 —311 +2407 661 +2407 | — 320 +1646) — 320 +1971 — 320 +2125 — 376 +2129} — 497 +2135) -735 + 863 —735 +1582 —735 +1706 —780 +1706 — 1006 +1706 T7SEYA +1631 — 337 +1955) = 337 +2108 — 393 + 2112 —518 +2117 -195 +1141 —195 +2076 —195 +2088 — 300 +2088 467 +2088 — 332 163 — 332 +1960 — 332 +2107 — 389 +2r11 — 516 +2116) ~ 798 , +1049 Bal 793 +1717 -793 +1804 -793 +1894 908 +1894 — 350 +1 —350 +1951 — 350 95) — 405 +2102 — 531 +2108 ~ 2 +1130 : — 22 +1898 — 22 +2084 —109 +2084 369 +2084 ~ 337 +162 997 +1949 = 337 9 — 394 +2102 = 525 +2107, -349 +1034 — 349 +1798 — 349 +1934 —397 +1934 478 +1934 16, T2216) tose] I 165| 2a otto © |-219) | 42ri0l | seat 3) eanto| 9") = - - + = +4 + — 332 +1617, — 332 +1944 — 332 paee — 388 +2096) —519 +2101 — 389 + 984 —389 +1608 —389 +1620 — 440 +1620 558 +1620 moss +1608 — 334 +1933 — 334 +2074) — 390) +2080 — 520 +2085) ~ 601 sor Oo 170 -601 +1939 Sc 880 +1963 - +1601 -3 +1925 — 342 +207 — 39 +2077 — 532 +2081 —309 +1227 —309 +1958 —309 +2023 —381 +2023 564 +2023 1887 ~ 341 + 160. —341 +1926 — 341 +2068 — 396 +2075) — 533 +2079 YOL. XXXV. PART 3. 2M PROFESSOR C. PIAZZI SMYTH ON Taste XXVI.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Fina ACCUMULATIONS, MADE GOOD ON THE WHOLE, OF Usrrun PLANT-GRowTH TEMPERATURE FOR EACH MonTH FROM THE BEGINNING TO THE END OF THE YEAR CONTINUOUSLY. 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 January Successive Obsd Means, — 239 —195 —217 — 84 73 — 74 — 148 — 202 = —159 -177 — 162 -112 —155 —108 — 149 —180 —152 — 229 — 160 - 81 = Ss} -—316 — 166 —140 — 164 - 50 —156 —189 —158 — 254 — 164 — 93 — 160 -— 8&7 —156 -— 46 —150 - 71 — 146 — 8&7 —136 — 143 —124 — 142 — 341 —I51 -161 —I51 — 428 — 162 — 22 : 257 —115 255 — 53 —152 —189 —153 — 245 —156 —140 February. March, April. Successive Successive Successive Obst Means, ees Means, pea. Means, — 309 —390 — 321 -271 — 358 —337 =290 5374 — 329 — 258 — 336 — 282 : -279 — 362 — 313 —116 — 8 — 88 : — 238 — 292 — 257 — 434 5 — 546 —561 -27 — 343 — 318 — 247 —275 -173 ead mek — 294 —165 —295 —217 — 257 — 32 — 283 —130 — 102 — 30 — 241 — 298 — 251 — 426 — 566 — 443 — 262 — 328 —272 — 456 — 602 — 467 — 281 — 356 — 292 — 229 Z — 353 — 293 — 27 =S55 = 292 — 333 —513 — 414 — 281 — 368 — 302 —152 —127 = nn —271 3152) =279 — 53 — 183 — 36 —256 — 338 — 262 -—379 é — 457 y —310 — 264 — 34 — 265 — 282. — 263 — 248 — 265 — 341 — 26, —116 —122 — 26 ‘ —256 — 328 — 250 i) — 343 — 259 — 257 =e — 251 —136 — 96 + 45 — 251 — 316 — 235 —231 — 293 — 158 —250 —31 — 231 _ 935 5 315 3 — 249 — 206 247 —138 : —242 — 565 —256 -170 —252 — 641 — 267 —- 14 —258 -163 —2 —134 4 —250 — 287 —252 — 455 —258 — 204 —256 May, Obsd Successive Means, -175 — 95 35 — 50 +219 —807 — 82 + 47 — 60 + 65 — 42 +175 —195 ee} -191 — SI -110 : = 56 —244 — 72 +284 — 44 + 60 ae tsi/ — 46 — 38 + 9 = 35 +141 — 24 -107 +203 +143 eke) June Successive oie Means. +164 +367 +266 +457 +32 +657 si +411 + 23 +334 +503 od + 362 +377 +36. +535 pre +38 +147 i +359 +262 +349 +318 3 +346 +125 6! +328 +692 +356 +393 +358 +362 +358 +351 2 +358 4-534 > + 368 +310 +365 +587 3 +377 +503 +383 MEAN SCOTTISH METEOROLOGY. 227 Taste XXVI. continued.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Finat ACCUMULATIONS, MADE GOOD ON THE WHOLE, oF UsrruL Puant-GrowTH TEMPERATURE FOR EACH MonTH FROM THE BEGINNING TO THE END OF THE YEAR CONTINUOUSLY. July. August. September, Successive Successive Successive Obed. Means. ore Means. ON Means. + 610 +1078 +1345 + 863 +1421 +1844 + 736 +1250 +1594 + 891 +1384 +1759 + 788 +1294 +1649 +1184 +1674 +1983 + 887 +1389 +1733 + 497 + 881 +1127 + 809 +1288 +1612 + 962 +1439 +1790 + 834 +1313 +1641 + 743 +1177 +1519 + 821 +1293 +1624 + 972 +1397 +1640 + 840 +1306 +1626 + 603 + 987 +1299 + 814 +1271 +1590 + 770 é +1207 +1687 + 810 +1264 +1599 + 775 +1178 +1460 + 806 +1257 +1587 + 522 + 999 +1341 + 783 +1235 +1566 +1262 +1774 +2110 + 820 +1277 +1608 + 929 +1366 +1717 + 827 +1283 +1616 + 908 +1404 +1752 + 833 +129 +1625 + 838 +1362 +1668 + 833 +1296 +1628 +1070 +1520 +1805 + 847 +1309 +1638 + 822 +1268 +1550 + 846 +1306 +1633 +1126 +1557 . +1881 + 860 +1320 +1646 + 971 Ee +1470 +1842 ate +1327 +1656 4- 792 ae +1282 +1576 : + 862 +1325 +1652 + 621 F +1027 +1282 : + 851 +1311 +16 +1118 a +1633 +2002 3 + 863 +1325 +1651 + 128 + 562 + 847 : + 832 +1294. +1618 + 946 : +1485 +1881 + 837 +1301 +1628 + 256 5 + 612 + 924 + 815 +1275 + 1601 +1108 +1582 +1876 + 825 +1286 +1611 + 685 +1125 +1449 + 820 +1280 +1606 + 919 +1427 +1793 + 824 +1285 +1612 + 595 an + 955 +1219 + 81 +1274 +1599 + 360 5 + 800 +1106 Or +1259 +158 + 918 +1364 +1649 = + 805 +1262 +1585 October. Obsd Successive ‘ Means, +1556 +2080 +1818 +1849 +1828 +2101 +1896 +1251 +1767 + 2022 +1810 +1677 +1791 +1789 +1791 +1417 +1749 +1811 +1755 +1665 +1747 +1477 +1725 +2197 +1761 +1881 +1770 +1885 +1777 +1829 +1780 +1923 +1789 +1621 +1780 +2021 +1792 +1997 +1802 +1818 +1803 +1428 +1786 +2216 +1805 + 971 +1770 +1893 +1775 +1011 +1746 +2062 +1757 +1585 +1751 +1945 +1758 +1231 +1740 +1338 +1727 +1714 +1727 November. Successive Obsd. Means, +1487 +2131 +1809 +1771 +1796 +2023 +1853 +1164 +1715 +1917 +1749 +1530 +1718 +1822 +1731 +1384 +1692 +1793 +1702 +1641 +1697 +1465 +1677 +2113 +1711 +1833 +1720 +1798 +1725 +1727 +1725 +1902 +1735 +1597 +1728 +1994 +1742 +1913 +1750 +1779 +1752 +1443 +1738 + 2096 +1753 + 926 +1719 +1788 +1721 +1101 +1698 +1975 +1708 +1537 +1702 +1891 +1708 +1180 +1690 +1362 +1680 +1642 +1679 Obsd. +1860 +2221 +1706 +1775 + 919 +1793 +1524 +1785 +1303 +1821 +1598 +1366 +2070 +1618 +1534 +1603 +1787 +1613 +1650 +1817 +1717 +1359 +1746 + 700 +1621 + 986 +1715 +1456 +1727 +1062 +1083 +1459 December. Successive Year repeated. Means. 228 PROFESSOR C. PIAZZI SMYTH ON TaBLE XXVIa.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. February. March, April, May. June. 1857. Min. Max. Max, Min. Max, Min, Max, Min. Max, Min, Culloden sapil 93°7 111°8 24°5 | 114°5 271 | 122°; 30:0} 131°8| 31:1 Castle Newe . - - 105°5 14:0 } 101°6 21:0 | 115°0} 29:0} 1240] 28:0 Braemar . - = = = = = = = = = Barry - - - - - - 19:0 | 1040] 24:0] 120°:0} 31:0 Kettins . - - - - - - - - - - Perth 780 12:0 950 105:0 20°0 95:0 22:0] 106:0] 26:0] 1280} 34:0 Pittenweem - - - 66:0 - 78:0 - 85:0 - 106°0 - Nookton. - - 72:0 72:0 | 18:0 88:0 20°0 |} 103:0| 25:0] 118:0] 32:0 Millfield . 860 10:0 90:0 81:0 18:0 92:0 20'0 |} 1080} 25:0} 126°0] 35:0 Row 5 5 - ~ - - - 91:0 26:4 96:0} 29:0 | 115°8| 36:8 Moile House . - ~ - 80°7 29°5 84:0 | 29°7 |] 105°0| 34:0] 1215] 36:0 Smeaton - - - - - 100:0 22°0 } 112°) 28:5] 1380°0| 29-0 Thirlestane Castle . _ - 87:0 21:0 98:0} 28:0 | 138:0] 30:0 622°0 | 119°0 | 931°1 | 228°2 } 11551) 278°5 |1359°1 | 322°9 +7 +6 +10 | +10 | +11 | +10 | +11} +10 237°0 | 37:1 | 350°7 +3 +3 +4 84-1 +4 MEANS. “ 79°0 12°4 87°7 21'0 88'9 19°8 93° 22°8 | 105°0| 27°38 | 1236] 32°3 January. February. March, April, May. June, 1858. Max Min Max Min Max Min Max Min Max Min Max Min, Culloden 5 : ' A s 61:0 25:0 82°5 152 87:0 18°8 | 121°2 22.2} 119%) 32:4] 188:0) 41:2 Castle Newe . 4 é ° a 82:0 19:0 | 110-0 2:0 | 110-0 16:0 | 107°0 18:0 80:0] 27:0] 1280] 36:0 Braemar s : 6 5 539 15:0 60:1 6°5 75'8 131 90:2 16:2 85:1] 25°8 96:0] 380°2 Banchory : é . . : = = = ce = = = = = a = = Barry . A : 4 4 : 63°5 12°5 76:0 9:0 | 104°5 11:0 | 110°0 12:0] 115:0/ 23:0] 140°0| 386-0 Kettins . 3 5 & 5 = = = = = = = = = = = - Perth . : - 4 4 ° 81:0 19:0 880 12:0 | 102°0 11:0 | 112°0 20:0 | 109:°0| 23:0} 130°0| 35:0 Nookton 5 F 4 ‘ ‘ 53:0 13°0 65:0 10:0 860 12°0 | 101:0 14:0} 109°0) 19:0} 118:°0| 25-0 Millfield . F 5 : ; 5 750 11:0 950 10:0 82:0 7:0 | 103-0 10°0 93:0} 20:0] 101:0} 30:0 Otter House . : 6 6 ; = = = = = = = = = = = = Moile House . 5 3 : : 52:0 28:0 63:0 19:0 97°5 20°5 - 21°0 - 31:0 - 380 Auchengray . : 9 3 c = - - - - - - - - - 1180} 33:0 Paisley . : ° ; : : = = = = = = = = = = = = Smeaton 7 5 0 : > 79:0 18:0 91°0 13:0 | 1060 17:0 } 118°0 170} 115:0| 26:0] 122:0} 33:0 Thurston A . ; 3 - - - - - - - - 105°0 - 108:0 - Thirlestane Castle . 5 5 2 770 13:0 87:0 8:0 | 1170 6:0 | 124:0 14:0] 117:0} 25:0} 180:0) 33:0 677°4 | 173°5 | 817°6 | 104°7 | 967°8 | 1382-4 | 981°4 | 164°4 | 1047-7 | 252-2 | 1329-0] 370 4 +10 +10 +10 +10 +10 +10 +9 +10 +10 +10 +11 +11 Means. : 5 67°7 174 81'8 10'S 96'8 13'2 | I09'0 16°4 | 104°8] 25°2 | 120%] 337 January. February. March. April. May. 1859. a y P y June Max. Min. Max. Min, Max, Min. Max. Min. Max, Max, Min Culloden 52°7 21°7 62°7 22-1 70:0 20°1 80°3| 23:0} 101:0| 27:9] 103:8] 36:8 Castle Newe . 74:0 | 170] 75:0) 13:0] 74:0] 18:0] 85:0] 18:0] 103:0] 25:0] 106:0| 32:0 Braemar . 63°0 1D:2 62°1 11:0 66°2 18°8 74:2} 19:0 98'2| 23°57 113° ‘0 29°1 Banchory - - 78:0 | 170] 78:0] 185} 91:0] 105} 935] 18:0 24-0 Barry . 96-0 18:0 730 13:0 87:0 17:0 | 102:0| 16:0} 1250} 31:0 33°5 Kettins . - - - - - - - 17:0 - - 136-0 30°0 Perth 85:0 17:0 94:0 11°0 | 101°0 17:0} 115:0} 18:0] 180°0} 23:0} 185:0} 33-0 Nookton . 64:0 150 76:0 15°0 85°0 18:0 98:0] 15:0 - 20:0 | 115:0} 26°0 Millfield . 4 67°0 14:0 93:0 70 97:0 14:0 96:0} 13:0} 112°0| 20:0] 11770} 25:0 Otter House or Moile House . 64:0 190 SS = ee = 90:2} 26:5 a 3 - 420 Paisley . : - - - 23:0 74:3 19°5 89:0} 17:0] 108:°2| 23:0] 115:0} 28°5 Smeaton. 730 13:0 83:0 14:0 92°0 13:0} 110°0|] 16:0} 1150) 17:0} 112°0} 22-0 Thurston 5 64:0 ~ 74:0 - ~ - 82°0 - = = 2 Thirlestane Castle . 89°0 16:0 89-0 15°0 | 107:0 15:0 } 102:0|} 13:0] 128:0} 20°0 30°0 791°7 | 165°9 | 859°8 | 161°1 |] 931:5] 188°9° 1214-7, 222°0 | 1113°9 248°4 | 1277°3. 391-9 +11 | +10 7 +11 | +11 | +11 | +11 | +18 | +13 [| +10 | +11 +11 | +138 MEaNs 720 | 6°} 782] x46] 84'7| 17'2] 934 | x7'x} 1114] 22°6 MEAN SCOTTISH METEOROLOGY. 229 TaBLeE XXVIa. continued.c~BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. August, September, October, November, December. 1857. Max, Min, Max, Min. Max, Min Max, Min. Max, Min. Culloden 115°8| 37-0] 893| 355] 828] 28:0| 728| 258] 58:3| 29-7 Castle Newe . 122:°0} 32:0} 103:0| 36:0] 113:0} 27:0 94:0} 18:0 81:0} 27:0 Braemar - 21°2 90:0} 20:3 90:0} 10:0 90:0 4:0 79:0 9:0 Barry . 1160} 35:0} 105:0| 35:0 - - 80:0} 18: 65:0] 17:0 Kettins . 1290} 340] 1080} 34:0 - - = = = = Perth 113:0} 38:0} 112°0} 31:0 99:0] 23:0 83:0} 20:0 86:0} 21:0 Pittenweem 94:0 - 86:0 ~ ~ - 58:0 ~ 59-0 - Nookton . c 6 4 3 ; 113:0} 32:0] 1000} 30:0 83°0 | 22:0 - 14:0 59:0} 20:0 Millfield . b ‘ 5 3 . | 117:0} 3804] 115:0|} 34:0] 121:0} 30:0] 109°0} 22:0 88:0] 19:0 70:0} 23° Row 5 : : : 3 . | 105°8} 40:2 - - 1080] 40:0 95°8 || 33:7 ~ - - - Moile House . ; ‘ A . | 1010] 41:0] 114:0] 42°0 85:0} 39-0 77°0| 30°0 59:0} 28:0 - 33°5 Smeaton. ; r E : . | 128:0) 39:0] 125:0) 39:0] 123:0) 35:07 100°0| 28:0 85:0} 20:0 84:0} 25°0 Thirlestane Castle . 3 : . | 123:0] 35:0] 188:0} 35:0] 180°0; 30:0 - 103:0} 15:0 89:0} 19:0 1852°5 | 407-0 | 1294°8 | 379:2 | 1860°3 | 395°8 | 849°6| 223°7 | 812-8 1823 730°8 | 224°2 +12 +12 +11 +11 +138 +12 +9 +9 +10 +10 +10 +10 Means. C = |) Tt27 | 33i9))) 12777) ars || 10456)| “33°70 94°4| 24'°9 813 | 18°2 731| 224 July. August, September, October, November, December. 1858. Max, Min. Max, Min, Max, Min. Max, Min. Max, Min, Max. Min. Culloden. . . ~~. ~~. | 103-8 40-4| 1006| 401] 880| 322] 766| 272] 65:8| 127] 543] 248° Castle Newe . 7 3 ¢ . | 1020; 3880] 112°0) 33:0] 102:0} 30:0] 102°0| 25:0 68:0 7:0 66:0} 20:0 Braemar F , ; s 3 93:0] 31:2 90°8] 29°8 85:1] 26°5 75°4| 20:5 62°9 75 52°71} 22:0 Banchory 3 F , ‘ ° = - - - - = - - - - 57:0 - Barry . E é 5 . | 137:0| 37:0] 140°0} 33:0] 1382°0) 32:0] 109°0| 23-0 99:0] 16°07 100°0] 12:0 Kettins . 5 0 ; - . | 185:0] 36:0] 124:0] 35:0] 126:0} 30:0 - - - - - - Perth . . : ¢ es . | 1190} 35:0] 125:0| 34:0] 123:0| 29:0] 107:°0) 21:0 97:0) 11:0 85:0} 17:0 Nookton a b : 5 . | 11970; 30:0] 117:0| 27:0] 106:0} 26:0 - 17:0 74:0} 11:0 59:0} 11-0 Millfield . , c F F c 97:0; 23:0] 116:0] 26:0] 116:0} 26-0 97:0} 19:0 84:0} 14:0 80:0} 15-0 Otter House . 4 f : ‘ - 119:0} 39:0] 110°0} 35:0 96:0} 25:0 81:0} 21:0 60:0} 28:0 Moile House . ; . 5 : - 35:0 - 31:0 - 25:0 - = = - - - Auchengray . Fi 5 ‘ F - - - - - - - 7 - - - - Paisley . 2 i 5 5 : - - 106'2} 35:0] 104°5| 27°8 86:0} 24:0 - 13°0 530] 25-0 Smeaton. 0 : : : . | 119:0| 32:0] 118:0| 32:0] 1110) 28:0 92:0} 18:0 74:5 9-0 - 14:0 Thurston : : 6 a . | 100°0 - 107°0 - 110:0 - 81:0 - 75°0 - 63:0 - Thirlestane Castle . - : . | 180°0) 32:0] 185°0) 32:0] 127:0} 27:0} 117:0} 22:0} 102°0; 10-0 97:0) 16°0 1254°8 368°6 | 1510°6 425°9 | 1440°6 | 374°5 | 1039'0| 241°7 | 883:2) 132:2 | 826-4] 204°8 +11 +11 +13 +13 +13 +13 +11 +11 +11 +11 +12 +11 MEAns F ‘ | II4’r 33°5 | 1162] 32°38] rro'8| 2878 94°5 22'0 80°3 I2‘0 |. 68'9 18°6 September, October, November. December. 1859. Max. Min, Max, Min, Max, Min, Max, Min. Qullodn . . . . .| 990| 414] 91-9; 384] 984| 319] 856| 217] 705) 241] 540] 112 Castle Newe . : : . . | 105-0 360 |} 100°0} 35:0 87:0 29°5 86:0} 18:0 72:0 23:0 63°0 0-2 Braemar 3 ; 4 ; p 96-2 29:0 - - ~ - 80°5| 10:9 58:0 19:0 48:0 | -—7:0 Banchory 3 A 3 : . | 100-0 25:0 | 110°0} 26:0 94:0 20:0 | 100°0| 13°5 79:0 18:0 62°0 3°0 Bey c E A . P . | 126°0 35:0 | 124:°0| 34:0 7 118-0 27:0 99:0 9-0 94:0 15:0 79:0 10:0 ettins . 4 3 fi = = = = = = = = - - ~ - Perth . 4 P , 7 ; - ~ 134:0| 36:0 | 130°0 31:0 | 112°0| 138°0 92:0 16-0 81:0 4:6 Nookton : 4 fi 5 . | 1150 35°7 | 1100] 33:0 97°6 26°7 956} 14:7 64°6 18°7 486 | -6:0 Millfield h 3 ; é . | 1100 30°70 | 103:0} 32°0 - - 90:0} 10:0 72:0 17:0 72:0 5:0 Moile House . ’ : i 4 < Zs = ss = = a 2 = = = Paisley . 0 4 : ; «| L102 31:0 |} 102°0} 32:0 89:0 26:0 87:0} 11°5 66:0 16°5 53°0 30 Smeaton ae , 5 3 . | 1240 29:0 | 111°0} 31:0 | 103°0 21:0 | 111:0 6:0 81°0 9:0 67:0 1-0 Thurston | b : fs i - i Et ff, iy E Bs ss = = es ie Thirlestane Castle . A : : - 30°0 | 127:0] 32:0 | 115-0 27:0 } 111°0 70 88:0 130 71:0 6:0 985-4 | 3221 |1112-9| 329-4 | 932-0 | 240-1 | 1057-7| 135-3 | 927-1 | 1893] 698-6 | 30-4 a +10 +10 +10 +9 +9 +11 +11 +11 +11 +11 +11 MEANS : - | f09°5 | 32.2] 11173) 32°9 | 103°6 | 26'7 962 || 123} 761 | 2] 6355 2°8 VOL. XXXV. PART 3. ais 230 PROFESSOR C. PIAZZI SMYTH ON TaBLE XXVIA. continued.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. January, February. March, April. May. June, 1860, _——— Max Min Max. Min Max Min Max, Min Max Min Max, Min East Yell F , 4 “ + = - = = = - 77:2| 29°0 - ~ 1020) 41:4 Kirkwall 5 : F 4 5 - ~ - - - - - - - ~ - - Harris ‘ : : A 5 - - - - - - - 27:7 - 33°2 - 42:7 Stornoway . 3 - : = _ = = - = - 25:0 - 33°0 - - Culloden , 3 : ; 58:0 20°7 64°6 9°5 70°8 22°6 83:9] 22°9 91°4 28°9 87'1| 30:8 Forres . p , 3 ‘ , - - - - - - 93°2| 25°4 ] 101°0 30°7 | 1014] 34:8 Castle Newe . 4 A 5 ; 63:0 10:0 75:0 | —7°0 750 20:0 93°0| 22:0 | 103:0 26:0 89:0] 34:0 Braemar . . 5 F ‘ ~ - 52°8 | —8:5 - - - - - - 86:0] 24:8 Banchory . 5 : 5 : (fils) 13:0 86:0 2°0 81-0 16°0 88:0] 13:0 95:0 23:0 92:0] 28:0 Barry . “ 5 s ; 4 - - 87:0 8-2 | 109°0 18°7 | 125:0| 20-9} 118°0 31:7 | 114:0| 36:0 Kettins . A ‘ 5 : , - - = = - - - - - - ~ = Perth 3 ; : : ; 85:0 12:0 | 103°0 | —4:0 | 106°0 20°0 | 114°5} 20°0 - - 125°5) 32:0 Nookton : F : é ; 58°6 9°7 81:0 7:0 79°6 20°7 92°6| 14:7 | 1076 26°7 | 117°0| 27:4 Millfield . . . , 5 63°0 11:0 790 3°5 760 17°0 = - - ~ ~ - Callton Mor . 2 2 . 5 - 21°5 - 16:0 - 23°0 - 25°0 - 29:0 - 35:0 Oban ; P : A . 5 - = - - - - - - - - - - Paisley . 6 5 A 5 54°6 150 69°0 | -1°5 717 18°4 91:7 18°4 | 108°0 19°4 89°7 |} 33:9 Smeaton . r fs E - . 70°0 11-0 83°0 1:0 87:0 9°0 98:0 8:0 | 114:0 1770 | 108:0| 22-0 Thurston - js ; 4 ‘ 720 - 89:0 17:0 86°0 21:0 } 105°0| 25:0 | 118-0 - 1190] 35-0 Thirlestane Castle . 5 5 ; 84:0 2°0 98:0 0:0 | 109°0 10:0 } 120:0| 15:0 - 24:0 - 25°0 679°7 | 125°9 | 967°4 43:2 | 951'1 | 216-4 | 1182:1| 312°0 | 956°0 | 322°6 | 1230°7| 482°8 +10 +10 +12 +13 +11 +12 +12 +15 +9 +12 +12 +15 Means. . 68°0 12°6 80°6 3°3 86'5 18'0 98'°5| 20°8 | 106'2 269 | 102°6| 32°2 January. February. March, April, May. June, 1861. Max, Min, Max, Min Max. Min, Max, Min, Max. Min, Max. Min. East Yell - ‘ : : ; 61°6 - - - ~ - - = - - - - Kirkwall “ : : : : 515 180} 60:6] 22:0 67:0] 20:0 876) 2755 89:1) 28:0 - - Harris . : : ; : 5 646] 23:7] 77:4] 26:0 67°2| 29°7 82:2] 29:2 77°4| 31°2] 114°9|] 42:7 Stornoway . , ; : : = - - - 90°0| 25°5 87:0} 22:0] 89:0) 240} 97:0} 32:0 Culloden ; ° * 5 ; 63°7 131 64:7 | 211 74:0| 26°8 86:0} 22:6] 1075) 23:6] 1131] 3867 Portree . ; : : ° ° = - 67°6| 14:0 74:0} 24:3] 10270} 190] 113°0} 180] 1182) 34:0 Forres. - ; ; 2 5; 60°7 120] 706) 181 816] 25°5 97°38} 20:9] 107:0| 201] 1185] 28-8 Castle Newe . é 3 ’ : 68:0} -10:0} 72:0} 12-0 72°0| 28:0 95:0} 25:0 90°0| 25:0] 1060) 37:0 Braemar . . ; ; . 58°7| — 2:2] 57:3] 11:0 65°2) 23:0 89:2} 13°0 84:9} 13°5 95°5| 34:0 Banchory ; - - : - 80°0 80} 78:0 7:0 86:0] 18:0 89:0) 19:0 98:0) 19:0 99:0; 35:0 Barry . F : - : : 68:0} 125} 75:0} 12:0 89'°0} 25:0] 1100) 28:0} 10770} 21:2] 1180} 37:77 Kettins . : ; ; - - 6:0 - 12:0 - 23°0 = 20°0 - 23°0 = 36°0 Perth . : ; 5 : ¢ 770 4:0} 97:0] 10:0] 110°:0) 25:0] 124:0) 20:0} 128:0) 19:0] 135°0) 42:0 Nookton F A ; : 5 60:0 34 65°0| 134 78:0} 21:4] 112:0} 17-4] 1070) 15:4] 1140] 28-4 Callton Mor . : E 5 : 72°0 15°5 72:0} 20°0 74:5) 26:2 83°5| 24:0 84:0) 21:0 93°5 | 36:0 Oban. ; ; ‘ : ; 51:0 90} 59:0] 14:0 71:0} 24:0 88:0) 22:0 94:0} 19:0] 1080} 40:0 Paisley . : : . . 54°7 2°4 647] 11:9 73°7 | 27°4 92°77) 20-4 93°7| 17°5 99:7 || “4g Douglas Castle : - ” - ~ - - 86:2) 25:0] 108:0} 17:2] 10770} 13:0} 1105] 29:0 Smeaton ; , : : 4 69°0 - 90:0} 19:0 92:0} 22:0] 10870) 20-0] 111:0; 19:0] 1150) 37:0 Thurston ‘ : - ; ; 86°5| 11°5 92'0} 20:0 96:0} 25:5 | 105°0} 24:0] 110°0} 25:5] 121:0| 39:0 Thirlestane Castle - : : 68°0| — 7:0] 101:0 0:0 85:0} 20:0] 11270} 15:0} 112:0) 14:0] 1340] 31:0 Mungo’s Walls r 5 - - 65:5] 13°5 73°8| 22°8 94:4) 209] 1160] 187] 1216} 361 11150} 119°9] 1329-4 | 277-0 | 1606-2} 508°1 | 1953-4 | 447-1 | 2025°6 | 428-7 | 2132°5| 714°3 +17 | +16 | +18 | +19 | +20 | +21 | +20 | +21 | +20 | +21 | +19 | =20 MEANS, ; ° 65°6 75 73°9| 146 80°3] 24°2 97°7| 21°3] 101°3| 204] 112°2| 35°7 MEAN SCOTTISH METEOROLOGY. 231 Taste XXVIAa. continued.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. July. August, September. October, November, December, 1860. Max. Min, Max. Min, Max, Min, Max, Min, Max, Min, Max. Min, East Yell ; : - 2 A 93:2} 40°8 96°6 - 85:1 = 87:0 = 63°0 - = = Kirkwall : : : 0 ; - = 1020} 31:0 81:0} 23:0 76:0} 22:0 516} 22°0 46:0 18-0 Harris . . : ‘. b 6 = 42-2 = 43:0 = 38°8 = 33°6 94:4] 28-2 78°0 19°0 Stornoway . 6 : c 3 - - - - = = = = = 2 et i Culloden ‘ “ ; 3 ‘j 98°6| 39°8 - = 97:7 | 33°8 68°7| 25:2 59°8| 16°6 49°9 6:2 Forres. : 4 ; : . | 110-4] 3812] 104-2) 36:0] 1075} 35:1 69:7} 29°5 63°2| 18-7 52°0 15) Castle Newe . 5 b ¢ . | 1100) 37:0 99:0} 32:0} 1020} 31:0 91:0} 27:0 770} + 19°0 60:0} —19°0 Braemar 4 EC 0 F . | 1058) 31:0 91:0} 30°0 94:0] 25:0 73°8| 24:4 528 93 484] — 01 Banchory 4 5 ‘ c 4 94:0} 35°0 94:0} 26:0] 105°0} 22-0 88:0] 20:0 76°0 = 580) — 9:0 Barry . “ . 5 : . | 112:0|} 38:0] 125:0| 33°0} 115:0;} 27:0] 100:0) 21°5 79:0] 21:0 72:0 45 Kettins . : 4 > dj c - 37:0 = 34:0 - 26:0 - 20:0 - 13°0 - — 3:0 Perth . : c : : . | 188°5|) 40:0} 135:0| 37:0] 127°0| 18:0] 120°0} 21:0 93:0} 15:0 74:0} — 5:0 Nookton . : : - ; . | 1140] 36:4] 119:0) 32:4} 1050) 21-4 Sor Ou ee 69°0| 14-4 59:0] — 86 Millfield : : ; : = - - - - - - = = = = ZA Callton Mor . : c : : = 35°0 97:0} 33:0 - 29°0 = 25:0 800} 21° 90:0 8:0 Oban . C - 0 ¢ F - = - - = = = = = = 48-0 8:2 Paisley . “ : 7 : . | 109°7| 35°4] 115:0) 34:4 7 1100) 24-2 88:0} 20:0 717} 13-4 66:0} —11°0 Smeaton . ‘ : . | 1140) 27:0] J13:0} 260] 1080) 17:0 98:0} 13:0 82:0 9-0 65:0 - Thurston ; z : : . | 12270) 39:0] 128°0| 39°0 | 120°0| 32:5] 110°0} 25-0 97:0} 23-0 89:0 85 Thirlestane Castle . ‘ - : - 31:0 = 26°0 = 16:0 | 105°0) 21:0]° 95:0} 14-0 750 | —16°0 1322°2 | 582-7 | 1418°8 | 492°8 | 1357°3 | 419-8 | 1267°2| 365°6 | 1204:5 1021°3| + 8-2 +12 | +16 | +13 | +15 | +13 | +16 | +14 | +16 |] +16 29 |} 2 alge MEANS. . . | rro'2| 364] rog1|] 32°38 | 1044] 26'2 go’5| 22°8 753 63'8 0'5 July. August, September, October, November, December. 1861. Max. Min, Max, Min, Max, Min, Max. Min, Max, Min Max. Min East Yell P > - - = = = = = 86°5| 37°8 80:0} 33:1 = = = - Kirkwall ® ; 5 < . | 1026) 41:0 87°6| 37:0 = = = = = = = = Kallin . . 3 : - .f 1119] 41:2 - 39°0 - 35°2 83:4} 33°8 65:4] 29:0 539} 30:2 Stornoway . - c j 7 96:0] 33°5 92:0} 33°0 99:0} 305 77:0} 29°5 70:0} 18-0 67:0} 25:0 Culloden ; : A . 96°0| 39°7 88'°8| 38:8} 103°9| 34:9 76°7| 24:9 62°83} 138°6 58:9} 22°6 Portree . : 3 > : - | 1165) 30:0 93°99} 34:07 91:8} 265 81:3] 22°0 68:7) 13°5 685} 201 Forres. é : : : . | 1052} 36:0 98:4} 366 90°6 | 32:3 TA] | ALF 65:3} 21°7 67°3| 16°8 Castle Newe . : : f . | 101:0} 38:0] 102:0| 36°0 94:0} 25:0} 1080} 23:0 77:0} 10°0 79:0} 15:0 Braemar a ° c : : 85:0} 34:0 85:1} 32°0 80:0} 30°38 79:0} 24:0 72:0) 13°5 64 0; 14:0 Banchory fi 5 : 3 2 99:0} 32:0} 100°0|} 30:0 930} 23-0 92:0} 20°0 69-0 5-0 72:0} 15:0 Barry . a . r c . | 1210} 42°57°117:0) 41:0] 1160) 39:0] 101°0; 27:0 79:0} 17:0 65:0} 19:0 Kettins . o é : : c = 36:0 - 38°0 - 31:0 ~ 26:0 = 12°0 - 14:0 Perth . 6 - 5 . | 1230} 37:0] 112:0} 35:0] 126:0) 30:0] 1150} 22:0 97:0} 14:0 73:0| 12:0 Nookton : c 5 C . | 1110} 31:4] 103:0) 33:4] 1120] 3074 87:0| 23°4 65:0} 12-4 58:0} 13°4 Callton Mor . = : : ; 87'°5| 32°0 82:0) 36°5 - = 80:0} 27:0 69:0} 16:0 65°8| 22:0 Oban. : = . : . | 107:0}| 37:0 96:0} 38:0 87:0} 33:0 72:0} 26:0 OO) l9:0 51:0} 19:0 Paisley . < - - é . | 1062) 39° 88-7 | 39-4 93:2] 28-4 75:0} 244 67°77} 16-4 59°7| 1674 Douglas Castle . . | 1045] 36°0 96:0| 35:8] 1022] 26° = = 76:0 35 68:0} 10°5 Smeaton 0 é : : . | 1100} 38:0] 1120) 36:0] 1110} 27-0 94:0] 24:0 73:0) 14:0 66:0} 12°0 Thurston : : 4 ; . | 119:0] 41:0] 106-0) 43:0] 1140] 300] 1190} 305 97:0} 16-0 78:0} 185 Thirlestane Castle . 4 : . | 117:0) 32:0} 107°0 - 111:0} 23:0} 109:0} 16-0 92°0 3°0 86:0 8-0 Mungo’s Walls 2 : : ; = = = ee = =e = - - - - - 2019°4 | 727-8 }1767°5 | 692°5 1 1711-2] 574:6 |1606-5| 4783 | 1316-9] 267-6 | 1201-1) 323°5 SQ || £50) \) Sik | Sie) || yA) ae) |) Peasy) seal) |) eae |) sels) | tes || eal Mzans : - | 1063] 364 98'2| 364] 100'7| 302 89'2| 25°2 73°2| 4 66'7| 17'0 PROFESSOR C. PIAZZI SMYTH ON . Taste XXVIAa. continwed.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES, A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. March, April. June, 1862. Max, Min Max. Min. Max, Min Max. Min. East Yell 4 : . ; I 51:4} 26°6 89° 16°2 82:0] 24:0 = = Kirkwall : , : : ; - - (abel) ali? 85:1} 18:9 97°3 | 31:9 Harris . 3 ; ; 5 ; 59°4| 28°7 74:5 | 22:2 88:4} 29:0 91:4) 32:6 |. Stornoway . ‘ ' . é 63:0} 26:0 78:0} 14:0 79:0| 23°0 90°5| 31:0 Culloden : ; ; é P 64:8 | 24:1 89:0 97 | 111:2| 22°6 107°8} 335 Portree . F : ‘ F : 70°5 | 23:0 97) 121 98'7| 22:5 115'2|} 265 Forres . 5 é ‘ A ¥ 72:0} 28:0 78:5) 11:5} 1062) 25:5 1050} 32:0 Castle Newe . ; 2 ; ‘ 74:0| 27:0 89:0} 11:0 76:0} 21-0 83:0] 28:0 Braemar : 4 : : ; 82:°0| 25:0 101°0| 11°3 77:0 | 22:0 905} 31:2 Banchory H 4 ; } 79:0} 19°0 850 60 81:0} 20:0 89:0] 28:0 Barry . j ‘ : : 5 69°0| 23:0 110°0 8:0 - 240 = = Kettins . ; : : 4 " - 25°0 - 8:0 - 20:0 - 34:0 Perth 5 . : 5 . - 220 - - 114:0| 22°0 1290} 33:0 Nookton F 2 . 5 4 as 21°4 87:0 8-4 98:0} 17°74 109°0| 29:4 Balloch Castle f : ; z - - 750 9:0 99:0} 20:0 1100} 36:0 Otter House . 5 : ; : - - - - - - 90:0 - Callton Mor . A : ; ; 64°5| 25:0 74:0) 11°5 78:2) 18:0 85:0 | 32:9 Oban . : 5 . ; : - - 71:0} 16:0 90:0} 22°0 99°70} 30:0 Paisley . ‘ : ; ; : 60°0| 24:0 70°7| 154 80°'7| 11:9 101°7 | 32:4 Douglas Castle , 5 e 5 66°0| 17:0 - = - = 11070} 24:0 Smeaton : 4 : : F 66:0 | 23°0 88-0 3:0] 1050} 22:0 1050} 30:0 Thurston 3 5 : : : 80:0} 20:2 92°0| 11:2} 108:0| 23°0 11070} 36:0 | Thirlestane Castle . F 5 ; 82:0} 13:0 97:0 4:0 | 106°:0} 17°0 1250} 25:0 1168°6 | 441:0 | 1473:4 | 326°4 11617°5 | 219°9 ]1763°5| 445-8 2043°4 | 617°4 +17 | +19 | +19 | +21 7 +19 | +20 | +19 | +21 +20 | +20 MEANS. 5 : 68°7| 232 GAs le. Lilley 8571 || ro 92°8| 21'2 102°2| 30°9 February. April, 1863. Max. Max, Min, Min, East Yell - - = - Sandwick 61°7 772| 26°5 31°3 Kirkwall 581 82:2) 27-2 34:9 Harris . 69°4 83°5 | 30°9 42:9 Stornoway 73:0 75:0| 25-0 28:0 Culloden 82:4 106:0| 27:7 376 Portree 73°0 99°8| 23:0 27°8 Forres . ‘ 79°5 - - - Castle Newe . 750 78'0| 25:0 27°0 Braemar 78:0 74:5 | 26:0 322 Banchory 78°0 81:0) 15:0 22:0 Kettins - - 25°0 320 Perth . - - 23:0 30:0 Nookton 75:0 93°0| 18:4 24:4 Dollar. - - - - - Balloch Castle 580 94:0} 20°0 29°0 Otter House . - - - - Drishaig 3 SI | - - - Callton Mor . ; ‘ ; 60°0 70:5 | 924:0 32:0 Oban. ; ; 3 A . 49:0} 23:0 510 82°0| 26:0 35:0 Paisley . ; ; : é é 74:5 | Q7°4 705 81:5] 25:4 354 Douglas Castle . “ ; ; 65:0} 20-0 - 95:0] 19°0 28°0 Smeaton . { ; ; 64:0} 18:0 820 95:0} 21:0 27:0 Thurston A ‘ ; : : 86':0| 25:0 | 102°0 101:0} 29:0 86°5 Thirlestane Castle . : ‘ ; 78:0} 16:0 93°0 102°0} 18°0 25:0 South Cairn . 5 ; ; - - 55:0 72:0| 32:0 41:0 1190°3 | 426°1 | 1374°6 01:9} 431°6 | 1648°2 | 5071 | 1798'3| 5 659°0 +19 | +20 |} +19 ~20 +21 +22 | +19 | +21 9 | +2 Meass ; F 627 | 213 72°3 86'7| 24°r 314 I MEAN SCOTTISH METEOROLOGY. 233 TaBLeE XXVIa. continued—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. July, August, September, October. November. December. 1862. Max Min Max. Min, Max Min. Max, Min, Max, Min, Max, Min, East Yell - - 99-4] 3874 - - - = - - = - Kirkwall 0 c e : 100°7| 36-0 976 | 31:9 94:1) 27°6 69:°1| 27:4 556 | 18:9 53°4| 28°8 Harris, Kallin, and Benbecula 89:6] 39:9] 1102} 45:9} 101:2| 43-1 826] 32:9 70°4| 311 71:4) 281 Stornoway 3 ¢ ; 83:0} 36:0 85:0} 38-0 89:0) 31:0 77:0} 27:0 73:0} 22:0 59°0| 27:0 Culloden 112°2| 396] 113°0]} 36:8] 1053] 34:7 IES 27-7 74:8| 16:9 54:5] 22°6 Portree . 1100) 356] 1087} 3820] 109°7| 26-0 94:5] 18:4 Tekiily Oa! 71:0} 26:0 Forres c 100°8} 37:5] 105:0) 34:9 991} 34:0 91:0] 26:3 71:0} 12:5 58:0] 23:5 Castle Newe . 88:0} 30:0 89:0} 30°0 92:0) 29:0 97:0) 24:0 70:0) 12:0 57:0] 27:0 Braemar 86°5}| 34:0 88:0] 381-0 98°27) 29:0 932} 26:2 700) 11:2 560} 26:0 Poory 94:0] 30:0] 1000} 81:0} 102°0) 27:0} 103:0} 20-0 74:0} 10:0 66:0} 19:0 arry . - - - - - - - - - - - -- Kettins . - 350 - 35°0 - - - 28:0 - 10:0 - 25:0 Perth 1180] 36:0] 132:0} 30:0] 1388:0} 28-0] 1240) 21:0 - - - - Nookton 5 106'0| 32-4] 108:0} 3824] 1040] 25-4 92:0] 18:4 69:0) 11:4 54:0] 19°4 Balloch Castle 103'0| 37:0} 106:0} 40:0} 109°0} 32:0 80:0} 25:0 53°0] 14:0 - - Otter House . 90:7. = ~ - 95:5 - 92°0 - - = - = Callton Mor . 79°0| 34:5 88:0} 3875} 1100} 29°) 80:0] 23:2 705) 21:5 55°5| 29°0 Oban 96:0] 33:0 99:0] 37:0 95:0} 29:0 75°0| 25:0 56:0] 17:0 - - Paisley . C 88:7 | 37:4] 103:°5) 35:4] 1087) 27:9 89°0| 26:4 745| 13°6 64:3] 21°6 Douglas Castle 103°5| 22°57 1075] 24:0} 113°) 195] 107:0|) 20°5 750 9-0 66:0} 15:0 Smeaton 111°0| 35:0] 1130) 32: 1090} 26:0 94:0] 26:0 82:0] 12:0 68:0} 23:0 Thurston 3 c 1140} 39:0] 1200} 39°] 127°:0} 33:0] 112:0|} 29:0 98:0} 18:0 600} 28:0 Thirlestane Castle . 1050} 25:0] 120°0) 26:0] 122°0) 180] 121:0 13°0 | 105:0 8:0 79°0| 22:0 1979°7 | 685-4 | 2092:9 | 718-7 | 2122°3 | 549°2 | 1872:2| 485-4 | 1320°5| 285:°2 | 993:1} 411°0 +20 +20 +20 +21 +20 +19 20 = 20 ~18 -19 =16 =17 Means 99°0| 34°3] 104'6| 342] ro6'r| 28'9 93°60)" 2459 73-4) 15°0 625] 24°2 August, September, October, November. December, 1863. Max. Min, Max. Min. Max. Min, Max, Min East Yell = - - = -- - ~ - = = - - Sandwick 111:2| 34:0 94:2] 32°7 88:0} 31:8 65:0] 23°7 55'8| 23°2 50°2 - Kirkwall 106°4} 31:3 95:6] 3804 89°6| 31:4 68°8| 25°4 = 229 - 22°9 Harris 104°3) 41:9] 103:°5]) 42:1 97:0] 41°6 = - = = - - Stornoway 89:0} 29:0 90:0] 32:0 880} 30:0 72:0} 28:0 75:0} 26:0 58:0} 20:0 Culloden 1140} 33-4] 107°0]} 35:6] 1020} 346 82°2| 25-1 68°5| 21:9 57°0| 181 Portree 1174] 24:8] 1148; 308] 1051] 28-0 92:0 | 22°7 73°4| 16:0 57:0} 11:0 Forres. < = - - - - = - - ~ - - = Castle Newe . 100°0] 28:0 96:0] 31:0 95:0] 27:0 80:0] 21:0 74:0) 20:0 65:0} 13°0 Braemar 104-2} 31:0] 107:0) 318 97°8| 32:3 O1:0)))| 21:0 83-8] 15:0 71:0} 14:0 Banchory 101:0) 22:0 99:0] 27:0 92:0] 20-0 88:0] 18:0 = = 68-0 9-0 Kettins - 28:0 - 32:0 - 30°0 ~ 22°0 - 17:0 - 20:0 Perth 1490} 25:0] 127:0} 29:0] 115:0} 25:0] 106:0} 18:0 88:0} 14:0 73°0 8:0 Nookton 1180} 16:4] 1100} 25:4 95:0] 22:4 780) 13-4 63°0| 12°4 53:0} 12:4 Dollar . ; - = = = = = = - 73°7| 21:7 64:7 | 21-7 Balloch Castle 111:0} 30:0] 1080} 33:0 95:0] 32:0 69:0] 26°0 56:0] 18-0 - - Otter House . 130°0 - 126-0 - 110-0 - 83:0 - - - - - Drishaig . - = - - - - 1956} 20:0 - - - - Callton Mor . 85:5} 29:0 93:0) 31:2 79'°5| 32:0 74:0} 26:0 - - 65:0] 21°5 Oban c 1020] 29:0 98:0] 32:0 87:0] 31:0 65:0 | 24:0 54:0} 21:0 50:0} 19:0 Paisley . ¢ 99°3| 26:9 99:°5 | 32°4 83} 31:2 88:0] 21:1 CU |) ZAR) 65:7} 16:4 Douglas Castle = - 107'°5| 25:0 98:0} 25:0 - - 700} 13:0 - - Smeaton 110:0} 24:0} 1080} 27:0 98:0} 26:0 87:0} 21:0 7070} 13:0 67:0} 11:0 Thurston 6 : 1100] 30:0] 106:0} 39:0] 101:0} 35-0 96:0] 29:0 76:0] 23:0 60:0} 20:0 Thirlestane Castle . 1180} 20:0} 1160] 240] 113:0} 26:0] 106:0|) 18-0 91:0} 12:0 68:0} 11:0 South Cairn - - = = = - - - - - - - 2080°3 | 583-7 | 2106-1) 623-4 | 1931°3 | 592-3 | 1596°6 | 423-4 | 1149-9] 331-1] 992°6| 269:0 +19 +19 +20 ~20 ~ 20) ~ 20) 19 ~19 ~16 ~18 ~16 =17 MEaNs Tog'5} 28'r |] I05°3] 312 966] 29°6 84:0} 22°3 7i'9| 18'4 62°0| 15°38 VOL. XXXV. PART 3. 20 234 PROFESSOR ©. PIAZZI SMYTH ON TaBLE XXVIA. continued-BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES, A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. Sandwick : ; 93:2| 23:2] 101°7| 24:77 101:0] 338-4 Kirkwall : y 86°83 | 22°6 94:4] 23:9] 104:2] 33:9 Stornoway : 4 88:0] 26:0 85:0} 29:0 90:0} 34:0 Culloden : ; 3° 1060} 26-4] 1068} 28:8] 1083] 29:6 Portree : 63'2| 17:2 : = - 106:2| 25:8] 106°8}| 24:8 Castle Newe . 71:0 7:0 —2:0 90:0} 24:0 94:0) 22:0 93:0} 26:0 Braemar 75:0 88 30} 105:0} 25:7] 1089] , 26°8 98:0} 26°8 Banchory 68:0 6:0 - 95:0} 15:0 95:0} 20:0 93:0] 22:0 | Kettins . - 8:0 . 2°0 - 22°0 - 27:0 - 27:0 Perth . 730 8:0 0 60] 110:0] 20:0] 115:0} 28:0] 1160] 280 Nookton . 67:0 64 Ole 24. 95°0| 19:4] 110°0} 204] 1060} 224 Dollar ‘ Toa AGT Se Ore A) LOM 7a) eer) LOL 7al mera 99°7 | 29°7 Bloomhill or Cardross - - - - - 28°0 - 29°5 ~ ol Balloch Castle 50:0 9:0 78:0} 10:0} 102°0) 25:0} 111°0) 25:0} 1100] 260 Callton Mor . 64:0] 17°5 65'5| 19:9 86:0} 265] 115:0] 26:0] 1000} 27-0 Oban : - = 71:0} 20:0 94:0} 28:0] 101:0| 28:0] 109:°0} 27-0 Paisley . 72°2 54 779 89 91:2) 27-7 97°1| 25°4 86:1} 23°9 Glasgow : 73°0| 12:2 86°8| 18:0 - 27°3 - 27:5 - 28:2 Douglas Castle 63:0} 14:0 91:0 8:0} 1080} 25:0] 117:0| 18:0] 106:0| 260 Smeaton 69:0 5:0 92:0} 10:0 98:0} 18:0} 117:0} 15:0} 110°:0} 16:0 Thurston 5 A 71:0} 15:0 80:0} 23:0 96:0} 30:0] 120:0} 29:0] 109°0} 82:0 Thirlestane Castle . 68:0 30 4 00} 1170] 18:0] 184:0} 19:0} 1170} 22°0 770} 34:0 93°0| 37:0} 90:0} 40-0 184°1 | 1624'4 | 266°2 | 1839-9} 539-5 | 2123-8 | 578°5 | 2053-1) 637 2 +21 +20 | +21 7 +19 | +22] +20 | +28 | +20 | +28 South Cairn 1384:1 MEANS 72'8 88 638i) 24:5 oi reer) |) la5ur 102°7 27°7 Sandwick Kirkwall Stornoway Culloden Portree . 3 Castle Newe . Braemar . Aberdeen Banchory Kettins . Perth Nookton. Dollar Cardross c Balloch Castle Callton Mor . Oban. Paisley . Glasgow a Douglas Castle Smeaton Thurston 3 : Thirlestane Castle . South Cairn . eb oo CONMIGO GCOmMENEN |; | NIG] a SEIS SSOKRASAUS MIS OW OOD | RENAWOON GH 1191-0| 195-5 =19 | +23 1742°6 | 418°6 | 2 +21 | +23 62°7 8'5 83°0 MEAN SCOTTISH METEOROLOGY. 235 Taste XXVIA. continued.t~BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. August. September, October, November, December, 1864, Max, Min. Max. Min, Max, Min. Max. Min. Max. Min, Sandwick 96:4) 31-4 91:4) 33:3 808} 272} 590) 232) 52:0; 21-2 Kirkwall 96:6] 40°6 88:9} 33:3 - 24°4 = 214 = 229 Stornoway 88:0] 38:0 830} 38:0 86:0} 29:0} 67:0] 28-0 520} 32:0 Culloden 104°0| 34:1} 1050) 32°6 99°8| 27-4 705} 21°7 56°8| 19°6 Portree . : 114-0} 25:2 = = 91°38} 22:8 770} 200} 53:5) 19:0 Castle Newe . 1040} 28-0 95:0} 27:0} 89:0) 21:0} 72:0; 19-0 64:0} 14:0 Braemar 1110} 33:0} 1040} 31:09 1030) 25:0] 81:0} 192} 75:0} 145 Banchory 970} 21:0] 95:0} 200 87:0} 13:0} 78:0} 100) 690; 15:0 Kettins . - 27:0 29-0 - 230 - 18:0 = 18:0 Perth . 1180} 26:0} 112:0) 29°07 120:0} 15-0 85:0} 15-0 690} 16:0 Nookton 104°0| 27°4 98:0) 27-4 88:0) 15:4) 77:0) 154] 55:0; 11-4 Dollar . : 10477) 33°77 | 1037 | 347 94:7) 24:7 87°7 | 21-7 60°7 | 22-7 Bloomhill or Cardross - 35°C - 35:5 - - - 25:0 - 23°0 Balloch Castle TS"0))| 95:0} 32:07 80:0} 22-0 = 20°0 = 20:0 Callton Mor . 1085} 28:0 86:0} 29-0 770) 180} 64:0) 17:0) 53:0} 13:0 Oban 1000} 30:0 90:0} 34:0 760) 25:0} 59:0} 24:0 530] 21:0 Paisley . 1003) 28-9 86:5 | 33°4 78°5 | 22-2 = = = = Glasgow : 1218) 27-2) 1140) - 1030) — 66:2} 190} G51} 21:3 Douglas Castle 1190) - 1040; — 91:0} 22°0 = = 60:0) 17% Smeaton 1170} 20:0} 105:0|) 22-0 95:0] 14:0 74:0) 12:0 64:0} 150 Thurston : - 1120} 85:0] 1050) 37:0] 94:0] 28:0 80:0} 260} 605) 24:0 Thirlestane Castle . Z : : 130°0| 21:0} 120:0|) 22:0} 1080} 17-0 98:0} 15°0 78:0| 12:0 South Cairn . : : : ° 93:0) 40:0] 90:0} 38:0 85:0] 40-0 82:0} 360] 65:0) 27:0] 58:0) 26:0 2355°8 | 811-4 | 2254°3 | 628-5 | 1966°5 | 620-2 | 1824-6 | 472-1 | 1260-4] 417°6 | 1098-6 | 419-1 +21 | +23 | +21 | +21 | +20 | +20 | +20 | +21 | +17 | +21 | +18 | +22 MEANS ° . . | TiI2"2 35°3 | 107°3 29°09 98°3 310 or'2 22°5 742 19°9 61'0 I9"0 Augusty November. December, 1865. Min, Max, Min Max Min Sandwick 36°8 63°2| 23:2 55:2) 22:0 Kirkwall 26'5 - 21°3 - 24:5 Stornoway 24:0 73:0 - 64:0] 26:0 Culloden 40°5 70:0} 22-1 - - Portree . 30:0 77:3 | 12:0 62:0} 221 ‘Castle Newe . 30:0 76:0} 21:0 70:0} 22:0 Braemar . 31:3 75:0} 11:3 72'°2| 25:2 | Aberdeen 29:0 80:0} 195 font || 2333 Banchory 91:0 76:0} 14:0 73°0| 17:0 Kettins . 32:0 = 16:0 - 22:0 Perth 82-0 92:0} 12:0 750} 18:0 Nookton 29°4 730] 154 58:0] 17:4 Dollar 35-7 = - 67:7 | 23-7 Cardross : 385 = 24:0 = 23-0 Balloch Castle 33:0 570] 15:0 52:0} 19:0 Callton Mor . 30:7 60:4 | 22:5 53°7 | 24:8 Oban : = - - - ie Paisley . 39°4 785] 16:2 68-7} 19:8 Glasgow z 34:6 92:3} 22°6 79:0} 19:3 Douglas Castle 37-0 81:0} 17:0 730} 19:0 Smeaton j 22.0 780} 20:0 74:0} 19:0 Thurston c ; 39°5 96:0} 25:0 : 25:0 Thirlestane Castle . 23:0 1000 9°0 11:0 South Cairn . 40-0 56:0] 29:0 32°0 5:8 | 728:°9 461°9 | 1454°7 | 388°1 | 1292°2| 475-1 =98 +19 | +21 +22 Mrans Siz, 76'6 18 5 21'6 236 PROFESSOR C. PIAZZI SMYTH ON Taste XXVIa. continwed—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. January, April, 1866 Max. Min Min, Max. Min, Max, Min, Max. Sandwick P 52:0] 24-0 88 71:2} 18:0 94:7] 19:2 99°7 Kirkwall - - - - 9-0 766} 19°5 95:5 Stornoway 5070} 12:0 11:0 81:0 9:0 86:0 8:0 92°0 Culloden ~ 62°0| 17°6 12°8 - - - - 117°0 eee - 62:0 9-0 12°5 92°38} 15:0} 1158} 15:8] 115-0 Elgin. : ~ = = - = - =: - Castle Newe . 710} 12:0 50 77:0| -—4:0 97:0| 22:0 91:0 Braemar 12:3)| B18 9°8 90'2| -—2:0 | 1060} 21:2} 106°5 Aberdeen 64:0] 13-0 13:0 79:0 9:0 75°3 | 21:0 86°7 Banchory 65:0 4:0 4:0 78:0 3:0 93:0} 15:0 90:0 Kettins . - 11:0 14:0 - 9-0 - 18:0 - Perth 78:0 9-0 130 89:0} 12°0 97:0} 15:0 | 104:0 Nookton . 56:0] 18°4 14:4 80:0 9°4 99:0) 18:4} 106°0 Dollar GL75\) 1987, 19:7 - - - - 97°7 Cardross 4 - 15:0 17:0 - 17:0 - 23:0 - Balloch Castle 52°0 5:0 10:0 65:0) 10°0 88:0} 19:0 99:0 Cairndow . 74:6] 15:2 17:0} 1069) 173] 122:°5) 238°3 | 127°8 Callton Mor . DS:0)|) Loeb 21°5 74:2| 17:4 97°5| 21:0] 105°4 Eallabus - — - ~ = - - - Paisley . 58°8| 11:4 15:0 74:0 - 805} 20:4 93°5 Glasgow . E 821] 12°3 10°6 | 1057] 16:2] 114:7|) 20:1 | 120°7 Douglas Castle 62:0 7:0 12°0 80:0} 10-0 85:0 | 24:0 | 102°0 Smeaton . 77:0] 12:0 17:0 86:0} 10:0} 101:0) 14:0} 116°0 Thurston 5 ; 64:0] 20:0 25°0 77:0| 19:0 92:0] 25:0 | 106:°0 Thirlestane Castle . 82:0 9-0 15:0 | 102°0 00] 1180) 13:0] 118°0 South Cairn . 54:0| 24:0 - 29:0 - - 70:0} 30:0 75°0 1354-0 | 302-9 11603-9| 327-1 | 1509-0| 204°3 | 1909-6 | 420-9 | 2264-5| 481-0 | 2494-7| 630-2 +91 | +93 | +21 | +93 | +18 | +20 | +20 | +22 | +22 | +23 | +92 | +93 MEANS 64°5| 13°2 76'4| 14'2 83°38] 102 95°5| I9'I | 102°9| 20°90] 113°4| 27°4 January. May. June, 1867. Max. Min Min Max, Min. Sandwick . : : 3 : 51:0 6°5 : 21°5 94:4] 32°5 Kirkwall - : ; 5 : - 3°6 ‘ - 89°5} 33:0 Stornoway . : ; F . 49:0 1:0 : - 88:0 - Culloden : : : ; ; 57°2 4:6 4 29°5 | 134:0| 34°6 Portree - 3 : : 61°3 6:0 : 25°8 | 119°3| 26:0 Elgin. ; : f E . — 4:0 ; - - - Castle Newe . . p 5 3 63:0} -—9:0 4 25:0 | 108°C} 31°0 Braemar : ‘ : ; : 79°2 3°5 : 27:0 | 1060} 35% Aberdeen 5 . ‘ 5 - 74:3 8°4 : 23°0 94:5] 28:0 Banchory r ; ; 4 : 69:0 3°0 ; - 98:0] 22:0 Kettins . - ‘ H A Fs - 4:0 : 28-0 - 35°0 Perth 74:0 6:0 : 22°0 | 116°0} 25:0 Nookton 58°0 6°4 i 19°4 | 116°0] 34:4 Dollar - ~ : 317 93°7 | 38°7 Cardross : - 13:0 : 30°0 - 30°0 Balloch Castle = - 15°0 - 117:0| 34:0 Cairndow 79'1| 14:0 20°1 24:8 | 1241) 283 Calton Mor ~ 8°5 20:0 26:0 |} 1165} 30:0 Eallabus. 67°5 ~ - - 111°6 - Paisley . 59°5 5:4 11°4 25°4 94:7] 33°9 Glasgow . 91 6:0 15°6 25:0 | 1346) 33°7 Douglas Castle 59-0 20 11:0 220 | 111°0) 31:0 Smeaton . 73°0 9-0 170 21:0 | 1160] 30:0 Thurston : 56:0} 12:0 23°'5 28°0 | 1040} 38:0 Thirlestane Castle . 82:0; - 12:0 22°0 | 185:°0] 25°0 South Cairn . - 18-0 - 30:0 | 1100] 38:0 11912} 135°9 | 1588-0 | 425-4 1523-6 | 231-3 | 1903-6 | 554-3 | 2207-1| 507-1 | 2531-9] 727-4 =18 | +92 | +20 | +24 aD) 93 | +93 +18 | +21 | +21 | +22 | +22 | +20 Means. : : 66'2 6'2 MOAN) 7g 84°6| I1r'o g0°6| 252] 1003) 254] r10'r] 31'6 MEAN SCOTTISH METEOROLOGY. 237 Taste XXVIa, continued—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. Sandwick Kirkwall Stornoway Culloden Portree . Elgin. ‘ Castle Newe . Braemar . Aberdeen Banchory Kettins . Perth Nookton. Dollar Cardross 5 Balloch Castle Cairndow @ Callton Mor Eallabus . Paisley . F Glasgow . : Douglas Castle Smeaton Thurston d ‘ Thirlestane Castle . South Cairn . MEANS Sandwick Kirkwall Stornoway Culloden Portree . Elgin. ‘ Castle Newe . Braemar . Aberdeen ‘Banchory Kettins . Perth Nookton Dollar Cardross : Balloch Castle Cairndow ; Callton Mor . Eallabus Paisley . Glasgow ‘ Douglas Castle Smeaton Thurston : Thirlestane Castle . South Cairn . : MEANS VOL. XXXV. PART 3. July. August. September. October, November, December, Max Min Max Min. Max. Min. Max Min, Max Min Max Min, 94:0} 32:2 94:2 31:0 96:2] 301 78:4 23°7 58°8 23°8 51:0] 22-4 92:4} 31:6 87-6 30°4 80-1 27:0 716 21°5 - 21:9 - 23°6 96:0 - 87:0 - 87:0 - 89:0} 26:0 69:0 180 52°0 20:0 119°9} 3886} 115°8| 388] 101:2} 311 95:0] 25:4 83:0] 22:8 57°5 24:6 - - 118°0} 32:0] 10771 29°3 | 102°5} 25:2 77:0 16°3 - = - - - 33°5 - - - 24:5 - 25:0 - 23°5 1040} 31:0 96:0 28:0 87:0} 28:0 | 100°0 23°0 70°5 22°0 64:0 19:0 121:0) 35:0] 1202] 32:4] 105°8 28:0 | 125°0 16:2 920 17:0 73°83 20°4 1050} 27:9 93°5 28:0 96:5 23°5 98°8 26°2 830 - 70:0 18°4 1110} 31:0 95:0 28'0 91-0 22°0 99:0 19-0 780 13:0 63°0 10:0 - 33°0 - 32:0 = 28:0 - 25:0 - 20:0 - 21:0 121:0} 33:0 - - 110°0| 26:0 - - 78:0 16:0 69°0 18:0 1140} 34:4] 1080} 33:4] 106°0 25°4 93-0 23°4 66-0] 14:4 55:0 13°4 107°7| 33:7 97°7 33°7 96°7| 34:7 90°7 23°7 else 21°7 66°7 23°7 - 42°0 - 40:0 - 36°5 - 27°0 - 22:0 - 23:0 121:0} 34:0] 101:0) 32:0 95:0 27°0 78:0 22:0 - 18-0 - 20:0 134:5] 33:0] 132°3 32°6 | 113°9 34:2] 112°9 28°4 87°6 176 74:2 21°8 115:0| 38:0 951 35°0 90:0} 32:0 76°1 25°6 - - 63:0 25:0 119°5 - 102°8 - 105° - 991 - 79°5 ~ 74:4 = 1040} 34:0 89°5 29°4 82°5 31°4 74:5 23:2 65°5 18-4 61°5 18:4 133'2} 37:1} 129-1 34:1 | 118°3 322 98:0} 23:4 83:0 16°4 67°8 18°7 112°0} 36:0 97-0 32°0 | 100-0 28:0 89-0 19-0 78:0 15:0 66:0] 21:0 1280} 31:0] 113:0} 32:0} 1050 27:0 95:0 23°0 880 16:0 67:0] 20:0 1150} 35:0] 102°0} 35:0 97:0} 34:0 94-0 32°5 77°0| 25:0 58:0] 26:0 1350} 28:0} 1190} 20:0} 118:0} 20:0} 113°0 17:0 94:0} 12:0 850 10:0 88:0} 42:0 75:0} 43:0 75:0 40:0 - - - - - = 2491:2| 751°5 | 2268°8| 746°3 | 2264:3 | 675:4 | 1972°6 | 543°9 | 1479°6 | 412°3 | 1238:4| 461-9 +22 | +22 | +22 | +23 | +23 | +23 | +21 | +28 +19 | +22 | + +28 1132] 34°2 | ro3'r| 324] 984] 294] 93°99] 236] 77°99) 187] 65'2| 20°r July, September, October, November. December, Max Min. Max, Min Min Min Max, Min. 98:0 26:0 | 101°0} 28:0 92°3 29°5 7s 26°8 59°5 | 26°7 54:°2| 22:0 - - 87:6 | 289 88°8 30°4 61° 22°4 14°8 - 20°4 95:0 - 94:0 - 88:0} 21:0 74: 22:0 63:0} 21:0 - - 119°8 38°8 | 117:0| 36:6] 102°0| 33:7 88° 28°2 69°8 26°7 55:0 22°1 119°7 28:0 | 119°0] 30:0 - 30°0 - 25:2 - - 18°8 1000} 30:0} 107:0; 28:0 94°0 26:0 96:0} 21:0 85:0 19:0 69:0 19-0 - - 1050} 376 98:0] 31:8 - 24:3 25°3 - 19:0 94:0} 2875} 100°7 27°5 99:0] 24:8 96°5 14°5 2 13:0 69-0 12°0 100°0} 26:0 99:0} 28°07 100°0 25:0 = = 77:0 12°0 64:0 13:0 - 36:0 - 41:0 - 32:0 - 24:0 - 24:0 - 18:0 - - 12070} 36:0 - - - - - 22°0 - 19:0 117:0| 31:4] 121°0 34:47 10370] 29°4 89:0 18°4 77:0} 20:4 58°0 16:4 99°7 31°7 = = 34°7 88°7 26°7 84°7 24-7 65°7 | 20°7 - 38:0 ~ 42:0 35'0 = 27°0 - 25°0 - 22°5 1140} 32:0} 107°0|} 35:0 25°0 72:0 | 20-0 = - - - 1383°2|} 304] 122°4 38°0 31'2 | 103°1 24:7 96:4] 22°6 76°7 21:9 1140 34:0 | 117°0 37'8 36°5 83°5 24:0 61°8 PA - = 121°0 - 119-0 - - 86°5 - 74:0 - 50:0 - 98°5 33°8 89°5| 38074 32:0 76°5 24:4 73°5 19°8 62°3 14°8 134:7| 33°5] 134:0] 38°5 29°1 97°-2| 22:8 75°5 161 57°5 15°5 109°0} 33:5} 101°0 40:0 28:0 86-0 22:0 80:0 17:0 61°0 10:0 119°0 30:0 | 120:0} 37:0 28:0 89:0} 22:0 80:0 20:0 16 15:0 106:0 389°5 | 110°0| 44:0 41°5 89-0 26°0 80:0} 27:0 65:0 22°5 126:0 34:0 | 119°0|) 26:0 21:0} 111°0} 13:0} 102°0 18-0 86-0 12:0 112°0 42:0 | 112°0 44:0 38:0 85:0] 32:0 70:0] 25:0 56:0} 25°0 2230°6 | 657:1 | 2422-2 | 768:7 | 2083-1] 693-6 | 1643°3] 511-4 1 1894-4 | 461°3 |1010°4| 379°6 +20 +20 +22 +22 +23 +19 +22 +18 +22 +16 +21 IIl'S 32°9 | II0'L 34°9 30°2 86'5 | 23°2 77°5| 2r°0 63'2 18°r 2, We 238 PROFESSOR C. PIAZZI SMYTH ON TABLE XXVIA. continued.—BLACK-BULB THERMOMETERS, MAXIMA AND MIN IMA EXTREMES, A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. Sandwick 562) 17-7 85:2| 27:0 93:4} 29-1 Kirkwall -- 18°5 W77| 25:7 88:7 | 26:4 Stornoway 55:0} 13:0 75:0) - - - Culloden 65:4] 16°6 105°0|} 25°7 | 1081) 26°6 Portree . - - - 21:0 - 25:0 Castle Newe . 65:0 6:0 84:0] 24:0 88:0} 22:0 Braemar - 12°35 ~ 22°3 - 25:0 Aberdeen - - 90'2| 186 90:2} 18°6 Banchory 59:0 9°0 87:0} 17:0 95:0} 16:0 Kettins . - 13°0 - 25°0 = 27:0 Perth 62:0} 12°0 90:0} 19:0] 103:0] 24:0 Nookton 64:0} 12°4 1020} 194] 105:0} 19-4 Dollar 64:0} 18:0 - = = = Cardross : - 20:0 - 230 - 280 Balloch Castle - - 96:0} 18:0] 106°0] 20:0 Cairndow 84:7 - 129°4) 23:0] 125°7) 27°5 Callton Mor . - - : 27°2 Paisley . : 66:1} 16:4 6 23°0 Auchendrane . - = = Glasgow 5 757 | 16:3 2 26°7 Douglas Castle 71:0| 15:0 0 23°0 Smeaton 62:0} 13:0 0 17:0 Thurston ; s 59°0} 21:0 x Thirlestane Castle . 770 9-0 South Cairn . 54:0| 22°0 1040-1 | 281-4 =16 | =19 1326:2 +18 | +22 1605°3 | 450°3 nary 458-0 | 1809°0 | 524°5 | 2211-9 725-9 1 . MEANS 6570} 14°8 January. February. March. April, June, 1869. Max. Min, Max. Min, Max, Min, Max, Min, Max. Min, Max, Min, Sandwick 5 : 5 4 : 54°2) 22:3 68:0 24:0 75:9] 20°8 84:2) 11:0 85:0 19°0 93:4) 26°5 Kirkwall : F 5 6 - 20°4 64°6| 12:4 76°8| 20:0 95°38} 15:0 82°6| 13°9 85:5] 254 Stornoway . 5 A 4 : 58:0 - 65:0 190 82:0 - 84:0} 14:0 83°0 - 95:0 - Culloden E “ A : 69:0} 201 84-1 24°6 96°0 176} 1120) 18:0} 111°7| 246] 1129) 27:8 Castle Newe . ; . A 5 65°0| 10°0 69:0 | 25:0 81:0] 17°0 97:0} 20:0 90:0} 12°0 99:0] 26°0 Braemar 4 Fi 4 F : ~ 15°3 - 21°8 - 17:0 - 21°0 = 20°6 - 26°2 Aberdeen 5 ’ 3 : “ 73°3 | 21:2 85:0| 25°6 78°4| 22°8 89°3 | 23°8 85'3| 23°2 94:0) 34:0 Kettins . A : “ ; : - 8:0 - 25:0 - 12:0 - 150 - 22°0 - 26:0 Perth . 5 5 5 : 65° 13°0 79° 21:0 94:0] 13:0 - - 110°0} 20:0} 120:0| 27:0 Nookton ; 5 4 . 58:0} 19:4 76:0} 23:4 96°0| 15°4] 104:0] 16:4} 103°0} 19°47 113:0] 26-4 Dollar . o ; 4 - - 54:7 25°7 70°7 26°7 82:7 | 23°57 | 1038s7| 227 92°7| 26°7 97:0) 347 Cardross * r A 5 - 24°0 - 30°0 - 25°0 - 26°0 - 29°0 - 32°0 Balloch Castle , 4 A é - 20:0 - 25°0 90:0] 17:0 - - 110:0} 22:0} 121:0} 28°0 Cairmmdow 4 A , P 76°4 19:0 85'1 26:2 | 112:°9 16°9 | 1381°8| 21:3} 187:0| 21:3} 181°5) 24:3 Callton Mor . c F 5 7 5270} 24:0 62°0| 25°0 830} 19°38} 109:0) 23:0] 10770} 25:0] 1180) 28°5 Eallabus r “ , : - -— - - - - 100°5 18:0 | 102°0} 28:0} 111°5) 21:0 Paisley . - n 5 fs 4 62°8| 17°4 795 25°4 80°7 15:4 90°5} 14:9 91:5} 20°4 94:1] 2674 Auchendrane : 5 3 ; 61:0} 21-0 69:0 28°0 76:0} 20:0] 10970} 23:0] 113°0} 19:0] 122°0; 26:0 Glasgow f A ‘ 5 z 76°8| 21°5 88°3 22°4 | 103°8 20°0 | 1145} 23:5] 1191] 242] 14071) 29-4 Douglas Castle : 4 j : 59:0} 14:0 78:0} 25:0 80:0 15:0 | 102°0) 19:0} 101°0] 17:0} 102°0} 25°0 Smeaton “ ; F , 70:0 15:0 82:0 21:0 90°0| 17:0} 105:0} 14:0} 1040} 18:0] 116:0] 220 Thurston ‘ ; A z 63°0| 22°5 73°0| 26°5 75:0] 25:0 97:0} 23:0 93:0} 27:5 | 102°0| 32:0 Thirlestane Castle . 4 i : 730 15-0 91:0 21:0 98:0} 15:0} 1120] 19:0] 109°0} 18:0] 117:0| 27:0 South Cairn . ; : A - 56:0] 27:0 58:0} 28:0 60°0| 25:0 90'0 | 28:0 85:0] 80:0 98:0} 36:0 —_—— 1147°2| 415-8 1497 °3 552°0 11712°2| 410°4 [19381°3 | 429°6] 21149] 495-8 | 2283-0 6331 +18 | +22 | +19 | +238 | +20 | +22 | +19 | +22 | +21 | +23 | +21 | +28 Means. : : 637 | 18'9 I51} 24'0 85°6| 187] tor'6| 19'S | r00°'7] 21°6] 108'7| 27°5 MEAN SCOTTISH METEOROLOGY. 239 Taste XXVIA. continued BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. July. August, September, October, November, December, 1868. Max. Min, Max, Min, Max. Min. Max. Min. Max. Min. Max, Min. ae eS Se Se =| = == = = = = = Sandwick . . « ° . | 103°2) 37°8 90:7] 35°8 85:6} 34:2 72:2| 23-0 54:2} 14:0 18:0 Kirkwall ‘ 5 = C . | 1007} 36:1 88°38 | 23-4 $15} 3074 67:5 | 22°6 = 13-4 15-4 Stornoway . . : ° 4 98-0 - 1000} 12:0 88:0] 23-0 82°0 = 62:0} 15:0 - Culloden . A : é . | 123°8} 38:6] 125°0| 37:4] 107:2} 306 83°8| 23°6 65:0} 17:4 18°6 Portree . : : : A - 312 - - - 24:8 - - = = we Castle Newe . é . . . | 1040} 300] 1100} 31:0 91:0} 29:0 85:0} 21:0 69:0] 18-0 18:0 Braemar . . ° : 5 — 330 = 35'0 = 28°0 = 22°8 - 19-0 - 18°3 Aberdeen é * : : . | 104°3} 26:9] 127°3) 27:6] 1035] 35-1 92°3| 24:1 74:0} 25-9 73°8| 22:9 Banchory 2 o - = = = 1000} 22:0 92:0] 12:0 - = = = Kettins . < : 2 : , = = = 380 = 28°0 _ 22°0 - 18:0 - 15:0 Perth . . ° : a . | 125:0| 86:0] 128:0| 34:0] 1200} 31:0 94:0} 19:0 73°0| 15-0 63°0| 15-0 Nookton 5 c : 6 . | 1200} 36:4] 1260} 35:4] 1180] 26-4 86:0} 18-4 74:0) 15:4 54:0) 17-4 Dollar . . c c : | 107-7) 41:7 | 114:7| 39°7 | 104:7| 34:7 91:7} 27:0 ThE | 2277 57:0| 22°0 Cardross : 7 - 5 0 - 41:0 - 45:0 = 32°0 - 25°0 - 20:0 - 26:0 Balloch Castle 5 7 4 . | 126:0} 35:0} 119:0| 37:0} 102°9| 24-0 80:0} 15°0 57:0} 10°0 - - Cairndow c c 2 . | 143-4] 37:1] 18571 36:0 | 1380°8| 27:7 | 125°8| 23-7 91°3| 13°6 75°4] 16°3 Callton Mor . 5 a 2 . | 1235] 36°38} 109:0| 37:0 95:5} 30:1 75°0| 25°0 54:2} 18:2 53°5| 19°5 Paisley . 3 : 4 : - = 106:0| 40°6 91:6) 26-4 715 20°9 72°5| 14:3 64:5] 16°6 Auchendrane . A 2 - = = = = = - 79:0} 24:0 60°0] 19-0 53:0} 20-0 Glasgow : d 5 3 . | 141°3} 39°57 129°7| 41:3] 116°9} 3171 90°3} 24:0 751) 163 66°7| 21:2 Douglas Castle . : -* . 7 11270) 33:0] 115:0} 36:0 92:0} 25:0 89:0} 19°0 72:0] 12°0 63:0} 15:0 Smeaton é : ‘ : .| 1175} 34:0] 1160} 37:0} 102°0|) 31:0 91:0} 180 750) 16:0 70:0} 15:0 Thurston 6 . c ; .| 1120] 41:0] 115°:0) 44:0] 1070} 36:0 91:0) 27°C 71:0) 25:0 64:0} 23°5 Thirlestane Castle . 5 5 . | 121:0| 25:0] 126:°0; 31:0} 112°0} 26-0 87:0] 19:0 81:0} 180 750} 10-0 South Cairn . - c < . | 125°0| 45:0] 1200} 44:0 90°0} 35:0 72°0| 33-0 58:0] 26:0 64:0} 28:0 2108°4 | 715-1 | 2201°3 | 778-2 | 2039°3 | 701°5 | 1804:1} 509-1 1 1316-0} 402-2 | 1068-1] 391-7 +18 +20 +19 +22 +20 +24 +21 =e +19 +23 +17 +21 MEANS. » > | TI7‘r|. 35°38 | Ir5°9| 354] o2'0| 29°2 85'9 | 22°T 69°3| 17°5 62°8 | 18°7 July, August, September, October, November. December. 1869, Max, Min. Max, Min, Max, Min. Max, Min, Max, Min, Max. Min, Sandwick 5 ; é - 6 96:2} 38°5 90-7} 30°0 87:0} 26°2 76:0} 23°11 586} 15:0 49°7| 11:3 Kirkwall é ‘ : . c¢ 94:0} 39°9 876] 31:4 84:2} 25-4 68:6} 22-4 = 23°4 = 13°9 Stornoway . -. 2 ¢ A = - 84:0 - 86-0 5°0 84:0 - 62:0} 17:0 47:0) 15-0 Culloden : c c é ~ | 117-2) 37:19 1180) 33:1] 107:0). Sl1) 107-0) 22°6 79°8 9°6 58:0 78 Castle Newe . “ * : . | 1040} 32:0] 1020} 26:0 89:0; 29:0} 1000} 23:0 74:0 9:0 61:0} —5:0 Braemar . ; : 4 . 5 - 30°8 - 21:2 — 23°0 - 180 - 7:0 - 1:0 Aberdeen C - : : . | 1000} 380] 1093] 286] 119:°0) 32:0] 115°7} 27-0 85:7] 171 67:2) 165 Kettins . c : : : g - 34:0 - 24:0 - 30°0 - 21-0 - 12:0 - 30 Perth . 5 c ° é . | 188°0} 35:0} 128°0] 26:0}.113:0] 32:0] 103:0} 20-0 58:0] 12:0 - - Nookton c : . . | 1160} 344] 1120) 23:4] 103°0] 23-4 90°70} 15:0 77:0) 1374 51:0 4:4 Dollar . : : . é . | 117-7] 38:7] 115°0} 308] 104:0] 36°8 - - - = 68:0] 15:0 Cardross A Sane J o = 46:0 = 31°9 - 35°5 = 26°5 - 21:0 = 17°4 Balloch Castle . . 5 . | 124:0| 34:0] 117-0] 25:0} 110°0] 30-0 83:0] 19:0 58:0} 13:0 48°9 5:0 Cairndow . c ci é . | 133°) 385°5 | 13845) 34°57 1176] 25:1] 1091) 18:0 86:2} 102 776 6°6 Callton Mor . - - . | 115:0} 39:0] 1050} 29:1] 109:°9} 36°5 78:2] 24:0 69:9) 181 530 8-2 Eallabus - 5 ¢ : . | 10970} 25:5} 1040} 16-9 90:5} 23:0 84:0 = 59°0 = 48-0 - Paisley . - a c ° < 98:7} 3846] 1035} 22:9 96:0] 31:4 88:0} 21-4 = 15°4 - 70 Auchendrane c c . . | 1240] 38:0] 112°0) 24:0} 107:0) 29:0 91:0} 200 66:0} 14:0 53:0] 10:0 Glasgow 3 c c C . | 1346] 40° | 136:2} 285] 12799] 33°6 91:9} 21:0 64:9} 12:5 66°6 77 Douglas Castle 3 5 - . | 11380} 35°07 115:0} 21:0 89:0} 3810] 1100} 18:0 78:0} 10:0 71:0 6:0 Smeaton 0 c : cl . | 1100} 34:0] 117:0| 22:0] 100°0} 27:0} 100°0} 20-0 76:0} 10:0 60:0 8-0 Thurston : 2 ° . 2 = = 109°0} 33:0 97:0] 36:0 97:0} 29-0 67:0} 20:0 54:0) 20:0 Thirlestane Castle . : : . | 117-0} 31:0] 120°:0) 21:0 98:0} 29:0 95:0} 23:0 80:0} 14:0 81:0} 13°0 South Cairn . : e - - | 1100} 400] 115:°0} 25°0 80:0} 35-0 82:0} 32:0 60:0} 25:0 56:0] 20-0 2171:9| 791°6 | 2334°8 | 609-3 [2115-1 | 696-0 | 1853°5 464-0 1260:1 | 318-7 | 1071-0] 211°8 +19 | +22 | +21 +23 +21 +24 +20 | +21 | +18 | +22 | +18 | +22 MEANS “ 2 . | 114°3| 36°0 | r11'2| 26°5 | 100'7| 29'0 O2t7a| 2255 7o'o| 14°5 59°5 9°6 240 PROFESSOR C. PIAZZI SMYTH ON Table XXVIa. continued —BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES, A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. January, February. March, April, May. June, 1870. Max, Min Max Min. Max Min Max Min. Max Min Max, Min, Sandwick 54:3] 20°5 66:2} 13°6 (px 19°3 81:2 317 93°2} 28°5 | 1022) 313 Kirkwall - 21°9 = 17:0 - War 81-1 28°9 83°5 24°4 928} 29:4 Stornoway 500} 16:0 57:0 70 79°0 5:0 85:0 - 87'0| 34:0 89:0] 33:0 Culloden 72°6| 16°6 82:0 13°9 96:0} 166} 113°8) 24:1] 119°8 27:'2 | 1198) 321 Dunvegan. - 225 - 12:0 - 17:0 - 25°5 - 29°0 - 32°0 Castle Newe . 69:0} 13:0 65:0 7:0 80:0} 16:0 - = = = = = Braemar. 61:0} 13:7 750 9:0} 101:0} 13:0} 112°3} 232] 1200) 275] 1283) 33:6 Aberdeen (2:6) B72 91:0} 16°38} 1003) 20:2 - = 140'8| 286] 1482] 285 Kettins . - 12:0 - 15:0 - 15:0 - 24:0 - 28:0 = 34:0 Perth 57:0 150 82:0 12:0 97°0| 14:0 - - - - 1260] 31:0 Nookton 65:0 9°0 750 1°4 93:0 8:4] 1010} 22:4] 1100) 23:4] 109°0| 29-4 Dollar 677 | 16:7 77:0 13°7 = = 95°7 277 99°71) 31:7 |) 104:7\) Seven Cardross E - 24:4 - 16:0 = 21:4 = 29:0 - 26°5 - 42:0 Balloch Castle 50:0 15:0 65:0 4:0 77:0} 10:0 89:0} 15:0] 102°:0} 12:0] 115°0}) 27:0 Cairndow 4 793) 75 99°5 95} 102-1 16°3 | 118-7 25:2 | 127°4 21:0 | 132°9| 34:2 Callton Mor . 499 13°5 60:0} 12:0 75:0} 18:9 89:0} 23:0 | 104:0} 195 7 109:0} 38:0 Eallabus . 56:0} 23°0 60:0} 20:0 750} 20:0 770) 25:4 94:0 - 100°2 - Greenock — = = = = = - = 90:0} 32:0} 1000} 40:0 Paisley . 4 69°5 22°5 80:0 - - - 94:5 - 95:0 = 97:0 - Auchendrane . 53:0} 16:0 67:0} 14:0 91:0} 17:0] 104:0| 25:0] 1140] 23:0} 122:0| 40°0 Glasgow . : 66:1 179 88°8 78 91:2) 16:0] 1124) 25°67 117:3] 25°77 128-1 37°9 Douglas Castle 70°0 15:0 74:0] 10:0 90:0} 14:0} 102°0} 22:0] 105:0} 23:0] 115:0| 36:0 Smeaton 70:0 50 73:0 8-0 83:0} 13:0 | 100°0 19:0} 1100} 22:0] 1140) 32:0 Thurston 5 : 59°0| 17°5 72°0| 18°0 81:0} 22:0 96:0} 27:0] 103°0} 32°57 102:0] 40°0 Thirlestane Castle . 85:0 70 - 1:0} 1020} 13:0] 119:0| 18:0] 1240] 24:0] 1280} 34-0 South Cairn . 5 50:0} 18:0 52:0} 16:0] . 68:0} 19:0 78:0 | -26°0 86:0} 26:0 95:0} 36:0 13270 | 406°4 | 1461°5| 274°7 | 1656-7 | 362°8 | 1849°7 | 487-7 | 2225°7| 569°5 | 2478-2] 789°1 +21 +25 +20 +24 +19 +23 +19 +2 +21 +22 +22 +23 MEANs 63°2| 16°73 7pehas | aaaely-t 87'2| 15°8 97°4| 244] r06'0| 25°9 | 112°) 343 January, February. March, April, May. 1871, Max, Min, Max, Min Max. Min. Max, Min Max, Min, Sandwick 50°3 16°5 60°1 26°8 78:2} 21°5 972 18:3} 100:'7| 24°5 Kirkwall - 18°9 21°9 66:0} 20° - 114 - 12°4 Stornoway 50:0} 15:0 64:0] 19:0 86:0 9°0 86:0} 12:0} 102°0|) 16:0 Culloden 77:0 12°9 88:0 13°7 - - 1100} 19:4 = = Dunvegan - 24°0 180 - 18-0 - 23:0 - 26:0 Braemar 600 4°6 753 18:9 | 104:0| 19°87 110°0} 18:0] 123:3] 23-0 Aberdeen 66:0] 11°4 99:0] 24:27 114:0] 13:0] 13803 17:0 } 1388':0| 20-0 Kettins . - 100 22:0 - 15:0 - 23°0 - 24:0 Perth 62°0| 10:0 88:0| 17:0 - = - - = - Nookton . 57:0 7°4 75:0 17:4 93°0 8:4 97°0| 17°4] 119°5| 15:2 Dollar - - - 93°7| 21°7 - - 1057) 19°7 Cardross 4 - 22°0 25°0 - 21°0 - 28:0 = 24:0 Balloch Castle 48:0} 15:0 55:0| 18:0 75:0| 18:0 90:0} 21:0} 112°0} 25:0 Cairndow : 76°1 14°6 93°5| 22°51 112°7| 18°83] 1143} 25-8] 125°7| 16°7 Callton Mor . 48°5 12:2 68°5 272 84:0} 21:0 95:0} 24:3 7 1000) 21:5 Eallabus 510} 20°5 67°0| 30°8 90:0} 16°5 90:0} 26:5] 115:0} 22°8 Greenock 48:0] 21°5 60°5| 26°0 75:0] 21:0 86°0} 26°0 - 27:0 Paisley . f 64:0 - 75°5 - 88:0 = 83°5 - 106°5 Auchendrane . 510)) 11:0 40} 14:0 93:0) 13:0} 102°0) 22:0] 119°0| 21:0 Glasgow . : 59°6 14:1 270} 20:0 97-7) 11:0] 1175) 28:4] 1828) 21-1 Douglas Castle 71:0 7:0 2:0} 12:0] 113°0| 11:0 930} 15:0} 106°0| 16:0 Smeaton 4 64:0 7:0 6:0} 19:0 96:0} 12°0 93°0| 15:0] 112°0} 17:0 Thurston 76:0} 17°0 790) 28°0 95:0} 23:0 96:0} 25:0] 103:0| 26-0 Thirlestane Castle . 900 30 30} 2070} 120°0]} 12:0} 120°0| 16:0] 129:0] 19:0 South Cairn . 48:0} 15:0 56:0} 24:0 72'0| 24:0 74:0} 26°0 86:0} 23-0 12175 | 310°6 | 1501°4| 485-4 | 1846°3| 369°3 | 1884-8 | 453°5 | 2036-2) 460-9 | 2185°8| 606-9 +20 +23 +20 +23 +20 +22 +19 +22 +18 +22 +19 +21 MEANS 60'9}| 13°5 75-0) nae 92°3| 16°8 99°2| 20:6] 113°] 21'0 | I15'0| 28°9 MEAN SCOTTISH METEOROLOGY. 241 Taste XXVIA. continued.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES, A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXYVII., XXVIII. August, September, October, November, December. 1870. Min, Max, Min, Max, Min, Max. Min, Max, Min, Sandwick 32°5 92:0} 33°5 90°2| 24:7 589} 21-5 52°9 6:0 Kirkwall 27°0 80°'7 | 23:4 66°9) 21:4 563) 20:0 = 72 Stornoway 29°0 89:0} 21-0 87:0} 22-0 64:0} 16:0 48-0 6:0 Culloden 34:0 | 111°2| 266 105°0} 21°6 83'4} 15°6 50°4 7:0 Dunvegan. é 370 = 27°5 - 23°2 = 18:0 - 10°0 Castle Newe . fs - - - - = - - - - Braemar 36°38 | 11670] 25:0 § 1125} 23:0 71:0} 202 63°7 0:0 Aberdeen - ¢ : 30°1 | 125°6| 27-44 1083] 23:0 81:9} 19:1 67-2 4:0 Kettins . - P . s 34:0 = 30°0 = 26°0 - 20:0 - 0-0 Perth . 2 Fi c 32°0 | 112:0| 24-0 92:0} 20-0 82:0} 18:0 56:0 20 Nookton 5 . 32°4 | 103°0| 28-4 94:0} 19-4 85:0) 14:4 52:0 74 Dollar . c c 385°7 | 107°7| 33°7 f 109-7 | 28-7 91:3} 22°7 70°7 37 Cardross c i 35°4 = 340 - 29-4 = 25:0 - 10°0 Balloch Castle - = - _ 26-0 65:0} 18:0 50:0 7:0 Cairndow : 28°8 - - W191} 25:2 98:5 | 16°6 899 8:0 Callton Mor . 32°0 97:0} 28:0 84:0} 25-2 64:0} 21:0 50:0 8-0 Eallabus 39°4 99-0 = 892 - 69:0 | 21:2 65:0} 11:0 Greenock 31:0 87:5} 300 75:0} 27:0 615} 21:0 560} 14°5 Paisley . f - 96:0 = 78:0 - 73°5 - 66:0 - Auchendrane . 31:0 | 101:0} 33:0 97:0} 24:0 66:0} 17:0 50:0 7:0 Glasgow 382'2 | 117°8| 30°8 92:5 | 25:5 80°1 19-0 575 | —5:0 Douglas Castle 29:0 } 109°0} 25:0 115°0| 24:0 91°70} 14:0 70:0 30 Smeaton : . 27:0 | 107°0| 22:0 f 100°0) 19:0 83°0} 15:0 63:0} —1:0 Thurston 6 é 40:0 | 1053} 34:0 99:0} 31:0 85:0} 24:0 58°0 1:0 Thirlestane Castle . 83°0 | 115:0| 25:0} 114:0|} 22:0] 107:0} 18:0 90-0 0:0 South Cairn . ; 350 78:0} 38:0 85:0} 30°0 66:0} 22:0 560] 12:0 754°3 | 2049°8 | 600°3 | 2013-4} 561°3 | 1683-4) 457-3 | 1282:°3|] 138°8 +23 +20 +21 +21 +23 +22 +24 +21 +24 MEaAns 32°8 | ro2°5| 28°6 95°9| 24°4 76'5 1g°I 61'r 58 | August, September, October. November, December, 1871. Min. Max, Min. Max, Min, Max, Min, Max, Min, Max, Min, Sanawick 34:7 309 - - 59:3} 21:0 685] 183 54:°2| 14:5 Kirkwall 33°2 30°4 - 21:4 - 24°6 - 19°4 = 19-4 Stornoway 26:0 27:0 | 1030} 11:0 85:0} 10:0 65:0 5:0 53°0| 11:0 Culloden 375 35°9 | 115°8| 23-0 96:5] 23:0 83°0| 18-7 61°9| 156 Dunvegan 34:5 36°5 - 16°5 - 19°7 = 18:0 - 20:0 Braemar 30°2 31:3 | 111:7| 23°7 90:2} 20:2 70:0} 16°0 70:2} 11:8 Aberdeen 34°5 30°0 | 128:2} 24:7} 1138-9] 22-1 69°8| 18°3 55°3| 14:5 Kettins . 360 34:0 - 26:0 - 24:0 - 18:0 - 10:0 Perth . - - - - 96:0} 18:0 78:0} 15:0 63°0 9:0 | Nookton 34:2 35:2 | 105:°5| 28:2 895] 19:2 67°5| 11:2 505} 14:2 Dollar . 42-7 40°7 } 113-7] 32°7 96-7 | 26:7 TF | 1927, 73°7| 14:7 Cardross < 43:0 41°0 - 32°0 - 30°5 - 220 - 20:0 Balloch Castle 34:0 32°0 90:0} 20:0 7070} 18:0 52:0} 12:0 55:0} 10:0 Cairndow 3 - = - ~ 102°8 - 90°9 - 82°4 = Callton Mor , 33'0 37:2 = 22°0 = 25:0 = 20°0 - 15:0 Eallabus 32°0 31:0 | 10270] 22:1 90:2] 23°8 64:0] 18-2 61:0} 14:5 Greenock = = = = - = = = = - Paisley . ; - = - - = = = = = = Auchendrane . 39°0 38:0 | 106°0| 27:0 86°8| 24:0 64:0} 16:0 59:0} 13:0 Glasgow . : e 39°2 36:7 | 118°8| 25°83 99:0} 23:0 84:5] 14:3 715) 175 Douglas Castle C . 34:0 34:0 | 110°0| 22:0 86:0} 18:0 75:0} 12:0 68:0} 11:0 Smeaton 5 A 3 34:0 34:0 | 103°0| 28-0 84:0| 20-0 74:0} 16-0 57:0} 15:0 Thurston : , 42:0 40:0 | 106:0} 35-0 92:0| 26:0 89:0) 21:0 61:0} 23:0 Thirlestane Castle . 320 32°0 | 1250} 25:0] 115°0| 18-0 99-0) 11:0 88:0} 14:0 South Cairn . 3 39°0 380 88:0} 28:0 74:0] 25:0 58:0] 24-0 58:0) 20:0 744°7 725°8 | 1626:7 | 494-5 | 1626-1} 479-8 | 13829°9| 364-1 | 1142-7 | 327-7 +21 +21 +15 +20 +18 +22 -18 +22 18 +22 MEANS 3505 34°6 | 108°4| 24°7 go"3| 21'8 73°9| 16°6 63°5| 14°9 VOL. XXXV. PART 3. 2Q 242 : PROFESSOR C. PIAZZI SMYTH ON Taste XXVIA. continued.i-BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES, A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. January. February, June 1872. Max Min, Max. Min, Sandwick : ' A 5 . 55:0 19°5 1170} 26°5 Kirkwall c 5 4 ; e - 20:9 1080} 30:0 Stornoway . . . : : 570 17-0 1060} 25:0 Culloden : . d Z f 84:0 20°6 1230] 33:4 Dunvegan. ‘ . - - - 20:0 = Braemar 5 ‘ é A 5 66:2 20:2 : a 1248} 32:3 Aberdeen : “ 5 , 682 19°4 ‘ 246 | 143°4] 28-4 Kettins . A 4 F : 2 = 22:0 : = - 36:0 Nookton. ‘ ; 5 3 57°5 19:2 : 22:2 | 109°5| 29:2 Dollar . a 3 : 4 2 71:7 22:7 ; 26°0 | 104:7| 26°7 Cardross hs i = F 3 - 27°0 23°0 - 29:0 - 40:0 Balloch Castle 54:0 20:0 17:0 95:0} 20:0 98:0} 27:0 Cairndow - 79'1 - - 119°9 - 120°8 - Callton Mor . - 315 19°5 93°0 1) 99:0} 34:0 Eallabus 57:0 27:2 178 102:0) 23:0} 1095] 29-5 Paisley . : 64:5 25'7 19:0 90:0] 25°7 89:0] 31:0 Auchendrane . 60°0 25°0 19-0 4 4 122:0| 34:0 Glasgow . : 80°9 225 16:0 122°0| 32°5 Douglas Castle 62:0 25:0 14-0 1020} 82:0 Smeaton . F c q 60:0 17-0 14:0 101°0} 21:0 Thurston 2 « 5 : : 69:0 27:0 25°0 108°0) 37:0 Thirlestane Castle . 0 : - 85:0 170 : 1200} 25:0 South Cairn . i : - 5 49:0 26:0 90°0| 28-0 1180°1 | 394°4 | 1516-3 | 492-4 | 17614 490°6 | 2048-0 | 465°1 | 2217-7 | 638-5 +18 | +21 +22 20 22 20 ; = =? +20 | +21 Means. c - 65°6 22'4 I02"4| 23°3] Ir0'9} 304 January. February. April, June, 1873. Max. Min, Max, Min. Max, Max, Min . Max, Min. Sandwick 53'2| 20°5 63:0] 10°1 81-2 94:3) 19:0 - 122:4| 25:5 Kirkwall A : 3 54:8} 21°9 60°9 2°9 78°9 97:1) 19:7 12:4] 121°8| 25-4 Stornoway . - - ~ 55°0| 15:0 63°0 9:0 840 85:0] 18:0 14:0 98:0] 23:0 Culloden : - - - - 93°2 86 - - - ~ - - Braemar : : 3 c ; 69°0| 14°0 63°7 73 95°2 115°0|} 22:0 22:0 | 127:0| 26°0 Aberdeen ‘ = “ ; . 700} 20:0 91°7 2:4} 101°5 1170} 205] 140°3] 19:0] 184:8) 36:2 Kettins . : “ ; : : - 16°0 - 4:0 = - 24:0 - 24:0 - 34:0 Nookton - A 5 5 55°5 8:2 73°5 8-2 84:5 1015} 16:2} 104°5]} 17-2] 1175] 28-2 Dollar 64:7) 16°7 79'7| 10°7 86°7 97-7) O37 - ~ 101°7 | 384°7 Cardross - ~ 25:0 - 20°0 = 4 - 29:0 - 30:0 - 39°0 Ballock Castle 500] 18:0 65:0) 10:0 67:0} 18:0 98:0} 18:0} 107:0| 20:0] 1100] 32:0 Cairndow = > 5 5 f 76°6 ~ 98°9 - = = = = - - - - Callton Mor . - A . é 63°0| 13:0 67:0) 15:0 77°0| 23:0 88:0} 21° 97:70} 25:0} 102:0} 32:0 Eallabus. “ 5 5 : 54:6} 17°5 770} 115 78:0} 21°0 92°0} 19:0] 112°0} 22:0] 122:0) 28°0 Paisley . 5 65:0} 17-0 78:0} 12°0 75° 22:0 99:5) 205 94:5] 23°5 96:0] 383°5 Auchendrane . 56:0} 10:0 66:0} 13:0 87:0} 20:0] 102°0) 19:0] 1180} 22:0] 1180] 83:0 Glasgow. 5 78:0} 19°0 92:0) 10:0 97°2| 2071] 121°8) 21:2] 122°9] 23:2] 184:0) 30-0 Douglas Castle “ 7 A 86:0} 13°0 91:0} 10:0} 105°0} 18:0} 126°0} 20:0} 1080) 24:0] 111:0} 32:0 Smeaton. . ; 5 : 3 66:0} 12:0 69:0] 11°0 78:0} 12:0 87°0| 16:0 93:0} 15:0] 105°0} 23-0 Thurston . ‘ “i 3 5 66:0} 22°0 79:0] 19°0 90:0} 20:0 99:0) 27:0 99:0} 27:0 97:0] 37:0 Thirlestane Castle . P : A 87:0| 14:0} 102-0 - 1040] 15:0} 120°0} 19:0] 128:0] 20:0] 120°0| 31:0 South Cairn . A ; 52:0} 21:0 64:0] 16:0 58:0} 18:0 75:0) 19:0 86:0] 22:0 95:0} 27:0 1211°8 | 333°8 | 1537°6 | 210°7 | 1528-7 | 393°8 | 1815-9 | 407°8 | 1728-4 | 382:3 | 2033:2| 610°5 +19 | +20 | +20 | +20 | +18 | +20 | +18 | +20 [| +16 | +18 | +18 +20 Means 5 F 5 63°8| 16'7 769} 10'S 84'°9] I9'7 ] I00’9] 204} ro8'o| 2r'2] 113'0] 30°5 MEAN SCOTTISH METEOROLOGY. 2438 Taste XXVIa. continued.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. August, September, October. November. December. 1872. Min Max. Min Max Min Sand wick 0 5 Z 4 ; i 1113] 29% 991) 26°3 75°38 | 22:5 Kirkwall : A F ; é ; 4 1177 | 304 97°9| 24:2 82:8} 23:9 Stornoway . 5 3 5 “| y : 10070} 23:0 95:0) 15:0 72:0} 12:0 Culloden 3 : - , A 2° 113°8} 33°9] 107°0] 28:4] 102°0| 22:8 Dunvegan 2 . 5 : = = = = - Braemar 5 5 - 5 Z " ‘| 123°0| 3813] 107:2| 29:9 95°3| 206 Aberdeen c < : : 6 33°4 | 139°0| 29:0] 128°0} 27°83} 102°2) 23°6 Kettins . Fi 34:0 36°0 - 30°0 - 22°0 Nookton c 5 : c 1 381'2 | 111°5] 33:2 f 103°5] 24-2 ro Matos a Dollar . 6 : “ 4 .| 1167) 387°7 = = 102°7| 27°7 93°77} 21:7 Cardross 7 5 fi : ; - 41-0 - 42:0 - 35°0 - - Balloch Castle 1100} 28:0} 101:0} 25-0 78:0} 18:0 64:0] 15:0 Cairndow 144-4 - 138°6 - - ~ - - Callton Mor . 1050] 33:0} 114:0} 33:0 90:°0} 25:0 78:0} 18:0 Eallabus. 122-4] 31:5} 1140} 31:0 96:0} 27:0 79:0} 20:0 Paisley . A A 109°0| 33:0} 1015] 32:0 96:5] 26:0 815] 19:0 Auchendrane . A 118:0] 37:0} 110:0} 37:0} 1080} 30:0 82°0} 20°0 Glasgow . : 131:0| 34:8 } 182:°2]} 398] 1166) 30-5] 102°8) 25:0 Douglas Castle 1240) 31:0 | 124:0} 33:0} 115°0} 23:0] 109°0|) 15:0 Smeaton 1110] 23:0} 103:0} 22:0 90:0} 18:0 85:0] 12:0 Thurston s : 114:0| 38:0} 1040} 380 95:0] 34:0 99:0] 27:0 Thirlestane Castle . 4 . | 1380°0] 24:0} 128°0} 25:0] 111:0| 20:0] 106:0| 19°0 South Cairn . : = c 98:0) 32-0 86-0} 36°0 - - 72°0| 22:0 2399:0 | 676°7 | 2171°6| 640°1 | 1836°5 | 520-0 | 1663°6 | 398°3 | 1351°8| 398-1 | 12131} 306-7 +20 | +21 | +19 | +20 | +18 | +20 | +19 | +20 | +18 | +19 | +20 | +20 MEANS T20'0| 32°2} 114°3] 32'°0} 102°0| 26°0 87°6| 19°9 751| 21°0 60°7] 15°3 August. September, October, November, December, 1873. Max, Min, Max, Min, Max, Min, Max, Min, Max, Min, Sandwick c 1121} 305] 1033) 30°5 81°1 57:2] 24:5 Kirkwall 99°6 | 2674 95:4) 28-0 85:0 - 18°7 Stornoway 101:0} 32:0 97:0} 25:0 92:0 560] 14:0 Culloden = = 1111} 29:2 98°0 72°3| 20°8 Braemar . < 121°0| 26:2] 115:0} 29°8 95:2 77°8} 20:0 Aberdeen 137°5| 30°83] 185°5] 301 - - 22:7 Kettins . - 38:0 - - - - - Nookton. 103°5| 31:2} 1065} 28:2 91°5 57:5 | 16:2 Dollar . A 10277) 37:°7} 101°7| 29°7 97°7 = = Cardross A é ; n c ‘ - 40:0 - 30°5 - - 24°5 Balloch Castle c 5 4 . | 1140} 32:0 95:0} 26:0 98:0} 20:0 75°0 54:0} 20°0 Cairndow 0 : : c 5 - - - - - - - - - Callton Mor . 7 4 5 ni 99:0} 30:0 98:0} 35:0 95:0} 28:0 78:0 53'0| 21:0 Eallabus . “ c 5 3 . | 1110] 3805] 1065) 33:0] 103°0} 28-0 91:0 57:0] 20:0 Paisley . 2 : A ¢ 5 97:5) 30° 85:5] 315 99°5| 26:0 78°5 62:0] 21:0 Auchendrane . . : 5 . | 121:0] 36:0] 110:0] 37:0 980} 33:0 84:0 53:0} 22:0 Glasgow . c 2 0 : . | 1381°2] 34:0] 126:7) 29:9] 113°6} 29-2 882 67:0} 21:2 Douglas Castle d . - . | 120:0] 35:0] 119°0| 34:0] 127:0} 28:0} 109°0 65:0} 19:0 Smeaton 5 4 c 6 . | 115°0) 30:0 97:0} 25:0} 107:0} 30:0 92:0 70:0} 20°0 Thurston : : Cc . | 1150} 41:0 97:0} 39:0 96:0] 32:0 86°0 62:0} 26:0 Thirlestane Castle . 4 ; . | 125:0) 32:0] 116°0| 26:0] 125:0) 22:0] 111°0 - 19:0 South Cairn . 2 9 : : 29:0} 30:0 85:0] 31:0 72°0| 28:0 75°0 54:0} 18:0 1964-1 | 657-2 | 1913-1 | 640°2 | 1999°6| 565-2 | 1608-2 917°8 | 388°6 +17 +19 | +18 +20 | +19 +20 | +18 +15 +19 MEANS : 4 . | 115°5| 34°6]| 106°3} 32°0] I05°2] 28°3 89°3 6r'2| 204 244 ; PROFESSOR C. PIAZZI SMYTH ON TaBLE XXVIA. continued.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. Sandwick = 3 24: Kirkwall 5 4 4 5 : - 20°4 - 4-4 - Q1°4 Stornoway . 2 fs f il ole 140 77:0| 16:0 89:0 9:0 Culloden a a : : : 871 20°6 86:0} 15°6 - - Braemar A i 2 : E 73°8 | 12:2 786 | 14:0] 113°8} 15:4 Aberdeen S A : A , - 19°7 : 21°6 - 22-0 Nookton . Z ‘ * ; 625 | 72 73°5 9:2 90°5| 13:2 Cardross s 5 6 4 5 - 26:0 - - - 17:0 Balloch Castle . 3 - eel 90:0)| 2020 65:0| 15:0 75:0| 12:0 Callton Mor . i : a : 60:0 | 21:0 68:0} 19:0 73'°0| 22°0 Eallabus ‘ 5 . : ‘ 57:0 | 23:0 - - 77°0| 20:0 Paisley . 3 3 5 5 ; 62°5 | 25:0 67°5| 15:0 74:5} 10°5 Auchendrane . ‘ A 5 5 58:0 | 25:0 67:0} 15:0 81:0} 13:0 Glasgow ; 5 ; . ‘ 74:0 | 23:0 91:3} 18:0 92:4) 15°3 Douglas Castle : 5 é - | 69:0] 20:0 91:0} 17:0} 105:0} 14:0 Smeaton A 4 4 $ Ze 79:0 22°5 85:0 9°5 93:0} 16°5 Thurston : . ;: ; . 79:0 | 25-0 89:0} 21:0 92°0| 22-2 Thirlestane Castle . ; 4 A - 21:0 - 10:0 - 13:0 South Cairn . 4 6 : 5 52:0 | 22:0 50:0| 18:0 560} 15:0 9741 | 399°6 | 1064°6 | 268°6 | 1187°4 | 296-0 | 1537°5| 430°3 +15 | +19 | +14 | +17 | +14 | +18 : MEaNs . ° | 64°9| 2r'0 76'0| 15°8 848} 164 January, February, March. June, 1875. Max, Min. Max, Min, Max, Min, Max, Min, Max, Max, Min Sandwick Z 57'°2| 16:5 64:2] 21°5 79'2| 27°4 94:0] 25°6 - - - - Kirkwall : - - - - - - - - - - - - Stornoway 4 5370} 15:0 74:0} 11:0 87:0] 14:0 97:0} 18° 88:0} 20:0} 104:0} 20-0 Braemar 71:0} 15:4 76°3 50 | 101°3 17:2} 117:0] 19°8] 119:°0] 29:0] 123:0] 28°8 Aberdeen - 12°5 - 16°9 - 26°6 - 30°4 - 30°5 - 33:2 Nookton 55°5 6:2 65°5| 102 88:5] 17:2] 101°5| 15:2] 1045) 26:2] 1005) 272 Balloch Castle 50:0 8:0 55:0} 12:0 7070] 15:0 90:0} 15:0 85:0] 30:0 98:0] 30°0 Callton Mor . 55:°0| 24:0 64:0} 18:0 81:0] 20-0 91:0} 23:0 89:0} 32:0 95:0} 35:0 Eallabus 63°0| 24:0 73°0| 15:0 83:0] 16:0} 104°0) 205] 110°0| 265] 114:0| 28°5 Paisley . 66°5 5D 72°5| 14:0 705} 16:0 91:°5| 16:0 90°5} 29°0 | 1005} 29:0 Annanhill 62:0} 18:0 74:0} 20°56} 108:0| 19:0] 131°7| 28°5 - - 135'2| 37:0 Glasgow 59°5 9:2 60°38} 14:8 73°2| 15:7 83°9 89:9} 33:9 86:9] 32:2 Ridge Park - - ~ - - - - - - 104:0| 36:0 Douglas Castle 81:0} 14:0 83:0} 16:0 87:0} 15:0 | 100-0 90:0} 28:0] 104:0|} 80:0 Smeaton 75:0 1:0 75:0} 12:0 85:0] 14:5 7 102-0 113:0| 27:5] 105:0} 26°5 Thurston 3 3 73'°0| 14:0 74:0] 21:0 80:0] 23:0 | 105°0 " : 106:0} 35:0 Thirlestane Castle . 12°0 81:0 7:0 92:0] 15:0] 106°0 109':0} 20:0 195°3 | 992°3| 214:9 | 1185-7} 271°6 | 1414-6 11789 | 365°6 }1485:1| 448-4 +15 +14 +15 +14 +15 +14 +12 +13 +14 +15 MEANS 13'0 7o'9] 14°3 84°7| 18'r | Tor‘o 98'2| 28'r | 1To6'r| 29'9 MEAN SCOTTISH METEOROLOGY. 245 TaBLE XXVIa. continued.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. September, October, November, December, 1874. Min Max, Min. Max, Min, Max, Min, Max, Min Sandwick 35°5 B34] - = 2 = 552| 13:3 Kirkwall - - - - = - - - Stornoway 30°0 25-0 75:0} 22:0 - = 49:0 11:0 Culloden 373 29-9 - - - - 579 6°6 Braemar . 30°0 28:0 | 110°0 18:2 90°0 12°3 76°8 5:0 Aberdeen 36°5 30°5 - 24:4 - 24°6 = 10°8 Nookton 38-2 27:2 89:5] 21:2 67°5 152 48°5 3°2 Cardross : 43:0 = = = . a = = Balloch Castle 39-0 82°0 63:0} 25:0 55:0 20:0 45:0 5:0 Callton Mor . 40:0 34:0 76:0} 26-0 66:0 25°0 55:0 14:0 Eallabus 29°5 31:0 91-0 24:0 67:0 24°0 75:0 12°0 Paisley . c 38:0 30°5 84:5) 24:5 69°5 19:0 61°5 5:0 Auchendrane . 380 35'0 93:0} 24:0 590 20°0 49-0 8:0 Glasgow A 33°3 23°8 73°8| 23:2 66°8 17:2 48:0 5°5 Douglas Castle 33°0 31:0 | 104:0| 24:0 89:0 18:0 70°0 5:0 Smeaton 85°5 27°5 88°0 22:0 78:0 14:5 59°0 1°5 Thurston A ; 42°0 350 96°0 30°0 86:0 25°0 58:0 13:0 Thirlestane Castle . 32:0 27°0 - 24:0 - 15:0 - —6°0 South Cairn . 32°0 - 68:0} 23°0 62°0 20:0 = - 642°8 | 1630-4 480°8 | 111°8| 355°5 | 855°8 | 269°8 | 807°9 | 112°9 +18 = +16 +13 +15 +12 +14 +14 +16 MEANS 35°7 30°0 85°5 23°7 713 19°3 57°77 71 iene July. August, September, October, November, December. 79. Max Min Max. Min Max. Min Min Max Min Max. Min Sandwick - 114:2] 35:0] 106:2/ 28:0 85:2] 28°3 61:4 18°5 - - Kirkwall = - - - - 64°5 - - - - - Stornoway 112°0) 29:0 98:0} 29:0 98:0] 32°0 73:0 | 25:0 57:0] 20:0 52°70] 15:0 Braemar . 1340) 32:0] 125°8) 31:8} 115-4 27:0 92°3 23°2 68°8 30 69:0} 11°8 Aberdeen 34:5 - 40°5 - 312 28°0 - 16°7 = 22°1 Nookton c 116°5 - 102°5 - 99°5 31'2 82°5| 23:2 63°5| 16:2 50°5 18°2 Balloch Castle 110:0;} 30:0} 110°0} 33:0 90:0) 25:0 60:0} 22:0 55°0 10:0 55°0 5:0 Callton Mor . 108:0} 36:0 | 103:0 350 97:0} 30:0 760} 27:0 60:0 16°0 61:0 16:0 Eallabus 118:0} 30:0] 123°5 32°0 J} 104:0) 33°0 80:0} 24:0 68:0 16:0 52°0 12:0 Paisley . 103°5 | 27:0 | 105°5) 29-1 97:5 | 23:0 82:5] 22°0 75°5 22: 63°5 11:0 Annanhill 1386°4| 38:0] 136-4 42:0 | 126°0| 36:5] 118:°0| 286 87°5 19° 69°5 17:0 Glasgow 106°7 320 89°4 371 92:0) 31°5 : 20°6 64:8 9: 57°8 8:9 Ridge Park . 1015} 37:5} 100°0 38°5 | 101:0| 36:0 27:0 70°5 ie 50:0} 16:0 Douglas Castle 108:0} 300] 116°0) 33:0} 126°0} 27:0 21°0 87:0 9: 79°0 9:0 Smeaton 11070) 25°57 10970) 315] 104:0| 25:5 ; 17°5 77:0 12° 68-0 15°5 Thurston r “ 1100} 36:0] 113°0 44:0 } 108:0| 35:0 4 28°0 86:0} 22° 61:0} 24:0 Thirlestane Castle . 1150} 25:0] 122-0 32:0 | 117°0 26:0 99:0} 18:0 98-0 12:0 71:0 7:0 1589°6 | 442°5 | 1668°3 | 523:°5 | 1581°6 | 477°9 383°4 | 1080:0 | 238°9 | 859°3 |} 208°5 +14 +14 +15 +15 +15 +16 +16 +15 +16 +14 +15 Means 1135 | 31°6} z1r'2| 34°9f 1054| 29°9 24°0 720| 14'9 61'4| 13°9 VOL. XXXV. PART 3. 2 246 PROFESSOR C. PIAZZI SMYTH ON Taste XXVIA. continued.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. January. February, March, April. May. 1876. Max. Min, Max, Min. Max, Min, Max, Min, Max, Min, Sandwick A : ‘ : ; 54:3] 20°5 - - 65°7 | 24:0 - - 84:5 84:5 Kirkwall : z : : : - - = - = - ~ 90°6 Be Stornoway : ; 2 : - 18:0 - 11:0 - 18-0 15:0 -- 32°0 Culloden 88:0) 11:8 90:0} 13°5 | 102:0) 13:9] 123°5] 19:9] 1380-0 316 Braemar . 65°2 9:0 780} 10:0 96°38} 11:2] 108:0} 16:3] 119°2 27:2 Aberdeen - 16:1 - 20:2 = 18°7 - 21°4 - = Ochtertyre 03:0} 14:07 105°0} 17:0] 111:0} 14:0] 122°0} 14:0] 109:0 30°0 Dollar . A aha Stee sVAe\) aller 84°7 | 21°7 94:7 | 21:7 | 104°7 36°7 Balloch Castle 55:0} 11:0 46:0} 11:0 75:0} 12:0 98:0} 10:0} 100°0 25:0 Callton Mor . 65:0} 18:0 66:0} 20:0 72°0| 20:0 91:0} 22:0 95:0 32:0 Eallabus 65:0] 15:0 760) 15:0 - _ ~ = = = Paisley . 69°5| 19:0 62°5| 14:0 65:5) 14:0 - 16:0 - = Annanhill 61:7] 19-0 81:4} 20:0] 1045) 17:5] 124:7] 18:0 - - Glasgow 54:2} 155 59:0} 14°5 59'°9| 15:2 76:9} 16:0] 133°2 30°2 Ridge Park . 53°0| 18:0 56:0] 20°0 64:0} 19:0 81:0} 20:0 96-0 845 Douglas Castle 78:0} 12:0 81:0} 10-0 830} 14:0 87:0} 17:0 97-0 29:0 Smeaton 67:0} 10°5 72:0| 12°5 69:0} 165 91:0} 12°5 92:0 26°5 Thurston 5 e 70:0} 15:0 81:0} 22°0 75:0] 23-0 93:0} 18:0 : 380 Thirlestane Castle . 72:0 5:0 83°0 8:0 90:0} 13:0} 102:0 - = 1093°6 | 265°1 | 1124-6 | 260-4 | 1218-1 | 285-7 | 1292°8 | 257-8 | 1453-2) 383-7 | 1629-3 | 407-2 +16 | +18 | +15 | +17 | +15 | +17 | +18 | +15 | +14 +13 Mrans 68'4| 14°7 75'0| 15°3 81'2| 168 99'4| 17°2] 1038 31°3 1877. Min Sandwick ‘7 = =. Stornoway = 14:0 - 16:0 Culloden - - 1090} 166 Braemar . - 16:0 - 12:0 Aberdeen - 19:0 - 14:0 Ochtertyre 92:0} 21:0 95:0) 21:0 Dollar . , 82:7 | 17:7 84°7| 19:7 Balloch Castle 52:0] 15:0 55:0} 15:0 Callton Mor . 59:0} 20:0 65:0} 19:0 Eallabus 65:0} 19-0 78:0} 16:0 Paisley . 68°5| 13:0 98°5| 15:0 Annanhill 850 95] 10271) 20-0 Ridge Park 59°0| 13:5} 74:0} 165 Douglas Castle 49:0] 14:0 96:0} 11:0 Edinburgh - 16°5 91:0} 18:0 Smeaton ; 80:0} 12°5 4 : Thurston F i 5:0} 23°0 Thirlestane Castle . 1147-0 | 3043 =13 | +15 90671) 254°4 +14 | +18 910°3 | 268°4 | 1212°3 | 269°3 +13 | +17 | +14 | +17 1359°5 | 321°8 +14 | +16 1441°2 +13 | +15 7o'o| 15'8 86°6| 15°8 64'7 I4°I 88'2] 20°3 97°I| 20°§ | I10'9| 33°5 MEAN SCOTTISH METEOROLOGY. 247 Taste XXVIa. continued. BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. 1876 July, August, September. October. November, December. 76. Max Min Max Min Max. Max Min Max. Min Max, Min, Sandwick ? : ‘ é . | 1045) 3856 93°4| 36°5 77:2 63:2 | 32:5 - - 472) 26:1 Kirkwall : g . j 5 98°6 - 78°6 - 91-1 - - ~ = - Stornoway . : 2 ; ; - 350 - 36'0 - 28°0 - 24:0 - 24:0 Culloden 5 ; F : . | 189°8| 37:7 | 141°7| 33°38 | 1305] 28: 122°4| 246 : - - Braemar 2 e i 4 . | 1298) 30°3§ 127°0| 31:2] 115:1 Y - - - 68°8 | 22:0 Aberdeen P : : : ; - - - 342 - 30°1 - 22°5 - 24°8 Ochtertyre . ; 0 . | 1180] 36:0} 121:0} 32:0} 111:0 q 1030} 29:0} 100°0|) 14:0 76:0 | 21:0 Dollar . 5 : ‘ F . | 110°77| 40:7] 117°7| 37:7} 104:7 y 94:7} 33:7 O17 87 64:7 | 23°7 Balloch Castle : F : . | 1200] 35:0] 115:0|} 80:0] 102:0 y 65:0} 22:0 65:0} 14:0 45:0} 16:0 Callton Mor . : A ; . | 105:0| 35:0} 107:0} 33:0 91:0 : 83:0} 26:0 68:0 | 20:0 58:0] 25:0 Eallabus C : 3 : . | 1200} 31:0] 117:0} 32:0] 104:0 87:0] 27:0 71:0] 20:0 57:0] 24:0 Paisley . F : nome ; - 36°0 - 28:0 - 27°0 - 12°0 61:5} 21:0 Annanhill . C : a . | 1388:2| 39:0} 136-2} 30:0] 128°0 123°0| 25:0 94:2) 18°7 61'2| 25°0 Glasgow ri ' 5 . . | 133°7] 382°0] 126°8) 31:2] 124:0 : 113°2} 22°8 99:3 | 13:1 66°8 | 21°6 Ridge Park . - d F . | 105:0) 40:0} 119:0| 31:5 88-0 2" 74:0 | 29°5 59:0} 10:0 49°5| 24:0 Douglas Castle c a ; . | 103:0| 33:0] 118:0| 28:0} 102-0 85:0 | 24:0 80:0} 11:0 66:0} 20:0 Smeaton ‘ F d A . | 115:0) 26:5] 115:0| 265] 103-0 94:0] 24:5 72:0) 16°5 68:0 | 20°5 Thurston : “ : . | 116:0} 37:0] 117:0| 88:0] 101°0 i 101°0} 32:0 83:0} 25:0 71:0} 28:0 Thirlestane Castle . c : . | 123°0 - 122°0 - 103°0 4 92:0} 21:0 81:0} 12:0 79:0 9-0 1880°3 | 559°8 | 1872:4| 549°6 | 1675°6| 540°0 | 1300°5| 458-7 | 964:2) 251°5 | 939°7| 375-7 +16 +16 +16 +17 +16 + 14 +17 +12 +15 +15 +17 Means. ; = I) 21745)" 35:0] BE7‘0)|| 3279) ]) 104°7 ; 92°9| 27'0 80°4| 16°38 62°6| 22°r July November, December, 1877. Max, Min 3 Min, Min, Sandwick ‘ 4 ‘ é . | 1061} 40°3 - 32°3 SBF) 123*5 22°4 15°5 Stornoway . ; : ‘ : - 37:0 37°0 30:0 = 25:0 24:0 18-0 Culloden i dq ; F c - - ~ - - - - - = Braemar ; ‘ x 3 . | 186:0| 33:8] 184:0] 25:2 25:4 | 114°4] 19:0 15:3 9-0 Aberdeen 5 i : ‘< : - 39°2 - 34:2 311 - 22°8 21°9 9°6 Ochtertyre . 7 ‘ : - | 108:0| 37:0] 122°0) 34:0 29:0 | 112°:0] 19°0 17:0 12:0 } Dollar . d : 3 : . | 101°7, 34:7] 107°7| 30:7 - - - 21°7 16°7 Balloch Castle . re 5 0 - - 100°0} 32:0 28°0 78:0 | 24:0 22:0 15:0 Callton Mor . c : 5 , 90:0; 39:0] 100:0) 300 27°0 70:0} 25:0 26:0 18:0 Eallabus c : ; : . | 109°0) 30:0] 108°0| 33:4 260 79:0] 23-0 25:0 25°0 Paisley . 3 5 6 6 0 86:5] 33:0 89°5| 29:0 21:0 865} 24°0 20:0 14:0 Annanhill . 2 F : . | 1383:0] 39:0 ~ - - 100°3| 25:1 27:1 20:0 Ridge Park . “ 4 6 “ 775 | 37:0 90:0} 36:0 30°0 85:0] 25:0 24:0 20:0 Douglas Castle é i 0 . 850] 33:0 92:0} 32:0 25:0 | 103:0} 23:0 22°0 15:0 oe ee = = 30°9 27:0] 94:5] 18-0 17:0 17-4 Smeaton F ; . ‘ a 98:0] 30°5 96:0} 26°5 23°5 ‘| 4 13°5 15:5 Thurston 5 - ; i é 94:0} 41:0 : q 35°0 24:0 18:0 Thirlestane Castle . j 5 . | 109:0} 29:0 27-0 16°0 14-0 1333'8 | 533°5 | 1250-2 1157°8 | 358°9 2727 +13 | +15 +15 | +17 +17 MeEans fi ‘ : 102'6 35°6 77 2 211 16’0 248 PROFESSOR ©. PIAZZI SMYTH ON Taste XXVIAa. continued.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES, A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. June, 1878 Max, Min Sandwick 112°2} 27:4 Stornoway = 27°0 Braemar 141:0} 27°7 Perth . 120°0| 34:0 Ochtertyre 1150} 29-0 Dollar . - 108°7| 32°7 Balloch Castle - = Callton Mor . 1020} 32:0 Eallabus 116:0] 27-0 Paisley . 98°5| 24:0 Annanhill 140'9] 31:0 Ridge Park 107'0} 28°0 Douglas Castle 109°0| 22-0 Edinburgh - - Smeaton 1135] 195 Thurston : “ 1050} 34:0 Thirlestane Castle . 1160} 26:0 1223°9 | 381°3 | 1316°0 | 251°8 | 1259°7 | 281°5 | 1252:0} 344°8 | 1604°8 | 421°3 +16 | +17 [| +15 | +16 | +138 | +14 | +12 | +138 | +14 | +15 MEANS 765} 224 O7e7A\ MLBEy. 96.9} 20°'r J 104°3}| 26°5 | 1146} 28'r January, February, March, April. May. 1879. Max. | Min, Max. Max Min, Max, Min Max Min Sandwick ; : F ‘ : 60-1 95 65°2 772) 14:7 84:1] 205 96:2} 22:9 Culloden “ x 3 ; ; 87'3| 10:0 - 110°0 78} 1245] 21°57 181°0] 20:9 Braemar - : , i 5 64:8 30 99:0 121°2} 16:0] 122°0) 16:0} 183°8) 17:2 Perth . : : ‘ ; ; 67:0 70 - 76:0 - 101:0 - 1080 - Ochtertyre . : 5 : 2 89:0} 13:0 94:0 92:0) 17:0} 101:0} 21:0] 110°0} 22:0 Dollar . 2 : 5 ‘ ral 7657) 8:7 80°7 74:7) 16°7 89°7 | 24:7 877) 2657 Balloch Castle : ; 4 : 45:0 3°0 61:0 6070} 14:0 80:0} 20:0 900} 16:0 Callton Mor . 3 : : : 55°0| 13:0 65:0 66:0} 18:0 ~ - - - Eallabus 4 ; : ; 3 58:0 9:0 62:0 70:0} 15°0 82:0} 20:0 91:0) 21:0 Paisley . 4 + : : 73°5 8:0 715 82°5| 15:0 77°5| 19°90 89°5| 16:0 Annanhill . 3 : si ‘ 565) 14:5 717 LO5*7 1) 205 I) L7G) 2-7 ~ = Ridge Park . : : : : 52°0| 13:0 59:0 67:0] 12:0 79:0} 24:0 84:0] 23°5 Douglas Castle : : . 65:0 2:0 84:0 80:0 9:0 92:0] 15:0 99:0) 13:0 Edinburgh ; : : : - - 735 - - 9070} 21:3} 104:0} 19° Smeaton : : " ; 60°0 1:0 66:0 88-0 65 88:0} 15°5 98:0] 15°5 Thurston - : : ; 71:0| 15:0 71:0 8070} 22:0 86:0} 25:0 92:0} 25:0 Thirlestane Castle . - : : 770 0-0 82:0 101°0 4:0] 1000} 12:0] 1160) 15:0 ) 1057°9| 184°7 | 1105°6 13513 | 209-2 7 1514°4| 297-2 | 1530:2 | 274-0 | 1794:9| 479°1 +16 | +16 | +15 +16 | +15 | +16 | +15 | +15 | +14 | +17 | +16 MEANS. 4 : 66°r 84 73°77 22 84°5| 13°9 94°6| 198] t02°0] 19°6 | 1056] 29°9 MEAN SCOTTISH METEOROLOGY. 249 Taste XXVIa. continued.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. Sandwick Stornoway Braemar . Perth . Ochtertyre Dollar . 3 Balloch Castle Callton Mor Eallabus Paisley . Annanhill Ridge Park . Douglas Castle Edinburgh Smeaton Thurston c P Thirlestane Castle . MEANS Sandwick Culloden Braemar . Perth Ochtertyre Dollar . : Balloch Castle Callton Mor . ‘Eallabus Paisley . Annanhill Ridge Park Douglas Castle Edinburgh Smeaton Thurston 3 < Thirlestane Castle . MEANS VOL, XXXV. PART 3. July August. September, October, November, December, Max Min. Max. Min. Max. Min, Max Min, Max, Min, Max, Min, 103°0| 41:7} 1082} 32:3} 105:0] 38:0 762) 27-5 57'4| 18:3 50°2| 13:7 = = = 36°0 = 34:0 = 25:0, = - - = 1475} 31:0} 141:0) 29-7] 1260} 29-4] 116-7) 22-0 90:0} 14:8 84:3 1:0 127:0| 36:0] 1240] 35:0] 113:0| 340 98:0} 26-0 85:0} 17-0 63:0 5:0 123:0| 340] 119°0} 36:0] 1150} 32:0] 107:0; 23-0 88:0} 20-0 79:0} 11:0 109°7 | 29°77 | 108°7| 39°77] 105°7| 383°7) 97-7) 27] 86%) 27) 72:7 97 1150} 37:0 = = 1000} 30°0 750} 26:0 58:0} 17:0 40-0 8-0 1110] 36:0] 1080} 34:0 96:0} 38:0 82-0} 29:0 63:0 = 61:0} 11-0 1150} 33:0] 1040; 34:0 97:0} 33°0 78:0} 24:0 59°0} 18:0 57°0 8-0 1025) 3860] 1045} 3840] 1005] 31-0 93°5| 19-0 845] 16-0 69°5 2:0 1367} 40:0} 185°9| 426] 125-2} 32:5] 107:0} 26:0 764) 21:3 = = 1170} 40:0] 1160} 40-0 90:0} 36:0 73°0| 275 56°0| 17:05) 46:0 2°0 1060); 32:0] 111°0} 31:0] 112°0| 27-0 96:0} 19:0 75:0} 14:0 60-0 2:0 - - 125:0| 33:3 = = 103-0} 25-0 72°5| 195 = = 114:0) 265] 111°0} 305] 105-0} 20°5 93:0} 17:5 67:0| 155 62:0 0°6 108:0} 40:0] 107:0} 41:0} 102°0} 38-0 95°0} 31:0 790} 25:0 730} 10-0 1230} 31:0} 1120) 35:0] 123:0} 25:0] 1080} 21:0 91:0} 15:0 77-0 30 1758°4 | 523-9 | 1735°3 | 564-1 | 1615-4 | 512-1 | 1499-1) 417-2 | 1188-5) 270-1 | 894-7 87.0 +15 | +15 +15 | +16 | +15 | +16 | +16 | +17 | +16 | +15 | +14 | +14 1172| 349] 1157] 35°3| 1077] 320] 93°7| 245] 74°3| 180] 63°99) 62 July August, September, October, November. December, Max Min Max. Min, Max, Min, Max. Min, Min. Max. Min 97:2) 3865} 110°2) 395] 115-1] . 35°5 782) 26°5 23°3 57:7 11°5 1310] 37:0} 13843] 33:0] 124:3| 27:8} 117-0) 20-0 17°8 61-8 68 1375] 30:0} 1302] 29:0} 1202} 23:3] 118-8} 16:3 127 70:0} — 30 1200} 380] 1150} 40:0 = = = = = 58°0 70 1180} 37:0] 1140; 320] 1050} 25:0] 109°0} 21:0 15:0 74:0 8°0 103°7| 35:7 | 1037 | 34:7 = = = = 2 = = = = = = = = = = 15-0 50-0 8-0 95:0} 38:0 93:0} 31:0 91-4} 326 74:4) 26° 20°5 51°4 10°5 98:0} 34:0 95:0} 30:0 89:0} 28:0 81:0} 22°0 19-0 50°0 8:0 93°5| 36:0 875] 30:0 93°5 | 25:0 = = = 69°5 50 = = 131-1) 35:9] 1191) 32°5] 109-4) 20-4 17-1 62:0 5:0 96:0} 41:5 99:0) 36:0 85:0 | 29°6 85:0} 20-0 18-0 51:0 0-0 96:0} 35:0} 1015) 28:5} 1105) 22:5] 1145) 14:5 10°5 81°5| — 6:0 123°7| 30°7 | 127:0) 33:8 = = 82-7 | 18:7 135 520} — 2:0 1070) 31:5} 107:0) 285 96:0} 20°5 92:0) 14:5 10°5 67:0 | — 4:5 98:0} 40:0} 105°0| 420] 1000} 32:0] 100:0} 28:0 = = = 129°0| 3820} 127:0) 32:0] 125°0} 24:0} 125-0) 20-0 14:0 = —11-0 1643°6 | 532-9 | 1780°5 | 535-9 | 1374:1| 357-7 | 1287-0 | 268-4 206°9 | 855°9 | +43°3 +15 | +15 | +16 | +16 | +13 | +13 | +138] +13 +13 }) +14 | +15 Tog'6| 35°5} IIz3| 33°5] 105'7] 27°5 990 | 20°6 159 61'r 2°9 28 250 PROFESSOR C. PIAZZI SMYTH ON ‘ TaBLe XXVIA. continued —BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. January. February. March, April. May. June, 1880, Max, Min, Max. Min, Max, Min, Max, , Min Max, Min Sandwick : é : 7 é 56°2| 251 60°3| 25:3 70°2| 25:5 80°1 : 98:0} 316] 1097} 305 Culloden zi : 5 ‘ : 90:2; 15:0] 101°0} 18:0] 113°0} 18:5] 125-0 i 130°8; 24:0} 132:0} 28:0 Braemar. 5 7 : : ; 87:2 9°6 98°8| 183 115°3) 11:0} 119-0 : 137°0} 19:5 | 146°8| 26-0 Perth . . . : . 5 72:0] 12:0 79°0| 25:0 98:0 | 20:0] 101°0 H 1140} 26°07 120°:0] 34:0 Ochtertyre . 5 A 5 E 81:0} 14:0 19°0 110: 0} 19:0} 113-0 2 125:0| 22:0 | 120°0)|) 270 Dollar. 3 5 - : 62°7| 15:7 74: 7| 23°7 22:7 86°7 ‘ 109°7 | 27:7 | 100°7 |) Sis7 Balloch Castle 4 P . , 55:0] 10:0 60:0} 24:0 19°0 880 4 1050} 24:0] 1100) 28:0 Callton Mor . S ° : > 61:4] 18°5 714) 26:5 25°5 85°4 y 92-4) 26°57 1004] 30°5 Eallabus ‘ 3 E : : 54:0} 14:0 600} 22:0 ° 23-0 90:0} 22° 104:0} 24:0] 115:0} 25-0 Paisley . 4 : . 5 62:5] 11:0 69°5| 21:0 16:0 88°5 : 96°5} 20-0} 1035] 240 Annanhill_. : : : . 68:7 | 18:0 85°38] 26:0 221 } 122°2 : - - - Ridge Park . ; : ¢ “ 52:0] 11:0 66:0} 28:0 21:0 87:0 ‘ 89:0} 25:0] 103°0} 31:0 Douglas . 5 5 = ‘ - 81:5 65 905] 18:5 9D 97°5 ‘ 91:5) 185 98°5| 215 Edinburgh. , : : : 64:0} 12:0 81-7} 175 17°6 91°5 q 104:5| 26:4 - - Smeaton 4 A t 79:0 55 7670) 155 105 93°0 f 100°0} 12:5] 108°0} 17:5 Thirlestane Castle . 5 5 5 69°0 30 69:0} 22:0 17:0 | 101°0 15:0} 1180} 19:0 1086°4 | 200-9 | 1143-7 | 345°3 1456 0| 297:9 1568-9. 9 342" 3 | 1497-4] 342-7 | 1585°6 | 373:7 +16 | +16 +15 | +16 +16 +16 +15 | +14 | +14 Means 5 . s 67'9| 12°6 76'2| 21°6 18°6 98'r I0o7'0| 22°8 | 113°3| 26'°7 3 . . 0 5 Inverness A : i 0 Braemar . 86:0 | — 38:0] 93:8 27} 1083 0:0 | 117°0 9:0 | 1384:2) 21:2 Ochtertyre 84:0 0:0} 103-0 90} 110°0) 16:0] 114:0| 180] 125:0} 24:0 Dollar . 66°7 Zeit \| AN 12°7 86°7 8:7 8927 2027 4) LOG:7 | 2727; Balloch Castle - - = - - - 95:0} 15:0} 122:0} 24:0 Callton Mor . 56:4 55} 66:4 19°0 73°4| 13°5 82:4} 19°5 99:4] 25:5 Eallabus 54:0 2:0] 62:0 150 750} 12:0 - 17:0 - 25°0 Paisley . 615 | -— 7:0] 785 15:0 86°5| 10:0 91:5} 16:0] 109°5) 25:0 Ridge Park 48:0 | — 60] 61:0 16:0 80:0} 11:0 81:0; 19°} 115:0| 29°0 Douglas Castle 75°5 O05} 85°5 115 | 105°5 65 88'°5| 13:5} 1105) 21°5 Edinburgh : 28 z : : 87 Smeaton 1 5°5 q 4:5 4 f Thirlestane Castle . 85:0 | -15:0] 94:0 4:0 | 105°0 1:0 | 108°0 60 |} 126°:0|} 15°0 8261 | —25°3} 953°6 | 155°7 | 1194°3} 112°4 | 1257°7 | 229°9 | 1514:0 +12 | +12 | +12 | +12 | +13 | +13 | +18 | +14] +13 14 13'0 919 86 96°7} 16'4] r16'°5| 24°5 January, June. 1882. Max. Min Max Min Sandwick H E 5 ; Z 57*2)| 27:0 ‘ ’ : ; : : 1054} 30: Inverness : 3 3 3 _ 82:0} 24:0 : : : P ; ql dl 28:0 | 120°0} 35°0 Braemar : : ; , : 84:0} 12:0 : 4 ‘| : ‘ : Us 156 | 1402) 26-4 Ochtertyre . : : : 5 87:0} 21:0 ; f ¢ : : ‘ ; 28:0 | 1160] 27:0 Dollar . ; ; 7 A 62:7| 21°7 : f ; 3° : : : 26:0 | 102°7| 29:7 Balloch Castle ; a 52:0] 12:0 q , 4 A : 1 ‘ 21:0} 116:0|} 26:0 Callton Mor . < F : 5 58°4| 24°5 p q . : : : Q 28:5 | 106°4| 32°5 Eallabus : ‘ 5 : : 550} 26:0 ‘ P ; ; : ; A 25:0 | 1060] 33:0 Paisley . 3 - 3 % 5 645} 23:0 { 2 { i : : Hl 27°5 | 110°} 31° Ridge Park . : : ‘ F 54:5} 25:0 ‘ : ; : : ' : 26:0 | 109:0| 285 Douglas Castle . : : , ~ - : ; i 3 : ; | 23:0] 1005) 29° Edinburgh . 3 Hs A : 78°0| 22°5 : : 4 i‘! : : : 28:0 - = | Smeaton : : . : ; 75'0| 18°5 | ; 4 | : ; : 25°51 105:°0} 28°5- Marchmont . ; : 4 : 57:0} 20°0 : : : ; : 21:0 | 1200} 29:0 867°3 | 277°2 2° ‘6 | 850°9 | 1457'7| 386°6 +18 | +18 ; - ; : +13 | +13 Means. : 5 66'7| 21°3 : ‘ ' ' : $ 25x | I12"r] 29°7 | MEAN SCOTTISH METEOROLOGY. 251 Taste XXVIa. continued.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. July. August, September. October, November, December, 1880. Max Min. Max. Min. Max, Min, Max. Min. Max. Min, Max, Min Sandwick a Me ie 1063| 424] 973] 325| 742| 21-7] 572| 195] 51-6| 12-0 Culloden 135°8 136:0} 3888} 131°8| 29:5] 112°0; 18:0 92-0 3:0 69-1 7:0 Braemar . 138-0 136°0| 31:0} 180°3) 282} 114°8 9-2 88°5 16 71:2) -~-0°5 Perth - - - - - = - = - - - Ochtertyre 126°0 126:0} 33:0} 123:0| 30°07 1100] 15:0} 103:0 11:0 93:0 80 Dollar. A 102°7 109°7 | 32°7 = 94-7 | 107 - - 64:7 37 Balloch Castle - - - - - - - - - - - Callton Mor 97-4 104°4| 36°5 94:4] 33:5 Tied | i825 56°4 1255 54:4 15°5 Eallabus 1140 1180} 32:0 99:0] 29:0 94:0} 16-0 66:0 11:0 58:0 13:0 Paisley . 107:0 109°5| 31:0 99°5 ~ 87°5 - - - 71°5 70 Annanhill 131°7 - - 13-7 | 31:0} 11382) 15:8 699 9-0 71:2 14'8 Ridge Park. 105:0 112:0} 38:0 98:5} 33:0 79°5| 16:0 60°5 1:0 53°0 10:0 Douglas Castle 110-0 145s || V82rb Ns) |) Wa 105 55) 86°5 0:0 §2°5 12°5 Edinburgh 110°0 115:0} 38°5 - - (5D) | el7-0) (55 13:0 57°0 15:0 Smeaton A :. 116°0 1100) 26:0} 111@) 15:5 88-0 - 73°0 10°5 68:0 155 Thirlestane Castle . 1170 133°0)|| “8L50)}| 123°0)|| 25:0 97:0 9-0 82:0} —6:0 84:0} —1:0 1618-0 | 4733 |1530-4| 443-4 | 1352-0| 311-7 | 1323°3| 167-4 | 9165| 861] 919-2 | 1395 +14 + +43 +13 +12 +11 +14 +12 +12 +12 +14 +14 MEAns 1156 77,1) esdail| te7 "|! 62823 94°5| 14'0 76°4 ae 65°7 9°5 July. August, September, October, November. December. 1881 ’ Max Min, Max, Min. Max. Min Max Min. Max, Min, Max. Min Sandwick | 109-2 37-4] 1081) 323] 041] 330] 73-7/ 315] 612] 31-7] 53-4| 21-6 Inverness . | 1220) (43:0 | 122°5) 32:0] 125°0) 38-0] 107:0) 28:5 88:0] 27-0 80:5} 20:0 Braemar . = | 188:0)) 29:0) W324) 23°3)) 19b"0 |) 25:2) L421 7-1 88:0} 14:0 - - Ochtertyre . | 117:0| 30:0] 119°0) 28:0] 121°0} 28:0 7 105:0); 20°07 100°0) 23:0 84:0} 17:0 Dollar . : 5 94°7| 347 7 103°7) 30:7 | 102°7] 317 EE |) PADETE lO esi 60°7 15°7 Balloch Castle . | 113°0| 25:0] 101°) 16:0] 101°0) 15:0 76°0 (om) 650 9-0 51:0 2°5 Callton Mor a 97°4| 37°5 964 | 29°5 91:4] 31:5 - - 65:4} 23:0 ayaa || allays) Eallabus . , 89:0 ~ 94:0 - 90°0 - 75°0| 22:0 65:0} 26-0 49:0} 19:0 Paisley . c 93°5| 29-0 96:°5| 25:07 101°5) 25°0 (a LE - - 7075 | 13:0 Ridge Park 5 94:5 | 36°5 99:0} 31:5 86:0] 380°5 89:0) 21-0 70°0| 23:0 500) a7 Douglas Castle 0 94°51) to2sD I) LOD) |) (28-55) LO9%5)) 2275 965 | 16°5 82:0] 18:0 64:5) 15°5 Edinburgh - | 1060) 385°8] 125:0] 31°8\f 113°0} 31:7} 10L°0} 21-7 85:0} 21:7 60:0} 20°5 Smeaton : : . | 113°0} 31:5] 108:0} 30:0 96:0) 30°5 9070) 20°5 75:0 180 68:0) 15°5 Thirlestane Castle . . | 125:0| 30:0] 123:0) 23:0] 116:0} 20:0} 125°0; 11:0 - ~ = = 1506°8 | 431°9 ]1534°6| 361 6 | 1472:2 | 367°6 | 1223°6 | 251- 920°3 | 253-1 | 749:°0| 194:3 +14 +13 +14 +13 +14 +13 +13 : ~12 ~12 12 +12 MrANs 1076] 33°2 }| 109°6| 27°83] 105°2] 28°3 94°I 19°3 y Lo by ae a 62'4| 162 September. October, November. December. 1882. Max Min. Max Min, Max Min. Max Min, Sandwick ah. 105°3| 324] 882] 273] 67-4| 205] 534] 125 Inverness 1150} 32:0} 1100) 27:0 89:0} 21:0 67:0 10:0 Braemar 122°0] 22:0} 1080) 19:2 86:0} 15:0 74:0 | —11:0 Ochtertyre 1240] 25:07 1180} 18:0 98:0} 17:0 81:0 3°0 Dollar . 0 100°0| 26:0 85°0 - 197 - - - Balloch Castle 103°0| 26-0 75:0} 19:0 62°0| 195 475 10-0 Callton Mor . 90:4} 30:5 79'4| 24:5 54:4] 21°5 48°4 14°5 Eallabus 87:0} 29:0 83:0} 21-0 54:0} 20-0 50:0 11:0 Paisley . 102°5 |. 28:0 80°5} 19:0 81:5; 18:0 56°5 11:0 Ridge Park 89:0} 31:0 70:0 | 23°5 56:0] 21:0 49:0} — 02 Douglas Castle 1050} 27-0 83°5 | 19°5 86°5| 14:5 50°5 2°5 Edinburgh 3S a = = = = = = Smeaton 105°0| 24:5 88:0] 21°5 72°70} 20°5 64:0 1°5 Marchmont 1050} 24-0 87:0 | 20°0 63:0) 15:0 58:0} — 4:0 13532 357-4 1155°6 | 259°5 | 949°5 |) 223°5 | 699°3 60°8 +13 +13 +13 +12 +13 +12 +12 +12 MEANS Io4°r| 27°5 88:9] 216 73°0| 18°6 58°3 or 252 PROFESSOR C, PIAZZI SMYTH ON Tapte XXVIA. continwed.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES, A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. January, February, March, June, 1883. Max, Min, Max. Min, 5 in, . in, Max, Min, Sandwick 5 | 63:8 117-4| 98-7 | * Inverness 2" 88:0 128°0} 33:0 Braemar 8:2 99:0 : 188°5 | 25:0 Ochtertyre 21:0 - : 1250} 31:0 Dollar. F ~ - - 87'7| 25:0 101°7| 35:0 Balloch Castle 22:0 700} 21:0 7070} 16:0 113°0} 27:0 Callton Mor . 24°5 59:4] 26°5 73°4) 17:0 99:4) 32°5 Eallabus 22:0 56:0} 23:0 70:0) 16:0 109:0] 33:0 Paisley . 240 79°5| 26:0 81:5} 14:0 97°5| 31:0 Ridge Park . 21°5 58:0} 23:0 - - 955} 31:0 Douglas Castle 17:0 815} 18:5 95°5 9:0 92°5| 26:0 Edinburgh 190 79:0} 22°0 - - 108°0} 28:0 Smeaton 155 79:0), (215 79:0} 175 102°0} 25°5 Marchmont : : 14:0 76:0} 13:0 109°0} 26:0 882°2 | 262:0 | 1028°4|) 183°8 }1124:5| 2 ‘5 115365 | 412°7 +12 7 +12 | +12 3 ]+14 | +14 Mrans 21'8 95°7 | 1573 1098 | 29°5 January, February, March, April, May, June, 1884, Max. Min, Max, Min, Max, Min, Max, Min. Max. Min, Max, Min Sandwick é : e 6 4 54:4] 25-4 62'2| 23:8 78:2 82:4} 22:4 87:4] 28:1] 1102] 29:5 Inverness : é : 3 > 720} 22:0 87:0} 22:0} 107-0 108°0| 27:0} 116°0} 28:0] 123:0| 37-0 Kingussie : - : 2 3 90:0 45 94:0} 17:0 - - - - - 139°0} 26-0 Braemar x ; : Pe 0 68°8|} 14:0 93:0} 15:7 | 107-0 117'°3} 12:0 | 123:0} 16:0 - - Ochtertyre . 5 : c 5 87:0} 17:0 98:0} 16:0 98-0 115:0) 26°07 124:0} 31:0 - - Dollar. 4 , é . 5 66:7 | 24:0 79°7 | 23:0 89°7 87°7| 27:0} 101°7| 30:0} 1037] 87:0 Balloch Castle ; - ; 52:0| 22:0 65:0} 20°5 82:0 98:0] 19°0] 110°0} 22:0] 126:0| 28-0 Callton Mor . ‘ 0 A ° 514] 25°5 64:4} 20°5 69°4 86:0} 26-0 984} 26°59 1014] 3835 Eallabus - 5 5 4 5 54:0} 26:0 61:0} 21:0 69:0 84:0} 24:0} 1030} 23:0 110:0} 28-0 Paisley . A : : : 65:0} 17:0 79°5 | 23°0 78°5 92°75} 23:0 83°5 | 29°2 93°5| 32:0 Ridge Park . * : 50°0| 22°5 565} 25:0 72:0 84:0} 25:0 | 105°5| 28:0} 112:0| 82:0 Douglas Castle ; : : 5 53'°0| 15:5 805} 20°5 90°5 100: 195 | 1075} 2657 1065} 295 Edinburgh . F - , . - 19:0 - 17:0 - - 19:0 - 26:0 ~ - Smeaton - 5 5 6 é 59:0} 15°5 73°0| 14:5 88-0 90:0} 155 | 1060} 205] 105:°0) 28-5 Marchmont . . : 4 4 65°0} 15:0 64:0} 11:0 87:0 98:0} 11:0} 109°0} 21:0} 1200] 26°0 878°3 | 284°9 1 1057°8 | 290°5 1 1116°3 | 303°8 | 1243-4 | 296-4 | 1875:°0 | 355°8 | 13850°3 | 367:0 +14 | +15 | +14 | +15 | +138 | +14 | +13 | +14 | +138 | +14 | +12 | +12 Means : 5 : 62°7| I9°0 75°6| 19°4 85°9 956} 2r'2] ro5'8| 254] r12°5} 30°6 | January. February. March, April May. June, 1885. Max, Min. Max. Min, Max, Min, Max Max, Min, Max, Min, Sandwick 56°2) 21°70 65°7 8:3 73°7 | 23°4] 102:2 93°2| 22:4] 100-4] 25-9 Inverness 55:0} 15:0 88:0} 14:0 98:0} 23:0 | 112°0 1170} 29:0} 118:0| 33:0 Kingussie - = 98°5 55 | 1050} 12:0 = = = = = Braemar 770 30 86:2 70] 102-4] 13:8} 115°8 1112} 21:4] 132:0) 27 Ochtertyre 77:0} 18-0 95:0} 18:0} 108:0} 20:0} 115:0 115:0| 26:0} 121:0| 32:0 Dollar . 7 57°7 | 22:0 (ETE PAY) 87°7 | 20:0 84°7 91:7| 28:0 | 105°7| 33:0 Callton Mor . 50°4] 17°5 61°4]} 17°5 79°4| 195 80°4 87°4| 26°5 97°4| 29°5 Eallabus 57°0| 14:0 55:0} 16:0 700) 17°3 78:0 95:0} 20:9] 1040} 275 Paisley . B 49:5} 16:9 57:0) 19:9 62°3 18°7 68:0 71:9} 24:8 93:3] 380°3 Douglas Castle 535} 18:5 75°5 45 88:5} 13°5 97°5 82:°5) 19°5 | 1005) 265 Edinburgh = 17:0 - 15:0 - 18:0 - - 22:0 - 280 Smeaton 58°0 8°5 78:0 ~ 88:0 - 101°0 95:0; 19°} 115:0) 265 Marchmont 51:0 8:0 65°0 80 82:0} 12:0 980 1050} 20:0 | 129:0} 25:0 642°3 | 174°4 | 903-0) 154-7 | 1045:0 | 211°2 | 1052°6 | 250°2 | 1064°9} 280°0 | 1216°3| 344:°6 +11] +12 | +12 | +12 | +12 | +12 7 +11 : +11} +12 ] +11 | +12 MEANS. 5 F 58'4.| 14°5 752) || ets) 8740) 1776 95'7 96°38} 23°3} 1r10°6| 28°7 MEAN SCOTTISH METEOROLOGY. 258 Taste XXVIa. continued—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. oe July. August, September, October. November, December, Max Min Max Min. Max. Min, Max Min, Max. Min Max, Min Sandwick 113] 339] — — | o72! ais] 762) 315] 651) 215] 571] 26-5. Inverness 126:0| 36:0} 127:0| 40:0} 114:0| 31:0] 1080) 28-0 93:0} 23:0 72:0 | 27:0 Braemar 142°3) 27:3] 140°0) 300] 1212) 24:0] 1080) 20-0 86:0} 13:0 65:3} 10:0 Ochtertyre - - - - 120°0| 29:0} 125:0) 24:0 7 1020) 19:0 85:0} 19:0 Dollar . 5 105°7| 40:0} 104-7} 38:0] 109°7| 36:0] 107°7| 26:0 94°7 | 22:0 66:7} 25:0 Balloch Castle 1160} 31:0} 109°0} 37:0} 101:0| 27:0 - - - - = = Callton Mor 93°4| 36°5 99:4) 40°5 95:4} 30°5. 87°4] 26°5 64:4} 21°5 50°4| 20°5 Eallabus 117:0} 31:0} 103:0} 34:0 97:0} 27:0 82:0} 24:0 62:0} 19:0 51:0} 19:0 Paisley . | 104°5| 35:0 99°5| 36:0} 1045] 29-0 95:0} 21:0 83°5 | 13°5 66:0} 18:0 Ridge Park 101°0|} 35:0 975} 38:0 86:0} 30°0 71:0} 27:0 61:0 | 20-0 50:0} 19-0 Douglas Castle 98:5] 30°5] 109°5} 35°5 | 110°5] 27:5 99°5) 21°5 88°5 | 13:0 - - Edinburgh 112°0} 35:0] 1020} 38:0 - = = = = = = = Smeaton 108°0) 33:5 110:0} 84:5] 100°0] 28-0 95:0} 20:5 73°0| 16:5 55:0} 21°5 Marchmont 125:0} 31:0} 122°0| 33:0] 1000} 29°0 90:0) 23-0 60°0| 17:0 57°70} 20:0 1460-7 | 435-7 | 1323-6 | 434-5 [1356-5 | 379-5 | 1144-8| 293-0] 933-2] 219-0 | 675-5] 225-5 ~13 ~13 ~12 12 +13 +138 +12 +12 +12 +12 +11 +11 Means 112"4| 33°5] 110°3| 36'2] 104°3| 2972 95°4| 24°4 77 Oi\) 13-2 6r"4| 20°5 duly, August, September, October, November. December. 1884. Max Min, Max, Min, Max, Min. Max, Min Max Min. Max, Min, Wgandwick 105-2| 28-9] 1082| 375] 992/ 333] - | - | - - | 473| 21-0 Inverness - - 1200} 36:0} 112°0} 35-0 96:0} 29:0 66°0 | 19:0 54:0) 19:0 Kingussie - - 184:5] 305] 122:°0| 25:5] 107:0} 20:0 83°5 8:0 63°5| 10:0 Braemar 126°7| 33:0] 122°2| 31:07 134:0| 27:0] 117°0/} 20-0 81:0 9°8 62°77) 11:0 Ochtertyre 118:0) 37:0] 125:0) 38:0] 115°0) 3820] 112:0] 21:0 89:0} 15:0 73:0} 17:0 Dollar . ; 10777} 36:0} 111:7|} 32:0] 11777] 29:0] 103:0|] 26:0 76:7 | 15:0 62°77] 18:0 Balloch Castle 1160} 3805] 115°0] 32:0} 107:0} 28:0 90:0} 23:0 - - - - Callton Mor . 97°4| 35°5 95°4| 35°5 85°4| 34:5 72°4| 30°5 56°4| 19°5 57°4 17:5 Eallabus 105:0} 32:0 90:0 - 88:0} 29°0 74:0} 29:0 57:0] 18:0 - - Paisley . 86:5 | 36°6 94:8] 37:2 79°5| 32°9 715] 26-0 63:0 | 19:2 53°3 18:0 Ridge Park 113:0} 33:0] 1100) 37:0} 1000) 335 86:5} 25°5 585) 16°5 51:0] 15:0 Douglas Castle 1045) 30°53] 1115) 32:5) 112°5| 305] 1075) 22°5 76:0] 11:0 bs}sy45) |] 115) Edinburgh - - - 32°0 - - - 24:0 ~ 15:0 - 17:0 Smeaton 1050} 28:5 7 110°0) 305 98:0] 26°5 91:0} 21°5 71:0} 10°5 55-0 9°5 Marchmont 119:0) 29:0] 119°0} 28:0} 102°0| 26:0 90:0) 12:0 61:0} 11:0 530} 11:0 1304:0 | 390°5 | 1567°3| 469°7 | 1472°3 | 422-7 | 1217:9} 330°0 839-1. 187°5 | 688°4| 196°5 +12 +12 +14 +14 +14 +14 +13 +14 +12 +13 +12 +13 MEANS I08'7| 32°5 | r12°0|/ 33°6 } r05'2| 30'2 63°71 2350 699} 14°4 57°4| I5‘1 : July. August. September. October.. November. December. 1885. Max, Min. Max. Min, Max. Min, Max. Min. Max. Min, Max. Min, Sendwik . . . . .{ 1097| 274] 973) 975] 901] 295] 691); 205] 6o9| - i : Inverness - ; : : .| 127:0) 41:07 119°0} 31:0] 1140] 30:0 93:0] 20-0 83:0} 20:0 74:0] 18:0 Kingussie : : ; : . = - - = 1220] 14:5] 103-0} 10-0 ~ - - - Braemar : : : 4 | 125:2) 31°87 121:0) 25°5 | 122:0} 20°07 100°0 9-0 87:0 6-4 83°8 8-C Ochtertyre é : : i . | 1340] 35:0} 123:0] 29-0} 115°0] 23:0} 1050) 19:0 89:0] 13-0 95:0} 13:0 Dollar . _ : 2 . | 112°7| 39:0] 108-7) 84:0] 103-7] 27:0 91:7} 24:0 76-7 | 18:0 75:0| 14-7 Callton Mor 3 : 4 .| 106-4} 31:5] 1060] 31:0 86:0} 23:0 78:0] 23:0 57°0| 24:0 50:0} 11:0 Eallabus . : ; : . | 1160} 32:0} 107-0} 31:0 87:0 | 22°0 68:0] 17:0 62:0} 16:0 520} 14:0 Paisley . 5 91:3! 37°5 93°0} 383°2 76-1) > 24c 64:2} 19°3 60°9| 15°5 54:3.) 12:7 Douglas Castle 120°5| 30°57 106°5) 285] 1085} 19°5 98'°5| 165 (a) O05) = — Edinburgh = 34:0 - 27:0 - 18:0 - 15:0 62°3 8°5 54:5) 11:0 Smeaton . 1140} 36:5 | 102:0| 325 99:0} 22°5 81:0] 19°5 70:0} 12:5 62:0 9°5 Marchmont 1240) 26:0} 109:0} 27:0} 102°0} 20:0 76:0) 23-0 67:0] 10-0 59:0} 10:0 1280-8 | 402-2 | 11925 | 357-2 | 1225-4| 293-1 | 1027-5| 235°8| 8513 | 149-4 | 659-6 | 121-9 +11 +12 +11 +12 +12 +13 +12 +18 +12 +11 +10 +10 MEANS 1164] 33°5] 1084] 29°38] ro27T}] 22'5 85°6| 18°r 7o'9| 13°6 66'0| 12°2 VWOln XXXV. PART 3, 2T 254 PROFESSOR C. PIAZZI SMYTH ON TaBLE XXVIA. continued.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. January. February. May. 1886. Max, Min. Max, Min ; Max, Min Ineo” = 5 - | 860] 20:0] 1020| 17-0] 1070} 240] n65| 265 Kingussie 98°5 | —14:0 - - - - = Braemar . 88:2] — 3:2 96°2 2:0} 11174 1129} 17:3 Ochtertyre 77°0 4:0] 10077} 11:0 97:0 112:0} 24:0 Dollar 69°7 11:0 795 | 16:0 94-0 93°0| 31:7 Callton Mor 56°0 13:0} 64:0] 11:0 66:0 92:0} 27:0 Eallabus . 50:0 11:0 -- 14:0 - 88:0} 17°5 Paisley 50:9 13°9 50'9| 10:0 69°7 80°9] 29:2 Edinburgh 51:2 6°5 54:9 - 77°4 - - Smeaton . : : 59:0 75] 80:0) 10°5 83:0 1050} 21:5 Marchmont . z 520 0:0 70:0} 11:0 90:0 1120} 15:0 6525] 49:7] 682:2| 105:5 | 790-5 912-3] 209-7 +10 |} +10 +9 +9 +9 +9 +9 MEaANs 652 Bol F578) T07 87°8 I0I’*4| 23°3 28°3 January. February. March. May. June, 1887. Min, Max, Min. Max. Max, Min Max Min ae Las, Or: 20-0) 91:0! 27-0] 97-0 112-0} 29:0] 121-0/ 400 Braemar . 98} 101°0} 12:0] 120°0 1142} 193] 1387:0} 26:0 Arbroath .- 88:5] 14:0] 100°5 97°75} 21:5] 1200] 275 Ochtertyre 16:0 99:0} 16:0] 107°0 120°0} 27:0] 1400} 3810 Dollar . 21:0 777 | 18:0 87°7 98°7| 30:0] 108:7| 27:0 Callton Mor 11:0 71:0} 25:0 83°0 10070} 27:0} 114:0|] 37:0 Eallabus . 13:0 60:0] 23:0 71:0 1050} 18:0] 121:0] 3810 Paisley 19°1 61:2} 16:0 62°3 82°2} 3811] 104:2) 351 Smeaton . 14°5 88:0] 11°5 90:0 1100} 20:5 | 125:0| 265 Marchmont 9:0 78°0 8:0 79:0 107°0} 18:0} 183:0] 23:0 133°4 | 815-4] 170° | 897°5] 143°9 1046°6 | 241°4 | 1223-9] 304-1 +9 +10 | +10 | +10 | +10 +10 +10 +10 | +10 MEANS 14'8 81'5| 17°0 89'°8| 14°4 104°7| 24°r | 122.4] 30°4 MEAN SCOTTISH METEOROLOGY. TaBLe XXVIAa. continued.—BLACK-BULB THERMOMETERS, MAXIMA AND MINIMA EXTREMES. A PREPARATORY TABLE FOR THE FROST AND FIRE RETURNS OF TABLES XXVII., XXVIII. July. August. September. October. November, December. 1886. Max, Min Min Max, Min Max, Min —e ... ..-]- ~ 38-0 | 109-0| 35-0| 99:0] 28-5 Kingussie = = = a = = = Braemar 129°8| 30:8 28°4 | 125°38] 24:0] 111°8] 20-0 Ochtertyre 129:0] 32:0 36°0 | 117°0| 31:0] 116°0} 29:0 Dollar 108°7| 37:0 37:0 | 112-7} 30:0 98:7 | 34:0 Callton Mor 1000] 32:0 32°0 95 29°0 88:0} 28:0 Eallabus . 1030] 31-0 = 92:0] 27:0 80:0} 26°5 Paisley 875 | 365 33'0 87:1} 26°74 726) 27:8 Edinburgh - - - - - = - Smeaton . 1160) 31-1 - 107°0| 25:0 93:0 | 26°5 Marchmont 122°0} 30:0 28:0 | 105:0} 20:0 90:0} 23:0 896-0 | 260-4 232°4 | 950°6| 247-4] 849-1| 243-3] 698-2] 220°3| 5491| 982-4 +8 + +7 + + +9 +9 +9 +9 +9 +9 MEANS I12'0 32°6 33°2 | 105°6 27°5 94°3 27°0 776 24°5 610 9°2 July, August September, October. November. December. 1887. Max, Min Max Max. Min, Max. Min, Max, Min, Max. Min. Inverness ., | 1240! 37-0] 120-0 114-0} 28:0] 103-0) 25:5] 840] 260] 73-0] 21-0 Braemar 128:2) 29:0] 1238:2 118'0| 22:2) 117°0| 19:2 93°2| 15°4 71:3 5:0 Arbroath 110'0} 26:0 | 115°0 1175] 23:0.f 112°0} 19:0 88:0} 17:0 770} 10:0 Ochtertyre 134:0| 32:0] 123-0 1180} 300] 1180} 25:0} 107:0} 22° = - Dollar . é - - 103°7 10277] 310] 100°0] 28-0 85:7 | 23-0 69:7] 18:0 Callton Mor . 107°0| 34:0 98:0 92:0} 30:0 92:0] 25:0 66:0] 18:0 49:0} 16:0 Eallabus - - - 90:0] 26:0 75:0 | 22:0 65:0} 14:0 51:0] 14:0 Paisley . 911] 386°9 88:0 82°77} 30°9 81:9] 20°3 57°1 18°9 61:3} 17:1 Smeaton 119:0| 27:57 110:0 107-0} 21°5 97:0] 17°5 58:0) 17°5 52°0} 12°5 Marchmont 123'0| 26:0] 116°0 103°0} 22:0 91:0} 16:0 65:0} 15:0 51:0} 12:0 936°3| 248-4 | 996-9 1044-9| 264-6 | 986-9] 217-5] 769-0| 186-8] 545°3| 125-6 +8 +8 +9 +10 +10 +10 +10 +10 +10 =e +9 MEANS 1170} 31'0 | 1108} 324] I04'5| 26'5 987} 21°8 76'9| 18°7 60°6} 14'0 256 PROFESSOR C. PIAZZI SMYTH ON Tastes XXVII. anp XXVIII; or “FROST AND FIRE” IN EACH MONTH; OR THE FROST, AND BY DAY FOR FIRE, we, SOLAR Taste XXVII. repResENTS “ Frost” ONLY, BEING THE Maximum DeEprREssION IN EACH MontH By Nicur REPRESENTS “Firp” oR SOLAR RADIATION ONLY, BEING THE Maxrmum ELEVATION IN EACH TaBLE XXVII.—“ FROST.” January. February, March, | April. | May. June, July, | es _ SS SSS SS SS aS SS a ae Succes. Sueces, Succes. Succes, Succes, Succes. Succes, Obsd Means. Obsd. Means, Obsd. Means; Obed. Means, Obsd. Means, Obsd. Means, Obsd. Means, 1856 1857 | —19°6 —11°0 —12°2 -— 92 — 4:9 +1°9 1858 | —14°6 —21°5 —18°8 —15°6 — 68 +15 —17°I —16'2 —15°5 ena: = BFS +1'o Ce hy/ 1859 | —15°4 -17°4 —14°8 -14:9 — 94 +0°2 —JOrs —16°6 —1573 —13°2 —6'8 00 re 1860 | —19°4 —28°7 —14:0 -112 -— 51 +44 —17'2 —19°6 —15'0 —12°7 —6'4 +0°L +2'0 1861 | —24°5 -17°4 — 78 —10°7 —116 +44 —18°7 —19'2 —13'5 =—12°3 -7'4 +0'8 +2°5 1862 | — 88 -165 —21°0 —10°8 — 56 +23 —17'0 —18°8 —14°8 eT: =—7'1 +0°5 +24 1863 | —10°7 —10°5 —12°4 - 79 — 58 -3°9 —16'I —17°6 —14" =I1'5 —6'9 +0°3 +1r° 1864 | —20°2 —23°2 —19°3 os - 75 — 69 +3'3 : —16°6 S335} —15'0 —IIr‘o —6'9 —o72 +1°8 1865 | —23°5 —24°6 —13°8 —101 — 58 +0°6 -17'4 —19'0 —14'9 —10'9 —6'8 -—0%3 +16 1866 | —18°8 -17°8 —21°8 —12°9 -111 +22 =) —18°9 —15'6 Sn —-7'2 —o'8 +17 1867 | —25°8 —14°3 —21°0 ~ 68 — 66 +0°9 =18°3 —18"4 —16'L —10'7 -7'2 -0'7 +1°6 1868 | —17-2 —10°6 —11°5 —10°2 - 81 +3'8 ; —18'2 —17'8 -—15°7 —10°6 -7'2 —0'6 +1'8 1869 | —13:1 — 80 —13°3 -12% —10°4 +4:0 —17°8 —17'0 —I5'5 —10°8 -7'5 —0'9 +2°'0 1870 | --15°7 —20°6 —162 - 76 - 61 +45 S17 S768 —15°6 — 10°6 -7'4 OW, +2'2 1871 | —18°5 —10°9 —15:2 —11-4 -11:0 +3°5 Sat rf —16°9 —15'5 —10°6 -7'6 —0'8 +2°2 1872 | —13°2 — 9°6 —13'8 — 86 — 87 +0°2 —17'4 —16°4 —15" — oy -77 —0'9 +2°1 1873 | —15°3 —21°5 —12°3 ee —116 —10°8 +2°6 —17°3 —16'7 —15° —10°6 -7'9 —0o'9 +2'1 1874 | —11°0 —16°2 —15°6 = - 8&1 — 9-4 +37 i 7 fTo} dou, —15°3 —10"4 —8'0 Ir +2'2 1875 | —19°0 ao far -13°9 —11-4 — 39 —0°4 —17'1 —167 —15°2 —10°5 -7'8 —1'2 +2°1 1876 | —17°3 —16°7 —15:2 —14'8 -— 98 +3°0 —17'1 —16'7 —15'2 —10°7 -7'9 -I'1 +2°T 1877 | -17°9 —16°2 —16°2 -117 -11'9 +36 —17'l —16'7 —15%2 —10°7 ; —8'o —1'o 1878 | —16°4 — 96 —16°3 -11'°9 — 55 —3'9 +2°9 07 — 164 —15°3 —10°8 -7'9 —I'L 1879 | —23°6 -—19°9 —181 —12°2 —12°4 —2°1 +35 —17'4 =16°5 —15°4 —10'9 —8'r —1'2 1880 | —19°4 —10°4 —13°4 —10°6 — 92 —5'3 +18 17'5 —16°3 —15'°3 —10'8 —8'2 =r4 1881 ) —34°1 —19°0 —23°4 —15°6 -— 75 —6°8 ale —18°r — 16°4 —15°7 —IL'o -8'r —16 1882 | —10°7 - 88 - 83 -13°3 - 69 —2°3 +5°0 —17'8 —16'1 =—15'4 =IL°x —8'r —1'6 1883 | —12°8 —10°2 —167 — 88 — 93 —2°5 +1°5 —17'6 -15'9 —154 —I11'o —8'1r —1'6 1884 | —13°0 -12°6 —10°3 —10°8 — 66 —-1°4 +0°5 —17°5 —15'8 —15'2 —I1‘O —8'2 —1'6 1885 | —17°5 -19°1 —14°4 -11:2 - 87 —3'3 +1°5 iz 5 —15'9 —15'2 -—I1‘o —8'r -1'7 1886 | —27°0 —20°3 —21°4 -10°5 - 87 =O +0°6 —17'°8 —16'0 —15'4 —11'0 —8'r -17 1887 | —17°2 —15:0 -17'6 -12'1 - 79 -16 -10 MEAN SCOTTISH METEOROLOGY. 257 EXTREMES OF THE EXPOSED BLACK-BULB THERMOMETERS, BY NIGHT FOR RADIATION, BELOW AND ABOVE 32° F. OF THE MEAN OF ALL THE EXPOSED BLAcK-BULB THERMOMETERS BELOW 32° F. ; waite Taste XXVIII. Monts, sy Day, oF THE MEAN OF ALL THE EXPOSED Biack-BuLB THERMOMETERS ABOVE 32° F. TaBLE XXVII.—“ FROST.” August, September, October, November. December, Mean Month Successive of Observed } Means of the} Year 5 Sue Gases Suédes saéen Quantities in | Accumulating | repeated, beds eas, | Ee wei es Means, eee Means, id Means, azely Veer. Meare: 1856 +25 +1:0 - 71 -13°8 * 96 - 68 1857 +0°8 -32 —10°0 — 20:0 —18°4 —10°0 1858 +1°6 -1r' — 86 —16'9 —II'S — 84 +0°9 —53 -—19°7 —14°8 — 29:2 —11'8 1859 +1°4 —2°5 —12°3 —16'2 7a = 975 +0°8 -58 — 92 —14'8 —315 -11:2 1860 +1'2 = 08) —Ir'5 =t5:8 —20'°9 —10'0 +44 -1°8 — 68 -17°9 4 -15°0 — 84 1861 +1'9 —3°0 —10°6 --16°3 =i) 7 — 96 +22 —3'1 ea -17°0 — 78 —- 79 1862 +1°9 -3°0 —10°1 — 16"4 17/43) — 94 —0°8 —2°4 —- 97 -—13°6 —16°2 - 79 1863 +1°5 —2°9 —I0'0 —16'0 —17'5 — 9°r 21 -1:0 - 95 —12:1 —13°0 — 96 1864 +11 27, —I0'0 =15'5 —17'0 — 92 -0°3 +0°4 —11°9 —13'5 —10°4 -— 96 1865 +0'9 24 —10°2 —153 Gre — 9'2 +0°4 —2°6 — 84 —13°3 -—11°9 —10°0 1866 +0'9 —2°4 —10'0 =I5'r Sass t5) —- 9° +2°9 —1'8 — 88 —11:0 —13°9 - 89 : 1867 +1'I —2°3 - 99 —14'7 —15°6 = 933 +3°4 —2°8 — 99 —14'5 —13°3 —- 75 1868 +L; —2°4 =) Si) —14'7 —15°4 = 95 —55 ‘ -3°0 -— 99 -17'5 —22°4 — 97 1869 +0°7 —2°4 = 1959) —14'9 —16'0 -— 92 +0°8 —3°4 -— 76 —12°9 —26°2 -— 91 1870 +0'7 8) Bi grZ —14°8 —16'7 = +2°6 -7:3 —10°2 —15°4 -17:1 — 95 1871 +0'9 2:3 -— 98 —14'8 —16°7 — 92 00 -6:0 -121 —11-0 —16°7 — 84 1872 +0'8 —3°0 - 99 —14°6 —16°7 = oT 0:0 —37 -11°0 —12°3 —11°6 - 91 1873 +0'8 = shh —10'0 —14°4 — 164 = (ori +0°4 —2:0 — 83 —12°7 — 24-9 — 9:0 1874 +0'7 = 52 — 99 —14'3 — 169 — 91 +2°9 —21 - 80 —17'1 —18-1 — 92 1875 +0°9 —2'9 — 98 —14'5 = & = oa +0°3 —2°0 — 50 —15°2 — 99 — 86 1876 +0'8 = 2G) = 95 —14'5 —16°6 — git -—0:2 —4-2 — 97 —10°9 —16°0 — 92 1877 ‘ +0'8 —3°0 = Oy —14°3 —16°6 = Of +33 0:0 — 75 -—14:0 —25°8 - 87 1878 +09 —2°8 = ORS —14°3 —17'0 = O° +155 —4:5 -11-4 -16:1 — 291 —12:0 1879 +0°9 ae) — Mes) —14°4 Syl SS = Oe +2'1 -37 —18°0 —24°8 —22°5 -111 1880 +1'o —2°9 yg —14'8 ~ L757 = 93 —4:2 -37 —12°7 -10°9 —15'8 —12°7 1881 +0'8 -—3°0 —I10'o 547, —17°7 eA: +13 —45 —10°4 —138°4 —26°9 — 83 1882 +0'8 —3°0 —10'0 —14°6 —18'0 — 94 +42 —2°8 -— 76 —13°8 —11°5 = (9 1883 +o0'9 —3°0 -— 99 —14'6 —17'°8 —- 93 +1°6 -18 — 84 -17°6 —16°9 — 81 1884 +0°9 =5o = oe) —14°7 Sh Tf =9°3 —-2:2 —9°5 —13°9 18-4 —19°8 —11°4 1885 +0'8 —32 —I0'0 —14'8 —17'°8 = oy! +12 —45 — 50 - 75 —22°8 —10'8 1886 +0°8 —3°2 -— 9'8 —14°6 —18'0 — 94 +04 —5°5 —102 —13°3 —18°0 -— 99 1887 +08 =38) - 99 —14°6 —18'0 — 94 VOL. XXXV. PART 3. 2U 258 PROFESSOR C. PIAZZI SMYTH ON Tastes XXVII. anp XXVIII; or “FROST AND FIRE” IN EACH MONTH; OR THE FROST, AND BY DAY FOR FIRE, 2.2, SOLAR TasBLeE XXVII. REPRESENTS “ FRost” ONLY, BEING THE Maximum Depression In EACH Monta by Nicar REPRESENTS “ Fire,’ OR SOLAR RADIATION ONLY, BEING THE Maximum ELEVATION IN BAGH TaBLeE XXVIII.—“ FIRE.” February. rch, il. : June, July, Succes, 8. 5 I Succes, Succes, Obsd. Obsd, Means: Obsd. Mean +91°6 +80°7 +88°8 +82°1 +90°2 +81°4 +841 +775 +882 +80'r +70°6 +78°2 +83'8 +79°6 +80°2 +743 +831 +78°6 +70°2 +67°0 +80'9 +76°6 +68°6 +77°5 : +79°2 +76'8 +70°7 +80°2 +78°1 +77'2 +80°2 +79°6 | +78°3 Brie’ +81°4 +812 +78°6 +77°8 +78'1 +795 | 7 +78°6 +78'0 +78°6 +851 +78°6 +78°6 +76°7 +823 +784 +78°9 +80°6 +86°6 +78°6 +79°4 +830 > +82°5 +78" +796 +78°9 ; +88°0 i +78'9 +80'r +81:0 +83°5 +79'0 +80°3 +80°6 +845 +79°I +80°6 +741 +81°5 +78'8 +80'6 +84°4 +85°5 +79'! +80'9 +78°9 +70°6 +79°1 +80'4 +82°6 +852 +793 +80'6 +73°6 +776 +79°0 +80°5 +81°3 +83°6 +79'I +80°6 +860 +75°6 +79°4 +80"4 +80°1 +81°2 +79°4 +80"4 +778 +80'4 +79°4 +80°4 +80°5 +767 +79°4 +80°3 +78°6 + 84°4 +79°4 +80'4 +79°1 +80°0 : +79" +00°4 +90°4 oe +85'0 +79°7 +80°6 MEAN SCOTTISH METEOROLOGY. 259 EXTREMES OF THE EXPOSED BLACK-BULB THERMOMETERS, BY NIGHT FOR RADIATION, BELOW AND ABOVE 32° F. OF THE MEAN OF ALL THE EXPOSED BLACK-BULB THERMOMETERS BELOW 32° F.; wHILE TABLE XXVIII. MontH, By Day, oF THE MEAN OF ALL THE EXPOSED Buiack-BuLB THERMOMETERS ABOVE 32° F, Taste XXVIII.—“ FIRE.” August. Succes, Obsd. Means, +85°7 + 84:2 +85°0 +79°3 +83°1 +771 +816 +662 +78°5 +726 IT'S +733 +76'9 +75°3 +76°7 +735 +76'4 +711 +75'8 +781 +76°0 +83°9 +76°7 +79°2 +76'9 +869 +77°6 +854 +78'1 +82°3 +74:3 +78°r +76°7 +78°1 +79°2 +78°r +85:0 +78'5 +722 +78'2 +83°7 +78°4 +78°3 +78°4 +85°7 +78°7 +77°6 +78°7 + 85-2 } +78'9 +78°3 +78'9 +80:0 +78'9 +764 +78°9 +760 +78°8 +78'8 +78'8 September. October. November, December. Succes. Succes, Succes, Succes. Gps Means. abee: Means, Cue Means, oes Means, +72°6 +62°4 +49°3 “441-1 +78°8 +62°5 +48°3 +369 +757 +62°4 +48°8 +39°0 +716 +642 +441 +31°5 +74°3 +63°0 +47'2 +36°5 +72°4 +58°5 +43°3 +31°8 +73°8 +61'9 +46'2 +35°3 +68°7 +572 +41°2 +34°7 +72°8 +61'0 +45'2 +352 +74:1 +61°6 +41°4 +30°1 +73°0 +61'1 +44°6 +344 +646 +52:0 +39°9 +30°0 +718 +59°8 + 43°9 +33°7 +66°3 +59°2 +42°1 +29°0 T7I'I +59°7 +43°7 +33°1 +74°3 +65°8 +446 +36°0 +71°5 +60°4 +438 +33°5 +66°4 +61°9 +45°9 +33°2 +71°0 +60°5 +44'0 +33°4 +67°2 +54°5 +45°5 +31°2 +70°6 +60'0 +44°1 +33°2 +70°0 +53°9 +37°3 +30°8 +70°6 +59°5 +43°6 +33'0 +68°7 +60°7 +380 +27°5 +7074 +59°6 +43°1 +32°6 +70°5 +63°9 +445 +29°1 of +70°4 +59°9 +43°2 +32°4 +7674 +58°3 +41°9 +31°5 xe +70°8 +59°8 +43°2 +323 +70°0 +55°6 +43°1 +28°7 +70°8 +59'5 +43°2 +32°1 +782 | = | -+57°3 +376 +292 +70°9 +59°4 + 42'8 +31'9 +67°3 +53°5 +39°3 4+25°7 +70°7 +59°L +42°6 +31°6 +73°4 +517 +40°0 +29°4 +70°9 +58°7 +42°5 +31°4 +727 +60°9 +48°4 +30°6 +71'0 +58°8 +42°8 +314 +69°8 +59°8 + 45:2 +30°6 ; +70°9 +58'8 +42'9 +314 +75°7 +61°7 +42°3 +31°9 +701 +59°0 +42°9 +31°4 +73°7 +67°0 +50°2 +29°1 +712 +59°3 +43°2 +313 +80°7 +62°5 +444 +33°7 +716 : +59°4 +43'2 +31°4 +732 +62'1 +44°7 +30°4 +717 5955 +43°3 +31° +721 +56'9 +41°0 +26°3 2 a7 2a7) +59°4 +43°2 +31'2 +723 +63°4 +45°8 +294 +717 +59°6 +43°3 +311 +73°2 +617 +37°9 +25°4 +718 F597. +43°1 730'9 +701 +53°6 +38°9 +34:0 TILT +59'5 +43'0 +310 +73°6 +62°3 +45°6 + 29°0 zeae +59°6 +43° 1 g0%9 +725 +66°7 +44°9 +28°6 +718 +59°8 +43°1 +30°9 Mean Month of Observed each Year, Successive Means of the Year | Quantities in | Accumulating | repeated. Years, 1856 1857 1858 +65'0 1859 +63°6 1860 +62°6 1861 +61'4 1862 +60°6 1863 +59°6 1864 +59°3 1865 +59°4 1866 +59°3 1867 +59°2 1868 +59°1 1869 +59°1 1870 + 59°2 1871 + 59°4 1872 +59°4 1873 +59°4 1874 +59°3 1875 + 59°2 1876 +59°3 1877 +592 1878 +59°3 1879 +59°3 1880 +59°4 1881 +59°5 1882 +59°5 1883 +59°5 1884 +59°5 1885 +59°4 1886 +59°4 1887 +59°5 260 PROFESSOR C, PIAZZI SMYTH ON Taste XXIX.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Winv Force per Monts. January. February, March, April. May. June, July. Year, |——————___]———_—_ Ie —_ 1 __“qqe _—iy_c_‘|cmo Ovsd. | Steams, | Obs | Steane, | Obed. | Seecee | onsa, | Sees | onsa. | Sreeee | oped. | Sreane, | P84 | ean 1856 | 37-82 63:80 5115 29:40 30-07 57-00 41-54 1857 | 38-75 49°56 58-28 35-40 24-49 19°50 48-05 1958 | 718 |? | 5o40 | © | sed | 7 | asco | @ lacs | 7 ao-go| > | Sea 150 | 91-45 |?" | zaze | °°? | gpeo | 2° 1 goo | 2 eosin | 2°92 1|-ao-g0 | © eae 60°30 59°63 66°73 44°55 30°54 41°78 42°16 isco] 5518 | | 6757 | | 0-45 46-50 44-02 aso | | 2697 | 1861 | 41-23 7 62:16 i 81°84 aa | 33-90 vey 36-58 — 26-40 a 43-71 a 1962] 52-08 | | 3808 | | 2238 i | 47-10 sey Pets, DOD 5456 | 1963] 6198 || 80] | ra a) 56-10 seg | (oases aI | sey 2193 | 1864 | 47-74 37:99 45°57 30-60 35-08 43-80 35°65 55°42 55°28 60°52 43°60 34°72 39°70 40°16 1865 | 61:07 35°84 50-22 36-60 45°88 33-30 30°38 1866 | 67°58 ve 52-92 i ices | © ag-20 |? Vegoag || = p80 ae 27°90 os 1867 | 44°33 Ee 59-64 be 50°53 rg: 55:20 a 40°61 in: 29-40 rae 32-24 i 1868 | 59°52 93-09 66-03 46-80 46-19 47°40 29°14 ise | 5678¢| > | e740 | | amas | 527° | woo | 4 | args | 2°7511 ga-c0| 2” "S| cece 56°29 56°89 57°26 44°23 37°31 37°54 37°20 1870 | 32-24 47-60 40-61 49°80 45°57 33-60 32°55 sen |azas | | ose | 7 | srar | 9S | aon | 4° | gare | 278° | sean | 7" | aut ee sg7a | 66-08 |=" | s507 | °° | san | °° | oe-20 | “42° | soon.| 27 | asso | 22° | s565 is7s | 5-26 |°*° | sa08 | °°? | so-ao | 2° | auto | 22/1) gay | 2°25 Igoeo.| > Ieasaa gs save | 6a-ae | °°? | ge-ag | 4 | ar-g0 | 23 | ao-e0 | S| soon | 2°94 | a5a0 | 7 || ace 55°88 54°41 56'19 45°68 38°47 37°45 36°43 1s75] 5425] | 892 | | 4526 _ 30-60 ell Pl Lge a0 ie 70 | 1s76 | 7347 |? | 5336 | | 991 7 59°10 oe |e 5160 | G47 | eg 1877 | 93-31 1 16 | 7 | 8m aa 81:90 kee £090 | 5 |e 1878 | 59°52 47°88 75-02 47-70 56-11 38-10 39°37 1a79 | 5804 |" > | aoa |? | coms | 7 | oszae | 727 | goog | “22 1] aogo | >” Hl coon - 58°18 54°34 60°08 47°51 41°40 38°99 39°54 1880 | 56-42 gor | | corse | 1% ou 61:80 soos |? | gas ie) fl eae ae | iss | 3937 |" | 5432 | > | 88-07 56°10 58-90 6030 | ~ | e293 | - 1882 | 90°52 im 79-24 . 113-15 ie 7410 50°53 ve 51:30 oe 46-19 e. 1883 | 90-21 111-72 92°69 64-80 78-43 47-40 48:36 1884 }121°52 a 92°51 a 71:92 eee adage ae 65°41 43 | 7-70 od 37°20 “a 61'87 59°62 63°85 49°70 45°15 40°97 7 1885 | 72:85 75°60 89°59 69:90 69°13 49-20 41-85 | - ssa6 | 08:69 |" | goog | "5 | g0.09 | 7 | reo | 37 | gute | 2 | e570 | + | cons sse7 | 95:56 12 | eeed |e Peper ee depends Wteene oo alee ene MEAN SCOTTISH METEOROLOGY. 261 Taste X XIX. continued.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Winp Force per Monta. August. Succes Obsd. Gan 31°31 32°24 31°78 30°69 31°41 48-98 35°80 35°65 35°77 59°52 9°7. 25°42 ee 7°6 35°34 ig 37°39 83°79 36°99 27°28 36°02 35°96 36°02 30°07 5°52 49-60 Z 36°60 35°96 36°56 26°04 *86 39°06 2 36°06 28°83 6 38°44 33 ‘7 43°09 7? 36°17 39°37 6" 56°42 gree 7 2 45:26 a? 7°6 43°71 gree 79 49°91 ee 38°41 25°73 ‘oI 62°31 gr 8°8 59°21 a *60 62:00 4 0°40 43°40 ee 40°50 52°70 O'9I 5270 |” I'2 38°75 ic 41'21 September, Succes. Je Means, 50°70 41-40 6°90. 50°40 ae “50 54:00 ve 49°12 82°70 8. 41-40 wy 45°10 27°60 42°60 50°70 ‘OI 45:00 re 43°77 37°50 r 40°80 as 42°93 43°80 43°00 36°30 42°48 57°00 43°52 33°90 42°88 31°20 42°15 45°60 42°35 40-20 42°23 49°50 : 42°62 37°20 42°34 40°80 42°27 50°70 42°65 72°00 43°9. 61-20 ane 44°65 44:10 44°63 45-00 44°64 51°60 44°90 56°70 45°32 57°30 45°73 73°80 46°67 59°70 47°09 52°50 47°26 October, Succes, Obsd. Means, 27:28 39-99 33°64 58:90 42°06 50:53 44°18 72:54 49°85 39°68 48°15 64:17 } 50°44 45:26 49°79 38°75 48°57 5363 49°07 32-86 47°60 42-47 47°17 50°84 47°45 50-22 47°65 46°50 47°57 44:02 : 47°35 56°42 47°89 40°61 47°48 5611 47°94 80°91 49°58 62:93 50'22 83°39 51°73 88°35 53°32 42°78 52°88 59-52 53°15 104°47 55°12 64:17 55°46 76°57 56°21 93-98 57°52 76°57 58°15 54°87 58°04 69°44 58°40 VOL. XXXV. PART 3. November, December, Succes, Succes, pa Means, ORst Means. 57°97 7122 3105 64°94 55-80 31°60 61°90 51°77 33°52 59°36 42°47 33°36 55°99 2 3720 39°60 52°86 66-65 7°37 548 sa 74:09 3 37°84 57°2 40°61 . 37°40 55°39 77°50 6'8 ‘60 39°04 55-80 57 8° 57°4 a3 4960 i 7°72 56°78 : 52°39 . 8 6" 37°9 57°35 59°44 39°39 56°51 39°68 8°8 Bie 39°04: 50-84 39 8°96 55'10 et 58°90 2 0°06 : 4 60:76 55°33 0°58 6 49°5 40°30 55193 40°52 54°82 56°11 0'8 8 40°03 81°84 54°69 1°31 6°r 41°3 69°13 59°17 43°00 56°76 . 43°09 43°62 56°16 62°93 44°66 56°45 75°95 46°26 57°23 75°95 48°76 57°95 60°76 49°99 58°05 79°67 50°81 58°82 79°67 51°52 59°54 88°35 51°70 60°50 69°13 52°21 60°78 64°48 52°51 60°90 Mean Month of Observed Successive Means of the Quantities in Accumulating each Year, Years, 42:26 41-05 41°66 47-57 43°63 58°34 47°30 46°26 47°10 47°87 47°22 44:27 46°80 46°97 46°82 39°04 45°96 43°42 45°79 43°14 45°47 42°40 45°22 51°53 45°79 47:94 45°86 38°27 45°36 42°29 45°16 50°81 45°50 43°95 45°41 48-04 45°55 44°32 45°49 61:10 46°23 70°42 47°33 55°68 47°69 57°21 48°09 56°74 48°44 68°33 49°20 68°56 49°92 73°45 50°76 68°84 51°38 68-04 51°94 66°51 52°41 59°18 52°62 Dex 1880 1881 1882 1883 1884 1885 1886 1887 262 : PROFESSOR C. PIAZZI SMYTH ON Taste XXX.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Winp Foros, AccumuLaTED QuANTITIES FROM MontH To Monta. January. February, March, April. May. June, Year, a Go Goes Gn nee ee ls: SCCSCOCtStS:t—CS~S Successive Successive Successive Successive Successive Successive —— Means. Eau Means, oo Means, oe, Means. Obsd, Means, PEE Means, 1856 37°82 101°62 152°77 182-17 212°24 269°24 1857 38°75 88°31 146°59 181-99 206°48 225°98 38°28 94°96 149°68 182‘08 209°36 247°61 1858 73°16 123°56 182715 22565 267°19 307°99 y 49°91 104.50 16051 19661 228 64 267°74. 1859 91°45 166°21 265°10 335°00 i 361°04 410-84 , 60°30 11993 186°66 231°21 261°75 303°53 1860 55°18 122°75 183-20 229°70 273°72 312°12 59°27 120°49 185°96 230°90 264°13 30523 1861 41°23 103°39 18523 219°13 a 255°71 282°11 56°27 11764 18584 228° 262°73 301°38 1862 52°08 90°16 13232 179°42 4 218°79 268°89 55°67 113°72 178°20 221°87 256°46 296°75 1863 61°38 : 114'58 162°32 218:42 253°76 285-26 56°38 113°82 176'21 221° 256'12 29531 1864 47°74 85°73 e 131°30 161°90 % 19693 240°73 55°42 10°70 I71‘22 214°82 249°54 28924 1865 61:07 96°91 147°18 183°73 229°61 262°91 55°99 109°33 16882 21°72 247°56 286 62 1866 67°58 120°50 166°38 212°58 245:18 270°93 57°04 IIO0'34 168'59 2I1'7 247'°33 28518 1867 44°33 4 103°97 154°50 209°70 7 250°31 279°71 : 55°9 109 ‘81 167°42 21162 247°58 284'73 1868 59°52 152°61 218°64 26544 311-63 359-03 56°25 I13°IO 171'36 215°76 | 252°51 290°45 1869 56°73 114:13 3 158-46 200°46 P 245°10 277°50 56°29 11318 170°44 214°67 25198 289'52 1870 82°24 79°84 120°45 170°25 215°82 249-42 54°68 II0'95 167°LO 21°70 249'56 286'°84 1871 42°16 101°52 15949 200°29 4 235°01 267-11 53°90 I10°36 166'62 210°98 248°64 28560 1872 66:03 122-00 177°80 24200 291°29 32669 54°62 II1'05 167°29 212°82 25117 288'03 1873 63°86 101°94 142:24 186°34 224°47 264:07 55°13 IIO'54. 165'89 21134 249°68 286'70 1874 69°44 10584 17714 226:94 7 267 86 313°16 55°88 I10°29 166°48 21216 250°63 28808 1875 54°25 93°17 13843 169-03 204°68 23768 © 55°80 109"44 16508 210'00 248°33 285'56 1876 73°47 * 126°83 220°14 27924 324°50 376°10 56°64 11026 167°70 213°30 251'96 289'87 1877 93°31 5 176°47 244-67 326°57 - 400-04 46094 - 58°31 I13°28 17121 218°46 258°70 297°6' 1878 59°52 fee 107°40 = 182°42 ‘ 230°12 ‘ 286°23 32433 58°3 11302 17169 218'96 259°89 298'8r 1879 53°94 100°98 193 °36 246°46 4 29854 33904 58°18 II2"52 172°60 220°11 261'51 300°50 1880 56°42 ‘ 143°42 186°51 248°31 310°93 35653 58°11 113'76 173°16 221'24 263°49 02°74. 1881 39°37 93°69 182-66 238°76 297 66 357 °96 : . 57°39 I12"99 173°52 22E'QL 264°80 048 1882 90°52 Ne 169°76 282°91 a 35701 4 40754 45884 : 58°61 11508 177°56 226°90 270°07 310°55 1883 90°21 201°93 29462 35942 437 °85 485 °25 59°74 r18'18 181'74 231°64 276'07 316'79 1884 121°52 214:03 28595 330°05 895°46 443°16 61°87 121'49 185°34 23504 280'19 321'16 1885 72°85 P 148-45 238°04 807 ‘94 37707 42627 2 2°24. 122°39 187°10 237°47 283°42 324'6 1886 93°69 E 135°97 216:26 294°86 35934 425-04 3°25 122°8 188’0. 239°32 28587 327°90 1887 85°56 152-20 a 208°31 ‘ 267-11 a4 328°49 369°59 63°95 123°75 MEAN SCOTTISH METEOROLOGY. 263 TaBLE XXX. continued.—SCOTTISH COUNTRY AND TOWN STATIONS, METEOROLOGY OF. Winp Forces, AccuMuLATseD QuANTITIES FROM MontH to Monts. July. Successive Obsd. Means. 310°78 274:03 29240 342°40 309°07 455-48 345°69 33909 344°35 325 °82 341°27 323°45 338°73 31719 336°04 76°38 329°40 293°29 325°80 298°83 323°34 311°95 322°39 38817 327°46 31718 326°72 281°97 323°73 301°52 322°34 362°34 324°70 297°86 32321 348-19 324°51 271°47 321°86 440-27 327°50 51829 336°18 _ 3863°70 : 337 °37 40104 ; 340°04 39094 342°07 420:°89 345°10 505-03 35101 533-61 35735 480°36 4 361°78 46312 65°32 494°17 pa 69°48 423°22 a 371-17 August, September, October, November. December. ona, [Piece] ones, |Sigceie”®] oma, |Suzemlred ona, /Syzstsr®] ones. |Ssana”® 342-09 392-79 420-07 . | 44917 507-14 306-27 347-67 387-66 420-66 492°58 37309 ‘ice tg | 8 48239 ei 515-09 | “24°” | 570-89 a 504-46 ee 558-46 ee 60899 | “2° °* | 648-29 as 700-06 cae 381°49 430°61 474°79 508°3r 567°67 374-74 407-44 479-98 512-68 555-15 385°34 ‘mi 426-74 ers 466-42 pee ser22 | >” | 574-42 08 348-87 i < 376°47 os a4o-es | 7*°5 | s64-64 as 531-29 ea 352°53 ken 493-03 |“? 448-49 ees 489°59 ee 563°68 ae 310°17 eee 355°17 eee 39392 ‘acai 427 82 aad 468°43 oe 366°39 410°16 458°73 496°13 551°52 320°57 358-07 411-70 443-50 521-00 334°79 oars 375°59 a 408°45 oP ies OR? 517-65 Sig ea02'| 93° | sesex | 4°79 | soe09 | 42°? | asore | °° | 50870 | 5°? 437°77 ae ayaon |? ) 594-91 ae 566-01 pat 618-40 hea 353°14 ree 410-14 vo 46036 | 2°? | 517-96 Nasa oe 363°28 406°80 454°45 493°84 550°35 308-01 341-91 388-41 419-61 459-29 340-58 a am7a | ~~” | a15-e0 | ©” * | 456-60 se 507-44 ae 391:17 a s3677 | > 493-19 479° | 550-79 ae 609-69 wa 336-30 rae 37650 ee 417-11 45°57 T 466-61 oe 527°37 Bee 391-28 ae A078 ne 496-89 ae 536-19 pees 576°49 ae 360°68 403°30 45124 491°76 546°58 310-84 348-04 428-95 475-75 531°86 496-69 shee sams | 600°42 a) Gare 490°4 | 733-6 oes 563°55 ee 614-25 a di 69764 ae 75°94 see 84507 2s 407-41 ea 479-41 oe 567°76 a 625-06 | > | 668-15 Gu 450-95 ee pies | 554-93 47°53 1 693-63 ae 68656 ee 378°45 423°I0 47598 520°64 57709 416-67 460-77 520-29 604-89 680-84 48320 eis 528-20 as 632°67 Ts 74397 24° | 819-92 aa 564-24 2 28 615°84 aa 680:01 pee 761-91 55247 | 599-67 aa 595-61 aoe. Gate 728°88 499°97 1 801-78 ae 881-45 te 523-76 eS eretoge\ eo 674:99 pe 74639 e606 Pile 402°28 448°01 50552 557°04 616°58 520-82 594-62 671°19 728-19 816-54 546-87 ae 60657 | “I ee1-44 > | 728-94 eve 798-07 ce 461-97 ae 514-47 fae 583-91 Ga 71 ee 710:19 tae 412'38 459°64 518'03 570°53 oemas Year repeated. 264 PROFESSOR C. PIAZZI SMYTH ON TasLE XXXI.—MONTHLY ELEMENTS OF ALL SCOTTISH METEOROLOGY, REDUCED TO ONE CENTRAL GEOGRAPHICAL POINT, VIZ:: LatitupE= 56° 30’ N.; Lonerrupr=3° 40’ W.; Hercur=256 Freer; Distance rrom GENERAL SeA-Coast, Fastwarp, 40; West, 90; Norra, 120; Sours, 120 Mites ;—anp For THE Mean Epocn oF THE Years 1856 to 1887 INCLUSIVE. Table. Subject. Terms, Jan, Feb. | March, | April. | May. | June, Old <> ; ST ae ; Tables, 1 | Barometric Mean Pressure, . : : ‘ -| Inches, . : . | 29°764 | 29831 | 29°833 | 29-888 | 29-930 | 29-928 2 |Monthly Range, . ; ‘ F : : -| Inches, . : . | 1671 | 1:480| 1°446] 1:264] 1:076| 0:919 5 | Temperature, Mean in Shade, . : ; eedvalis) 5 : . 18770 1384 |39 |44:2 | 48°38 |54:8 4 | Daily Range, Mean in Shade, 5 : : .|° Fahr., . : a || Gal 99 |11°8 |141 |15°4 | 15-6 5 | Mean of Max. Temperature by Day, . : -| ° Fahr., Expd. Bl. B., |48°7 |561 |64:0 |73°'7 |81:7 | 90-1 6 | Mean of Min. Temperature at Night, . : .| ° Fahr., Expd. BL B., | 283 |29°2 | 29°4 |82°3 |35°9 | 41-9 7 | Humidity, Relative, computed from the Wet al Pistia « \) sat.=100,. . .| 88 | 88 | 86 | 83 | 80 | a Depression of Wet Bulb below Dry, : : | ¢ Balin f 2 Pil nelao 15 1:8 2:0 30 3:0 Depression of Dew Point, ; : | gains ss : 3 |) oka) 3°6 4:0 4:4 6:0 59 Elastic Force of Vapour, a) 5 | Than, F : . | O19 | 0:20 | O21 | 0:24 | 0:28 | 0°35 Grains of Moisture in ed to foot of ‘Air, iy Grs., . : ; . | 2°20 | 2°30 | 2°40 | 2°80 | 3:10 | 3:90 Grains further required to saturate that 7 s : : z : cubie foot of air, .. \ Grs., . ; ; . | 0°40 | 0-40 | 0:40 | 050 | 0:90 | 1:00 8 | Rain, Number of Days on which it fell, A . | Days, ; j a lemelive 15 15 12 13 13 9 | Monthly Depth of Rainfall, . ; : -| Inches, . ; . | 4:08 | 3°14 | 2°83 | 2°24 | 2:27 | 2:58 Annual Depth of Rainfall, . : ‘ : - | Inches, . : ¢ - = = = - = 10 | Wind, Mean Force of, . : : a = - | Lbs. Av. on Sq. Foot, | 2°06 | 2:11 | 2:09 | 1:72 | 1°52 | 1:40 11 | Wind, Direction of, North, . : ; : . | Days, : : : 4 4 6 6 6 5 12 a 5S East, . 5 : ; . | Days, : : 5 5 6 8 8 6 13 a os South, . a 5 . | Days, 5 : ; 9 8 6 Uf il 8 14 a ee West, . 4 : 4 . | Days, ; i 4 11 10 10 8 9 10 15 | Sunshine, No. of Hours of, per Month, . “ .| Hours, . ; 5 63 85 124 162 201 217 ay a per Year, . ; - | Hours, 5 ; : = = = - - - 16 | Cloud, Mean Amount of, : . , : . | Hemisphere=10, .| 67 65 6-4 63 6:2 6-2 17 | Lightning, . ; : A : é ; . | Days, ; : a) uses 11 1:2 1:2 17 2:2 18 Stations, . = | 12 8 6 13 19 26 Days x Stations, . | 18:0 88 72 115° |32:3 | 57:2 19 | Auroras, . ; 5 , : C : : .| Nights, . F . | 2:0 19 2:0 18 1:0 O01 20 Stations, . ; 8 11 9 8 2 0 Nights x Stations, . {160 |20°9 |18:0 | 14:4 2:0 0:0 New Sap heya | ined ie an Tables. 21 | Mean Maximum Temperature in Shade, =|) ee cee ee F .|41°5 143-4 | 45-4 1513 |565 | 62°6 22 | Mean Minimum Temperature in Shade, ; -4\) *Ralhrsse ge : . (825 1335 (383-7 | 37-1 | 411 | 470 28 | Accumulated Rainfall, Depth, . : : > |iacHes anaes .| 4:03 | 7:17 |10°00 | 12:24 | 14:51 | 17:04 24 | Plant-Growth Temperature, . Above 42°, or + . | —155 | -101 | — 77) + 66] +211 | +384 25 | Accumulations of each md of Plant-Growth )| Above 42°, or + . | —155 | -—257 | —339 | —341 | —341 | —341 a sp reanee 5 AeA % Below 42°, or — : - O;} + 6) + 74] +285 | +668 ecumulations made go0 ko ant- t-Growt 0 Temperature, \ Below 42°, or — . | —155 | —256 | —3384 | —267 | — 57 | +3827 26 | Preparatory only for 27 and 28, . ; : : 27 | Frost, Exposed in each month, . : ; . | Below 32°, or — . | -17:8 | —16:0] —15°5] —11:0] — 81] — 1% 28 | Fire, Exposed in each month, , ; 2 . | Above 32°, or + . | +840 | +44°2 | +54°4 | +64°7 | +72°1| +797 29 | Wind-force per month, . i : oe . | lbs-pressure x into days} 63°95] 59°80| 64°93] 51°52] 47:01| 42°00 . sys The above from be- 4 H ; 2 : a 30 | Wind-force, Accumulated Quantities, . ; ‘ { ginning of year. \ 63°95 | 123-75 | 188°68 | 240-20 | 287:21 | 329-21 MEAN SCOTTISH METEOROLOGY. 265 TaBLeE XXXI. continued— MONTHLY ELEMENTS OF ALL SCOTTISH METEOROLOGY, REDUCED TO ONE CENTRAL GEOGRAPHICAL POINT, VIZ.: LatitupE = 56° 30’ N.; Lonerrupre=3° 40’ W.; Herient=256 Fret; Distance From GENERAL Sza-Coast, Eastward, 40; West, 90; Norru, 120; Soutn, 120 Mitzs,—anp ror THE Mran Epocn oF THE Years 1856 to 1887 INcLUSIVvE. | Table. Subject. Terms. July, Aug. Sept. Oct. Nov. Dec, ee : 7 — ee a eee eee en ee ee ee ee ae Se Tables, 1 | Barometric Mean Pressure, . : é é .| Inches, . ‘ . | 29°879 | 29°86] | 29-833 | 29:814 | 29°817 | 29-779 | 29°846 2 |Monthly Range, . ; : : ; : .| Inches, . : . | 0°897| 0:°974] 1188] 1:466] 1°5389|) 1:°563} 1-290 3 Temperature, Mean in Shade, ; : : le Rahm, © = ‘ . |57°4 | 56°8 52°8 46°6 40°4 | 387°7 46:2 4 | Daily Range, Mean in Shade, : ; : «(| oar, 3 ‘ . {15:0 | 14°5 136 11:9 10°3 9°5 12°5 5 | Mean of Max. Temperature by Day, . ‘ . | ° Fahr., Exp. Blk. B., | 9174 88°9 81:9 |68'4 |55°4 |476 | 70°7 6 | Mean of Min. Temperature by Night, . - .| ° Fahr., Exp. Blk. B., | 44°99 |442 |405 |353 |3802 |284 | 35-1 7 | Humidity, Relative, computed from the Wet a2 F NS) oeeiahliags | sat.=100,. . .| a2 | 84 | 86 | 88 | 88 | 89 | & Depression of Wet Bulb below Dry, : . | ° Fahr., 30 2°5 20 1:8 15 1:2 21 Depression of Dew Point, : ; . | ° Fahr., : Pa OES 48 4:0 3°8 3°4 30 45 Elastic Force of Vapour, . . | Inch, ‘ : . | 0°38 | 0:39 | 0:35 | 0°27 | 0:22 | 0:20 | 0:26 Grains of Moisture in Cubic Foot of ‘Air, . Grs., . : . | 430 | 4:40 | 3:90 | 3:20 2°60 | 2:20 | 3:10 Grains further required to saturate that 3 F gubic foot of air, ’ ‘ : \ Grs., 1:00 | 0°80 | 060 | 0-40 | 0-40 | 0°30 | 0°50 8 | Rain, No. of Days on which it fell, : F . | Days, : ; ; 15 lbs) 16 16 16 16 15 9 | Monthly Depth of Rainfall, . , A : .| Inches, ; . | 311 | 3°40 | 3:74 | 4:03 | 38°73 | 4:07 | 3:26 Annual Depth of Rainfall, . : : , .| Inches, . : P = = - - - - 39°12 10 | Wind, Mean Force of, . . : : , . | Lbs. Av. on Sq. Foot, | 1°35 | 1°33 | 1°58 | 1°88 | 1°75 | 1:96 | 1°73 Wind, Direction of, North, . : ; ; . | Days, ‘ ‘ : 5 i) 5 5 6 6 5 FA 5p East... : ; : . | Days, ‘ ; : 5 i} 5 6 5 4 6 55 A South, . : ; ‘ . | Days, F ; ‘ 8 8 8 8 7 8 7 a is West, . ; ‘ ; . | Days, 6 ; i 12 11 ll 10 10 11 10 Sunshine, No. of Hours of, per Month, . : . | Hours, 3 ; a) Pala 182 145 110 77 60 1386 ; i per Year, . : .| Hours, . a : - - = - - - 1637 Cloud, Mean Amount of, : ; hs : . | Hemisphere=10, . | 6:5 6°5 6:3 6°4 64 6°5 6:4 Lightning, . ; : ; : ‘ : . | Days, 5 ql 5 |) 28 18 1-4 15 15 15 16 Stations, . 7 29 25 17 13 10 9 15 Days x Stations, = |) eS 45:0 | 23°8 19°5 15:0 |135 | 24-0 Auroras, : ; : ‘ ‘ j ; .| Nights, . : - | 03 1:5 21 2:0 21 2:0 16 Stations, . . 0 5 8 ll 9 7 7 Nights x Stations, . | 00 75 16°8 | 22°70 | 189 14:0 |112 Mean Maximum Temperature in Shade, ; .|° Fahr., . i . 1649 |64:0 | 59° |525 |456 |425 |525 Mean Minimum Temperature in Shade, ¢ 5 |) Suess 4 . 150° |49 |46:0 |406 |353 |33°:0 | 39-9 Accumulated Rainfall, Depth, . . . .| Inches . . . {2015 | 23°55 | 27-29 | 31°32 | 35:05 | 39-12 Plant-Growth Temperature, . Above 42°, or + .|+ 478) + 457|+ 323) + 142/-— 48] — 133] +129 Accumulations of each kind of Plant-Growth l| Above 42°, or + . | — 841] — 341] — 341] — 341] — 396] — 533] - Temperature, . Below 42°, or — . | +1146 | +1604 | +1926 | +2068 | +2075] +2079); —- eee good of Plant-Growth \| Below and above 42%, | + 805) +1262) +1585] +1727| +1679| +1546] - Preparatory only for Tables 27 and 28, . Frost, Exposed in each Month, . : ; . | Below 82°, or — . | + 21) + 08] — 3:3} — 99} —14:6] —18-0] — 9-4 Fire, Exposed in each Month, ; : : . | Above 32°, or + . | +80°6 | +78°8 | +71°8 | +59°8 | +43°1 | +30°9 | +59°5 Wind-Force per Month, . : P : : . | Ibs. pressure xintodays| 41:96] 41°21] 47:26| 58-40) 52°51) 60°90) 52°62 Wind-force, Accumulated Quantities, . . . { The above from be- \ 37117 | 412-38 | 459-64 | 518-03 | 570-53 | 631-43] - ginning of year. VOL. XXXV. PART 3. 2Y y. Soc. Edin Vol.XXXV MED. SCOTTISH METEOROLOGY, 1856-1887. prarte (BSS 1360 (8&0 Sp ess 254Ser ep Osi aS er eporriaserey r of s.= Pp . 2 a © (ale Yj TMA b= aaa A IN I I\ N A \ \ f \A | I aan a, a | ft j\ A, Ritchte ¢ Son, Photo-lith. Vol .XXXV. SCOTTISH METEOROLOGY, 1856-1887. tee Roy. Soc. Edin. Vv q & Bf aaa [St =— Senne. ape Desc fric be a 1880 1880 Mo 3b 5674908 2345678 9IOI423 4356789 v we wees Bayo Rang "i a ar | | | | | tH Les MW y as 1870 /870 as /860 = eT aS OLS GSE TRO? 2 3 4 SO THIOTLIGSETBE®I , Photo-lit. Pwehwate'd Mew groups of SUM- SPOTS continued at Mew Observatory. | ess .0.ED. 9 9 ~ 5 d0¢ 3 a aa Ss sasasssadsesdoo0 7 Pek ae eee Ge co RN ln Sm et OS Om a ah al oe oe a Oe SS, er Gar iy a oil C2 a — a — 2 series babar: Roy. Soc. Edin. Vol.XXXV. .O£D. SCOTTISH METEOROLOGY, 1856 -/887. pare 3 | 470 1880 (855° 4860 a a 8904234567835 LS Ras a Be {7 0 ‘2 6 h 2 "0 s 6 vs 2 9 3 5 2 9 8 u 6 TABLE 3.) Mean Tempe ria Ture im | SS e Nw » NS = Q R x, (as) al 3 Mm 3 R a| x >’ a : i | =: Tot _ as : | VE mm \/ivyivy, | Ls le EE i, | i a | Gas LEE IEOW OE 24 5 6 THF OF Ls & 3 /860 1870 1880 4 L | < Q 1 4 y Q er | , ie ain S N Ss oO & N >.) ™N Che ¢ Son, Photo-lith. ~- Vol.XXXV . Edin. Roy. Soc 1880 O1234567890/23456 O.ED. SCOTTISH METEOROLOGY, 1856-1887, o sre 4. 89 | 67 87 CLS. obs. ¢ del. @) eae - 7 2 13 > ae 2 TE L880 [6 oe 8 a “7 = E » | (ah ace ce | zo. Black ieee Lae aes eee ey i. ww # | ry I (a) a ae 8 ae Age | aes. 1870 V 1870 E7EIOTU73SS5S678 {a} 5) ° (a) 5 7 fa) ° fe] Ps) a) i ° ° [?) Q OF 2 4 < 7 o A) 9 , om a: LATOR eNO UY eepenisd ar] Kew content ie] - ts () SNchwaée 's 4860 colt ¢ Son, Photo-lith. ; 1860 7890/2345 BSS B55 216789042345 6789 3 50 —<- nacrtomereeret fr Oo is tr j : 'S-= -_— ; Roy. Soc. Edin. Vol .XXXV WO.ED. SCOTTISH METEOROLOGY, 1956-1887, pare 6. 1860 1870 be 9 O/ 23 48 6> 90/2 34SEFESO12LIUSET BY ne (\y ( ; iim SS a (Ee =a en ee : R: -Ss oy eww OQsrere| a ahaa neil a ComPdsiTé Table Mean Shdde Temp. +| Mean Max. of Shade Temp. id = PSS pa 5O SEISG thie & Son, Photo-lith. gies oe G b o's oO Cc © J o f © c o - S) a 2b le G Cc ‘ : dhwasbe'’s Naw Groubs o Sun- SPO S$, Compa 7 at Kew bsevvalovy, Ra git | ©) y A ‘ | | ' 34 ad ' i Roy. Soc. Edin. Vol.XXXV 9.ED. SCOTT/SH METEOROLOGY, 1856-/887. mare 6 : ef (855° a 1870 1880 S7EVPOr2ZIESEZSSIOlL2A3S3 4S EF EBIDI42ZBKRSE CFE? ——-——_ | —_— aR | ia | 2 a) 8 16 | & Ik 10 le co fh 46 is 3 hil Liz a) {8 1! 6 Lhe ic midland thade Te a \_ ae eae | MEMO VN2Z Se 25678 7 O71 234567 ESOL RESET E® | | == OSS 1860 1670 | /880 tele ¥ Son, Photo-lith CPS. obs. ¢ aE, Roy. Soc. Edin. Vol.XXXV. JED. SCOTTISH METEOROLOGY, 1856-1887. rate 7 855 /860 (1870 1880 E7EPSOV2AZETEPBPOVUSESEZEPOV27~Z45E78BY F alfory. ay) a S ~ pate 45 — ee Ge GT fl ! dll ell ih tint | fit Stic I 426 Seequiece PROBtitiessciieirsrc=—=-- eee Weeerreiscsues TEE —— Ni lll en: LeN i 2 am —y— NY I 1 seases | fAN | 2 | sas he ¢ Son, Photo-lith. CPS. 06s. ¢ adel Roy. Soc. Edin. Vol.XXXV. O.ED. SCOTTISH METEOROLOGY, 1856-/887. pare 5 y of BSS 4860 1870 1880 sof 67897 O1 28445678 9OV2Z345E7BEIOV2Z3I456 72 F 2 o_ =. * = ves TWN Oo ~ Pop | ay } \| ff YX — We = ~ WS SSS ae Pj aN aes eo NN 8 (> Me tO eT OT ase CeO me ae eS $.\> YESS 1860 1870 1880 ch: & Son, Photo-lith CBS. obs. & del ; . a ' ¢ eoRY 3 / x, 2 a Xv : -“ s ~ : = * > < > . “ty ’ Roy. Soc. Edin. Vol .XXXV 0.ED. SCOTT/SH METEOROLOGY, IBEO-IOET. piate 0. wv of SSS 4860 (870 188 0 aL 6O78EPSOVA7AS ETEFBIQIMIASSZTEFEIOV2~A3 GES ETB ie ww Y ? © 4 I$), Hours oe oS | a . S'S OR a ae ee ent nt ea a: we ~ Pp ie oe o~ im > = ean) + — QO7 234 E7897 23 CSET IIT EST STI SG 60. gfe Y “Ine D ra es Sy) iF ‘y - Ww is, S15 S15 a ! Sy N S} 9 GEIS OGsn gael, ns, Roy. Soc. Edin. Vol.XXXV. 20. ED. SCOTTISH METEOROLOGY, 1856-1887 are 10 Year of (7 1870 ft b7 8901 2345676901 23656753 Cee. 9 8 = ? meee Sekwete's| Vew groups of SUN-SPOTS, contdued ot Key Observarohy an, AN k HIN ey AS /8 , c G 16 |TABLE Bis om Meh, 2 Y | _- 7° 9 TITTIES ESTT TT OTT TST ITT OTE T 23 25 67 8 9 =a , Pho = CEILS TAGs a aEL. ‘he Ls <= Re 6 Cea ~- 4 Pr mi. P . ' J } Vol XXXV PLATE 771. RO.ED. SCOTTISH METEOROLOGY, 1856-1887. _ reer of 0 —“. .. °«x. °° °° #« «4-0 °° °° '&t obs. Trans. Roy. Soc. Edin. 1860 1870 F SIO42Z3S4EFSOPEI O12 3EB45FEO6RPBICGQ4(2Z 3845678 50 4 AS Ad NN a a eo +4 ? ai OS Sa = Ls ae Sa Bee | os ee ae ae a | - leo + Aue _| __Nf \ Jat ly = EAR: ca tans I — wie Sa I, vi. TT i | | i\\ . A | \ 2 2 ee) A wa 0. OSATE Nuxe/ |\YR\ [ining (aha) Fawrola | as «i a ee aaa TT SR aE 1860 1870 /$80 TES SFE 77 CPS obs f del. | “ar es Ss. = Vol. XXXV rans, Roy. Soc. Edin. a o- ; . | wn fs 7 &:; ~ | ~ + § x 7s | S \o Yy ‘oO 6 = Ie : | S SS fe “t DS) N ses " ed % ae ro | a 2 2 oi 2 y Ne 9 9 S99 : : are . wr - ® > i = > - & ‘ o oh ‘ by S : . ws o a | a) : K ee 1 Hg = is aR ee ene . Pe XN ° Ke) == By R —————————_t 9° > Of 3&8 N S sf ° 3 y ———————_—_—— ° & 6 iN = ° ia - as SS ve KR —— . ly : S ZO by cS SS : = xy dj _ ————__ & %) @ S Ey 3 wf: ~ c i R me 9 ie of © 8} es R 3 an & =| To N ® sé ; N < SS |x |e k ; 3) Ie als = i) ; oh BS 8 i rT] 3 gs SASASHISAS CaeKROEIS SS SOSKROE ISAS SAORS i) gs a ees = = = ——— ROED. SCO7T/ISH METEOROLOGY, /856-1887. PLATE 19. ri — rans. Roy. Soc. Edin. Vol. XXXV Meme. SCOTT/SH METEOROLOGY, 1856-1887. erate 19. [Year of P= 1860 1870 7880 Meat C7EIOlV2ZSES EF EP Ol2ZZEZIZEOFV EI OI2ZSB GSE VES ~SFOTS, chntinuecl of Kew Obselrvatory. | ; ees 9 in ao 2G N re ns ae BS ak A eS te _— = es | ABLE 27 nn — — C—O ce ~~ OH 58 ~ i) w Gt ae as a EM ae lt Ss Ss Oe a Ge =e is =e ee oo S 5 far of MEMIONTIA S 2S67 87 OC RS4S56789O2BELSE PZ BY Obs. = [se 1860 4870 _ 1889 = 4% Son, Photo-luth. CPL. S. obs. ¢& del, a sb « ’ # ~ ‘ ell sae ~ MR aang 2 ~~ = @ Ta—~ a a ; . - ar * — 5 i . 4 * a“ es a* —. = ‘ ‘ i i 1 . ih ¥ + +] * - 7 ‘ \ \ \ - ‘ ee ‘ 1 - ' ) \* ’ a” ans. Roy. Soc. Edin. Vol. XXXV. R.O.ED. SCO7TT/SH METEOROLOGY, 1856-1887. pi src 14 Year of YOS yaee | [5p _ 1880 Oh =| 678 IFIOV2ZBLSTOFBIOs2A~S LSE VYEIOOIM2ABZLEETZ SG (4) Persson Poms a E SUN EEE oT) atoy vv . & oO ie) a \ 2s \ 7] ! ) lar of o. ETEFOI2IASETES OL 2 SESE? ESOTAS ESET ED BSS 1860 Oo 1880 A, itchte ¢ Son, Photo-lith. gy ty 4 S SN & Ro iy N MEAN SCOTTISH METEOROLOGY. . 267 PART III. THIRTY-ONE CHRONOLOGICAL TABLES oF Mean Scottish Merrorotocy, Montu sy Mont, FRoM 1856 To 1887 INCLUSIVE,—EXPLANATIONS OF. These Tables are derived by immense condensation from the bi-diurnal observations taken voluntarily and with remarkable assiduity, by the observers of the Scottish Meteorological Society, at 55 of their stations scattered over the whole country of Scotland (Highlands and Islands included) ; and computed by order at the Royal Observa- tory, Edinburgh, for the purposes of the Registrar-General of Births, Deaths, &c. in Scotland, for every month in every year from 1856 to 1887 inclusive. 1. Historic Origin of the Data. When the Astronomer in charge of the Royal Observatory, Edinburgh, was first called on by Government in 1858 to begin his part in the above Meteorological calculations for the purposes above stated, he found a generally excellent system already organised, and worked for two years by the late Dr Srarx, then the enthusiastic Secretary to the Scottish Meteorological Society, as well as a scientific and responsible officer in the depart- ment of the Registrar General for Scotland. Continuing that system, the ordinary instrumental corrections were carefully applied at the Observatory, and monthly means, collected from the bi-diurnal observations of all the stations, were exhibited and printed, first for each station by itself, giving all its individual characteristics untouched; and next for the mean of all the 55 stations; or for something very like the one geographical and physical centre of the whole Caledonian country. for, such an extensive condensation of the records of many instruments and many observers would, it was hoped, possess a certain solidity of accuracy ; and justify confidence in it to a greater extent than any single observer, either in town or country, could ever expect to attain to. But there was still no opportunity of ascertaining for any month in any year, how far that season might be an extraordinary one, as touching any, much more all, the usual meteorological items of study. The historical element as to annual recurrences, agreements or disagreements, and cyclical rises and falls of many years, was then in fact entirely wanting; and could only be expected to be supplied by continuous observation united with undeviating registration of them through many years. In a manner however quite suitable for a Government Observatory to engage in, and become responsible for. To supply this confessed want therefore, the Astronomer specially applied himself; and entered each month’s means for the collected country in ledgers, as the years went by, in the form best adapted for successive chronological digests being taken, for every succeed- ing accumulation of years from the beginning of the activities of the Scottish Meteoro- logical Society, down to the latest passing period. At first, from the frequently very great differences of the calendar months of one year, from those of another, even when the Mean of all the stations, or of the whole country, was concerned, these chronological means used to vary rather violently from each other. 268 PROFESSOR C. PIAZZI SMYTH ON But the differences were always decreasing, so that after 16 years had gone by, or in 1871, I thought it useful for the public to print all those annual returns in the 13th volume of the Edinburgh Astronomical Observations, as a contribution to the successive time-features of the climate of the whole of Scotland. So quickly however has time gone on since then, that now 16 more years. have been tabulated, and the final results are now for 32 years ;—giving thereby so great, though still not perfect, assurance of the limits of the surprises which Nature may have in store for this people in future years,—that if the first list was positively worth printing, the second must be far more so; and has now even become necessary for the prompt refer- ences and methodical conclusions required for the Registrar General’s work, as that great task of his still goes on, perpetually functioning simultaneously with the life and growth of the nation, and following in its mighty footsteps without a moment’s intermission. On this second occasion, however, of preparing for printing, besides the 21 Tables of which the old series consisted, taking up all the more ordinary, and orthodox meteoro- logical points, I have added 10 new Tables to represent the answers of observation to certain new requirements of scientific theory; and shall proceed therefore to describe some of their contents and bearing at rather more length than the others, after duly recording that the chief labour and merit of preparing the 21 old Tables up to the year 1880, out of the mzllions of figures concerned therein, were mainly due to the late Mr ALEXANDER Watuacer, M.A., then First Assistant Astronomer in the Royal Observatory, Edinburgh. While similar merit is now also most eminently due to Mr Tuomas Hzatu, B.A., of T.C.D., for continuing the old Tables from 1880 to the present year, and preparing the new Tables for the whole period from 1856 to the end of 1887. In September of that latter year, the 55 stations, carefully chosen for the Registrar General, by Mr ALexanprr Bucuay, the present able Secretary of the Scottish Meteoro- logical Society, were distributed as follows through the 8 Registration Districts of the country, including islands as well as mainland. | 1. In the Northern, : é 6 Stations. 2. In the North-Western, ‘ : 6 ie 3. In the North-Eastern, ; ; : 6 . 4, In the East Midland, : : he!) S 5. In the West Midland, ; , : 5 Js 6. In the South-Western, ‘ 5 5 7. In the South-Eastern, ‘ : 12 Vy 8. In the Southern, q ; f : : 5 4 Total for all Scotland, : : . 55 Stationg and have for their Mean or Central point, Latitude. . » =56° 30 ae %» 3 Longitude . ; . = 8 4058 and Height above Sea-Level : . = 256 Teer * The above given latitude and longitude are nearly those of “the fair city of Perth”; but the height above sea- level is nearly double, depending on the mountains North and West thereof, chiefly. Sea-distance from general Sea- coast however remaining untouched, viz., Eastward, 40 ; Westward, 90 ; Northward, 120; and Southward, 120, miles. MEAN SCOTTISH METEOROLOGY. « 269 This distribution, and these component numbers have not been always kept up exactly every year, notwithstanding the best efforts of the Scottish Meteorological Society so to do. But it is hoped they have always been preserved sufficiently near in Geographical harmony, to prevent the final Meteorological Means being seriously perverted. Wherefore the tables now presented, though sometimes of only 50, in place of 55, stations, may yet be regarded with approximation as equally distributed about the country’s central position. While of the original 55, no less than 31 have continued identical in place throughout the period from at least 1867 to 1887; though with 19 changes of observers amongst them. 2. Of the Old Tables newly continued to the Present Time. Table I. contains that necessary feature for all Meteorology, the mean monthly Baro- metric Pressure for each month, of each year, reduced according to order and precedent both to the temperature of 32° F., and to the sea level. The pressure is given in terms of British Inches, and amounts on the means of all the months and all the years to 29°846. But with an evident annual cycle having a Max. in May and June = 29929, and a min. in December and January = 29°764 inches. Table II. contains the Mean Monthly range of Barometric Pressure for all the stations, and amounts to 1:290 inch on the mean of everything. But with an annual cycle having a Maw. in the beginning of January = 1°671, and a mim. in July = 0°897 inch. Table III. is the biologically, botanically, and commercially important return of Mean Monthly Temperature of day and night, strictly in the shade, in degrees Fahrenheit, and amounts on the mean of all the months and all the years to 46°°2 F. But with an annual cycle having a Maz. towards the end of July=57°4, and a mm. in January = 37°°0 F. Table IV. is the almost equally important Mean daily range in each month of that shade-temperature; and amounts for a mean month of the whole year to 12°°5 F. Of which quantity, if half be first added to, and then subtracted from, the previous 46°:2, we shall have the highest and the lowest shade-temperatures in the cycle of a mean day of an annual average kind. See also the new Tables XXI. and XXII. But of such daily _ range there is an annual cycle ; whereof the Maw. occurs in June = 15°'6, and the min. in the beginning of January=9°'1 F. Table V. advances from Shaded to Exposed Temperatures, and by means of Black-bulb thermometers; of not always identical kinds, unfortunately; but for reasons stated on the back of the Observer’s printed Schedules by the Secretary of the Society. This Table V. then gives the mean of all the daily readings for each month, or the mean of the highest points reached every day in each month, at all the stations, by their Black-bulb thermo- meters, fully exposed, nominally to the Sun, really to the sky, but by day alone. It is therefore a very peculiar kind of thermometer reading, and claims for Scotland an average, on the mean of all the days of all the months, of all the years and all the stations, so high as 70°°5 F.; including therefore without doubt some 18° of Solar radiation as well VOL. XXXV. PART 3. 22Z 270 PROFESSOR C. PIAZZI SMYTH ON as the proper and acquired temperature in the shade of the atmosphere alone; which for the day half of the 24 hours is 46°2+6°2=52°4 F. But as to the annual cycle of these exposed Black-bulb day observations, its Maa. occurs in July=91°-4, and its min. in December = 47°'6 F. Table VI. gives the monthly means, of the cold extreme, or nightly observations of the same exposed Black-bulb thermometers, but now at night and the coldest part of each and every night. Establishing that such Mean, of exposed night temperature in Scotland, on the Mean as before of all the days of all the months of all the years and all the stations, is down so low as 35°°1 F.; and includes about 5° of negative radiation effects from the open night sky. The shaded thermometers at night yielding on the whole no lower result than 46°°2—6°'2=40°°0. But as to the annual cycle of these Black- bulbs exposed by night, its Maw. occurs in July = 44°9 and its min. between December and January = 28°°3 F. Table VII. sets forth the Mean monthly Humidity of the air, as measured by the depression of the wet, below the dry, bulb thermometer ; and computed according to Mr GLAISHER’s well known and most practical] tables. It is then found to amount on the whole year and years to 85, where saturation=100. While the number of grains of moisture in a cubic foot of the earth’s gaseous atmosphere, or any other direct and positive expression of the amount of moisture has to be computed from that 85 of Humidity in combination with the shade-temperature, and Barometric pressure at the time and place. But these having been already given, for the one general mean of all the stations and all the years, as 46°°2 and 29°846 inches, there results very nearly 3:1 grains of watery vapour present in each cubic foot ; 0°5 grains further required to saturate the same bulk of air ; and 0°26 inch for the elastic force of vapour present in the air. The depression of the wet, below the dry, bulb being 2°:1 ; and the depression of the computed dew- point below the observed dry-bulb being 4°°5. Or showing the general climate of Scotland to be usually within half a grain of manifesting visible mist, instead of concealing it as invisible vapour, or water gas. But taking the mere ‘‘ Humidity” return just as it stands, its annual cycle has its Maz. in December= 89, and its min. in May =80. Table VIII. gives the mean number of days on which rain fell in every month ; and which, on the whole year and years amounts to the round number of 15 for every month. The annual cycle however shows itself in having a Maw.=17 in January, and amin. =12 in April. Table [X. represents the still more important feature of rain-fall, viz. its quantity, as measured by its depth when fallen. And while the table gives such depth for each month, it likewise gives the accumulated depth for each year, and the mean of the years, viz., 39°12 inches. A quantity however requiring immense alterations for individual localities, sometimes + and sometimes —, according to local position, as will be taken up in the second part of these Meteorological explanations. The annual cycle however MEAN SCOTTISH METEOROLOGY. , 271 of the single months, which has for its mean=3'25,—has for its Max. in December =4:07, and for its man. in April = 2°24 inches, British. Table X. seeks to record the mean amount of strength of wind in each month of each year; the mean of the whole being 1°73 lbs. constant pressure by night and by day on every square foot of surface; implying a velocity of over 18 miles an hour. A high return, showing perhaps the effect of proximity to the sea-board of most of the Scottish stations, however centrally in the country the mean of the whole may be located. Or perhaps it may indicate the difficulty of observing the true mean pressure of the air through the whole 24 hours, both independently of the impact of the rain drops, and the effect of momentary gusts on the feelings of humanity at the instant of observation. The annual cycle however comes out pretty evidently, with a Max. in February = 2°11, and a min. between July and August= 1°34 lbs. on the square foot. Table XI. gives the mean monthly number of days on which winds of Northerly direc- tion blew, that is, all those entered North, and half of those entered N.-east; with the same for those entered N.-west; and amounting per mean month to 5. The annual eycle of these North winds is rather obscure, having something like two Maw., one in April and one between November and December, each=6 ; and two min., one in January and February = 4, and another in August = 5. Table XII. gives similarly the number of days per month, on which Easterly winds blew, viz., 6. The annual cycle showing a Maz. between April and May=8, and a min. in December = 4. Table XIII. the number of days per month, on which Southerly winds blew, viz., 8. The annual cycle having a faint Max.=9 in January, and a faint and short-lived min. in March=6. Table XIV. the number of days per month on which Westerly winds blew, viz., 10. The annual cycle having its Maz. in August = 12, and the mn. in April = 8. Table XV. gives the mean number of hours of Sunshine in each month, amounting on a mean of all the months to 136; but varying between December and June from 60 to 217, for astronomical as well as meteorological reasons. Table XVI. gives the estimated mean amount of Cloud per month, in decimals and tenths thereof, of the hemisphere; being, for a mean month=6°4. But varying between January and May between 6-7 and 6:2; or indicating a never very astronomical observ- ing climate. Tables XVII. and XVIII. both refer to Lightning. The former gives the mean number of days it is seen per average month,=1°6 ; and the latter records the number of stations reporting it = 15. The former kind of return arrives at its maximum in July, and=2°5; while the latter kind reaches its maximum also in July, and=29. Again the former kind attains its minimum in February, and=1°1; while the latter has its minimum very near it, or in March, and then registers 6. So that multiplying the two kinds of return together, we have— 272 PROFESSOR C. PIAZZI SMYTH ON Lightning max. in July=72, and Lightning min., between February and March=7. Tables XIX. and XX treat similarly of Aurora. The former giving the number of days on which it is seen per average month=1°6 ; and the latter recording the number of stations reporting it, viz., 7. The former table comes curiously and very decidedly to a double maximum; viz., in October=2°1, and in February=2°0. While the latter table confirms the former by coming also to a double maximum in the same months ; viz., in October=11, and in February = 11. Again the former table comes to its minimum in June and July=0'1; but partly owing to lengthened twilight days ; while the latter table comes also to its minimum in June and July, for probably the same reasons, and averages then per month less than 1. Wherefore combining the two kinds of return by multiplying into each other, we have the first maximum of Aurora in any whole winter season, occurring in October and registering 23; the second maximum in March=22. And the one, or at least the utter minimum of the whole year between June and July, with a record of something less than 1. While the comparative or necessary minimum between the two maxima, occurs in December, and reaches in its two components 2 x 7=14 on the whole return. The double annual maxima of Aurora are thus well marked out by the minima on either side of them, and are all the more interesting from being so absolutely opposed in date and character to the single annual maximum which Lightning obtains in the cycle of a year. That is tosay, Lightning has its one annual maximum in July, just when Aurora, but under forced conditions, reaches its one most conspicuous minimum of the year. While at the same time the dates of Aurora reaching its two maxima for any winter season, are not corresponded to inversely by both of those being dates for Lightning falling to a minimum; though the Spring maximum of Aurora does occur at the beginning of a nearly three-month’s minimum of Lightning, and corresponds rather to the period of dry North-East winds. So that on the whole, Aurora and Lightning, nothwithstanding that they may both claim electricity in large part for their luminous manifestations, are left by meteorology at singular points of variance with each other, just as spectroscopic analysis declares their molecular constitution entirely different. Thus far all these preceding 20 Tables of 32 years’ collection are the continuation of the older 20 tables of the first 16 years, under the same titles and the same numbers. But before we introduce their summings up for one mean epoch of time, as was done in the old Table XXI., to be re-introduced presently as Table XX XI.,—let us describe the new Tables already alluded to, and to be numbered from XXI. to XXX. inclusive. 3. Newly prepared Tables for New Derivations from the Old Observational Meteorology. Thus of the new Tables XXI. and XXII., the former of the Mean monthly Maxima, and the latter of the Mean monthly Minima, of Temperature in the shade,—it should be MEAN SCOTTISH METEOROLOGY. 273 explained that they are prepared to satisfy a want, often expressed in public, as to having these extreme quantities, or limits in either direction for the daily cycle of that kind of temperature clearly set before the eye, without giving the head of the reader the trouble of deducing them by simple arithmetic from the old Tables III. and IV. Where Table III. is the mean Temperature of the 24 hours in the shade, and Table IV. thedaily cycle or range of differences of the said shade Temperature in the same length of time. One half therefore of this latter quantity has been added to the old Table III. to form the new Table X XI; and one half subtracted from the same Table III. to produce the new Table XXII.; and both of them for every month, of every year from 1856 to 1887 inclusive. According to which new Tables XXI. and XXII., it will be seen as a first step, that the daily shade temperatures at any hour of the day in the coldest month, or January, will be on the average of 32 years, somewhere between 32°°5 and 41°°5. And similarly for the hottest month, or July, the daily shade temperature will then be anywhere between 50°°0 and 64°9. Which four quantities give a mean of 47°°2; indicating July to be more in excess by solar influences above its neighbouring months, than January is in defect below its neighbours ; or again it gives a useful warning, much required in Meteorology, that the mean of the two extremes of a cycle, is by no means necessarily the mean of all the smaller component portions thereof. For, taking the means for all the 12 months, instead of for 2 only, there comes out again the 46°'2 that appeared in our account of the old Table III., as the Mean Temperature of the whole year. Table XXIII, of Rain-fall depth, is based on the former Table [X.; but instead of - beginning each month’s chronicle of depth from zero, goes on accumulating it, month after month from the beginning to the end of the year; and this is believed to be a form of representing the rain-fall much approved by both agriculturists and engineers. Table XXIV., of “ day-degrees” of useful Plant-growth Temperature, sets forth per month the resulting number of Fah. degrees in the mean shade temperature of the month, either above or below the newly supposed botanical dividing plane of 42°-0 F., multiplied into the number of days in each month, agreeably with the new method practised by the Meteorological Office in London; and evidently giving the duration, as well as the intensity, of such or such a plant temperature in any and every month. In this first Table (XXIV.) therefore of this kind of return, we see that the average number of such positive day-degrees of possible botanical activity, performance and result in an average month of the whole year is 129°. Or again that the negative affects, which are —155 day-degrees in an average January, have become +478 in an average July, and sink down again to —133 in an average December. This Table XXIV. will therefore serve conveniently to compare any month in one year, with the same month in another year; but will not suffice to show instantly how the vegetation of any year, at some particular epoch of it, is getting on upon the whole ; and whether towards the end of it the plants have received all the stimulus and all the time they require for perfecting their growth and ripening their seeds. 274 PROFESSOR ©, PIAZZI SMYTH ON (Table XXV.) But towards this end, Table XX V.,—which is of double extent, has, in terms of the same day-degrees of botanical temperature, an accumulative character as well ; and goes on adding up in separate columns, from the beginning to the end of the year, month by month, the negative day-degrees in one column, and the positive day-degrees in another. (Table XXV. cont.) Whence we may see at once for either any year, or for the mean of all the years, how much negative or repressive effect, vegetation had to withstand during the earlier part of the year ; then how much positive and encouraging effect it received during the middle of the year; and finally by how much increase of cold, combined with duration of the same towards the end of the year, the growing powers of plants were sealed up again in winter sleep. (Table XXV. cont.) On an averageof all the years the repressive effects of the beginning of the year have exhausted themselves in the first three months, after scoring 341 day- degrees of botanical cold. Then begin and increase through the next seven months, or April to October, both inclusive, the positive day-degrees of botanical life and growth, scoring at last 2070 of such degrees. While after that, begins the cold of November and December, adding 192 day-degrees of cold to the Spring’s 341°; or making the repression = 533 day-degrees of cold for the whole year ; and leaving the positive effects of summer in excess by 1537 of such degrees. Out of which number, both Nature and the farmers of Scotland have to get all their annual living as they best can. (Table XXVI.) Both Table XXIV. previously described with its statical quantities, and Table XXV. last described with its quasi dynamic and accumulative ones, are often at variance with themselves, on contrasting one year with another, on account largely of the variability of our climate. So that in some years, some amount of positive botanical tem- perature begins in March; but is immediately followed by so much botanical cold in April and May, that the true spring of vegetation for the year only begins in June. Where- fore the false start it received so early in March, is a disastrous thing for the plants, and typifies an unfavourable, rather than a favourable, agricultural year. Hence a better notion of when the growing period really begins, may be obtained from the present Table XXVI., now to be described. It is a cumulative Table also, and of botanical day-degrees; but has its summations made up and combined in one monthly column only, and according to algebraic sign. The negative symbol therefore of the resultant, only changes into the positive, when the latter has, in a manner, eaten up the former: and the dates so obtained for spring-tide, are later than what would be derived from the first Table, viz. Table XXIV., but far more assured and practical. (Table XX VI. cont.) Hence by Table XX VI. Plant-growth, as shown by the negative quantities at the beginning of the year changing into positive, begins on the average of Scotland soon after the middle of May. But there have been years when it did not begin until the end of June, and others again when it fairly began before the end of April. (Table XXVI. cont.) in a similar manner the growing and ripening period in Autumn, if held to be defined by no more accessions of botanical heat, ends on the average with MEAN SCOTTISH METEOROLOGY. 275 October. But there have been years, and Table XXVI. will show which they are, when the heat-accession went on increasing up to, and even including, all December. (Table XXVI. concluded.) Again the absolute amount of botanical day-degrees of heat, recorded through each annual cycle, is so very different in different years, that while in the usual fulness of October, the average amount is 1727°—there have been some years when it reached 2216°; and have also been others when it attained to no more than 971°; or something ruinous then to those very crops, which had been a distinguished success in other years. 4. Frost and Fire. (Tables XXVIa., XXVII. and XXVIII.) All the previous new thermometrical Tables from XXI. to XXVI. inclusive are founded on the means of shaded thermometers. But there is another class of temperature observations, viz. of the exposed Black-bulb thermo- meters, in their occasional excesses once a month, both by day and by night, which are far more immediately suited to indicate some of the most trying influences to which all open-air structures, whether natural or artificial, are liable, both on their outside surfaces, and to some small depth within their substance according to its conductibility for heat. The important dividing thermometrica] plane to measure from in this case, being, how- ever, by no means the 42° F. of plant life, but the far more widely acknowledged 32° F., or the very freezing point of all watery Nature ; and that which brings on the often sudden change in water from its fluid, to its solid, condition, with all its then visible whitenings, irresistible expansions, and splitting of rocks exposed to it, with hardening of soft ground, and stoppage of building, agricultural and inland-navigation work. The efficient quantities therefore to be entered in these Tables XXVII. and XXVIII. are, for the benefit of practical men, not so much the actual readings of even the said exposed Black-bulbs by night and by day (as entered preliminarily in the large Table XXVIa.), but the differential amount of such readings in degrees, under or over, — or +, 32° F. And again they are not founded on the means of those exposed kind of read- ings for every day, and every night of the month (when day-degrees in monthly sums might be demanded, to show effects of long continuance ; and many an acute, if not crucial, experience of a single hot day, or a single freezing night, might be concealed)—but on the one extremest reading each way, or the highest one by day, and the lowest by night, during each whole month, at every Black-bulb station, 2.e., the mean of all of them. There is still therefore the effort, according to the whole tenor of all these 31 Tables, to present such a return by a mean from a number of stations; and not to risk the character of the whole country and the interests of science on the unsupported testimony of a single observer ; and this whether such solitary recorder’s station should have been arbitrarily chosen in preference to all the rest ; or whether the one, absolutely highest reading of all the Black-bulb stations should be taken each month, and quoted anony- mously, though it might appertain to a different station every month. Now this last plan was the method, for certain reasons, adopted from the beginning 276 PROFESSOR C. PIAZZI SMYTH ON by the Registrar General in Scotland ; so that in that Officer's quarterly returns, while the Black-bulb observations which we have utilised for Tables V. and VI. are the means of the readings for every day, at every Black-bulb station,—the extreme readings entered alongside them, refer to only one day and at some one, or any, station, whose name does not transpire, and may be different every month. As such a return would not suit the present 32 year discussion of means only,—Mr Heats, First Assistant, has been at the pains of going back over all the years of all the stations, and picking out the max. and min. readings of each, for every month, of every year; and taking the means rigidly, according to the varying number of stations at work at the time. This proceeding, however, has brought into prominent view, not only the terrible differences between the extreme readings of one station and another, as for instance 30° or 40° (and which may be characteristic of Black-bulb exposed thermometer observa- tions); but has also shown the utter defalcation from the original published plan of the Scottish Meteorological Society and the Registrar General as to the number of stations combined to give the Meteorology of the country. For while, for Barometric Pressure, Temperature in Shade and other important returns, the one mean quantity finally given out, represents seldom less than 55 stations,—the Black-bulb returns. Began in 1857 with 3 Stations. Increased in 1860 to 16 u . 1862 to" 23° ¥ 1870 “to 24 ee Decreased in 1873 to 20 ee Bs 1876 to 18 3 ‘ 1880 to 16 7. 6a ,, 1887 to 10 rf It seems therefore fairest for the public, and most honouring to the enterprise and devotion of those enthusiastic observers who did cultivate this extra branch of Meteor- ology, that their individual stations should be known by name, so long as they alone con- tributed the sparse items, which have hitherto passed as the condensed work of more than twice, or thrice their number of stations. ‘To this end therefore Mr Hzatn’s great table XXVIa., with his valuable and indeed unique collection of results of Black-bulb observa- tions, names of stations, and summations as well as means for every month, has been in- troduced entire; and forms the solid foundation on which the next two Tables XX VII. and XXVIII. have been prepared. They show too precisely, on the testimony of all the data of the kind, available over the whole country, the extreme temperatures in Fahrenheit’s Scale, to which exposed surfaces are hable by day and by night in Scotland, during any cycle of 24 hours. To distinguish these deductions from such extreme returns, effectually from all shaded Thermometer readings, and also from the simple mean readings of the exposed Black-hylbs a — EE MEAN SCOTTISH METEOROLOGY. QUE themselves for every day in the month, as given in the older Tables V. and VI.,—I have called these special figures of the new Tables XX VII. and XX VIII.—borrowing the phrase from the powerfully written geological volume of that too short-lived man of rare genius, the late CampBett of Islay,——Tables of “ Frost and Fire.” Table XXVIIL., representing ‘‘ Frost,” or the greatest depression of temperature below 32°, observed on one night in the month, but at the mean of all the stations actually named, under the corresponding date in the previous bulky Table XXVIa. And Table XXVIIL., representing “ Fire,’ meaning of course the Solar fire with its marvellous powers of heat radiation on its one maximum day in the month, but at the mean of all the stations particularised for that date, as before, in Table XVIa. For the “‘ Frost ” return alone, these numbers of Table XX VII. are not very different from those given already by the exposed Black-bulbs as their mean of every night ; or say 12°°5 lower ; or by the mean of every night of the shaded Thermometers, viz. 17°:3 lower, than them. But for the “Fire” returns, the numbers of Table XXVIII. are greater than what were deduced from the exposed Black-bulbs on the mean of every day by 20°°8; and from the mean of the shaded Thermometers by no less than 39°-0; and this on the mean of all the months of the average annual cycle. What is still more important too, as indicating the Solar origination of the excess, is, that this last extra quantity, though attaining only 34°-0 at mid-winter, rises to 80°°6 at midsummer, and cannot be neglected by open-air workers, either as a natural phenomenon, or a practical fact testifying to the existence of an orb in the heavens above us by day, of far more intense powers of heat-radiation, than there may be of cold radiation at night. Entirely vitiating therefore the assumed official method of taking certain means, by attending to the two extremes only. For if we take the mean of the hottest “ fire,” and coldest “ frost” month in a year, viz. + 80°°6 and —18°:0, their mean comes out 31°'3; but if of allthe 12 months of each kind, viz. +59°5 and —9°4, that result is only 25°°0; i.e. 25° above 32°=57°'0 F.; just as the first result means 31°°3 + 32°°0=63°°3 F. Even too does this intense Solar radiation in summer on exposed surfaces, make itself felt, though rarely, in some interiors. For on entering the dark, yet ventilated iron Dome of the Royal Observatory, Edinburgh, on the 17th of last July, and finding its atmosphere most unduly warm, I traced that effect to the invisible heat-rays coming through the solid iron plates at, and about, where the Sun was shining on the outside ; and with such force, as to produce a feeling on one’s face (though in darkness, and at a distance of several feet from the hot iron), like the sun-burning of an African desert. While on testing further the actual contact effect, by placing my hand on the middle of the back of each curved plate, above the cylindrical part of the Dome,—I found that there were four of those plates, extending over 90° of azimuth, so hot, that I could not keep my hand’s palm on them in close contact for more than a few seconds at a time. The plates next on the right and left of that horizontal subtense being only agreeably warm ; and beyond that range rather cool than otherwise. VOL. XXXV. PART 3. 3A 278 PROFESSOR C. PIAZZI SMYTH ON There are however some further deductions as to the annual cycle of Solar effects in this country, which it may be worth while to allude to at this point, from Mr Hearn’s peculiar Tables of Frost and Fire ; as thus,— (1) There are only two months in the year, July and August, when the exposed temperature does not go down, on some one night or other, below 32° F., so that we may say, Summer in Scotland lasts only 2 months. (2) But Winter lasts for 4 months, viz. December, January, February and March ; the last named being specially the month of snow. (3) Spring lasts 3 months, viz. April, May and June ; and Autumn also for 3, viz. September, October and November. (4) Or again it may be stated, that there is frost in the air of exposed places at night, during the 6 first months of the year, and the last 4. Wherefore in the matter of frost, June pairs with September, May with October, April with November, March with December, and January with February ; these latter being the most frosty two, just as July and August are the least frosty two. Not however the most fiery two ; for the occasional temporary heats in June, assisted by the greater altitude then of the Sun ;—exceed those of August. (5) The actual numbers, nevertheless, may be more satisfactory to be perused; and are given thus, together with the mean radiations by Black-bulbs every night ; and the mean temperatures of the Shaded Thermometers, also on every night ; thus, but all in terms of excesses below or above 32° F. “Frost” RETURNS, BELOW OR ABOVE 32° F. Whole Jan, Feb. | March, | April. May. June, duly, Aug. Sept. Oct. Nov. Dec. Year. Radiation on one night per month, . - : - | —17°8) —16°0| —15%5) —11:0| —81 | — 17] + 2:1) + 08] — 3:3] —9:9 | —14:6) —18°0) —9-4 Radiation on mean of all the nights per month, .| — 3°7| — 2°8| — 26] + 03] +39 | + 9°9} +12°9| +12°2/ + 8:5) +3°3 | — 18] —- 36) +31 Temperature, by shaded thermometer on mean of all the nights per month, | + 0°5} + 15] + 1:7) + 51) +91 | +15°0} +180] +176] +140] +86 | + 3:3] + 1:0} +79 “Fire” RETURNS, ALL ABOVE 32° F. Whole Jan, Feb. | March, | April. | May. June, | July. Aug. Sept. Oct. Nov. Dec, san Radiation on one day per month, . P , +340 | +442 454-4 | 464-7 | +7251 | +79°7 +80°6 | +78°8 | +71°8 | +59°8 | +43°1 | +30°9} +59°5 Radiation on mean of all \ the days, +187 | +24°1 | +82°0| +41°7 | +49°7 | +581) +59°4] +569] +499] +864) +234] +15°6| +387 Temperature, by shaded thermometer, on mean of all the days, . A .| + 9:5] +114] +134] +19°3 | +24°5 | +30°6 | +32°9| +32°0 | +27°6 | +20°5 | +13°6] +10°5 | +205 MEAN SCOTTISH METEOROLOGY. 279 5. Wind Force and Annual Cycles. (Tables XXIX. and XXX.) But after all that may be said for distinguishing various climates in Scotland, by all the possible refinements and varieties of Thermometrical registrations,—the practical results of the small limits of temperature-variation so found in this land, may be entirely overborne for the general population, unless aided by a concomitant and discriminating territorial return for each spot, of the wind force really prevailing there. For extra violence and constancy of wind movement, which is too often met with in Scotland, is of a most pernicious character in its effects on both human health and industry, as well as on plant life and growth ;—to an extent moreover not sufficiently taken notice of yet, in most of the scientific meteorological Journals. Thus as to the former more valuable kind of existence and activity, the human,— the most freezing days even of mid-winter by the thermometer, are often accounted, by those who undergo them, most pleasant and enjoyable, if it can only be said “ that there was not a breath of air stirring at the time.” While, on the other hand, in special situations where the sea-winds may blow perpetually, though they do happily prevent the thermometer from ever going down much below 32° F.,—yet they cause all the human discomforts and even distresses of really severe cold to be felt to an extent that is both ageravating, lowering to the whole system, and often intolerable. And then as to wind effects, whether in low or high degree, on botanical kinds of life and growth,—take the highest expression of plant glory, as it appears in a gigantic, wide-spreading, many-storied, leafy tree; in what sort of country as to wind-force do you find that? The old Roman poet had such a tree in his mind’s eye, when he wrote for the delecta- tion of the world through nearly two millenniums of years following, “ Tityre, tu patule recubans sub tegmine fag.” Some 15° to 18° of extra mean-temperature above the Scottish, may have aided in that particular result, but more in determining the kind, than the size and shape of the tree. For almost as fine examples in measure of what Nature can do for other species of trees, may be found in many a sheltered valley or home park in Perthshire or Inverness- shire ; simply because in those recesses the conditions as to wind force, approach those of the old Roman tree, grown as a later poet has declared, under “The tempest-proof, pavilion of the blue Italian sky.” And the demonstration thereof is not far to seek ; for within a few miles only of those more quiet neighbourhoods of the Scottish midlands, but down by the sea-coasts or up on the hill-tops the perpetually roaring gales of wind have caused a tree, of any species whatever, if seen at all, to become a mere ragged, lopsided, leaning-over bush; a mere scare-crow of vegetation, and a rarity which the native horses are said to shie at if met with by some road-side. 280 PROFESSOR C. PIAZZI SMYTH ON While if the geographical inquiry be pursued still further, to the smallest, the most exposed, and the most wind-vexed of the Shetland Isles,—trees are not only said to be non-existent there, in any size or shape; but the local botany, if here and there larger than mere grass or moss, assumes only a hummocky form, half-earth, half-compacted leaves, roots, and water; under which humps no man can hide his head from the possible Sun, or shelter it from the ever-present whistling wind and shrieking blast ; while a lost sea bird is wheeling in the dark grey sky above, and the white horses are prancing in driving mist over the deep blue waves below. So far too is this inhospitable vegetation from being a necessary consequence of the simple coldness of a high northern locality, that in the very same Latitude-parallel as those bald and frowning islets of ours, but away to the Hast in the midst of the immense con- tinent of Russia in Europe and Asia combined,—which has winters terribly more severe by the thermometer, but keeps the winds of her sea-coasts far, far away, as magnificent forests of trees in point of size (but usually with very small leaves), spread their branches on high, and rear their spiry heads, as in any of the warmer parts of the world. But then it is in an atmosphere where calms prevail for weeks, and almost months, at a time; and snow, once fallen, remains mechanically undisturbed for a large part of the season. In view, therefore, of this immense importance of the strength-of-the-wind element in the climate of our rather over wind-swept country, Tables XXIX. and XXX. have been constructed to call attention to the terrible significance, if true, of the few little figures often employed, almost at hazard, to express the mean force of the wind, by day and by night, and summer and winter, at many a station, of which better things might have been expected ; but where, of course, choice plants cannot grow upwards and flourish, if they have really something like 3000 day-pounds pressing them down to the earth on every square foot of their surface, from one year’s end to another. Finally, Taste XX XI. does little more than sum up and take the means of each of the preceding Tables of years, so as to present them for one point of time; as they were already presented for one point of space; and they being clearly titled will explain themselves without further letter-press, beyond a few words on the Humidity of the air. This curious but important technical name or quality, means little definitely, when by itself; but everything when taken in conjunction with the shade temperature and Barometric Pressure. These quantities are no doubt given in Tables III. and I.; but the derivation thence of what the ‘‘ Humidity ” return really means in absolute physics, is a rather intricate calculation; which every one is not always ready and willing to perform, even with the help of Mr JAmus GuaisHER’s very convenient “ Hygrometrical Tables.” 1 have therefore added here, and from thence in an approximate manner, to the Humidity and Temperature, the other forms in which Moisture of invisible water-gas may be chronicled; and trust they will be found useful in comparing these tables of Scottish Meteorology with those of other countries ; seeing that some Meteorologists concentrate their Humidity expressions in one, and others in another, of these separate terms. MEAN SCOTTISH METEOROLOGY. 281 6. Supra-Annual Cycles of Weather and Solar Phenomena. But before taking leave of the previous average Tables of many stations reduced to one central point of the country, with discussions of their most evident solar annual cycles from month to month throughout every year,—let us, as in duty bound, when so enor- mous a mass of reduced observations is before us, and spreading over a continuous range of 32 years,—lct us I say examine that series of results from year to year, and see if there are any symptoms of super-annual cycles of rise or fall in any of the Meteorological elements. And if there be such, whether they can be connected with any sufficient cause in Nature, to account for their production. If the Sun so decidedly rules the annual cycle, as we have already seen that it does, and is a mysteriously fiery, boiling orb,—he should be at least questioned as to any super-annual variations that may be found in our terrestrial Meteorology. And if such had been discovered only a few years ago, how ready many persons would have been then to hail them as simply dependent on the 11 year spot-cycle of the Sun’s luminous surface. But of late, rumours have gone forth from high quarters that in recent years the Sun-spots have failed, and that no one believes in them now ! Is it however the Sun-spots themselves that have failed, or certain human theories about them which have broken down ? Certainly if any persons have imagined that each 11 year cycle of spots is Just as like every other one, and should be accompanied by as closely similar weather on the earth, as if they were all the successive revolutions of a cast-iron wheel,—that is an egregious mistake ! Or again if the same persons have fancied that any influence from the Sun on terres- trial meteorology, was bound to produce a similar shaped curve of projection to that particular feature of the spots, viz. their united area and its growth with time—which many observers having hitherto found it the easiest task to measure, do therefore too often content themselves with, though the spots themselves are not the efficient cause of great changes in the Solar radiations,—-that is another and equally grave mistake ! In fact you might almost as well have micrometrically measured from day to day, and month to month through tne years 1884 and 5 the area of red-haze clouds spread over the sky, and neglected the previous Krakatoa eruption which took place in 1883, and really originated them all; although too that mountain’s crater is so small as to be in- visible on an ordinary geographical globe, and its actual action was all over in two or three days. But it started then instantaneously several sets of undulations, which went round and round the earth, sometimes running together to raise their maxima, and depress their minima, and sometimes again nearly neutralising each other, but on the whole decreasing continually from the Krakatoa date,-very much in the fashion of what was shown to characterise the super-annual cycles of earth temperature, in my discussion of the Edin- burgh Earth-Thermometers, before the Royal Society of Edinburgh in 1880. 282 PROFESSOR C. PIAZZI SMYTH ON Moreover it was then abundantly proved, that the chief manifestations of terrestrial temperature were by no means simultaneous with the greatest tabulated areas of Sun- spotted surface; but were on the contrary singularly coincident with something that rapidly took place in the Sun, during the first or second year only, or near the very beginning of each 11 year cycle of spot making and growing ; and that this peculiarity was borne out through a series of 5 of the cycles at least. Such manifestation too of extra temperature as then occurred on the earth, was not a long continued, broad and quiet existency,—- but more like the acute crest of a sudden wave, followed always, and preceded too, within a year or two, by abnormally low hollows ; or, so to speak, waves of cold. But all of them testifying to a violent variation of the Solar radiating energy, occurring at or near the beginning of each Sun-spot cycle, and being the one chief phenomenon of potency, to be recognised if possible, in each succes- sive 11 years, more or less, period. Now has that triple phenomenon failed of late years ? The unprecedentedly large number of the Scottish Meteorologic observations at present under discussion, eminently declare that it has not ! But how is such a point supposed to be proved ? In the present imperfect state of any Solar-physical theory, no dependence can be placed on any expectation of what future Sun-spot periods are to be. We can only trust actual observations of what they are, or have been. My first proceeding therefore on the present occasion was to obtain the observed number of new spots in each year, from 1856 to 1887. The first 22 years of that interval were supplied from the plate in the XXIXth Vol. of the Roy. Soc. Edin. Transactions, and the last ten years have been kindly furnished to me by Mr G. M. Wuippzs, from observations carried on, under his superintendence, at the Kew Observatory, in continuation of those of M. ScuwasgE, the first discoverer of any kind of periodicity in the Sun-spots. All these observations being duly projected for nnmbers and time, form three very distinct undulations. The third and last is indeed not yet completed, and will not be probably until 1890; but the limits of uncertainty in the shape of that part of the wave, are far too small to influence the whole result from 1856 to 1887——which is the full time- range of the Meteorological Observations they are to be compared against. At the top therefore of each of our 14 Plates I have repeated those three, or to be accurate 2.and ;%, Sun-spot waves ; and beneath them, for simultaneous times, have pro- jected the chief of this historic series of Scottish Meteorologic Observation Tables, as now presented to Royal Society, Edinburgh. And on looking through all these faithful Plates, in which do we find most, if any, approach to the Sun-spot cycle deduction just described; that is, in the testimony to a starting of a new set of undulations in the first or second year of each such cycle ; 7.e., in the years 1856-7, 1868 and 9, and 1880? MEAN SCOTTISH METEOROLOGY. 283 7. Temperature, Barometric Range, and Sun-Spots. Without any doubt the greatest similarity in that way will be found in the several temperature returns ; and after scanning the projections of each kind of temperature by itself, reference may be made to the composite Plate No. V. giving the mean curve derivable from the mean shade temperature, the maximum shade temperature, and the Black-bulb by day exposed thermometer. The characteristic outbreak being nearly as distinct in the beginning of the presently existing, not yet terminated Sun-spot cycle, as it was in either of the earlier cycles; or for the dates now confirmed by the tempera- ture observations, of 1856-7, 1868 and 1880. While of the last we may further point attention to the exceedingly cold waves both before and after the hot wave. But al/ the Terrestrial elements of Meteorology need not be exactly similarly and synchronously excited by Solar innate energy, when that is suddenly re-awakened at or just before each of the above three dates. And accordingly the next most remarkable depen- dence on a new Sun-spot beginning, but rather later than the temperature shock, say in the years 1860, 1870 and 1881, is found, first in the projection of Barometric pressure, and then and still more remarkably, in that of the Monthly range of that same kind of pressure. Now that is an important double result to have arrived at, because the Barometer is the most accurate and dependable instrument which Meteorologists possess. It is one too with which it is almost impossible to make a bad observation for this purpose ; one where no prejudice can exist at the time of making the observation; and where the numbers chronicled refer to something invisible to the eye, imperceptible to the feelings, and yet allowed already to be at the base and root of almost all Meteorology ; hardly ever too suspected to be in cosmical alliance with Sun-spot cycle beginnings, by the actual observers at the time. Yet look in these plates on the three Sun-spot cycle waves above, and the three groups of pressure range undulations below; both in the original simple Plate, I; and in the composite Plate II., where the absolute Barometric Pressure is combined with three times the value of the Monthly range thereof. And observe also how the third Sun-spot cycle, is borne out just as well as either of its predecessors, 2f we take account of its greater - yariation in shape from a standard Sun-spot cycle. 8. Details of Sun-Spot Cycles. Now I have already hinted that even a Standard Sun-spot cycle, though forming a very visible cyclical curve, is something much more complicated than the uniform revolu- tion of a solid wheel. Every Sun-spot cycle for instance yet chronicled, has the front of its undulation steeper than the rear ; testifying to the greater energy of the Solar radiations in that earlier part of the cycle; or when there is, mirabile dictu, more nearly a minimum, than a maximum, of visible spot area. And every cycle yet chronicled testifies also to the occurrence of another, though 284 PROFESSOR C. PIAZZI SMYTH ON smaller, outburst of energy in the course of the longer dying out of the principal wave ; sometimes single as in our first, and probably in the third, wave; sometimes double as in the second. But while the first of these three particular waves has nearly the normal steepness of front, viz. 4 years of rise to 7 years of fall, and a maximum height of 220 groups; the second of our three waves, rushes up in the short period of only 3 years, and then to the unparalleled height of 280 groups, but takes 8 years to decline therefrom. While the third wave is feeble and sluggish beyond example, employing 5 and a half years to rise slowly to its maximum, and that a poor one of only 160 groups. Taking all these features then of Solar variation itself into account, no one need be surprised at finding on the earth less Barometric monthly range in the days of the third Sun-spot cycle, than in the two earlier ones. Or, that im the times of the second Sun-spot cycle, the Maximum Barometric range on the earth shot up in the same excessive manner, and simultaneously with the Sun-spot curve’s then most exaggerated effort !!! 9. Aurora, Inghtning, and Sun-Spots. In fact the variations inter se of the three Sun-spot cycles which cover the duration of all the Scottish Society’s Meteorological Observations,—though entailing such alterations of weather-phenomena from one to the other, as to have caused some persons very need- lessly to lose their faith in any connection,—are a most fortunate feature to assist in the present investigation; and we have not to go much further in our research before alight- ing on another Meteorological curve which intensifies, while it synchronises with, the excess and acuteness of the energy-outburst displayed in the second Sun-spot curve; and equally confirms the deplorable defect of energy revealed in the third one. This singularly confirming curve is that of Aurora, its frequency and extent; or the number of times seen, and the number of stations reporting it each time. There can hardly be, it will be confessed on examining the Plates, anything more excessive and vivid in intensity than the Aurora returns during the second sun-spot cycle ; or more tame, flat, and miserable than during the third. While if the first spot cycle is not very conspicuously marked with Aurora, it is largely from the Aurora obser- vations not having been begun so early as the other items of Meteorology, and having therefore lost the critical epoch of the beginning of that cycle. Further, the ‘“ Strength of the Wind” curve, responds sensibly, though inversely to the Auroral curve. So that during years of abundant Aurora display, the winds were moderate in force, and chiefly from the West. But when Auroras left us in darkness, the winds became more violent and verged to East and North. But there is a more accentuated connection still, though by opposition, between Aurora and Lightning. The very maximum demonstration of all the Aurora being absolutely coincident in time, with the very minimum of Lightning, and wice versa; or that when Lightning is up, Aurora is down; yet they are both thought to be of an electrical nature. MEAN SCOTTISH METEOROLOGY. 285 Not content therefore with the separate curves of each, I have prepared in Plate XI. one projection showing a simple mean of Lightning with Aurora; and obtain thereby a very poor curve, deficient in the chief characteristics both in shape and time, of the Sun-spot curve hanging over it. But having also prepared on the same Plate another projection, showing the Lightning brought forward by two years, and then meaned with the Aurora, —all the intensities and dates of the Sun-spot curve are absolutely re-inforced. As may be further contemplated in Plate XII., where the Lightning, brought forward by two years is combined with three times its weight of Aurora; and the curve well shows that we have not been having of late any of those splendid displays which were so frequent in 1869, 1870, 1871 and 1872. Wherefore, if you ask why ;—the want of energy in the present Sun-spot cycle is the nearest phenomenon to the real cause, that can be quoted from erude observation. But enough has now probably been said of Mean Scottish Meteorology, its history so far as chronicled, and its probable cosmical relations. So that it is time to take up the too long delayed part of the local, the particular and the personal belonging to it. 10. Of an unfinished Paper on the indiidual characteristics of every Station employed. The said Part of, or Annexe to, the present large Paper of Means, was purposed to take up, one by one, each and every individual Station, which had at any time communi- cated two good years of observations to the Scottish Meteorologic Society ; and had been approved by that collective body to the extent of having been included in the “ Honours” list, of those presented monthly to the Registrar General of Births, Deaths, &c. in Scotland. Printed forms were accordingly prepared for each Month of the year, in two following years ; on which forms the divergences through all the chief Meteorological items, of any given Station, from the Mean of the whole country, in the same Month, and same year, were entered with their proper signs. The mean of two such annual discussions of months, forming the twelve single mensual lines of quantities proposed to be printed after each Station’s, Owner’s, and Observer’s, names, together with a general description of the locality in sociology, geology and geography. The work however turned out to be too extensive to be completed within the interval allowed for it, and the MSS. pages, so far as they were carried, are left in the official keeping of the Royal Observatory, Edinburgh. CoP. 8. VOl, XXXV. PART. 3. 35 EIGHT YEARS OBSERVATIONS OF THE NGW HARTH THERMOMETERS AT THE ROYAL OBSERVATORY, EDINBURGH, 1879-1888. By C. PIAZZI SMYTH, F.R.S.E. LATE ASTRONOMER-ROYAL FOR SCOTLAND. CONTENTS. PAGE Historical explanation of the Instruments concerned, : ‘ 3 5 : : : i : 289 Maker’s and Observer’s names, 5 ; , : : : A ; : : : 290 The new Thermometers compared with the ai ; , : 5 ; , ; : P : 291 Rise of temperature with depth in the ground, : ; : : : : ; : ; : 291 Of the four numerical Tables of Observation, : 292 The one Plate exhibiting their final results in direct conbest with San! pet Creve rece fon Kee, 292 Abnormal Solar-derived temperature-wave in June and July 1881, _ . ; ; ‘ : : : 293 M. Gaston Planté’s opinion thereon, : : F ‘ ; : ‘ : ‘ : : : 294 Table 1. Constants for the new Thermometers, é : : 2 5 : ; : 295 Table 2. Original Observations therewith, 1879-1888, d : ; : : ‘ 296 to 303 Table 3. Monthly, Quarterly and Annual taken Quarterly Means, . : : . 304 to 305 Table 4. Parallel Air-observations of Scottish Meteorological Society, : p : ; . 306 SUPPLEMENTARY PAPER, on Three years, out of the Hight, of Edinburgh Earth Thermometers, specially compared with Kew observed “ New groups of Sun Spots” through 1880, 1881 and 1882. Table 1. Annual Means and Sums collected Quarterly, . : i : : ; : : ; 306 Table 2. Annual Means and Sums, collected Monthly, . ? : : ; : ; : : 307 Table 3. Annual Sums and Means, collected Weekly, : : ; ; : : . 308 to 311 Plate 1, of the whole “ Eight years ” paper. Plate 2, or 1 of the Supplement, to the above. Plate 3, or 2 of the Supplement, to the above. Plate 4, or 3 of the Supplement, to the above. eee EIGHT YEARS’ OBSERVATIONS OF THE NEW EARTH THERMOMETERS AT THE ROYAL OBSERVATORY, EDINBURGH, 1879-1888. Of these gigantic thermometers, with their bottle-sized bulbs, their long capillary intermediate tubes, and their upper enlarged bores for scale-reading purposes, an account of their construction and being placed in position for observation on June 26, 1879, is to be found in Part II. Vol. XXIX. of the Transactions of the Royal Society, Edinburgh, for 1879-80, and it is only proposed in the present place to give an account of their performances since that time. But on examining them in May 1888 for that purpose, a melancholy and complicated stumble on the threshold was realised. Mr Ricrarp Api, the head of the optical firm which had supplied the instruments, and the last of that gifted family,—was dead. Mr THomas WEDDERBURN, the enthusiastic young optician who had succeeded him in the office, and had indeed really performed all the work both of manufacture and emplacement, was likewise dead. And an unexpected calamity had befallen the thermometers themselves. This was that five or six years after their establishment, a slow sinking of the shorter thermometers into the soft ground filling the bore-hole in the rock, began to be recognised. JI had apprised Mr WrppDERBURN of this circumstance in the beginning of 1886; and he at once declared his belief that he would be able to pull them up again to their proper heights, and fix them there, when the weather should allow him, in his then already broken state of health, to revisit the top of the Calton Hill. But that favourable occasion never came, and death overtook him somewhat suddenly on August 9, 1886, greatly lamented and much missed in the scientific circle of Edinburgh men, as a native genius who had never enjoyed full opportunity of showing all that he could do for the promotion of the science of his time ; though he had been found equal to every occasion that had actually come before him. Since then the downward march of the thermometers has been getting more rapid, and disturbed sideways as well; so that the two shortest of the four scientific thermo- meters, or t? and ¢*, have the upper parts of their scales thrown together, much sunk, and partly jostling the scale of ?’, which is also slightly sunk; leaving only ¢ the deepest, and fortunately the most important of all the thermometers, untouched, and uninjured in its originally intended position. Meanwhile however the regularity and assiduity of the Assistant Astronomers in taking the observations of each and every one of the thermometers every Monday, was 290 PROFESSOR C. PIAZZI SMYTH ON beyond all praise; particularly in their initiating an arrangement for taking them in duplicate, and discussing the results to a hundredth of a degree Fahrenheit, before leaving the Thermometers on each occasion. The names of the said Assistants being, in 1879 and 1880, First Assistant, ALEXANDER WALLACE, M.A. Second Assistant, 'THomas Hratu, B.A. 1881 to 1887, First Assistant, Thomas Hata, B.A. Second Assistant, Henry W. Ripe. 1887 to 1888, First Assistant, THomas Heatu, B.A. Acting Second Assistant, JAMES Forean. By a preliminary computation of the more salient observations, and an examination of the instruments themselves in their present condition, I have made out a Table of “Thermometer Constants”; and although it will not enable these new Thermometers to compete with the old ones as they were in Prof. ForBxs’ time from 1837 to 1845, as instruments of the most delicate Natural Philosophy chamber problems, I have been much pleased to find that step by step they have shown their full sufficiency, to keep up the differential historical record of super-annual cycles of temperature, which was in fact almost the only employment of the old Thermometers from 1845 to 1876, when they were destroyed by a human accident from without. The new earth-thermometers were constructed by Messrs Ap1E in 1878, in a closely parallel manner to the printed descriptions of the older thermometers in 1836, and brought to the Astronomer’s house in the spring of 1878, where they all had their bulbs put into one and the same tub of salt water, together with a standard thermometer, and the several scales as approximately graduated by Mr WrppERBURN, were read off by myself at different heights up the stairs of the house. A mean of ten sets of read- ings gave for Passa, P=48°31, P=A846 andi t= 48-39: This was so far a testimony, that when the bulbs were all on the same level, and in the same place, they read, with approximation, identically. The stair-case of the house, however, being too warm to enable the ultimate earth temperatures to be experienced there, Mr WerpprrzBurN afterwards erected them outside the house, and perfected the scales there by long and laborious steps of which I have no notes, and can only judge of by subsequent comparative readings. Thus the old thermometers were remarkable for every deeper one giving a higher temperature; and so, on taking the means of the new ones for several years, after they had been sunk into the ground their intended depths— new @ was found = 46°29; #=45°'93, = 45°83; and ¢t*=45°°77, or each thermometer greater than the shallowest by f=0 52, F=0° 16, 7=0 (06, and F=0, EIGHT YEARS OF THE NEW EARTH-THERMOMETERS. 291 —_ Now the old thermometers had greater increases; thus, taking the period 1856-—60— when #'= + 0°89, #?= +0°°60, 2= +0°'26, and ##=0. Their depths were indeed rather greater than those of the new Thermometers; but even if we reduce these results by simple proportion to the lesser depth of the new Thermometers, the above increases only become— forleld: | —0-474. F=@ 50,6 —0 <5, and t =0. Hence this is the first decided difference of results between the old and the new Thermometers; or the new ones have less increase of readings for the same increase of depth; and as it was never shown why the old ones had so much rise of temperature, the result is so far rather satisfactory for the strength, and capacity to resist pressure on the bulbs, of the new ones. But there is a greater apparent difference in the absolute temperatures indicated for the earth-crust on the Calton Hill by the two sets of instruments. For the new Earth Thermometers give for the mean of the annual means from 1880 to 1887, mewat—=46 29.7 —=45 93.¢—45 63, and ’=—45 77; while the old earth Thermometers in the last 5 years, 1856-60, of their complete existence ( having been broken by the frost in the severe winter of 1860-1) gave, when reduced to the slightly lesser depths of the new earth-Thermometers, P=A7 -28, 2=47°-:04, C=46°°69, and #=46°°54. But when further reduced to the colder temperature of the earth-surface at the epoch of 1880-7, that is by 0°°76—as given by the smaller publication of the Meteorological Society of Scotland, per the Registrar General of Births, Deaths, &c., in Scotland—for the “‘ Towns” stations only, by the successive annual means of mean shaded air tempera- ture, taken out for each component year, of the two groups of years concerned; the derived, or old é becomes = 46°°52, #=46°'28, = 45°'93, and t*=45°'78, in place of, as the new GAG 2950 — 45°93, 6 =—45 83, andt=45 77, or the differences are reduced to L—0.235, (—0)-35, 70 10,and 4=0701, where the old and the new earth-thermometers agree to 0°01 at the surface of the ground, but disagree to nearly 0°°30 at the lower thermometers; in the direction however of indicating an abnormal excess of apparent temperature, but perhaps of real bulbs bending in, for the older instruments. A result very probably to be considered creditable tothe late deceased optician, THomas WEDDERBURN; but raising some special questions in the future as to the increased means required of testing the index errors of even the deepest Thermometers from time to time in some absolute instrumental manner, in spite of their being buried more than 20 feet deep. 292 PROFESSOR C. PIAZZI SMYTH ON But for the present we may now go forward to consider the observations actually made in reference to the march of cosmical super-annual variations; and need not be delayed by any difficulty in obtaining new values of the minute corrections applied to the former set of instruments; for they seldom amounted to more than from 3}5 to 35 of the super-annual effects of the natural changes from without the earth, which it is now our proper business in an astronomical Observatory to inquire into. Without further detail therefore I introduce three varieties of numerical tables. Table I. Constants of the new Earth Thermometers, 1879-87. Table II. Original observations of the new Earth Thermometers, and two smaller auxiliary thermometers, weekly for the years 1879 to 1888. Table III. Monthly, Quarterly, and Annual Means taken quarterly, of the new Harth Thermometers from 1879-1888; the last column having annual, or seasonal, 7.e. summer and winter effects entirely eliminated. Table IV. Parallel observations of Scottish Meteorological Society in Shaded Air- temperature, and Rain-fall depth, each expressed in single annual means. Also one Plate, representing all the observations, together with the Sun-spot-numbers, as kindly furnished by Mr Wuiprprz, Director of the Kew Observatory, for the times concerned. Now on contemplating said Plate and its several contents, we can hardly but be struck with the remarkable testimony which each of the four earth-thermometer curves bears to the others, both in their resemblances and graduated differences ; the effect of any change of temperature always decreasing with depth, but increasing in retardation therewith ; testifying therefore to its production by waves of super-annual heat from outside the earth striking on the surface and being slowly transmitted into its substance. Also that such waves are of a very intense and powerful character, though short-lived, seldom lasting more than two years; and indicate radiations from the Sun, observing similar periods. These conclusions are borne out abundantly by the four earth thermometers, when their annual means are taken every quarter; but not very satisfactorily by single annual means, as with the Scottish Air temperature, the Scottish rain-fall, and the Sun-spots themselves. Wherefore I would beg to call attention among those Observatories which are concerned therein, to the importance of their present single annual means of various data, being replaced by quadruple annual means; or, better still, hy duodecimal annual means—whenever the search for super-annual cycles includes those of sub-annual char- acter as well. But can that necessity be distinctly shown in this case ? I am happy to say that it can be; and has just transpired in a new and very unexpected manner. Look for instance along each earth-thermometer curve, and note the length of line from quarter to quarter of a year, when the external temperature is increasing; and see EIGHT YEARS OF THE NEW EARTH THERMOMETERS. 293 how the extra length of that line from midsummer to autumn quarter in the one year 1881, is something perfectly phenomenal ; and at the same time is a fact as significant, as it is irrefragable for the physics of both Earth and Sun. With the lowest thermometer (as is proper with heat from outside the earth) the effect occurs later; viz. at the end of 1881 and beginning of 1882. But with the next less lowest, the chief effect is between autumn and winter of 1881. With the next still less low one, the effect is earlier, or between midsummer and autumn or a very little beyond. And with the shallowest of all the earth-thermometers, the effect, besides being tremendous in quantity—begins at midsummer sharp, and ends entirely by autumn leading one to infer that for air above the earth, the effect may have begun a few days even before June 30. Wherefore let us ask, did anything notably visible take place either in the Earth’s atmosphere or the Sun’s photosphere at or about June 25, 1881, capable of affecting the earth’s temperature to some very sensible degree 4 Now there was something of that kind, whether noticed yet in this category or not by other observers, I am not aware ; but it was recorded by myself in such an entirely independent manner at the time, without the slightest reference to Edinburgh Earth- Thermometers, that I was surprised indeed on completing their diagrams last night to have the 1881 date so pointedly and reiteratingly presented to me again, and shown to be something that had made its mark in nature. I was in the Island of Madeira at the time, spectroscoping the Sun, mapping the Sun-spots each day, and meteorologising. On June 21, 22, and 23, the Sun-spots were feeble exceedingly, and apparently bent on closing up. But on the 24th it is chronicled in my observing book that “two new outbreaks of Solar activity, appear in the Sun’s North Tropic, one East and one West.” On the 25th, the note is ‘The importance of the new centre of Solar activity on the North-East Limb is maintained. There are now three spots there and large facule.” On the 26th there were no spot observations. But on the 27th, the note runs thus,— “Sun-spots at 7" a.m. Solar definition horrible! caused probably by extra Solar heat. But the magnificent display of renewed Solar energy in the new Spots, especially those in the South Tropic, cannot be hid; and it may have a bearing on the wonderful Cloud, which so greatly astonished and alarmed the inhabitants here all yesterday after- noon and evening.” Now what was that cloud of June 26, with so unusual an aspect, that the inhabitants of Madeira were in consternation about it ? In the little book entitled Madeira Meteorologic (the expense of printing which was so kindly volunteered for and borne,—as I am now, alas! free to declare,—by that kindly and generous minded gentleman and F.R.S.Ed., the late Ropert Mackay Smrru), the whole of its “ Part iv.” or pp. 33 to 50, with two woodcuts and the very artistically en- VOL. XXXV. PART 3. 30 294 PROFESSOR C. PIAZZI SMYTH ON graved steel-plate frontispiece, are devoted to the said cloud, its appearance and meaning. This being presently deduced to be, an excessively intense example of the “ Leste”; or a hot wind which occasionally blows upon the higher hill tops in Madeira, straight out from the Saharan Desert of Africa. But that is a sort of furnace of reflection for Solar heat, and wherein the Palermitan Astronomers, observing the. out-bursting of hydrogen red prominences in the Sun, had already learned in 1872, to trace a connection between them, and the out-rushes of hot Sirocco wind and dust clouds from the same African desert. But in the little book above mentioned, I also attempted to trace the symptoms and opportunities of the cloud of June 26, being one of those remarkable cases which M. Gaston Pants (the distinguished inventor of secondary batteries, which, under the new name of accumulators, are now rendering the use of electricity in domestic electric lighting almost as easy and manageable as coal-gas from any Gas Company’s large gasometers), —M. Gaston Piants& I repeat, has endeavoured to demonstrate, respecting exchange of internal, and as it were innate electricity between the earth and the Sun. Having communicated therefore to that gentleman, the resurgence of the important date of June 26, and several following weeks in 1881, as a period of exaltation of heat external to the earth striking upon it, according to the testimony of the Edinburgh Earth Thermometers,—I was honoured by receiving the following letter from him :— Paris, 12 Rue des Vosges, 21 Mai 1888. (Translated). Fp ere I have read with a lively interest that which you have written to me of the elevation of the temperature of our globe on the 26th of June 1881. I recall to myself still the excessive heat, altogether ex- ceptional which we had in Paris, at that epoch. I find, on consulting my notes of that year, 1881, that the weather was very hot, and very heavy (lourd) and by consequence very electric, from the 25th to the 28th of June. Then on the 3rd, 4th, and especially the 5th of July, also on the 13, 14, 15, 16, 17, 18, and 19 July. The 19th of July in particular, when there occurred, according to the papers of that date, 38° Cent. in Paris; a temperature which I believe was never known to have been experienced before. It is then probable, that there was at that epoch, as you have thought, a sort of irruption of a flux of electricity on our globe; or a freeing (dégagement) of electricity in abundance, coming forth (émanant) from the globe itself under the influence of the Solar Electricity. ...... (Signed) Gaston PLantE. After this, the least that I could do, in utilising the original observations further, seemed to be, to recompute for the three most important thermometers all their simple readings concerned in the above phenomenal summer and autumn; or for the three whole years 1880, 81 and 82. Representing for that period of time, their annual means (our only method at present of eliminating the seasons or ordinary summer and winter divergences)—in three different modes, viz., by collecting strictly annual means first for every Quarter, then every Month, and finally every Week,—though the latter is probably a needless refinement. The numbers however arrived at in each case, have been given without reserve, in the Supplement of 8 pages appended to this paper; as well as exhibited in three Plates, appropriately drawn for their reproduction by Photo-lithography. And while they con- EIGHT YEARS OF THE NEW EARTH THERMOMETERS. 295 tain all the data which the Harth Thermometers can give on this interesting question, and which may be worked out in the future with fuller success by other scientists,—I should not scruple to confess, that to my limited view the testimony of the Earth- Thermometer curves is totally at variance with the ‘“‘ New Sun-Spot” curves,—unless the latter, mere telescopic phenomena of visibility, be allowed to precede their heating effects on the earth—whether by slowly producing first an intenser condition of Solar radiation, or otherwise,—by about the space of 9 months! This may seem at first a very extravagant idea, but is evidently of the same order of time effects, as the oftener proved case of Lightning and Aurora, described under head 9 and pages 284 and 285 of my longer paper on Mean Scottish Meteorology in the R.S. Ed. Transactions. While here, it must be confessed that the three thermometers hang con- spicuously together in testifying, that a remarkable change from a downward to an upward period of Harth temperature did begin about June 25 or 26, and lasted nearly a year. CPPS: Taste I.—PRACTICAL CONSTANTS FOR THE NEW EARTH THERMOMETERS ERECTED AT ROYAL OBSERVATORY, EDINBURGH, IN JUNE 1879, AND EXAMINED IN APRIL 1888, ee Surface of | Therms, j ‘ Max, Occasional ezine Soft Filling] in 1888 Present cet ‘ Readings actually taken. Dates of Reaching. N. Phil. | Differences Names| _°? cee up Ground} Found Biigtaeh felon eee Corrects.,| of the New. Centre of 5 Centre of). Readings of ¢ : of Buh from Found in | Sunk Be- Bulbs B in 5 fi ever by Reason ; s Be- Uniform Wide Mean of 2 Therm, Stirtace of 1888 Below} low their low Rock Inches, B Hotacen! al “ACM 1|/ AM Ma Mi Applied | of Super- ie Rock sur- | Former Suviae hearly. OTE CeCe! Rl iae are Ans ay ™. Ito the Old) annual face. Positions, e years: Therms, Cycles. — | — |r ee ae | 5 Inches, | Inches. | Inches. | Inches. |Inches.| ° ¥ 2 3 e . . inal 250 27 9 250 2:0 | 50°2 and 42°5 | 47-10 46°29 45°20 |Dec. 2|June 13; 0:03 065+ t2 125 for all aD 127°5 I 525). 40:9) 49-00 45°93 43:00 |Sep. 30 /April 9} 0:06 105+ t3 50 these 70 570 09 | 585 ... 39°0 | 52°50 45°83 39°80 |Aug. 21 |Feb. 13} 0:12 1°65+ at earth 4 25 |Therms.| 9°5 345 | 06 | 59°5 ... 37:0 | 55°00 | 45°77 | 37°50 |Aug. 5/Feb. 8| 0°25 | 2-084 at earth ~5 | 1 below 0 l below] 0°3 | 80:0 ... 20°0 60°0 45°2 31:0 |July 20? |Jan. 27? 0 27) Air | 6 above 0 |Gabove| Ol |115°:0 ... 0:0] 66:0 46°8 28°0 |July 10? |Jan. 17?) 0 2°6 296 PROFESSOR C. PIAZZI SMYTH ON Taste II.—ORIGINAL OBSERVATIONS OF THE NEW EARTH THERMOMETERS, AND CERTAIN AUXILIARY THERMOMETERS AT ROYAL OBSERVATORY, EDINBURGH, 1879-1888. ¢ 1. t 2. t3. t5. Air, Surface Observers. Remarks, Each Monthly | Each | Monthly} Each | Monthly} Each | Monthly | Therm. Each Reading.| Means, | Reading,| Means, | Reading.| Means, | Reading.| Means, Each Reading. Reading, 46°55 48°19 49°02 48°80 471 50:7 |A.W.andT.H.] Thermo- 46-66 ; 48-12 ; 48-72 , 48-08 465 | 49-0 , | meters 46°73 | 49°69 | 4g-o4 | 484 | 47-49 | 489° | ge-o2 | 4725 | 495 | 449 | 2 ”° | inserted 46°80 47°82 47°17 45°70 413 | 430 | 3 » [June 26 1879. 46-90 47-65 46-21 43 69 409 | 44:21 ,, » | The air 46-94 47°42 45°61 44-85 420 | 415 | ,, | tempera- 47-01 | 46°96 | 47-99 | 47°29 | 44-65 | 45°26 | 42-08 | 4326 | 44-7 | 50-2 | 2? ” I ture en- 47-01 46-90 44°59 42-44 383 | 39-4 | ;. ;, | tered here, is never 47-01 46°62 43-09 39°30 322 | 299 | ,, » |the mean 47-02 46°31 41-25 37:08 Bich. |) gorda s . | daily tem- 47°04 | 46°98 | 45°85 | 45°81 | 40°28 | qr‘20 | 88°17 | 38°51 41°7 46:2 50 >, | perature, 46:97 45°38 40-60 37:99 36-9 | 395 | 7 [but the 46°88 44-90 40°79 39°99 39°6 | 401 | 3, , | unduly elevated tempera- 46°88 44°82 41:48 aoe 42-7 47-1 5 », | ture near 46°78 44-62 41-90 40-0 32-7 | 309 | , *? | noon, the 46-68 | 49°73 | 44-51 | 44°5° | 40-54 | 49°87 | 37-68 | 3875 | 301 | 30:2 | 2 ” | hour when 46°59 44-28 39°55 36°42 20:00 1 827) Il. ;, | the obser- vations 46°51 43°98 39-67 39°70 45-2 MB. ». [were al- 46°43 43-69 40:82 40: 5:0 | 34-4 ? | ways 46°36 | 4°39 | 43-58 | 43°69 | 40-54 | 49°52 | 39-52 | 49% | 30-5 | 41-3 | 2 ” | taken. 46°24 43°50 41-05 40:90 395 | 403 | 7 i 46°14 43-43 41:30 41°32 41-4 | 39:2 | ,, i 46-07 43-42 41-43 41-72 400 | 43-4 | 2 i. 45°97 | 45°97 | 43°40 | 43°42 | 41°69 | 41°37 | 41°40 | 4o'90 40°2 43°1 5 sy 45°88 43-45 41-43 40°25 372 | 332 | ;, is 45°81 43-42 41-01 39:80 412 | 461 | ,, : 45°74 43°35 41-69 41°70 413 | 451 | ,, * 45°67 43°34 ; 42-14 | 40-7 | 42-8 | ° : 4558 | 45°52 | 43.35 | 43°37 | 42-33 | 47°3° | 49-78 | 42°°7 | 46-6 | 40-9 | 7” Ke 45°47 43-44 43-23 43:79 415 | 445 | 7 “ 45-48 43-61 43-59 44°67 437 | 419 | . 45°42 43°76 44-29 45-09 467 | 48-7 | 2 4 45-44 | 4542 | 43°99 | 44'oo | 44°71 | 45°03 | 45°41 | 46°23 45°3 50°1 y 6 45°43 44°19 46-06 48-19 47-7 | 493 | 7 x 45°35 44°46 46-50 47°79 48-4 | 50-7 | |, 5 45°35 44-76 47-12 48-52 48-0 515 | ,, , 45°37 . 45-08 47-48 . 49-68 , 51: 543 | ss 45-43 | 45°42 | 45-37 | 45°23 | 48-60 | 48°28 | 50-90 | 593° | 526 | 54:0 | > i 45°49 45°72 49-51 52°12 579 | 633 | | és 45°53 46-11 50-40 62°73 53:8 | 59:2 | ,, - 45°62 : 46°59 50°71 : 52:8 | 56:8 T. H 19] 45-69 | 455 | 46-91 | 4972 | 50-97 | 5°89 | 59-96 | 53°°5 | 55-0 | 59:5 > 26| 45-78 47-25 51°49 53°77 560 | 57°8 ‘ Aug. 2| 45°82 47°54 51°60 52:82 556 | 581 A.W. 9} 45-94 47°83 51°82 53°81 54-7 | 60:0 o 16| 46:14 | 46:08 | 4812 | 4813 | 52°78 | 52-48 | 55°57 | sq6o | 56-5 | 56-9 c. B.S. The fill- 23) 46-16 48-38 52-95 55°06 57-0 | 58-0 A.W. fing up 30] 46-32 48°76 53-23 55°75 60:2 | 65:8 : earth in the bore- Sept. 6 46-43 48-97 53-68 56 30 667 60-1 |A.W.andT.H.] hole, is 3] 46°5 ; 49°24 : f ; 3 ‘4 546 ; creatly 20} 46:66 | 4°62 | 49-47 | 49°32 | 59-52 | 52°83 | 51-89 | 5379 | 46-5 | 5071 | ” ” | contracted 27| 46°84 49°61 51°67 52°34 533 | 566 | | ” Tor lower- ed, Oct. 4] 46-94 49°53 51°53 50 62 43-2 | 43-2 | x 11] 47-09 49°52 49-9 42-8 | 493 | ” i 18| 47-21 | 4724 | 49-36 | 49°38 | 49-09 | 49°48 | 48-07 | 47° | 47-8 | 52-9 | ” a 25| 47°33 49°12 47°37 43°89 423 | 47:0 | |) EIGHT YEARS OF THE NEW EARTH THERMOMETERS. 297 TasieE II. continued —ORIGINAL OBSERVATIONS OF THE NEW EARTH THERMOMETERS, AND CERTAIN AUXILIARY THERMOMETERS AT ROYAL OBSERVATORY, EDINBURGH, 1879-1888. #1. €2: 3. @ 4. t5. Air, Surface Observers, Remarks, Each | Monthly} Each | Monthly} Each | Monthly} Each | Monthly | Therm. Each Reading.| Means, | Reading.| Means, | Reading.| Means, | Reading.| Means, Each Reading. Reading. 47°37 48°75 45°82 43:10 87:1 35:9 | A. W.and T. H. 47:46 4832 45°30 43°81 38°8 36°6 3 e 47°48 | 47°47 | 47°86 | 4792 | 45°30 | 44:65 | 44:22 | gors7 | 33:7 30°5 a fe 47-48 47°50 43-74 39°80 31°6 29°38 | ,, ‘. 47°55 47°18 43-08 41:90 43°8 45°3 o és 47°56 46-79 43-64 43:02 48:8 53:2 |, ss 47°50 . 46°52 Ee 44:38 ; 4352 : 40°6 41:0 ss - 47-42, | 4745 | 46:33 | 4°43 | 42:88 | 4372 | 39.93 | 424 | 34-7 Sul? || a 47°33 46-09 41°57 38°38 32:8 32:9 | ,, 47°35 45°74 40:78 38:99 40:2 42:5 T. H. 47-23 45°30 40°78 37°75 313 26:8 bs 47°14 | 47°15 | 44:97 | 44°96 | 39°60 | 39:43 | 35°70 | 36°25 24°9 20°0 - 47-05 44°59 38-40 34:50 28:0 27°8 i 46:97 44-18 37°60 34°30 31:8 38:0 ~ 46:84 43:68 38:00 36:20 32:1 32:8 be 46°72 Be 43-28 5 38-10 oF 35°80 | A¢. 33:4 34:9 f 46°59 | 4°94 | 42:98 | 4377 | 38-20 | 3°7° | 36:75 | 3°22 | 33:0 33:0 ie 46°43 42°74 38°10 36°15 31:8 28-2 |T.H.and H.R. 46°30 Ae. 38-60 35°10 31:7 34:8 T. H. 46°17 } 42,35 ; 38:60 : 39:10 : 41°6 46:8 |'T.H.and H.R. 46-00 | 469 | 49-15 | 42°3° | 40-00 | 39°28 | 4o-69 | 3822 | 34-0 | 315 | ,, * 45:88 42°19 39°50 37:97 365 415 | ,, oe 45°74 ee 39°10 37°50 ae 372 | ,, rs 45:64 , 4216 : 39-20 . 38°75 ’ 8:3 42-9 | ,, é 45-53 | 45°59 | 49-10 | 42°27 | 40-28 | 39°82 | 40-75 | 395° | 39-2 | 39-8 | ” ee 45°44 4218 40°70 41-01 44:2 48:0 | ,, a 45°32 4229 41-88 43°21 40°8 399 | ,, , 45:25 42°48 49-58 44°10 47:0 51:0 T. H. 45°18 | 45"19 | 42°71 | 42°78 | 43°92 | 43°66 | 45°88 | 45-54 | 43:9 45-2 |T.H. and H.R. 45°13 43:05 44-39 46:20 515 569 | = 45:09 43°39 45°58 48°30 545 64:9 | ,, i 45:05 43°79 47°70 50:99 ae a : ae i. Z 45-05 3 44:29 ; 47°37 d 48:70 ; 49° 49-4 |'T.H. and H.R. 45:07 | 45°06 | 44-74 | 44°48 | 47-98 | 47°99 | 50-20 | 5°25 | 539 | 58-8 | ,, is 45:09 45:10 48:90 51°10 52°5 54:3 | ,, s ee 45°49 49°30 51°66 56°7 60:1 x A 452 ; 45:90 : 4989 ; 52°10 : 576 640 | , 45:29 | 45°26 | 46-95 | 497 | 50-97 | 50°32 | 53-62 | 52°57 | 56:5 | 60-0 | ?? cA 45:37 46°63 51-12 52°90 53°6 559 | ,, Re . 45°47 47:01 50°85 5218 | 50°8 54-7 T. H. 45:58 47-29 51:10 53°40 56°7 59-0 a 45°69 | 45°70 | 47°52 | 47°50 | 5118 | so87 | 52°33 | 5x87 | 52°5 55:0 an 45:80 47°74 50°80 51°19 50°6 51:3 sf . 45-94 4792 50°40 50:26 47°9 50°8 |T.H.and H.R. 46-05 48-01 49-81 49:98 49°7 ae H. R. 4618 ; 48:05 , 50-00 4 50:54 ; 50°7 1: : 46-29 | 49°23 | 4-09 | 48°08 | 49-99 | 49°95 | 50-44 | 50°36 | 49-8 | 50-7 i 46:41 4816 50-00 50:46 50'8 54-2 ss 46°51 4822 50-00 50:54 48-9 52°3 IT. H.and H.R. 46°59 48-25 49-45 48:83 46°6 51:0 | ,, ss 46°68 46°67 48°23 48°12 48°18 48°14 45-40 46°76 40°4 45'1 oS As 46°75 48:08 47-00 4549 43:3 449 | ., * 46°81 47-84 | 46°09 43:53 36°7 38:0 | ,, x an 47°59 45-00 43:80 - e ae 6 55 ‘97 ’ 47:30 . 45:90 3 46:39 , : ; 35 46-98 | 45°96 | 47-09 | 47°24 | 46-18 | 45°°7 | 45-63 | 4493 | 461 | 479 | 2? # 46-98 46:99 45°60 43:90 41:9 44-5 | ,, 3 298 PROFESSOR C. PIAZZI SMYTH ON Taste IT. continued.—ORIGINAL OBSERVATIONS OF THE NEW EARTH THERMOMETERS, AND CERTAIN AUXILIARY THERMOMETERS AT ROYAL OBSERVATORY, EDINBURGH, 1879-1888. | Month Year, and Day. 1881 | Dee. 5 12 19 26 | | 1882 | Jan. 2 ea e 2. t3. Each | Monthly} Each | Monthly} Each Monthly Reading.| Means. }| Reading.| Means. | Reading.| Means, 46°98 46°84 44-98 46:97 46°64 f 44:09 46:93 | 46°96 | 4639 | 46°49 | 4-63 | 43°36 46°94 46°08 41°70 46°89 45°68 42°41 46°85 45°40 42°21 46°82 | 46°79 | 45°19 ‘25 | 42°30 2" 46°74 4503 | © OS Be eas 46°65 44-93 42°89 46°59 44°86 42°19 46°53 : 44°74 42°35 : 46-45 | 49°48 | 44-60 | 44°68 | 42.39 | 42°42 46°37 44:5] 42°79 eee ike 42°39 46:2 4 44°40 - 42°66 é 46-19 | 49°22 | 44-35 | 44°39 | 43.06 | 42°83 46°13 44°37 43°00 46:06 44:37 43°10 46°01 44°36 - 43°1 ° 45-9 | 45°99 | 44-7 | 44°36 | 45-08 | 43°39 45-93 44°35 43°51 45°88 4°37 43°69 ieee 44°42 44:06 45°82 | 45°83 | 44:50 "36 | 44:59 45:80 g 44°64 t 45°68 oo) 45°79 44°85 46°83 as at 48°28 7 . 4 Pi 45-73 | 45°78 | 4p-o3 | 45°72 | gag | 48°66 45°81 46°21 49°11 45°86 46°49 50°21 45°91 46°82 50:98 45°98 | 45°99 | 47°21 | 47°18 | 51°30 | sx‘r0 46°05 47°55 51°47 46°14 47°85 51°56 fe ae 48°10 51:90 “BE 48- 7 D« 46-44 | 45°40 | aggg | 48:50 | Page | Se'sz 46°55 48°91 52°40 46°66 49°10 51°95 46°78 49°20 Ir 46-00 | 45°84 | 4o95 | 492 | Big | st°40 47°03 49°28 50°71 47°14 49°24 50°49 le 49°18 50°40 : 47°30 | 49°12 | 4o°xr | 50°20 | 49°73 47°39 49°08 49-40 47°44 48°95 48°14 wee ce 47°35 . 4 "46 . 479 | 47°57 | 4805 | 4824 | 4a43 | 45°47 47°60 47°68 44:06 rie 47:27 43°00 “f . “9, ar-ss | 47°58 | aoa | 4° | 4ogg | 4°75 47°53 45°90 41°10 t4. Each Reading. 43°59 40°98 39°71 39°45 41°10 40°35 42°25 42°10 Monthly 41°43 41°36 41°17 4219 41°51 43°10 41°40 42°41 43°78 42°10 42°47 42°89 41°60 44°10 43°50 44°30 45°56 47°38 49°15 50°80 49-90 49°35 50°93 53°29 52°77 53°36 52°89 53°50 53°96 55°43 54°69 53°11 52°72 52°46 51:20 50°80 50°52 50°50 50°08 48-29 45°95 45°79 43°00 41°10 41°50 40°10 38°50 37°50 38°85 41°97 42°42 42°76 45°98 50°24 53°16 54°30 51°80 49°07 42°85 38°74. t5. Air, Surface Therm, Each Each | Reading. Reading, 41°5 42°7 37°3 38°3 34°8 35'2 44:1 47-0 40-1 42:2 37°3 39°9 43°9 45-2 42°8 45:9 36:1 35°8 39°8 41°6 45:0 47°7 41°5 45 +2 392 38:2 37°8 38:0 439 47:0 439 44°6 41°8 471 40°3 40:0 39°6 40°1 41°8 477 43°8 44:9 42-1 45°1 41°9 42°1 44°] 44:5 48°7 52°0 52°9 58°1 52°3 55:0 46°71 47°3 50°1 §2°9 52°9 58:0 57:0 59*1 54°3 56:4 55:5 58:9 52°2 55:8 54:1 56°8 55:3 58:4 59°1 63:0 541 55:8 53°4 55°4 51°8 52°9 49°9 BIL 47°7 48°3 518 55:9 516 54:7 50°2 52:0 46°4 461 44:2 46°8 41:5 42:0 41°6 43°8 381 39°3 859 87°1 85°4 35:0 37°4 37°8 32°4 30°6 340 39°2 36°3 369 Observer's, Remarks. 'T. H. and H. R. ” ” 4th ist, T. H. and H, R. ” ” ” 4} ” ” Led 2” T. H. T. H.and H.R. T, H. T.H. and H.R. ” ” ” ? bed ” ” ” ” ” > T. H. and H.R. > 408 él T. H. and H.R. Tals In T. H. EIGHT YEARS OF THE NEW EARTH THERMOMETERS. 299 TaBLE II. continued.—ORIGINAL OBSERVATIONS OF THE NEW EARTH THERMOMETERS, AND CERTAIN AUXILIARY THERMOMETERS AT ROYAL OBSERVATORY, EDINBURGH, 1879-1888, goin £2. t3. t4. t5. Alr, Month Year. and Surface Observers, Remarks, Day. Each | Monthly} Each | Monthly Each | Monthly Each | Monthly | Therm. Each Reading.| Means, | Reading.) Means. | Reading.| Means, } Reading.| Means, Each | Reading, Reading. 1883 | Jan. 1] 47-48 45°50 41-10 39-60 4.2 | 473 |T HandHLR. 8) 47°35 45-14 41:35 40-05 35:0 | 323 | ,, 4 15] 47:26 | 47°25 | 44:94 | 44°97 J 41:00 | qr‘to | 39°35 | 39°48 37°38 39°9 ss < 22} 47-15 44-73 41-20 39-80 38:6 | 41:2 | |, Af 29] 47-03 44-52 40:85 38:60 39:0 | 39-1 s - Feb 2 46°02 44:32 40°15 38:40 40:8 44's > . : f 44:09 . 40-30 : 39:10 , 37°8 Sh ‘ 19] 46°67 | 46°74 } 43-89 | 44°F | 40-45 | 4°°5t | 39-50 | 39°48 | 36-9 38-0 4 cf 26} 46°57 43°75 41-15 40-90 40:8 | 43-4 : E Man. 5 46°45 43-69 41-70 41-40 39:3 | 443 | ,, fo 46°33 . 43°68 ; 40:90 : 38:80 . 329 | 346 | , ; 19} 46-22 | 4628 | 43-59 | 43°59 | 40-00 | 404° | 37-40 | 387° | 30-6 | 33-0 | 2 : 26} 46-14 43-40 39°25 37:20 32-7 | 343 | ,, * Apr. 2] 46-06 43:17 39-15 38:30. 393 | 455 | ,, 4 45-98 42-94 40°45 41:20 438 | 471 | ,, ‘ 16} 45°89 | 45°88 | 42°90 | 43°05 | 41°85 | 4gr‘oq J 42°91 | qr'sx 41-1 43°7 7 oS 23] 45:78 43-04 4935 4953 405 | 41-7 | ,, ‘ 30] 45-70 43°19 4239 42°60 429 | 480 | ,, ‘ May 7 45 63 4831 49-78 42°80 43-2 7 2 Bs ‘ : 43°45 ; 49-79 : 43°59 ; 48-5 ‘ a i 21) 45-51 | 45°54 | 43-59 | 43°54 | 44-30 | 43°94 | ag-12 | 45°28 | 495 | 543 | ? i 28] 45-47 43°83 45°89 48-59 514 | 553 | ,, £ bens 4 45 44 4417 46°88 49-31 521 | 56:7 T. H. 2 : 44-57 4761 3 49:97 } 51:8 | 55-4 re 18} 45-41 | 45°42 | 44-96 | 44°774] 48-45 | 47°9° | 50-11 | 49°98 | 49-3 | 51-8 ss 25) 45:43 45°37 4866 50°55 516 | 52:4 i July 2] 45-47 45°75 49:30 51:86 56-1 62-2 % 45°52 46:10 5012 52:57 572 | 61-1 16] 45°58 | 45°59 | 46°47 | 46-42 | 50°40 | 49°86 | 51°50 | 51°34 50°8 54:2 oo 93| 45-64 46:78 49:86 50:36 48:6 | 51:0 ae 30| 45:73 47-02 49-60 50°39 515 | 54:4 |T.H.andH.R. | ug iS 45 83 47-16 49°97 51:36 52:9 56-0 F ‘ 2 : 47°3 A 49-98 ; 50°60 ; 51:7 : 5 i 20} 46-02 | 45°97 | 47-51 | 47°42 | 50-15 | 5°25 | 51-30 | 5*3° | 54.0 | 608 | ” HR. | 27] 46-12 47°66 50°51 52°19 559 | 59-2 a ept. 8 46 20 47:81 50°69 51:51 53-4 8 ‘0 iy, 2 : 47:98 : 50:29 : 50:50 : 51-2 4 ; 17| 46:38 | 4°34 | 43-09 | 48° | 50-08 | 5°29 | 50-86 | 5°°°9 | 59.9 | 565 T.’H. 24| 46-47 48°14 50-09 49-90 49:3 | 53-7 | 'T.H.and H.R. Oct. 1] 46°55 48-19 49-79 49-60 44-6 | 463 | ,, iF 8] 46-65 48-24 48-74 |, 47°88 503 | 63:7 | ,, a 15] 46°73 | 46-72 | 48°14 | 4810 48°60 | 48°35 48°34 | 47°48 48:0 49:2 A .. 22) 46-79 48-03 47-74 45°79 40-4 | 43:0 | ,, ‘, 29} 46:87 47-91 46°87 45°78 45-4 48-0 | ,, : Nov D 46-90 4769 46°70 45-79 416 ae 33 % : ; 47-48 ; 45°56 : 4293 35-0 ‘ F ‘ 19} 46-97 | 4°95 | 47-24 | 47°33 | 44-95 | 44°98 | 41-73 | 47°95 | 37-8 | 36-7 | > , 261 46-99 46:90 43-40 41°35 39°38 | 41:0 | ,, ; Dec. 3} 47:01 46-56 43-92 49°85 413 | 439 | ,, , 2 as a9 46-28 43-05 40-80 38:5 We 5p s : 46°95 46:00 | 46'or 42°69 | 42°98 40°60 | 4r‘5r 34°6 ; % 24] 46-94 45°75 49°45 41-10 42-0 | 485 | > % 31] 46-87 45°48 42-80 42-19 38:3 373 | i 1884 Jam, 7 ae 45-32 42-40 41:25 40-4 - p oh 4s 77 ; 45:16 : 4258 ; 41°30 : 43:0 ° ‘ % 21] 46:69 | 4°72 | 45-03 | 45°72 | 49-99 | 423 | 49-80 | 473° | ara | 42:3 | 3 ‘, 28) 46-59 44-99 4255 40°10 34:0 | 36:0 T.H 300 PROFESSOR C. PIAZZI SMYTH ON TaBLeE IT. continued.—ORIGINAL OBSERVATIONS OF THE NEW EARTH THERMOMETERS, AND CERTAIN AUXILIARY THERMOMETERS AT ROYAL OBSERVATORY, EDINBURGH, 1879-1888. Month and Day. Year. 1884 | Feb. 4 11 1885 Each Reading. Monthly Means, 46°44 46°13 45°82 45°63 45°58 45°76 46°14 46°66 47°14 47°40 47°44 47°24 46°85 t2. Each Reading. 44°82 44°58 44°44 44°31] 44-17 43°98 43°84 43°72 43°75 43°74 43°75 43°84 43°94 4399 44:07 44-15 44°38 44°65 44-94 45°25 45°59 45°94 46°33 46°79 47-20 47°58 47-84 48-08 48°34 48°61 48°86 49°06 49-13 49-19 49-24 49°26 49-18 49-04 48-82 48°65 48-49 48°27 48°04 47°71 47°35 46°95 46°62 46°30 45:94 45°55 45°23 44:92 44°59 44°35 44°18 44°05 Monthly Means, 43°89 43°82 45°27 46°98 48°22 49°10 49°08 48°36 4699 45°41 44°29 t Each Reading. 41°50 41°90 41°85 41°40 40:90 40°80 41-10 42°10 41°80 42°30 42°88 43°05 43°05 43°15 43°70 45:12 45°87 46°60 47°38 48-04 48°93 49°89 51:00 51°68 51°80 51°42 51°57 52°20 52°71 53°00 52°48 51°73 51°82 51°81 51°40 50°58 49°44 48°75 48°69 48-02 47°53 46°81 45°48 44°48 43°55 43°50 42°80 41°90 41°20 41:00 40°50 40°10 40°60 40°60 41°10 40°30 3. Monthly Means, 41°66 41°34 42°82 48°17 51°48 52°37 51°85 49°36 46°96 43°25 40°70 40°65 t Each Reading. 39°35 40°85 40°50 40°10 38°80 39°70 41°91 41-60 40°85 42°95 42°61 43°15 42°71 42°68 45°09 46°65 47°72 48-29 48°58 50°09 51°28 53°37 53°48 54°15 53°21 52°30 53°48 54°33 54:92 55°50 52°78 51°75 52°59 52°99 51°49 49°84 47°17 48-40 47°86 47°51 46°40 44°40 42°70 41°40 41°50 42°60 40°20 39°40 38°60 39°20 38°20 37°30 39°60 39°70 40°30 37°90 4. Monthly Means. 40°57 42°86 45°54 50°32 53°28 54°56 52°32 48°32 45°25 4102 38°32 39°38 Surface Therm, Each Reading. OO S109 = wt Per we Orr Or Or Or Oren O1 Orn O1 eONSS Kaos SSAN GIASS FING YSIS BOAAS KAIAGH WOSok HOnww of AGHA ANSAR GCSOEW Bor oo 9 G9 OD NID 09S AAAaAr Sons co G9 cn CO SI OVS SI Observers, Remarks, Each Reading. WAAWSH HENS Woks SHAGAMD Sedmwdw SoOrE BASS SATA WwWERW Ww, = ae NON Orr Or Oro. D O11 > Or COVE OF PPO Pee me Oro 0O COCO SAkSssy Ori. O19 SESS COWN Wr AES SNR OS 6 O10) CO CO ONT OF HR bo OO Nwo>wk onNnnn ” ‘0 |T.H. and H.R. 2 ” ” ‘9 ” ” 8 ” ” 0 ” ” . 8 ” ” 0 ” ” 0 ” ” 3 ” ” “4 T.H. 3 ” ‘6 |T.H. and H.R. | 8 ” ” 40:8 ” ” 34:2 ” 2 36:0 A ” 41:9 Abdel 38°5 ” ” 36:4 |'T.H. and H.R. 34°8 ” ” 43°8 —— = — EIGHT YEARS OF THE NEW EARTH THERMOMETERS. 301 Taste II. continved—ORIGINAL OBSERVATIONS OF THE NEW EARTH THERMOMETERS, AND CERTAIN AUXILIARY THERMOMETERS AT ROYAL OBSERVATORY, EDINBURGH, 1879-1888. é1. £2. aes t 4. £5. Air, Month Year, and Surface Observers, Remarks, Day. Each | Monthly ! Each | Monthly Each Monthly | Each Monthly | Therm. Each Reading.| Means, J Reading.| Means. | Reading.) Means, | Reading.| Means. Each Reading. Reading. 1885 |Mar. 2} 46-57 4389 41:00 40-30 35:5 | 36-7 |T.H.andH.R. 9) 46-46 43°78 40-50 39-10 33-4 | 33-2 H. R. 16] 46:37 | 46°36 | 43°67 | 43°67 | 40°40 | 40°68 | 39°60 | 39°78 | 39:4 | 42-2 > 931 46-25 43°54 40-70 39°50 33-7 33-6 T. A. 30] 46-17 43°45 40°80 40°40 36:5 | 37:7 -s April6| 46-07 4338 40:90 40-20 392 | 43:3 |T.H.and H.R. 13] 45-98 ; 43°34 : 41-00 : 40:40 39:5 | 42:7 | ,, 20| 45-92 | 45°95 | 43-30 | 43°34 | 41-50 | 4758 | 42-20 | 47°76 | 47-9 | 526 T. H. 274 45°83 4333 42:90 44-95 46°8 | 51°5 sf May : 45°74 43°48 43°70 ree 40°6 40:2 |T.H.and H.R. 11} 45-67 : 43°70 ; 43-22 ' 42: ; 40:5 | 44-7 ; F 18] 45-62 | 45°°5 | 43-86 | 43°74 | 43-20 | 4342 | 43-19 | 43°58 | 41-6 | 44-0 | 4 25) 45°58 43-94 43°58 44-12 45:6 | 50-5 T. H. Junel] 45:55 44-04 44:88 46-80 49:9 | 53-7 |T.H.and H.R. 8} 45-53 44-24 46:39 48-79 488 | 49-0 H. R. 15] 45°52 | 45'52 44°59 44°65 47°47 47°21 50°48 49°55 53°6 57:2 | T.H.and H.R. 22} 45:50 44-98 48-43 50:38 519 | 54-1 ;. i 29} 45-52 45-40 48-88 51°32 551 55‘6 T. H. July 6] 45°55 45-80 49°79 52°88 59-1 | 62:4 4 13] 45:59 ; 46-1 50°73 53° ; 53-9 | 55:3 oA 20] 45:65 | 45°3 | 46-62 | 49°39 | 50-75 | 5°65 | 5o-o4 | 5326 | 53-5 7 56.3 i 271 45:73 46:96 51:36 54:78 55:8 | 55:7 5A Aug.3] 45:80 47°30 51-98 54:09 53:3 | 51-4 od 10) 45-91 47°68 51:69 5300 55-7 | 60-1 * 17] 46:02 | 46°02 | 47°97 | 47°87 } 51°21 | sr-45 | 51°89 | 52°58 55:3 58°4 HR. 24) 46-13 48-15 51:29 52-61 547 | 58:8 i 31] 46-22 48-26 5110 51°30 493 | 51-1 is Sept. 7] 46-34 48°39 5075 ot 50 52-2 542 Ks 14] 46-45 : 48-45 : 5 ; 50-69 : 50-2 5 fs 21) 46:55 | 49°5° | 4g-4g | 48°45 | 50-23 | 5°29 | 50-28 | 5°22 | agg 51:0 |T. H.and H.R. 981 46-65 48-49 49-68 48-4] 453 | 49:0 | ,, . *A pproxi- Oct. 5] 46-74 48-43 48°70 47-61 42-9 | 45:0 | ,, ,, | mate read- 12} 46-33 : 48-28 : 47°69 d 45-91 ; 40:0 | 43:2 ; ,» [ings only 19} 46:90 | 46°86 | 4gog | 48°26 | 46-99 | 47°42 | 45-99 | 45°99 | 4-3 | 412 |? ” | possible ; 26} 46:96 47°86 46-28 44-10 428 | 45:0 | ,, » {the top of the Nov. 2] 47:03 47°64 45-49 43°57 462 | 505 | ,, »» | column of 9} 47-04 47°34 45-50 44-79 426 | 41:9 | ,, .» | spirit. be- 16] 47:04 | 47°04 | 47°10 | 47°13 45°28 | 44°70 | 43°20 | 42°93 33°3 31°7 _ Pear, 23] 47-06 46-92 43-72 41:30 389 | 40:0 | ,, », | too low to 30] 47-05 46-63 43°50 41:80 40°5 | 42-7 T. HH. bring the eye on a Dec. 7] 47-01 46:29 43:20 40-90 31:6 | 28-4 4 level with 14] 47-02 ’ 46:06 '| _. 41-7 : *39-00 : 42:0 | 46-9 ie it. 21} 46:96 | 49°97 | 45-71 | 45°88 | 49-50 | 42°45 | 41-40 | 49° | 40-2 7 413 4 T. H. 28} 46-90 45°44 49-40 41-20 40:8 | 41:9 a 1886 Jan. 4 46°84 45-25 42-20 41°50 38-2 | 363 |T.H.and HL R. 46-76 : 45-05 ‘ 41:40 1 *38-20 : 32:0 | 362 | ,, ¥ 18] 46-68 | 4°72 | 44-91 | 44°99 | 40-50 | 47° [38-00 | 38° | 31-5 | 28-6 | > | *A pproxi- 25] 46-60 44°48 *39-90 *37°50 32:5 | 32-9 TH. mate read- ings only. Feb. 1] 46-51 44-13 *39-40 *37°30 31-7 - a T. H.and H. R. 8} 46-44 ; 4382 : *39-00 : *36-50 ‘ 370 | 42: i! i 15| 46-34 | 4°38 | 43-50 | 43°68 | %39-69 | 39°35 | 39-00 | 37°58 | 34-2 | 33:3 | | % 22) 46-24 43-28 39-40 *37-50 355 | 363 | ,, és Mar. 1] 46-10 43-07 *38-80 *36-00 31-4 | 300 | ,, x 8] 46-01 42°85 *38-00 *36-50 12 a ‘ Ks 15] 45:90 | 45°90 | 42°70 | 42°6x | *87°50 | 38:42 | *35°50 | 37°28 31: ¢ 6, 224 45-80 42°35 *37-80 *37-50 44-0 | 481 | 2 is 29} 45-69 49-10 40-00 40-90 405 | 423 | ,, : VOL. XXXV. PART 3. 3D 302 PROFESSOR C. PIAZZI SMYTH ON Taste IT. continued —ORIGINAL OBSERVATIONS OF THE NEW EARTH THERMOMETERS, AND CERTAIN AUXILIARY THERMOMETERS AT ROYAL OBSERVATORY, EDINBURGH, 1879-1888. Month Year. and Each Reading. 1886 fApril 5 12 1887 Monthly Means. Each Reading. 42°15 42°25 42°35 42°45 42°55 42°75 42:99 43°20 43°41 43°67 43°92 44:24 44°60 44:98 45°42 4592 46°30 46°66 46‘96 47°16 47°36 47°56 47°76 47-98 48°15 48°25 48-23 48 20 48°20 48°16 48-08 47-94 47°80 47°54 47-29 4707 46°77 46°39 45-98 45°51 4507 44°65 44°31 44°03 43°94 43°90 43°75 43°59 43°53 43°53 43°45 43°25 43°08 43°05 43°02 43°02 t 2. Monthly Means. 42°30 42°98 45°66 47°34 48°04 48°20 47°73 46°55 44°71 43°80 43°44. Each Reading. Monthly Means, 40°90 43°15 46°36 50°0r 50°63 50°85 49°40 46°77 42°78 40°28 4o"92 40°65 £4, tb. Surface Each | Monthly } Therm. Reading.| Means, Each Reading. 40°40 ae 40:20 , : 41-30 | 40°88 | 39-9 41°60 41:3 42°50 45°7 44-68 42:5 43°30 | 44°04 44:0 44°81 46°3 44:90 44-5 46:56 52°8 48-00 : : 49-09 | 48°28 | 53-4 49-48 52°9 52:90 wee 52°26 ; 54: 51:90 | 525° | 58-1 52°96 52:9 51°48 501 51:91 54-2 51°45 | 52°03 54-9 52°21 53:5 53°10 58:6 5303 54:3 52°30 : 52:9 50:50 | 573° | 49-4 49°60 51°6 aa a: 5 0-18 ' 46:4 48:81 | 4922 | 46-7 47°79 45:4 47:80 47°4 45:90 41:8 44-58 | qscq | 44:8 44°70 39:7 44°73 43:0 41:90 41:8 40°70 s 34:5 *39:00 | 399° | 30:5 *38-00 316 *38-20 365 *37-50 32-5 *37-50 | 38°88 | 313 *39-40 38-9 41:80 40°3 oe re *38-90 : 36° *39°60 | 497° | 38-2 41°10 40:7 4120 38:1 #3910 , 31:8 *38°10 | 3947 | 33:8 *39°30 40°5 41:00 43-9 40°40 Bi 39-4 41:00 | 4779 | 43:8 42°35 39-4 Air, Each Reading. Observers. T. H. T. H. and H. R. ”? ” 2) 9 T. H. ”) ” 3) T. H. and H. R. H. R. T. H. and H. R. ” PP) ” ” > ” ” 9 Ley 9 T. H. T. H. and H.R. ” ” ” 2? 9 o> Remarks, *Approxi- mate read- ings only. EIGHT YEARS OF THE NEW EARTH THERMOMETERS. 305 Taste II. continued.—ORIGINAL OBSERVATIONS OF THE NEW EARTH THERMOMETERS, AND CERTAIN AUXILIARY THERMOMETERS AT ROYAL OBSERVATORY, EDINBURGH, 1879-1888. (lle t 2. t3 t 4. t5 Air Year. Surface Observers. Remarks, Monthly | Each Monthly | Each Monthly Each | Monthly } Therm. Each Means. | Reading.| Means. } Reading.| Means, } Reading.| Means. Each Reading. Reading. 1887 | May 2 43°10 42:00 41:90 42°3 46-2 | T.H. andJ. F. 9 43:18 42°80 44°15 48-7 51°3 - - 45°28 | 43°35 | 4342 | 43°99 | 43°8r } 45°18 | 44°67 51:7 570 A 3p 43°60 44°85 45°26 44:6 51:0 A - 43°89 45°40 46°85 46°8 477 5 - 44:18 46:02 47°40 52°8 58:1 59 » | *Approxi- 44°47 i 47°18 Ni 49°50 é 55:0 580 5 >> | materead- 45°17 | g4-g2 | 44°68 | 4g.6o | 47°94 | 50-10 | 5°52 | 53-0 | 55:0 | ” ;, | ings only. 45-26 49-95 53-10 572 | 616 | |. - 45°77 51 a 55°04 58°4 592 |C.P.S. andJ.F. 46°35 517 54:90 ; 57°8 60°3 55 4s'32 | 4g-83 | 46°56 | 52-02 | ste | Saag | 54°80 | 53.6 | 50-4 | ” * 4728 52°50 54°88 55:0 57°38 | T. H.and J. F. 47°67 52°51 54:28 54-4 59°7 |C.P.S.andJ.F. 43-01 52°50 54°59 57-9 | 60°38 | ,, i 45°8r | 48:26 | 48:27 | 52°39 | 52-24 | 53°10 | 53°66 51°3 53°8 | T.H. and J. F. 48°49 51°80 52°41 51:9 65:2 41C.P.S.andT.H. 48°63 52:00 53°90 580 59°3 T. H. 48°75 eee 53°10 52°5 54:3 | T. H.and J. F. ‘ 48:90 - ‘ : 51°55 . 48:1 49-0 T. H. 46°40 7 49.00 | 48°97 | 50-65 | 5t28 | 50-19 | 573° | 48-7 | 515 | T.HuandJ. F. 48°98 50°31 50°37 51°8 53°6 3 5 48-90 49-89 49°48 49°5 53:0 a on 48°78 49°35 48°10 412 417 3 95 46°89 | 48°68 | 48°57 | 47°58 | 48°04 | 45°10 | 46°66 42°9 45°8 i a 48°39 46°99 45°60 38°3 371 33 ‘ 48°11 46°41 45°00 40°5 40°3 35 A 47°83 fone 44:20 43°4 43°8 fe 5 47°53 ; : : 43°70 ; 37°6 35°0 . 47°I3 | 47-98 | 47°49 | 44-40 | 44°88 | 49-19 | 43°08 38.0 38-4 | | Fe 46:98 43°80 42°30 38°6 39°0 5 a 46°65 vee 42°90 39°0 41°3 55 Pr F 46°36 ; : , *40°10 : 33°4 33°4 e 7 47°08 | 46-09 | 4621 | 49-20 | 42°55 | *40-00 | 4°°4° | 33-8 | 340 |? i 45°74 *41-20 *38°60 35°7 36:0 |J.F.andC.P.S. 1888 45°38 *40°80 *38°30 32°0 30:3. | T. H.andJ.F. 45-05 *40-90 *40-40 463 | 516 | ,, a 46°80 | 44°75 | 44°84 | *41°80 | gr‘24 | *40°70 | 39°78 B71 364 ss 3 44-60 *41°20 *40:00 41°7 45:8 eA s 44-44 *4150 *39°50 33-4 | 340 | 7 es 44°30 *40°60 *39-80 43:3 46-0 re Dee % ; 44-10 : 41°20 ; *39°40 ‘ 31°9 30°8 5 - pproxi- 46°38 | 43.95 | 44°02 | 40-00 | 4°25 | %37-90 | 3°48 | 39-4 | 33-3 | 7) >> [mate read- 43°75 *39°20 *36°80 33°8 35°0 95 5, | ings only. 43°32 *39-00 *36°80 32°7 34:3 Ss As t 43-15 *39-80 *39-70 : 329 | 29-9 | > iH 45°99 | 49-99 | 43°08 Jx39.99 | 39°28 [37-99 | 3775 | 321 | 339 | > he 42°85 *39°00 *37°30 32°4 33:0 sa =e 42°62 *38°50 *37 20 382 39°6 35 3 42°49 *39°00 *38°30 354 37°5 A ; 45°54 | 42°28 | 42:40 | *39°70 39°83 | *40°50 39°67 44°3 48°8 a i 42:28 41-00 40-90 37°2 36°9 i a 42°40 40°95 41°45 433 44°8 ry 5 304 PROFESSOR C. PIAZZI SMYTH ON Taste [I].—MONTHLY, QUARTERLY, AND ANNUAL MEANS TAKEN QUARTERLY OF THE NEW EARTH THERMOMETERS. Year, » Month. 1879 October November December 1880 January February March April May June July August September October November December 1881 January February March April May June July August September October November December 1882 January February March April May June July August Septembe October Novembe December 1883 January February March April May June July August September October December November Monthly. é1. Quarterly. 46°36 45°48 46°12 47°35 46°63 45°73 46°86 46°50 45°87 46°41 45°61 Annual Taken Quarterly. 46°21 46°33 46°40 46°34 46°25 46°12 46-09 46°24 46°41 46°56 46°63 46°46 46°30 46°22 46°24 Monthly. t2. Quarterly. 47°05 43°89 44°20 48:06 47°91 43°48 43°14 44:88 48°30 47°98 44°19 Annual Taken Quarterly. 45°80 46°02 45°91 45°65 45°44 45°60 46-04 46°31 46°48 46°34 46:06 45°81 45°84 t3. t 4. Monthly. 48°10 45°26 41:20 40°87 40°52 41°37 42°36 45-03 48°18 50°89 52°48 52°83 49-48 44°65 43°12 39°43 38°10 39°18 39°82 43°66 47-99 50°32 50°87 49°95 48-14 45°67 43°36 42°54 42°41 42°83 43°19 44:97 48°66 51°10 52°51 51°40 49°73 45°47 41°75 41°10 40°51 40°46 41°24 43°94 47-90 49°86 50°15 50°29 48°35 44°98 42°98 Quarterly. 40°92 45°19 43°82 50°38 45°72 42°59 45°61 51°67 45°65 40°69 44°36 50°10 Annual Taken Quarterly, Monthly. | Quarterly. 47°15 43°26 38°51 38°75 40°11 40°90 42°67 46:23 50°30 53°05 54°60 53°79 47-66 42:57 41:04 36°25 36°22 38°22 39°50 45°54 50°25 52°57 51°87 50°36 46°76 44:98 40°93 41°43 41°97 42°42, 42°76 45°98 50°24 53°16 54°30 51°80 49-07 42°85 38°74 39°48 39°48 38°70 41°51 45°28 49°98 51°34 51°36 50°69 42:97 39°92 46°40 45°98 53°81 45°48 45°14 36°90 44°71 45°10 44:70 51°60 45°63 44°21. 46-08 41°94 46°40 46°33 46°38 53°09 45:90 43°55 45°59 39°22 45°20 45°59 45°15 51:13 45°44 47-48 42°95 41°51 43°98 45°64 Annual Taken Quarterly. 45°22 44°89 44°34 44°45 45°71 46°02 46°39 46°23 45:55 45°36 44°87 44:98 45°35 45°52 EIGHT YEARS OF THE NEW EARTH THERMOMETERS. 305 Taste III. continued—MONTHLY, QUARTERLY, AND ANNUAL MEANS TAKEN QUARTERLY OF THE NEW EARTH THERMOMETERS. Year, Month, 1884 January February March April May June July August September October January February March April May June July August September; October November December 1886 January February March April May Jnne July August September October Novembe December 1887 January February March April May June July August September October Novembe December 1888 January February March April é1. ¢2. Annual Annual Monthly. | Quarterly.) Taken Monthly. | Quarterly.) Taken Monthly. Quarterly. Quarterly. 46°72 45°11 42°63 46°44 46°43 44°54 44-51 41°66 46:13 43°89 41°34 46°29 46:04 45°82 43°82 42°82 45°63 45°68 44°15 44°41 44°46 45°58 45°27 48°17 46°41 46°29 45°76 46-98 51°48 46°14 46°19 48-22 48°10 52°37 46°66 49-10 51:85 46°50 46:28 47-14 49:08 49°36 47°40 47°33 48°36 48-14 46:96 47°44 46°99 43°25 46°51 46°15 47-24 45°41 40°70 46°85 46°82 44:29 44°46 40°65 46°36 43°67 40°68 46°48 46:02 45-95 43°34 41°58 45 65 45°71 43°74 43°91 43°42 45°52 44°65 47°21 46°38 45°75 45°63 46°39 50°66 46-02 46°05 47°87 47°57 51°45 46°50 48°45 50°29 46°26 45°57 46°86 4816 47°42 47°04 46°96 47-13 47-06 44°70 46°97 45°88 42°45 46°12 45°37 46°72 44:90 41:00 46°38 46°33 43°68 43°73 39°35 45-90 42°61 38°42 45°98 45:22 45°40 42°30 40:90 45°06 45°13 42°98 43°13 43°15 44-94 44-11 46°36 45:90 45°32 45:06 45°66 50°01 45°45 45°49 47°14 46°95 50°63 45:95 48-04 50°85 45°88 45°39 46°38 48:20 49°40 46°74 46°65 47°73 47°49 46°77 46°84 46°55 42°78 45-94 45°53 46°66 44°71 40:28 46°25 46:26 43°80 43°98 40-92 45°88 43°44 40°65 46:02 45°77 45°57 43:04 41°19 45-28 45°34 43°42 43°71 43°81 45°17 44-68 47°94 46°12 45°74 45°32 46°56 51:92 45°81 45°84 48-21 47-89 52°24 46°40 48-91 51°18 46°15 45°74 46°89 48°57 48°04 47°13 47:03 47-40 47°39 44°88 47:08 46:21 4255 46°80 44°84 41-24 46°38 46°39 44:02 43 98 40°25 45:99 43-08 39°28 45°54 42-40 39°83 t 3. Quarterly. 41°88 45°15 51:90 46°52 40°68 44:07 50°80 44°86 39°59 43°47 50°50 46°32 40°62 44°31 45°16 Annual Taken Quarterly, 46:09 46°36 46°06 45°52 45°10 44-83 44°68 44°60 44:97 45°23 45°44 45°47 45°38 Monthly. 4. Quarterly. 46°24 53°39 44-86 39°16 44:96 52°02 43°15 37°89 44°40 51°96 44°89 39°47 45°46 53°25 43°38 38°67 Annual Taken Quarterly, 46:08 46°30 45°91 45°59 45°25 44-82 44°50 44°36 44°35 44°78 45°18 45°44 45°77 45°39 45:19 306 PROFESSOR C. PIAZZI SMYTH ON Taste [IV.—PARALLEL OBSERVATIONS OF THE SCOTTISH METEOROLOGICAL SOCIETY. Country and Town Stations. Town Stations Only. r Air Shade , Air Shade : 7 Temperature, Rainfall. Temperature. Rainfall Mean Annual, Annual Depth. Mean Annual, Annual Depth. 2 inches. B inches. 1877 45°7 51°83 46°6 48°37 1878 46°8 36°28 47°5 29°93 1879 43°9 36°43 44:6 34:06 1880 46°4 34°73 47:4 30°07 1881 44:7 39°54 45°3 37:17 1882 46°7 44:92 476 42°31 1883 46'0 40°38 47:0 37°30 1884 46°7 39°44 47 °5 36°66 1885 44:9 35°42 46°1 29°48 1886 44:9 37°93 45°8 84°67 1887 46:0 30°96 46°8 27:02 1888 SUPPLEMENT TO THE EARTH THERMOMETER PAPER, viz. THREE YEARS’ OBSERVATIONS, 1880, 188] AND 1882, AT KEW OF NEW SUN-SPOTS, AND AT EDINBURGH OF THREE EARTH-THERMOMETERS, ¢ 3, ¢ 2, AND ¢ 1, (DrExEpxst). The above Observations collected and exhibited both numerically and graphically, in three different modes ; viz., by I. AnnuaL MEANS oR SUMS, COLLECTED QUARTERLY. IJ. Annuat Means ork Sums, contectep Monraty. III. Annuat Means orn Sums, coLLECTED WEEKLY. Taste I. AnnuaL Mzans, on SUMS, COLLECTED QUARTERLY. Simple Quarterly Means of Earth Thermometers, Annual Means of Earth Thermometers collected Quarterly, Ben veel Gan ae Year. Quarter, ‘Therm, 1,/Therm, 2,|Therm, 3, Middle Date. Therm. 1. | Therm, 2, | Therm, 3. Middle Date. Sums. a Diff, Diff. Diff, : Diff, 1880 | Jan. Feb. March | 46°36 43°89 40°92 || 1880 June 30 | 46°33 46°02 45°98 1880 June 30) 70 April May June | 45°48 | 4420 | 45°19 +°7 —‘Ir — "50 +°9 July Aug. Sept. 46°12 48-06 52 07 Sept. 30 | 46°40 45°91 45°48 Sept. 380] 79 Oct. Nov. Dec. | 47°35 | 47°91 | 45:75 -—"5 — "26 — "34 +°r9 Dec, 30 | 46°35 45°65 45:14 Dec. 30} 98 = 10 — ‘21 — "43 +12 1881 | Jan. Feb. March 46°63 43-48 38-90 1881 March 30 | 46°25 i 45°44 ba 44-71 i 1881 Mar. 30) 110 Prise: April May June | 45:28 43°14 43°82 tae al cane July Aug. Sept. 45°73 47-22 50:38 June 30 46 we ihe 45 oe es 44 Be - June 30| 117 i ‘ts Oct. Nov: Dees || 46'S | Aiea aia Sept. 30 | 46-09 ~| 45:60 ~ | 45-63 Sept. 30] 180 +105 | 4d | tas con Dec. 30 | 46°24 46-04 46:08 Dec. 30} 135 1882 | Jan. Feb. March | 46°50 | 44°77 | 42°59 +°17 +'27 +°32 -'6 April May June | 45:87 44°88 45°61 || 1882 March 30 | 46°41 46°31 46°40 1882 Mar. 30} 129 July Aug. Sept. | 46°41 48°30 | 51°70 +°I5 +17 — ‘oI + ‘II Oct. Nov. Dec. | 47°48 | 47°98 | 45°65 June 30 | 46°56 46°48 46°39 June 30} 140 EIGHT YEARS OF THE NEW EARTH THERMOMETERS. Taste IJ. Annuat Muans, on Sums, cottectep Montaty. 307 Simple Monthly Means of Earth Thermometers, Middle of Year.) “Month, 1880 | January . February . March . April . May June July August September October November December . 1881 | January February . March . April May June July August September October November December . 1882 | January . February . March . April May June July August September October November December . Mean of Month Therm. 1. 46°73 46°38 45°97 45°62 45°42 45°41 45°66 46-08 46°62 47°14 47-46 47°45 47°15 46°64 46:09 45°59 45°19 45-06 45°26 45°70 46°23 46°67 46°96 46°96 46°79 46°48 46°22 45°99 45°83 45°78 4599 46°39 46°84 47-30 4757 47°58 Mean of Month Therm, 2, 44°56 43°69 43°42 43°37 44:00 45°23 46°72 48°13 49°32 49°38 47°92 46°43 44°96 43°17 4229 42°17 42°78 44°48 46°07 4750 48°08 48°12 47°24 46°49 45°25 44°68 44°39 44°36 44-56 45°71 47°18 48-50 49-2) 49°11 48-24 46°60 Mean of Month Therm. 3, Annual Means of Earth Thermometers collected Middle Date. 1880 1881 1882 July 15 Aug. 15 Sept. 15 Oct. 15 Nov. 15 Dec, 15 Jan. 15 Feb. 15 Mar. 15 April15 May 15 June 15 July 15 Aug. 15 Sept. 15 Oct. 15 Noy, 15 Dec. 15 Jan. 15 Feb. 15 Mar. 15 April 15 May 15 June 15 July 15 New Sun-Spots, Annual Sums collected Monthly, Middle Date. 1880 July 15 1881 1882 Monthly. Therm, 1, | Therm, 2. | Therm, 3. Diff. Diff. Diff, 46°33 46:01 45°98 +03 +°04 = 47 46°36 46-05 45°86 +'o02 — "05 — "20 46°38 46-00 45°66 ‘02 = “te{0) — "18 46°40 45°91 45°48 — "OI — ‘IO She 46°39 45°81 45°27 — "02 — ‘Io es 46°37 45°71 45°15 — ‘03 — "06 — ‘Or 46°34 45°65 45°14 —*03 — ‘06 Oy 46°31 45°59 45°09 =) =‘o =I, 46°28 Z 45°54 2 44°95 : O38 "IO — "24 46°25 45°44 44-71 — "04 cata =‘kI 46°21 45°33 44°60 — 04 "06 +'o9 46°17 45°27 44-69 OS + ‘Or ‘o2 46°12 45°28 44-71 —‘o2 + ‘02 *26 46°10 45°30 44°97 —‘o2 +°13 +°36 46:08 45-43 45°33 ‘OI an *30 46:09 45°60 45°63 Giana i ie) + '28 46°13 45°79 45°91 + "05 +°28 + ‘II 46°18 45°94 46:02 +06 + "Io + '06 46°24 46:04 46-08 ole) +06 46°30 46°13 46°14 +06 08 +°14 46°36 46°21 46:28 +'05 sie) + °12 46°41 46°31 46-40 +°05 *08 +13 46°46 46°39 46°53 05 08 — ‘Or 46°51 46°47 46°52 "05 ‘Or = 4h 46°56 46°48 46°38 Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May 15 15 15 15 15 15 15 15 15 15 June 15 July 15 Aug. Sept. Oct. Novy. Dec. Jan. Feb. Mar. Apr. May 15 15 15 15 15 15 15 15 15 15 June 15 Sums, Diff. 308 PROFESSOR C. PIAZZI SMYTH ON TasLe IIT, WEEKLY OpsprvVATIONS OF SuN-Spots, ALSO WEEKLY OBSERVATIONS OF EartH THERMOMETERS 1, 2, AND 3. Aso ANNUAL Sums or SuN Spots, coLLEcTED Weexz~y, anD ANNUAL Meays or EartH THERMOMETERS 1, 2, AND 8 CoLLECTED Werxiy THROUGH THE Yuars 1880, 1881, anp 1882. ForttowrEp By THREE PLATES EXHIBITING THOSE NUMBERS DULY ProJEcTED To ScALES or TIME, AND QUANTITY. New New New Year Sun- Year Sun- Year Sun- and |Day.| Spots Annual eae collected and |Day.| Spots Annual See collected and ||Day.| Spots Annual gal collected Month, each See Month, each GIS Month. each Lee Week. Week. Week. 1880 1881 1880 1881 1882 1881 1882 “appa ey |e Jan. | 7 | ob | duly 15 to July 8. 99/7 | 7 | 2 | uly 15 to duly 8. 185 alee eile 22, 15 . 102 Or ae 2, 15. 133 alee lie 29 ” 22 | 102 rae 29” 22) 134 Aug. 5 ,, 29 . 104 Aug. 5 29 . 130 Ep ins soazellenielpes Bi Aug: fovel0ol ey Algae 2? Aug. 5. 129 ler ae 1s. 12 | 103 aa: 19°. 12 | 131 Alla Pale 26 19 . 103 18 26” 19 | 131 by | 7 | FO it deel col sees seo 26: 8105) ol | bey a ceceae 26 . 128 | o 1/3 9 ,, Sept. 2. 108 11/0 9 ,, Sept. 2. 125 Dee aes 162 9 | 108 ae 16 4 9. 126 ie ASti= 2 93” 16 . 109 Balle 23” 16 . 126 30 ” 23 | 108 30 ? 23 | 128 Bo at) @ DE Tl ie slOuk oles, 30. 109)| Pt ee Octet 30 . 129 tke aes 14” Oct. 7. 107 seal ae 147 Oct, 7% Hien ae oD ee a 4 | 107 ap 28 a1” 14 | 130 cana ahi 28” 21 ; 110 2s ge 28” 21 | 126 ; Nov. 4,, 28. 111 Nov. 4,, 28 . 127 nay ete edad ks TE; Nov. eco 10o!| My Sei 11” Nov. 4. 132 ate abe 18 > Hi. 119 Paes 18” 11; 133 Bu Al 25° 18. 114 ao Re 25> 18 | 134 Dec. 2 25. 113 Dec. 2, 25 . 138 re ra cane il ee Dee Piette OPE el 9” Dec, 2. 139 +B ler ‘aloe 16° 9. 115 ahs 16-, 9. 142 ae Sales 93” 16 . 118 lanes 93” 16 . 140 30” 93 117 2 30 ? 23 | 141 1880 1880 1881 1882 July | 1) 3 |g, 7toDec. 30. 69|)/U%y | 1) 3 |gan. 7, go.,a17 (9M | Ele aa ey 30 . 140 8) 1 1881 8} 2 1882 Att leo 14,, Jan. 7. 68 ihe 1d Jane $7 < 118 plac 21 14 | 65 21” 14 | 121 22 | 2 28 ” 21 | 68 22) 2 28 21 | 120 22| 8 29 | 2 ” 29| 4 » : 29 | 0 Feb. 4) 28 . 68 Feb, 4, 28 . 122 Aug.) 5) 1 11” Feb. 4. 68|At8-| 5) 2 Vi? Feb, 4. 198 | 408) 25.) 1 12| 38 18? 11 ; 68 12) 1 18 11! 12 12/ 3 19) 1 5 18 . 69 19} 1 25” 18 . 126 19) 1 26| 1 mii 26 | 3 » 26 | 0 Sapte] 9) | Oe eee erie Sept,| a2. 4 eee 2 oa be ae | Bepinl eae 9) 3 a. Ah 5 9} 3 i508 o| 4 16] 1 By lee 16| 2 re ayo ee 16| 2 23 | 2 a 3 28 | a » 93 | 3 oO) 2" aor 25. 77 St de ee 25 . 129 80) 04 Oct. | 7] 4 8, Apr. 1. 80] on | 7| 2 8,, Apr. 1. 130/o4 |] 7] 8 lee Tie 4 8. 82 ie ibe, 8. 132 AL 22 15 | 84 22 15 . 135 21| 1 » ai| 4 » 21| 0 Sislecn 29” 22 | 87 la 29” 22 | 135 bas ; May 6,, 29 . 87 May 6 29 . 136 Nov.| 4] 2 3 May 6. 89 Nov.} 4] 0 13 4 May 6. 136 Novy. 4) 5 rial! ilo 11 |: 5 20’ 13 | 90 20” 13 . 138 18) 1 7 20 | 90 18| 3 27° 20 | 138 18) 4 95| 2 » 25| 1 ” 25| 5 cm Jun. 3,, 27. 91 Jun. 3, Bi. Lor Deo. | 2) 1 10” Jun. 3. 93|| De | 2} 3 10” Jun, 3. 135|Dee || 2} 4 9) 0 17, 10. 94 aa i aes 10 | 136 dae? 16) 0 24” 17 . 95 16| 3 24” 17. 134 16) 1 23| 3 » 23 | 2 » 93 | 3 80) 1 | guy 1, 24 . 98 80) 1 | galy 1,, 24 . 133 Sone? 8,, July 1. 98 8 ,, July 1. 137 EIGHT YEARS OF THE NEW EARTH THERMOMETERS. 309 Taste III. continued; oR WEEKLY OBSERVATIONS OF SUN-SPOTS, ALSO WEEKLY OBSERVATIONS OF EARTH THERMOMETERS 1, 2, anD 3. Atso ANNUAL Svus oF SuUN-SPOTS, COLLECTED W2zEKLY, AND ANNUAL Mzays or EartH THERMOMETERS 1, 2, AND 3 COLLECTED WzzexLy THROUGH THE YEARS 1880, 1881, anp 1882. FonLowep BY THREE PLATES EXHIBITING THOSE NUMBERS DULY PROJECTED To SCALES OF TIME, AND QUANTITY. Annual Means for Middle Week of Year, Month, Day. Therm, 1. | Therm. 2. | Therm. 3. 52 continuous Weeks collected | Therm, 1, | Therm, 2. | Therm, 3. at every Successive Week for 1880 |-January. . 5 46°88 44°82 41°48 12 46°78 44°62 41:90 19 46°68 44-51 40°54 26 46°59 44°28 39°55 February . 2 46°51 43°98 39°67 9 46°43 43°69 40°82 16 46°36 4358 40°54 23 46°24 43°50 41°05 March .. 1 46°14 43°43 41°30 8 46:07 43°42 41°43 15 45:97 43°40 41°69 22 45°88 43°45 41°43 29 46°81 43°42 41:01 April. .. 5 45°74 43°35 41:69 12 45°67 43°34 42°14 19 45:58 43°35 42°38 26 45°47 43°44 43°23 Maier. |: | 3 45°48 43°61 43°59 10 45°42 43°76 44°29 17 45°44 43°99 44°71 "24 45°43 44-19 46:06 31 45°35 44-46 46°50 June... 7 45°35 44-76 47°12 14 45°37 45-08 47°48 21 45°43 45°37 48°60 28 45°49 45°72 49°51 : F : Jan. 5, 1880 to Dec. 27, 1880 46°32 46:00 45:97 es) Meee fl gaca | sea 12, Jan. 3 '1881/ 46:33 | 46:02 | 45-96 “ é e Feb. 2 if 24 46°36 46°05 45:90 eee Fylde | ace lw@eee ll ees do ta a al 46°37 | 46-05 | 45°86 3 46°16 48-38 52:95 23 9 14 46°38 46-05 45°76 30 46°32 48°76 53°23 Mar. 1 K 21 46°39 46-04 45°70 , A r ri 28 46°39 46:02 x amie Lh ee oe (peat 1 Mar. 7 46:40 | 46:01 | 45°59 20 46°66 49°47 52°52 22 ” 14 46°40 45:99 45°53 : A 2 Apr. 5 28 46°41 45-94 45°47 ey ata l aeege Weaees oes 12) Apr. 4 46-41 | 45-92 | 45-42 18 47-21 49:36 49-09 19 A 11 46°41 45°89 45 36 5 47 33 49-19 47°37 26 5 18 46°40 45°87 45 32 : ; ‘ May 3 5) 25 46°40 45°84 45°27 em icy gees gee | ae 10 May 2 46-40 | 45°82 | 45-24 15 47°48 47°86 45°30 17 ” 9 46:40 45°79 45:21 92, 47°48 47°50 43°74 24 ” 16 46°39 45°77 45°19 December .| 6 | 47:56 | 46:79 | 43-64 Joe 7 +, 30 eed oer eae Na 13 | 47:50 | 4652 | 44-38 youn se pe 20 47°42 46°33 42°88 2 » 13 46°37 45°69 45°15 97 47°33 46:09 41°57 28 ” 20 46°36 45°68 45°14 July 5 5) 27 46°35 45°67 45°13 VOL. XXXV. PART 3. 3 E 310 PROFESSOR C. PIAZZI SMYTH ON Taste III. continued ; oR WEEKLY OBSERVATIONS OF SuN-Spots, ALSO WEEKLY OBSERVATIONS OF EARTH THERMOMETERS 1, 2, anpd 3. Atso ANNUAL Sows or Sun-Spots, CoLLECTED WzreKkiy, anD ANNUAL Means or Earth THERMOMETERS 1, 2, AND 3 COLLECTED Wzexkzy THROUGH THE YEARS 1880, 1881, and 1882. Fotitowep By THREE PLATES EXHIBITING THOSE NumBERS DULY ProgecTED To ScaLus or TIME, AND QUANTITY. Annual Means for Middle Week of Year, Month, Day. Therm, 1, | Therm, 2, | Therm. 3. 52 continuous Weeks collected Therm. 1, | Therm. 2, | Therm. 3, at every Successive Week for dee Ye: eran den | $255 | $28 |svly12, 19880 to Tey 4, 1881) 4695 | 45186 45-11 17 4714 | 4497 | 39-60 19 » i foe «|: Gece ie 24 47-05 44°59 38-40 26 pe NS 31 46°97 | 4418 | 87°60 | aug 2 <2 A MOB 46:32 | 45:62 | 45-08 February .| 7 | 46:84 | 43-68 | 38:00 Se 6 ae ee | See 1é 46°72 | 43:28 | 38-10 23 Le Pas 4630 | 45:59 | 45-08 21 4659 | 42:98 | 38-20 » : 2 cael ae eee en 30 7 99 46-29 | 45-58 | 44-98 March . .| 7 | 46:80 | aso’ | sao [SP 8 +. face ~ | geen 14 4617 | 42:32 | 38-60 : » Sept. 5 21 46-00 | 42°15 40-00 20 » 12 ao) ee at Seago aaa ened 27 ip 46-27 | 45-49 | 44-74 April. = 6 |— 4% |p aya | apes: |) goag) Ore ae 28 ce | qe 11 45°64 4216 39-20 Dake ; : : 18 45°53 | 42-10 | 40-28 ue » W eeGeee | oe = peavey ce ee kee 25 eo ly 46-23 | 45:39 | 44-65 May home 9 45:32 42:29 41°88 Nov. 1 ” 24 46 ‘22 45 37 44 ‘64 é Fone. il) gece Wes 8 Sel a 46-21 || 45°35 | 44-65 16 45-18 42-71 43-92 15 » Nov. 7 eae) | Gees 23 45°13 | 43:05 | 44°39 59 es 4618 | 4532 | 4470 30 45-09 | 43°39 | 45°58 » fonds 5 «| 26) |) cab05- | capo = a7 eee ope arae ae one | Gee 13 | 45:05 | 44-99 | 47-37 18 » Dec. 5 oe if 20 45-07 | 44-74 | 47-98 20 » 2B 114 | ee ee ae aoe al aeeg 7) maaen 27 oti 46-13 | 45°32 | 44:77 Taiyo. Chae | oaetes Acasa) |) “aosae eee eel 4ea8. |) Geaetetee ll 45 23, 45 90 49 +89 10 ” Jan. a 18 45-29 | 46:25 | 50-97 7 » head trae | 25 45°37 | 46-63 | 51-12 24 » 116 it 31 me 46-10 | 45°34 | 44-97 ne ieee coe | ey eee Ee ee | 46-09 | 4535 | 45°07 es ae Nv aheee Meee 14 "Feb. 6 4609 | 4537 | 45-15 22 45°30 | 47:74 | 50:80 an mene ee | ee eee 29 45-94 47°92 50°40 ” 0 September .| 5 | 46-05 | 4g01 | 49-1 [Mar 7» ee \| Sees 12 46°18 48-05 | 50-00 »Mar. 6 21 13 46-08 | 45°54 | 45°55 red aoe. |} gouge: lNeaoR 28 > 86 4609 | 45:59 | 45-61 46-41 | 48° » October. .| 38 | 4651 | 48-22 | 5000 JAP 4 » . Wf 8 | ae 10 } 46:59 | 48-25 | 49-45 ae ee ; a 17 | 466 48:23 | 48-18 1S Peas. ee Su | 2a rif a Me ae hee 25 es) 46-11 | 45-75 | 45:89 Se Ma” Cee Ge eee se 4612 | 45:80 | 45-04 November .| 7 | 46:90 | 47:59 | 45:00 ao Ree oe | oe eee oe Ns aoe ween acee Big be) a 4617 | 45:94 | 46-04 28 46:98 | 46-99 | -45-60 » December .| 5 | 46:98 | 46:84 | 4493 [JMC S | 29 oy | eo ee 12 | 46-97 | 46:64 | 44-09 oes ‘ : 1610 19 46-93 46°39 42°68 20 » 1 46-21 46-02 27 a ag 46-23 | 46:04 | 46-11 26 46°94 46°08 41°70 July 4 x 26 46°24 ~ 46°06 46°12 3 EIGHT YEARS OF THE NEW EARTH THERMOMETERS. 311 Taste III. continued; oR WEEKLY OBSERVATIONS OF SUN-SPOTS, ALSO WEEKLY OBSERVATIONS OF EARTH THERMOMETERS 1, 2, AND 3. Atso ANNUAL Sums or SuN-SPOTS, COLLECTED W2zzKLY, AnD ANNUAL Mzaws or Earta THEeRMomeETERs 1, 2, AnD 3 COLLECTED WzrKLY THROUGH THE YEARS 1880, 1881, anp 1882. FoLLowED BY THREE PLATES EXHIBITING THOSE NUMBERS DULY ProJECTED To SCALES oF TIME, AND QUANTITY. Annual Means for Middle Week of Year Month. Day. Therm. 1. | Therm, 2. | Therm, 3. 52 continuous Weeks collected Therm, 1, | Therm, 2, | Therm. 3, at every Successive Weck for eee vannary . 4 4689 | 4568 | 42-41 | July 11, 1881 to July 31882] 46-25 | 46-08 | 4614 25 17 46-28 46°12 46-16 23 46-74 45°03 42°87 ” eo 2065) || S08" | 82:82" Wang. 1 a Tae 4629 | 4613 | 46-17 February 6 46°59 | 44:86 | 42-19 a Pee 2 pe ea ar oe El Bree Call ey cra ees oe ae ae ike 4633 | 4618 | 46-23 ae 29 21 46°34 46-20 46-27 27 46°37 44-51 42-79 » March 6 | 4630 | 44-45 | 42-39 [Sept 5 Sept or qe ale aca creas a ree toe ree 19 i 1 46:38 46-26 46°38 f ee ; 26 hs 18 46°39 46:28 46-41 27 46°13 44-37 43-00 , : ; Oct. 3 ye Pe 46°40 46°31 46°42 April . a oro aqaey | lgeae 10 ” Oct. 2 46-41 | 4632 | 46-43 A foe nice ae 24 : 16 46°44 46°36 46-49 31 : 23 46°45 46:38 46°53 May I 45°88 | 44°37 43°69 I Nov. 7 30 46-46 | 46:40 | 46-57 - roe eave va 14 Nov. 6 46-47 46°42 46-62 92, 45°80 44-64 4568 21 ” 13 46°48 46°44 46°62 ; : : 28 = @l) 46°50 46°46 46°59 29 45°79 44°85 46°83 ; : Dec. 5 Re 27 46°51 46-48 46°56 June . 2 aoe Fee ae 12 2 Deo, 4 46°52 | 46-48 46-52 io nee feos ree 19 s! inl 46°53 46-49 46-48 : : 26 18 46°55 46°49 46°44 26 45°81 46°21 49-11 my. 3 45-86 46-49 50-21 , | Jam. 2 1882, 25, 1882} 46°56 46-48 46-43 10 45°91 46°82 50-98 17 45-98 47-21 51°30 24 46-05 47°55 5147 31 46-14 47°85 5156 August 7 46:24 48-10 51:90 14 46°35 48:37 52-67 21 46-44 48-63 53-06 28 46°55 48:91 52°40 September . 4 46°66 49°10 51:95 vf 46°78 49-20 51-75 18 46-90 49-25 51-19 25 47-03 49-28 50-71 October . 2 47-14 49-24 50-49 9 47-23 49-18 50:40 16 47°30 49-12 50-20 23 47:39 49-08 49-40 30 47°44 48-95 48-14 November 6 47°52 48°75 47°35 13 47°56 48-46 46-04 (21) 47°59 48-05 44-43 27 47-60 47-68 44-06 December 4 47°62 47°27 43:00 11 47°59 46°83 41-95 18 47-58 46°40 40°95 25 47-53 45-90 41°10 Roy. Soc. Edin. | Vol XXXV PLATE 1, of this Paper. — oa Obs.* a New Earth Thermometers at Royal Observi Eas PScott 7 ed Scottis oT & Rainfall. Yy KY Ve DF liduergh Y : ae, new Barth eM Thermometers. ae —— 4S Of a e Suan RE Ppp An ON SIS Se Pes] ie ’ ‘ a ‘ a 4 ie a 0a - ox ee e | . 2 = | | Sire a . se ef a ee eee eee ere Sear ii i aes ogee CES. obs. ¢ del, . A, Ritchie ¢ Son,-Photo-lith. pe wim «. carehr € ee es ra mis pth ae ns. Roy. Soc. Edin. Vol.XXXV | SUBJECT Tseate | 8 etka FE S.D.MI. §.D.M.I. Annual Vumber of New Sun. Spots collected Quarterd y. | PLATE f. of GUPPLT. | to Eight Years Paper. Kew 06s.% Quarterly Sums. Kew 04s.¢ Earth Thermom. Ne 3. (Shallowe st) Its Annual Means collected Quarterly Earth Thermom | les a Its Annual Means collected Quarter! y- ee Earth Thermom™ W? 7. (Deefes €) LOSS 46°50 LF 46:46 | na /ts Annual Means Nae collected Qua rFevly. : aes : alt laa tg Ge A, Ritchie ¢ Son, Photo-lith. tm PLATE 2. of SUPPLEMENT to Eight Years Paper. “rans, Roy. Soc. Edin. Vol.XXXV \ SUBJECT. — Annual | number of NewSun- Spots | collected | Monthly. Kew 08s.» Monthly Sums, Kaw’ 053.4 ) . r Earth Thermom | Iva 3. | (Shallowes +) Li ae aay ee aS 46°20 46°00 45°80 Bt Ties AnnualMeans collected Month ly, ww } | | is r iS | Si Earth Thermow" | M2, NE SRRRSOCE) Uae les Annual Means}. | collected Monthly. TESTE TTT RT AD Earth Thermom. 1 AM f. | (Deefest). Its Annual Means collected | Monthly. | | | | A Le | LL ATT ans oy 3 iN STALL SELES Peli a gS ‘PS. obs. $ del. A. Ritchie ¢ Son, Photo-lith. i eae ae PLATE 8. of SUPPLEMENT to the Eight Years Pap PLATE 8. of SUPPLEMENT to the Eight Years Paper. f ight Years Paper. 3} Date (F232. Dale /7EGO\ for Midalle perisd of cath resulh, 1887 SDT TREN: est a £2 Dee. an, Feb. havch nA eZ. ; Dee ___ Feé, March. __ April. May __ June. Oct. ov. ee < elt ay June, July. Scare URJECT. SUBJECT, |Scale| 7 Ape Sept Oat Now. a Lae] ee et PAE PATEL TERE FEDS I Ota} Wk VER GB BIg FEUBEN BEE BOY 5 SRD EEE Y (017 Bis 15 2229 6 1219 26 B G16 2330F mw2eh 1525 a Sree = Sore wae oe 130 nnual ey = oa eal b cel b ¢ 120 of new 7S ene See are 110| SuN-Srors, 90) collected weekly, Kew 025.4 Annual Number of HE new SUN- SPOTS, Collected weekly. = Kew 08s”. ( 4 Z| Weekty Numbev Weekly-WVuméer, S , - b ow: ——_ collected WeeKly, O g oe : ‘ ealiceieey Weekly. Kew 05s. Earth-Therm= Ne? 3. Ghallc wes) Tts Annual Means, collected weekly. Barth-Therm* We } . (sha (Lowest); Tts Annual Means collected. weeKly. Earth -Therm= WE 2, Its Annual Means collected weekly. Its Annual Means collechd weekly. ql S 0) | A l o) \ " G sy 0) ea \ \ lo t J % ‘oj Fr Earth- Therm.~ Xe 7, (Bepest) Tts Annual Mean 5 o R a a Cy Tts Annual Means collected weekl ys collected wee ky. A Ritchie ~ Son, Phota-lith ae) A re igh add ol wa #259906) — 4 ee Pew SADO p "NS os a ; i ] = : o u : --— - 3 4? & ; eS ae ee ee Sy en ee 2 9 ‘ 4 _ — — ve — » oe Vee Res “~4 ereaionk) V.—On Neuropteris plicata, Sternberg, and Neuropteris rectinervis, Kidston, n. sp. By Ropert Kinston, F.R.S.E., F.G.S. (With a Plate.) (Read 30th January 1888.) Neuropteris plicata was described by STERNBERG in 1826, from a specimen from Mireschau, Bohemia, but the species seems to be very rare and imperfectly known. As other ferns have been identified as NV. plicata in error, I give a figure of what I believe to be SternBerG’s plant, an identification with which my friend M. ZEILLER entirely agrees. I also figure and describe a new species of Newropteris, which is identical with that identified as NV. plicata by RoEHL, but from which species it is essentially distinct. Neuropteris plicata, Sternberg (figs. 1, 1a). Neuropteris plicata, Sternb., Vers., i. fasc. iv. p. 16; i. p. 74, pl. xix. figs. 1 and 3. Description.—Frond tripinnate (?), pinne alternate (?); linear-lanceolate; pinnules sessile, approximate or separated a short space, cordate-ovate or cordate-lanceolate, apex blunt, margin plicate; nervation very fine, central vein dividing into numerous branches some distance below the apex; lateral veins numerous, curved upwards, and dividing three times. Terminal lobe elongate-triangular, small. Remarks.—The only specimen of this species which has come under my notice is that given on fig. 1. It was collected by Mr Jonn Warp, F.G.S8., Longton, from whom I received it. It is in an exquisite state of preservation, and shows the nervation very beautifully. The veins are too close and too fine to be represented in a sketch of natural size (fig. 1), but a portion of a pinnule, enlarged four times to show the nervation, is given at fig. la. There are five of the ultimate divisions of the veins in 1 mm. at the margin of the pimnule. The central vein appears to be formed rather by the united bases of the lateral veinlets than to consist of a mid-vein giving off lateral veinlets. The specimen I fioure is identical in all respects with the type figure; and, when the two figures are compared, they bear a wonderful similarity. Before seeing this example, I was inclined to regard N. plicata as identical with N. flexuosa,* being partly led to this belief by finding what I now regard as undoubtedly N. flexuosa identified as N. plicata.t As SrerNBERG has omitted to give enlarged details of the nervation of his fern, its identification has been made much more difficult. * Catal. of Palewoz. Plants, p. 94, where it is in error united with Neur. flecuosa. I however excluded Neur. plicata from Neur. flexuosa in my paper on the “ Radstock Fossil Flora,” Trans. Roy. Soc, Edin., vol. xxxiii. pt. ii. p. 359. + Lesquereux, Coal Flora of Pennsyl., vol. i. p. 96, pl. x. figs. 1-4. VOL. XXXV. PART 5. 3 F 314 MR ROBERT KIDSTON ON In addition to the type, two other published figures have been referred to NV. plicata. These are the figures given by LesquEREUX,* which are clearly referable to NV. flexuosa, Sternb., and those given by Rornt,t of which, probably both figures, but certainly one, is referable to my NV. rectinervis, which is described below. In NV. flexuosa, of which I have lately been able to examine many fine specimens from the Radstock Series, the terminal lobe is always very large, the pinnules more obtuse and not so lanceolate, and the lower auricle more pronounced than in NV. plicata. The nervation in LN. flexuosa is also stronger and not so fine, there being usually at the margin of the pinnules only four veins in 1mm. Occasionally, however, in some specimens of NV. flexuosa, immediately within the margin of the pinnule, a fourth dichotomy of the veins takes place, which makes them more numerous than four in 1 mm. Locality—Longton Hall Colliery, Longton, Staffordshire. Horizon :—Middle Coal Measures. From a bed about 2 feet above the Great Row Coal. Neuropteris rectinervis, Kidston, n. sp, (figs. 2-4.) Neuropteris plicata, Roehl (not Sternberg), Foss. Flora d. Steink.-Form. Westphalens, p. 38, pl. xiii. fig. 8 (? pl. xx. fig. 7). Description.—Pinnules sessile, alternate, oval or oblong, blunt, approximate or slightly separate, margin entire and free from plications; midrib very distinct, and extending almost to the apex; lateral veins distinct, numerous, fine, springing from the mid-rib with a gentle curve, and then running the greater part of their course at almost right angles to the margin of the pinnules, usually once, but occasionally twice, divided. At the margin of the pinnules there are five to six ultimate divisions of the veins in 1mm. Terminal lobe oblong. Remarks.—The specimens figured were collected in 1879, but, from their fragmentary nature, have remained undescribed till now, when, in treating of NV. plicata, it has been thought advisable to specifically distinguish this species, which has been confused with N. plicata, Sternb. I have the less hesitation in doing so, as the nervation is so characteristic, that NV. rectinervis can at once be distinguished from all other species. Of the two figures given by Rorut as NV. plicata, that on his pl. xii. fig. 8, is clearly N. rectinervis. About the other figure, given in his pl. xx. fig. 7, one cannot speak with so great certainty, though the probability is that it is also referable to NV. rectinervis. He says, in describing the nervation of his specimens,{ ‘the lateral nerves stand almost upright to the principal nerve, are very distinct, close together, once bifurcated, feebly bent ”—which agrees entirely with the character of my plant. The figures given show the variation in the size and form of the pinnules. * Loc. cit., pl. x. figs. 1-4. + Foss. Flora. d. Stenk.-Form. Westphalens, p. 38, pl. xiii. fig. 8; pl. xx. fig. 7. t Loc. cit., p. 38. NEUROPTERIS PLICATA AND NEUROPTERIS RECTINERVIS. 315 Locality.—Polton, Bonnyrige, Mid-Lothian. Horizon :—Lower Coal Measures. EXPLANATION OF PLATE. .—Neuropteris plicata, Sternberg. From shale above Great Row Coal, Longton Hall Colliery, Middle Coal Measures. (Collected by J. Warp, F.G.S.). Nat. size. . la, Nervation x 4, — [ 2-4.—Neuropteris rectinervis, Kidston, n. sp. From Polton, Bonnyrigg, Mid-Lothian. Lower Coal Nat. size. 2a, Nervation x 4. (aim) VI.—On the Fossil Flora of the Staffordshire Coal Fields. By Ropert Kinston, E.R.S.E., F.G.8. (With a Plate.) (Read 30th January 1888.) PAde I: On THE FossIL PLANTS COLLECTED DURING THE SINKING OF THE SHAFT OF THE HAMSTEAD CoLLIERY, GREAT Barr, NEAR BIRMINGHAM. The area comprised in the county of Stafford embraces five coal fields— I. The Goldsitch Moss Coal Field, in the extreme north-east of the county. II. The Cheadle and Churnet Valley Coal Field. Ill. The Wetley and Shafferlong Coal Field. IV. The Coal Field of the Potteries. V. The South Staffordshire Coal Field. The three first mentioned are of small extent, and as I know little of their fossil flora they are omitted from this series of papers on the Carboniferous Flora of the Stafford- shire Coal Fields. I, however, devote a separate communication to the fossil plants met with while sinking the shaft of the Hamstead Colliery, Great Barr, as a considerable part of the rocks passed through during this operation is clearly Upper Coal Measures, not Permian, as has been generally stated. The paleontological evidence, therefore, becomes of special importance in determining the age of the red shales occurring in the upper part of this sinking, which have been usually mapped as Permian. Strata of the same age also occur in the Potteries Coal Field, but the fossil plants are not so fully known from them as from the strata passed through in the sinking at Ham- stead. The determination, therefore, of the true position of the red shales at Hamstead assists one in dealing with the stratiography of other districts of Staffordshire. At the meeting of the British Association, held at Birmingham in 1886, Messrs Freperick G. Mracuem, M.E., and H. Instey, read a paper, entitled “ Notes on the Rocks between the Thick Coal and the Trias north of Birmingham and the Old South Stafford- shire Coal Field ;” this paper, of which an abstract is given in the Report of the British Association for 1886,* contains the only published opinion, as far as I am aware, that these red shales belong to the Upper Coal Measures. * Page 626. VOL. XXXV. PART 6. 3G 318 MR ROBERT KIDSTON ON THE Last year Mr Mracuem kindly gave me the opportunity of examining the fossils collected during the sinking operations at Great Barr, and the Upper Coal Measure Facies of many of the specimens is very pronounced. I revisited Hamstead Colliery this year, and went more carefully over the specimens. Mr Mracuem diligently collected examples of all the fossils met with during the sinking of the shaft, and at the same time noted at what depths they occurred, and the nature of the beds in which they were contained. The whole of this collection was most kindly placed at my disposal for determination and description. Mr F. G. Mracuem has further favoured me with the details shown in the following section, which give the general character of all the beds from which the fossils were derived, as well as the thickness of the beds, and the depths at which they occur. VERTICAL SEctTION, showing the position of the Fossiliferous Strata passed through while sinking the Shaft of the Hamstead Colliery. Depth from +1 Srfits in z hickness of Description of Bed. Fossil Contents. ed in yards. yards. Surface to Ao Red and brown sandstones, and 209 yards. light red marls. 209 2 Light marl. (?) Rachis of Fern. 243 34 Red Marl. Odontopteris Lindleyana, Sternb. | 2674 Unconformity. 336-346 10 Red marls (44 yards) and red | Pecopteris arborescens, Schl., sp. sandstone. Raindrop impres- “A unita, Brongt. sions and desiccation cracks 5 Miltoni, Artis, sp. occur at depth of 336 yards | Newropteris ovata, Hoffm. 3 in a blue band 6 inches thick. s Scheuchzert, Hoffm. = The “Spirorbis” Limestone iS jlexuosa, Sternb. a occurs at a depth of 341 yards | Alethopteris aquilina, Schl., sp. = 1 foot, with a thickness of | Calamvites, sp. = 8 inches. Annularia stellata, Schl., sp. 2 Sphenophyllum emarginatum, Brongt, 4 Lepidophyllum lanceolatum, L. & H. a, Cyperites bicarinata, L. & H. 5 Cordaites angulosostriatus, G’. Eury. 390 13 Brick-coloured mars. Walchia imbricata, Schimper. 400 54 Light purple rocky marl. Neuropteris rarinervis, Bunbury. 411 3 Purple and red shale. Calamites, sp. Pecopteris Miltoni, Artis, sp. Pecopteris, sp. Neuropteris rarinervis, Bunbury. Annularia stellata, Schl. Cyperites bicarinata, L. & TH. Lepidostrobus, sp. Stigmaria ficoides, Sternb., sp. [ Walchia imbricata, Schimper. FOSSIL FLORA OF THE STAFFORDSHIRE COAL FIELDS. 319 VERTICAL SECTION—continued. Depth from Surface in yards. ==) 440 Upper Coal Measures. oe Middle Coal Measures. 615 623-625 i 533-536 Thickness of Bed in yards. Description of Bed. Fossil Contents. 3 Red sandstone and grey shale. Unconformity and erosion of strata. Measures below this assume a much purpler hue. Blue bind. Grey shale. Dark grey clod, marine beds. Purple and grey shales. Top of “thick coal.” Shales above it devoid of fossils. Shales with ironstones. A few fossils, chiefly Stigmaria. “ Heathen coal.” Calamites Suckowti, Brongt. Calamites undulatus, Sternb. Calamites varians, Sternb. (var.). Alethopteris decurrens, Artis, sp. Lepidodendron Wortheni, Lesqx. Lepidostrobus variabilis, L. & H. Sigillaria, sp. Pinnularia capillacea, L. & H. Sternbergia approximata, Brongt., sp. Calamites varians, Sternb., (var.). Calamocladus equisetiformis, Schl., sp. Lepidodendron aculeatum, Sternb. Lepidostrobus variabilis, L. & H. Sigillaria reniformis, Bet. Sigillaria mamillaris, Bet. Sigillaria, sp. Cyperites bicarinata, L. & H. Stigmaria ficoides, Sternb., sp. Cordaites, sp. Cardiocarpus Meachemit, Kidst., n. sp. Carpolithus ovoideus, Gopp. & Berger. Edmondia rudis, M‘Coy. Productus semireticulatus, Martin. $5 scabriculus, Martin. Edmondia rudis, M‘Coy. Modiola lingualis, Phill. Anthracosia Urei, Flem, (= A. acuta), Sow. Leda attenuata, Flem. Goniatites, sp., allied to G. ewcavatus, Phill. Schizodus, allied to S. carbonarius, Portl. Calamites Suckowu, Brongt. Neuropteris rarinervis, Bunbury. Mariopteris muricata, Schl., var. nervosa (Brongt., sp.). The Fossil Plants can be most conveniently considered in connection with their geolo- gical positions. I. Those from the Upper Coal Measures, comprising the strata passed through from the surface to a depth of 451 yards. 320 MR ROBERT KIDSTON ON THE II. Those from the Middle Coal Measures, beginning at a depth of 451 yards, and comprising the remaining strata passed through. I. Toe Frora oF THE Upper Coat MEASURES. Calamites, Suckow. Group —Calamitina, Weiss., Steinkohlen Calamarien, part ii. p. 59, 1884. Calamitina (Calamites) varians, Sternb., var. Calamites varians, Sternb., Vers., i. p. 50, pl. xii. Horizon :—At a depth of 440 yards. Group II—Stylocalamites, Weiss., wdid., p. 119. Stylocalamites (Calamites) Suckowii, Bronet. Calamites Suckowii, Brongt., Hist. d. végét. foss., p. 124, pl. xiv. fig. 6; pl.xv. figs. 1-6 ; pl. xvi. figs. 2-4 (fig. 12). * Horizon :—At a depth of 440 yards. Stylocalamites (Calamites) undulatus, Sternb. Calamites undulatus, Sternb., Vers., i. fase. 4, p. xxvi.; Vers., ll. p. 47, pl. i. fig. 2; pl. xx. fig. 8. Calamites undulatus, Zeiller, Flore foss. du bassin houiller de Valenciennes, pl. liv. fig. 1, 1886. Calamites undulatus, Brongt., Hist. de végét. foss., p. 137, pl. xvii. figs. 1-4. Calamites Suckowit, var. undulatus, Weiss., Steinkohlen Calamarien, part ii. p. 135, pl. xvii. fig. 4, and text figure, p. 135, 1884. Remarks.—This plant is regarded by several writers as a distinct species, but by others as a variety of Calamites Suckowu, Brongt. Horizon :—At a depth of 440 yards. Calamites, sp. Remarks.—Several fragments, which, however, cannot be specifically determined, occur at depths of 336 and 411 yards respectively. Annularia, Sternb. Annularia stellata, Schloth., sp. Casuarinites stellatus, Schloth., Flora d. Vorwelt, p. 32, pl.i. fig. 4. Annularia longifolia, Brongt., Prodrome, p. 156. Asterophyllites equisetiformis, L. and H. (not Schloth.), Yossil Flora, vol. ii. pl. exxiv. Fruit.—Bruckmannia tuberculata, Sternb., Vers., i. fasc. 4, p. xxix, pl. xlv. fig. 2. Horizons :—At depths of 336 and 411 yards. FOSSIL FLORA OF THE STAFFORDSHIRE COAL FIELDS. 321 Sphenophyllum, Brongt. Sphenophyllum emarginatum, Brongt. Sphenophyllum emarginatum, Brongt., Prodrome, p. 68. Sphenophyllum emarginatum, Zeiller, Flora foss. du bassin houiller de Valenciennes, pl. Ixiv. figs. 3-5, 1886. Horizon :—At a depth of 336 yards. Neuropteris, Brongt. Neuropteris rarinervis, Bunbury. Neuropteris rarinervis, Bunbury, Quart. Jour. Geol. Soc., vol. iii. p. 425, pl. xxii. Horizons :—At depths of 400 and 411 yards. Neuropteris ovata, Hoffm. Neuropteris ovata, Hoffmann, Keferstein’s Zewchland geognostisch-geologisch dargestellt, vol. iv. p. 158, pl. id. figs. 5, 6, 7 (excl. fig. 8), 1826. Neuropteris ovata, Kidston, Trans. Roy. Soc. Edin., vol. xxxiii. p. 359, pl. xxii. fig. 1.* - Horizon :—At a depth of 366 yards. Neuropteris Scheuchzeri, Hoffm. Neuropteris Scheuchzert, Hoffm., Keferstein’s Teuchland geognostisch-geotogisch dargestellt, vol. iv. p. 158, pl. id. figs. 1-4, 1826. Neuropteris Scheuchzert, Kidston, Trans. Roy. Soc. Edin., vol. xxxiii. p. 356, pl. xxiii. figs. 1-2.* Horizon :—At a depth of 336 yards. Neuropteris flexuosa, Sternb. Osmunda gigantea, var. B, Sternb., Vers., i. pp. 36 and 39, pl. xxxii. fig. 2. Neuropteris flecuosa, Sternb., Vers., i. fase. iv. p. xvi. — Neuropteris flecuosa, Brongt., Hist. d. végét. foss., p. 239, pl. lxviii. fig. 2; pl. Ixv. figs. 2, 3. Horizon :—At a depth of 336 yards. a Odontopteris, Brongt. Odontopteris Lindleyana, Sternb. Odontopteris Lindleyana, Sternb., Vers., ii. p. 78. Odontopteris obtusa, L. and H. (not Brongt.), Fossil Flora, vol. i. pl. xl. Horizon :—At the depth of 243 yards. * Where remarks and further references will be found. ey) i) LN) MR ROBERT KIDSTON ON THE Pecopteris, Bronet. Pecopteris arborescens, Schloth., sp. Filicites arborescens, Schloth., Flora d. Vorwelt, p. 41, pl. viii. figs. 13, 14. Pecopteris arborescens, Brongt., Hist. d. végét. foss., p. 310, pls. cii. ciii., figs. 2, 3. Pecopteris arborescens, Kidston, Trans. Roy. Soc. Edin., vol. xxxiii. p. 366.* Horizon :—At a depth of 336 yards. Pecopteris unita, Brongt. Pecopteris unita, Brongt., Hist. d. végét. foss., p. 342, pl. exvi. figs. 1-5. Pecopteris unita, Kidston, Trans. Roy. Soc. Edin., vol. xxxiii. p. 367, pl. xxiv. figs. 2-9.* Horizon :—At a depth of 336 yards. Pecopteris Miltoni, Artis, sp. Filicites Miltoni, Artis., Antedil. Phyt., pl. xiv. Pecopteris Miltoni, Kidston, Trans. Roy. Soc. Edin., vol. xxxiii. p. 374.* Pecopteris abbreviata, Brongt., Hist. d. végét. foss., p. 337, pl. cxv. figs. 1-4. Horizon :—At a depth of 336 yards. Alethopteris, Sternb. Alethopteris decurrens, Artis, sp. Filicites decurrens, Artis, Antedil. Phyt., pl. xxi. Alethopteris decurrens, Zeiller, Flore foss. du bassin houiller d. Valenciennes, pl. xxxiv. figs. 2, 3; pl. xxxv. fig. 1; pl. xxxvi. figs. 3, 4. Pecopteris heterophylla, L. and H., Foss. Flora, vol. i. pl. xxxviii. Pecopteris Mantelli, Brongt., Hist. d. végét. foss., p. 278, pl. Ixxxiii. figs. 3, 4. Remarks.—This is most probably only a variety of Alethopteris lonchitica, Schloth., sp., with which I have previously united it. Horizon :—At a depth of 440 yards. Alethopteris aquilina, Schloth., sp. Filicites aquilina, Schloth., Flora d. Vorwelt, p. 38, pl. iv. fig. 7; pl. v. fig. 8. Horizon :—At a depth of 336 yards. * Where remarks and further references will be found. FOSSIL FLORA OF THE STAFFORDSHIRE COAL FIELDS. 323 Lepidodendron, Sternb. Lepidodendron Worthenii, Lesquereux. | Lepidodendron Worthenii, Lesqx., Coal Flora of Pennsyl., vol. 11. p. 388, pl. Ixiv. figs. 8, 9. Lepidodendron Worthenii, Zeiller, Flore foss. du bassin houiller d. Valenciennes, pl. 1xxi. Horizon :—At a depth of 440 yards. Lepidophyllum, Bronet. Lepidolphyllum lanceolatum, L. and H. Lepidophyllum lanceolatum, L. and H., Fossil Flora, vol. i. pl. vii. figs. 3, 4. Horizon :—At the depth of 336 yards. Lepidostrobus, Bronet. Lepidostrobus variabilis, L. and H. Lepidostrobus variabilis, L. and H., Fossil Flora, vol. i. pls. x. xi. Horizon :—At a depth of 440 yards. Lepidostrobus, sp. Horizon :—At a depth of 411 yards. Sigillaria, Bronst. Sigillaria, sp. Horizon :—At a depth of 440 yards. Cyperites bicarinata, L. and H. Cyperites bicarinata, L. and H., Fossil Flora, vol. i. pl. xliii. figs. 1, 2. Remarks.—The grass-like leaves placed under Cyperites bicarinata are the foliage of Sigillaria, and probably also of some species of Lepidodendron. These fossils, as far as I have been able to observe, have not two veins as supposed by Linpiey and Hurron. The little ledges formed by the two sides of a flat, central, single vein, form protected lodgments for the carbonaceous matter of the leaf, and often after the greater part of this substance has been removed from the other portions of the fossil, the prominence of these two lines of carbonaceous material, which frequently conceal the two edges of the mid-rib, have given rise to the erroneous opinion that the leaves contain two veins.* * Lepidophyllum trinerve, L. and H., vol. ii. pl. clii.; Lepidophyllum binerve, Lebour ; Illustrations of Fossil Plants p- 103, pl. lii., are subject to the same explanation. 324 MR ROBERT KIDSTON ON THE Stigmaria, Brongt. Stigmaria ficoides, Sternb., sp. Variolaria jicoides, Sternb., Vers., i. fase. i. pp. 22, 24, pl. xii. figs. 1-3. Stigmaria ficoides, Brongt., Class. d. végét. foss., p. 28, pl. i. fig. 7. Horizon :—At a depth of 411 yards. Pinnularia, L. and H. Pinnularia capillacea, L. and H. Pinnularia capillacea, L. and H., Fossil Flora, vol. ii. pl. exi. Remarks.—Probably rootlets of various plants. Horizon :—At a depth of 440 yards. Cordaites, Unger. Cordaites angulosostriatus, Grand’ Eury. Cordaites angulosostriatus, Grand’ Eury, Flore Carbon. du Départ. de la Loire, p. 217, pl. xix. Cordaites angulosostriatus, Zeiller, Végét. foss. d. tery. howill., p. 144, pl. clxxv. figs. 2, 3. Horizon :—At a depth of 336 yards. Sternbergia, Artis. Sternbergia approximata, Bronet. Sternbergia approximata, Brongt., Prodiome, p. 137. ; Sternbergia approximata, L. and H., Fossil Flora, vol. iii. pls. cexxiv.—cexxv. Remarks.—The fossils described as Sternbergia (and Artisia) are casts of the pith cavity of stems of Cordaites. Horizon :—At a depth of 440 yards. Walchia imbricata, Schimper. (Fig. 9.) Walchia imbricata, Schimper, Trait. d. palednt. végét., vol. ii. p. 239, pl. lxxiii. figs. 3, 3a, 30. Walchia imbricata, Renault, Cours. d. botan. foss., Quatrieme Anué, p. 85, pl. viii. figs. 7, 8, 1885. Description—Stem bearing closely placed distichous branches, patent, slightly curved. Stem leaves loosely imbricated, linear, thick, incurved, blunt with a sharp point, keeled, about 1 centimetre long. Branch leaves densely imbricated, short, sub- squamiform, pointed-obtuse, thick, back distinctly keeled. FOSSIL FLORA OF THE STAFFORDSHIRE COAL FIELDS. 325 Remarks.—Two specimens of this, the first true conifer I have met with in British Carboniferous rocks, have been found during the sinking of the shaft. That figured comes from a bed of red marl at a depth of 350 yards from the surface ; the other specimen is from a similar red bed, but at a depth of 411 yards. Fig. 9 is taken from the first-mentioned specimen, and shows a number of lateral branches springing from the main stem. ‘The leaves on the branchlets are tolerably well shown at various parts of the fossil, but the main stem is indistinct, and does not show any foliage. The stem leaves of this species are figured by Scutmprr. Both branch and stem leaves are distinctly keeled from the presence of a prominent mid-rib. The second example only shows a number of Jateral branchlets, and is not so well preserved as that given at fig. 9. ScHenk* unites Walchia imbricata and W. flaccida, Gipp., to W. piniformis, Schloth., sp., as younger conditions of development. The same author also unites several other species of Walchia with W. pinifornus. As there appears to be some difference of opinion as to the value of some of these species, I provisionally adopt Scuimprer’s name for the Hamstead plant, with whose figure and description it agrees in all respects. Walchia is essentially a Permian genus, but on several occasions W. piniformis, Schloth., sp., has been recorded from the Coal Measures.t Conversely, several species which attain their maximum development in the Coal Measures extend into the Permian formation. In fact, there is a much greater similarity between the flora of the Upper Coal Measures and that of the Permian than exists between that of the Upper and Lower Carboniferous Rocks. . In stating that this record of W. imbricata is the first occurrence of a coniferous plant in the Carboniferous Rocks of Great Britain, it should be mentioned that there is now the strongest evidence to show that the stems previously supposed to be coniferous (Araucarioxylon) are cycadaceous.t Horizons :—At depths of 350 and 411 yards. II. Tae Fiora oF tHE MippLeE Coat MEASURES. A very imperfect idea is afforded of the richness of the flora of the Middle Coal Measures, as developed in South Staffordshire, from the few specimens collected at _ Hamstead; but the meagre list of species recorded gives sufficient data for the comparison of the flora of the two divisions of the Coal Measures occurring at Great Barr. * Zittel’s Handbuch d. paleont., Band ii. Lief iii, p. 272, 1884. t Zeiller, Véget. foss. du terr. howil., p. 1385; Geinitz, Vers. d. Stinkf. in Sachsen, p. 33. f See Grand’ Eury, Flore Carbon. du Départ. de la Loire, p. 249, 1877; Schenk, in Zittel’s Handbuch d. Paleont., Band ii. Lief iii, p. 243, 1884; Renault, Cours. d. botan. foss,, 1881, p. 82. VOL. XXXV. PART 6. 3H MR ROBERT KIDSTON ON THE Calamites, Suckow. Calamitina (Calamites) varians, Sternb. Horizon :—At a depth of 533 yards. Stylocalamites (Calamites) Suckowii, Bronet. Horizon :—At a depth of 584 yards. Calamocladus, Schimper. Calamocladus equisetiformis, Schloth., sp. Casuarinites equisetiformis, Schloth., Flora d. Vorwelt, p. 30, pl. i. figs. 1, 2; pl. ii. fig. 3. Calamocladus equisetiformis, Schimper, Trazté d. palednt. végét., vol. i. p. 324, pl. xxii. figs. 1-3. Hippurites longifolia, L. and H., Fossil Flora, vol. iii. pls. exe., exci. Horizon :—At a depth of 533 yards. Neuropteris, Bronet. Neuropteris rarinervis, Bunbury. Horizon :—At a depth of 584 yards. Mariopteris, Zeiller. Mariopteris muricata, Schloth., sp., var. nervosa. Pecopteris nervosa, Brongt., Hist. d. végét. foss., p. 297, pl. xciv.; pl. xev. figs. 1, 2. Pecopteris nervosa, L. and H., Fossil Flora, vol. ii. pl. xciv. Horizon :—At a depth of 584 yards. Lepidodendron, Sternb. Lepidodendron aculeatum, Sternb. Lepidodendron aculeatum, Sternb., Vers., i. fase. i. pp. 20 and 23, pl. vi. fig. 2; pl. viii. fig. 10; fase. i, p. 25, pl. xiv. fig. 1-4; fase. iv. p. x. Lepidodendron aculeatum, Zeiller, Flore foss. du bassin houiller d. Valenciennes, pl. xv. Horizon :—At a depth of 533 yards. FOSSIL FLORA OF THE STAFFORDSHIRE COAL FIELDS. 327 Lepidostrobus, Brongt. Lepidostrobus variabilis, L. & H. Horizon :—At a depth of 533 yards. Sigillaria, Brongt. Sigillaria reniformis, Brongt., fig. 11. Sigillaria reniformis, Brongt., Hist. d. végét. foss., p. 470, pl. exlii. Sigillaria reniformis, Goldenberg., Flora Sarep. foss., Heft ii. p. 50, pl. viii. fig. 31. Sigillaria reniformis, Sauveur, Végét. foss. de la Belgique, pl. 1. fig. 1. Sigillaria reniformis, Zeiller, Flore foss. d. bassin houiller de Valenciennes, pl. Ixxxiv. figs. 4-6. Sigillaria cactiforms, Goldenberg, Flora Sarxp. foss., Heft i. p. 26, pl. iv. fig. 1. Description.—Ribs wide, straight, smooth. Leaf scars reniform, approximate or dis- tant, lateral angles distinct but not prominent. Vascular cicatricules; the two lateral lunate, central punctiform. Above the scar is occasionally a small cicatricule, and between each scar is a transverse line. Decorticated stem longitudinally striate; cicatricules geminate, the two parts oval, united with each other or separate, varying much in shape with age. Remarks.—The small specimen figured shows considerable difference in the size of the leaf scars and their relative distance apart. ‘Towards the centre of the specimen the leaf scars are smaller than those both above and below them, and the scars on the lower part of the specimen are much closer together than those at the top of the fossil. From the peculiar condition in which this specimen has been preserved, the sub- cortical cicatricules are discernible through the bark, as distinctly defined oval elevations, which are visible in most of the leaf scars. One of these scars enlarged at fig. lla shows this clearly. Fig. 11b gives the normal condition of the outer surface of the leaf scar, and is a reproduction of fig. 11a, with the subcortical cicatricules omitted. From this specimen is learnt the position held by the lateral cicatricules of the leaf scar to its germinate cicatricules of the decorticated stem. Had any evidence been necessary to prove that the genus Syringodendron, Stern- berg, was only a decorticated condition of Sigilaria, such evidence is afforded by the specimen now figured. Sigillaria reniformis, Brongt., is easily distinguished from Sigillaria Sawveurs, Zeiller,* by the presence in the former species of a notch on the upper margin of the leaf scar, and the absence of the transverse wrinkling below the scars. In regard to the function performed by these lateral lunate cicatricules, as exhibited on the outer surface of the leaf scars, there is every reason to believe that they are the * Zeiller, Flore foss. d. bassin houiller de Valenciennes, p. 559, pl. Ixxxiv. figs. 1-3. 328 MR ROBERT KIDSTON ON THE orifices of two secreting glands which are placed beneath the bark. These glands pro- bably fulfilled their secreting function (whatever the nature of the secretion may have been) after the fall of the leaf, and throughout the whole life of the plant, and considering the great number of such glands on each plant of Sigillaria, Renavut throws out the suggestion that perhaps it might be asked if the secretion from these glands does not form a large part of the inorganic matter found in coal.* The faint striations on the surface of the stem drawn at fig, 11 are caused by the striations on the subepidermal surface, which have been imparted to the outer surface by pressure. Horizon :—In Blue Bind at a depth of 533 yards.t Sigillaria mamillaris, Bronet. Fig. 10. Sigillaria mamillaris, Brongt., Hist. d. végét. foss., p. 457, pl. exlix. fig. 1; pl. clxiii. fig. 1 (var. intermedia). Sigillaria mamillaris, Goldenberg, Flora Sarexp. foss., Heft ii p. 32, pl. viii. figs. 6-8 (fig. 8, var. intermedia). Sigillaria mamillaris, Weiss, Foss. Flora d. jiingst. Stk. u. d. Rothl., p. 164, pl. xv. figs. 1-4 (figs. 1, 2; var. abbreviata, fig. 4, var. elongata). Sigillaria mamilluris, Zeiller, Flore foss. du bassin houiller de Valenciennes, pl. Ixxxvii. figs, 5-10. Sigillaria pyriformis, Brongt., Hist. d. végét. foss., p. 448, pl. cliii. figs. 3, 4. Description.—Ribs straight or slightly flexuous, separated by a well-defined furrow. Leaf scars hexagonal or pyriform-hexagonal, as broad as long, or longer than broad, lateral angles distinct (especially in the forms with hexagonal leaf scars.) The surface, of the leaf scar is elevated from above downwards, so that the inferior margin stands at a higher level than the superior margin; the interfoliar portion of the ribs immediately below the leaf scar slopes downwards, the leaf scar is thus placed on the upper slope of an elevated cushion. Vascular cicatricule punctiform or slightly elongated transversely, lateral cicatricules lunate-elongate. Leaf scars somewhat close or more distant. The interfoliar portion of the cushion on which the leaf scars sit, bears two lines of transverse wrinkles, between which the wrinkles frequently extend, and thus cover the whole of the interfoliar portion of the cushion. Above the leaf scars is a well-defined arched transverse furrow. Cone scars, quadrate or irregular-triangular, with a central subcircular cicatrice, situated on the ribs, and forming a verticil of several series. Decorticated stem striated longitudinally, and showing the three cicatricules, the lateral cicatricules almost straight or occasionally lunate and united at their extremities, thus forming a circle surrounding the vascular cicatricule. * Renault, “ Sur les cicatrices des Syringodendron,” Comptes Rendus, 24th October 1887. + The lateral cicatricules in the leaf scars of Lepidodendron, Lepidophloios, and Bothrodendron, probably performed the same function, When the structure of these lateral cicatricules is examined, they never show any trace of vascular tissue, but are filled with lax parenchyma, A good figure of their structure is given by Dr Felix (Untersuchungen fiber den Baw weslfilischer carbon Pflanzen, pl. ii. fig. 3 f, Kénig Preusseschen geol. Landesanslalt, 1886. FOSSIL FLORA OF THE STAFFORDSHIRE COAL FIELDS. 329 | Remarks.—Vhough the leaf scars of Sigilaria mamullaris are variable in the propor- tion of their length to their breadth, it is an extremely well-characterised species. The oradual elevation of the leaf scar from above downwards affords a character by which it is distinguished from several named forms, some of which are, however, most probably Sigillaria mamillaris in a different state of preservation. Of these may be specially mentioned Srgilaria pyriformis, Brongt., which does not appear to differ in any essential character, except that the leaf scars are horizontal with | the surface of the ribs—a distinction arising in all likelihood from pressure. Sigillaria / pyriformis is therefore united here with Sigidlaria mamillaris. | Other very close allies are Sigillaria elliptica, Brongt.,* and Sigillaria notata, Steinhauer, sp.t | This latter species differs chiefly in the leaf scars being of less width than the breadth of the ribs. STEINHAUER’S example came from the coal pits of Dunkerton, Somerset, which are now closed. I have, however, searched in Somerset for specimens of Sigillarie that could be referred to Sig. notata, Steinhauer, in shales associated with coals on the same horizon as that from which the original specimens came, but without success. The specimen of Sig. notata, figured by BroneniartT, came from Anzin, near Valen- ciennes,{ and Boutay remarks §{—“ Broneniart indicates this species from Anzin. 1 have collected very well-characterised specimens of it at the pit of Petite-Sorciére, near Jemmapes (Belgium). This plant, which Bronentart regarded as allied to Sigiularia elluptica, is more closely allied to Sigillaria mamillaris, of which it might well be only a condition or a fragment.” The question whether Sig. elliptica, Brongt., and Sig. notata, Steinhauer, sp., are only forms of S. mamullaris, or individual species, must therefore in the meantime remain open. Horizon :—In Blue Bind, at a depth of 533 yards. Sigillaria, sp. Horizon :—At a depth of 533 yards. | Cyperites bicarinata, L. and H. Horizon :—At a depth of 533 yards. Stigmaria, Brongt. . | Stigmaria ficoides, Sternb., sp. | Horizon :—At a depth of 533 yards. | | * Brongt., Hist. d. végét. foss., p. 447, pl. clii. figs. 1,2; pl. clxiii. fig. 4. + Steinhauer, Trans. Amer, Phil. Soc., 1818, p. 294, pl. vii. fig. 3 (Phytolithus notatus). { Brongt., Hist. d. végét. foss., p. 449, pl. cliii. fig. 1. § Boulay., Le terrain howiller du Nord de la France et ses végétaua fossiles, p. 43, Lille, 1876. 330 MR ROBERT KIDSTON ON THE Cordaites, Unger. Cordaites, sp. Horizon: —At a depth of 533 yards. Cardiocarpus, Brongt. Cardiocarpus Meachemii, Kidston, n. sp., figs. 5-7. Description.—Seed cordate, about 13 mm. broad, 13 mm. long, base emarginate, apex acute. Nucule cordate, central, with a medial line extending from the base to the apex. Wing about 4 mm. broad. Remarks.—Several of these little seeds are given on figs. 5-7. That at fig. 5a shows the outline of the seed, but the form of the nucule is not clearly defined ; this deficiency is supplied by the isolated nucule given at fig. 7. The margin of the specimen shown at fig. 6 is not distinctly exhibited in the fossil, but there is an indica- tion of a line surrounding the nucule, about halfway between the nucule and the margin of the wing. The apparent emarginate apex of fig. 5b is the result of an accidental splitting of the testa. Cardiocarpus Meachemui is closely allied to the Cardiocarpus figured by FEISTMANTEL as C. emarginatum, Gépp. and Berger (not Brongt.),* and differs only in its smaller size. My chief reason, therefore, for applying a new name to the Hamstead seeds is the circumstance that there is little evidence to show that the specimens figured by Frtst- MANTEL are similar to the Cardwocarpum emargimatum, Gbpp and Berger t—in fact, from the imperfect nature of the figures given by these authors, it seems impossible to arrive at what are the true characters of their species. Should FEIstMANTEL’s specimens eventually prove to be specifically similar to my Cardiocarpus Meachemu, his fossils might be distinguished as var. major. I have pleasure in naming this seed after Mr F. G. MEacHEm. Horizon :—In Blue Bind, at a depth of 533 yards. Carpolithus, Sternb. Carpolithus ovoideus, Gépp. and Berger, sp. Fig. 8. Rhabdocarpus (?) ovoideus, Weiss, Foss. Flora d. jiingst. Stk. u. d. Rothl., p. 206, pl. xvii.. fig. 4; pl. xviii. figs. 10-14, 18-21. Rhabdocarpus ovoideus, Gopp. and Berger, De fructibus et seminibus, p. 22, pl. 1. fig. 17. Rhabdocarpus ovoideus, Goppert, Foss. Flora d. Perm. Form., p. 173, pl. xxvii. figs. 9, 10. Rhabdocarpus Germarianus, Goppert, Foss. Flora d. Perm. Form., p. 270, pl. Ixiv. fig. 14. Carpolithus membranaceus, Gopp. and Berger, De fructibus et seminibus, p. 25, pl. ii. figs, 19, 20. Carpolithus membranaceus, Goppert, Foss. Flora d. Perm. Form., p. 178, pl. xxix. figs. 19-21. (?) Carpolites ellipticus, Sternb., Vers., i. fase. 4, p. xl. pl. vii. fig. 1. (?) Carpolites regularis, Sternb., Vers., 1. fasc. 4, p. xl. pl. vii. fig, 2. * Vers. d. Bohmaschen Kohlenablagerungen, Abeth. ii. p. 46, pi. xx. figs. 4-6. + Gopp. and Berger, De fructibus et seminibus, p. 24, pl. iii. fig. 35. FOSSIL FLORA OF THE STAFFORDSHIRE COAL FIELDS. 331 Description.—Small oval or elliptical seeds, sometimes almost circular from pressure acting in the direction of their axis; one or both extremities rounded, or more or less pointed. Seeds bracteate, sessile, borne in two opposite alternate rows on a spike-like axis. Remarks.—The form of these little seeds much depends on the direction in which pressure has acted upon them. When flattened with pressure acting at right angles to their axis, they are usually elliptical and pointed, as at fig. 8b, 8d; but when pressure acts on the apex or base of the seed, they are more or less circular, as at 8c. Between these two extremes are intermediate forms. The surface of the seeds generally shows foldings of the testa, and in some cases the seeds appear to have a narrow surrounding border ; but this appearance is also due to pressure. Horizon :—Many specimens on the surface of a small slab, of which fig. 8 gives four examples, from a depth of 550 yards. GENERAL REMARKS. From an examination of the foregoing lists, it will be seen that a proportion of the species recorded are common to both horizons. Annularia stellata, Sphenophyllum emarginatum, Neuropteris ovata, Newropteris Scheuchzeri, Neuropteris flecuosa, Odontopteris Iindleyana, Pecopteris arborescens, Pecopteris unta, Lepidodendron Worthen, Cordaites angulosostriatus, and Walchia imbricata are, however, specially characteristic of British Upper Coal Measure rocks, though a few of these species have been observed in the Middle Coal Measures, but there they are much more scarce. The Middle Coal Measure facies of the flora, collected from the strata of that horizon at Hamstead, is more characterised by the absence of Upper Coal Measure species than by the occurrence of species restricted to the Middle Coal Measures. Sigillaria mamallaris is, however, a specially characteristic Middle Coal Measure plant. On the publication of lists of the fossil flora of the South Staffordshire Middle Coal Measures, the peculiar characteristics of the Middle Coal Measure flora will be much more distinctly seen. In comparing the list of fossils from the Upper Coal Measures of Hamstead with those of the Upper Coal Measures of the Radstock and Farrington series of the Somerset Coal Field, one cannot fail to be struck with the great similarity of their fossil contents. All those found at Hamstead, with the exception of Calamuites undulatus (which may be only a form of C. Suckowit), Alethopteris decurrens (which is, perhaps, a variety of A. lonchitica that occurs at Radstock), Lepidophyllum lanceolatum, and Lepidostrobus variabilis,—all occur in the Radstock series, and the greater part of the species also occur in the Farrington series. From the Red Shales which separate the Radstock and Farrington Series I have seen few vegetable remains, BBY MR ROBERT KIDSTON ON THE but, as the Hamstead plants are found both below and above these Radstock red shales, it is clear that they existed during the deposition of these beds; and further, the few fossils which I have seen from them are similar to those of the Radstock and Farrington series, I therefore conclude that the Upper Coal Measure red shales that overlie the Middle Coal Measures at Hamstead are a northern extension of the red shales which form such a well-marked horizon over a considerable portion of the Somerset Coal Field. The Molluscan remains, for whose identification I am indebted to Mr Jonn Youne, F.G.8., are of considerable interest, and bring forcibly forward some points in their vertical distribution which do not appear to have received the attention they deserve. Mr Meacuem informed me that, through an accident happening to the collection, a number of the specimens of shells were completely destroyed, and among these was a Huomphalus. The species examined and identified do not, therefore, represent the whole fauna collected, but only those that are still preserved. The Mollusca identified are— Productus semireticulatus, Martin. Productus scabriculus, Martin. Edmondia rudis, M‘Coy. Schizodus, sp., allied to S. carbonartus, Portl. Modiola lingualis, Phill. Anthracosia Urei, Flem. Leda attenuata, Flem. Goniotites, sp., allied to G. ewcavatus, Phill. Leaving out of consideration those individuals which are only generically identified, two of the species, Modiola lingualis and Leda attenuata, have been recorded from the upper beds of the Calciferous Sandstone series.* P. semireticulatus, P. scabriculus, and Edmondia rudis are frequent in the Carboniferous Limestone series of Scotland, while Anthracosia Urev is usually restricted to the Lower Coal Measures. Any one, judging of the age of the rocks from the Molluscan remains, would, without doubt, class them as Lower Carboniferous, whereas they are undoubtedly of Upper Coal Measure age. This case is not an isolated one, and Mr Jonn Youne has referred to such occurrences in his paper entitled “‘ Notes on the Occurrence and Range of Lingula in the Carboni- ferous Series of the West of Scotland.”+ Speaking of the apparent extinction and reappearance of an organism in a higher horizon, the paper concludes with the following remark :—‘ Of such changes we have evidence in several of our coal seams, formed of the remains of a terrestrial vegetation accumulated in swamps at or near the sea level, and now found to be overlaid by a great thickness of fossiliferous marine strata. But * Mem. Ceol. Survey of Scotland, Explan. to sheet 23, Lanarkshire Central District, p. 57. + Trams. Geol. Soc. of Glasgow, vol. ii. p. 144. FOSSIL FLORA OF THE STAFFORDSHIRE COAL FIELDS. BB wherever we find a sudden extinction of the organic life in any stratum, we are not to suppose that such extinction was universal. In most cases it must have been com- paratively local, for a total extinction would imply a new creation of the same forms in every succeeding stage of strata in which they are met. The most probable supposition is, that during all the long geological ages in which our fossiliferous strata were being deposited, or from ‘the first appearance of life on our globe, there never has been, at any one time, a total extinction of the flora or fauna from the remote period till the present time ; and when we find in our Coal Measures the constant reappearance of certain well- _ known species after each local extinction, in higher and higher stages of strata in the same locality, we are naturally led to conclude that, while they become extinct over these tracts, they must have continued flourishing in other parts of our Carboniferous sea, and that they spread from these spots into their old localities wherever the condition of the sea-bottom again became favourable to their growth and development.” In a letter, dated October 26, 1887, he further says:—‘ There can be no doubt of the repeated occurrence in higher and higher horizons of many of the marine and fresh water forms of life found in our Scottish Coal Measures. Since this paper (that quoted above) was printed, I have been able to trace other forms besides Lingula, that range from the very lowest fossiliferous marine beds up into that of the Permian Formation. It is, therefore, quite unsafe to take any one organism as characteristic of any special horizon, for closer investigation of the strata in any country is constantly proving their recurrence or occurrence in higher or lower beds.” Now, with organisms possessed with the property of locomotion, this is quite what may be expected. As the conditions became unfavourable for their growth and existence, they would remove to more suitable situations. Of course, conditions may arise which are unfavourable to the life of organisms that previously flourished in a given locality ; and should no favourable conditions arise or exist within suitable distances for migration, there would be a total local extinction of species, which, perhaps, might extend over large areas, but that such occurrences were not universal is evidenced by the repeated recurrence of species in higher and higher zones, separated by great masses of strata destitute of their remains. In regard to plants the case is different. They being fixed to the localities in which they grow, are of necessity obliged to succumb should any subsidence or unfavourable condition for their growth arise, and did the conditions again become favourable, de- scendants from the original individuals could never more return. Of course, similar species were no doubt flourishing in other localities, and when the subsided area had again been elevated into dry land, it might have been peopled with new individuals of the same species, and it is true that certain species again revisit the old haunts of their kindred, but it is only comparatively few that ever do so, and with them they always bring new associates. Thus the change in the flora gradually pro- gresses. It is also true that there are vast masses of rock that show little change in their flora, VOL. XXXV. PART 6. 31 334 MR ROBERT KIDSTON ON THE but these are succeeded by rocks in which many of the old species have disappeared and new species take their place by the side of the survivors. This state of matters maintains throughout the whole of the Coal Measures, and fur- ther there does not seem to be the same complete disappearance, and then after a time a reappearance of the same old forms, as in the case of the Mollusca, but instead, a constant eradual change. This gradual change is, however, so marked, that it leaves a most sure and certain stamp for the recognition of the comparative age of the rocks in which the fossils occur. This leads me to believe, and every additional experience confirms this opinion, that for the classification and correlation of the rocks of the Carboniferous Formation, the evidence derived from plants is more reliably conclusive, and less liable to variation, than that derived from animal remains. While speaking on this subject I might add further, that from the base of the Car- boniferous Formation to the base of the Millstone Grit, the flora has a facies peculiar to that period, and of the many species of plants occurring in Lower Carboniferous rocks in Britain, it is very doubtful if any species pass into or above the Millstone Grit. I[ have seen slight evidence to think there may be one exception, but as far as I at present know, only one.* From the Millstone Grit, though the difference of the flora is sufficiently clearly defined to admit of a satisfactory threefold division of the Coal Measures, there is no such sudden break as occurs between the Lower and Upper Carboniferous, nor does a sudden break take place even at the top of the Upper Coal Measures, for several of the Upper Coal Measure plants pass into the Permian Formation. For the facilities I have had given me for examining and describing the Hamstead fossils, my thanks are due to Mr J. Meacurem, Manager of the Hamstead Colliery, and especially are they due to Mr Frep. G. Mracnem, by whom the records of the sinking were kept, and from whom I have received the particulars contained in the section given on pp. 318-19. I am also indebted for assistance to Mr H. Instry, Ashton. It is to be hoped that all who have similar facilities for collecting the fossils met with in Pit Sinkings and other mining operations, will avail themselves of these opportunities, as such collections as that made at the Hamstead Colliery, where the horizon of each specimen has been carefully noted, are of the utmost importance in working out British Paleontology. * I exclude Stigmaria, which is the root of several Lycopods, and as none of the Lower Carboniferous Lycopods pass into or above the Millstone Grit as far as I know, Stigmaria, being the root of any one of these Lycopods (Lepidodendron, Sigillaria, Lepidophloios) cannot be regarded as a true, individual species, and though these Lower Carboniferous Stigmaria are individually undistinguishable from the Stigmaria of the Upper Carboniferous, they cannot be regarded as specifically the same. FOSSIL FLORA OF THE STAFFORDSHIRE COAL FIELDS. 395 EXPLANATION OF PLATE (figs. 5-11). Fig. 5-7. Cardiocarpus Meachemit, Kidston, n. sp. From shaft of Hamstead Colliery, Great Barr, oe a depth of 536 yards. Middle Coal Measures. Nat. size. _. Fig. 8. Carpolithus ovideus, Gopp. and Berger. From shaft of Hamstead Colliery, Great Barr, at a depth of 550 yards. Middle Coal Measures. Nat. size. Fig. 9. Walchia imbricata, Schimper. From shaft of Hamstead Colliery, Great Barr, at a depth of 350 ds. Upper Coal Measures. Nat. size. Fig. 10. Segillaria mamillaris, Brongniart. From shaft of Hamstead Colliery, Great Barr, at a depth of yards. Middle Coal Measures. Nat. size. 10a, Leaf scar x 2. - Fig. 11. Stgillaria reniformis, Brongniart. From shaft of Hamstead Colliery, Great Barr, at a depth of 533 yards. Middle Coal Measures. Nat. size. lla, 110, Leaf scars x 2. <7 Trans. Roy. OCs wemm— Vol KRY, R.KIDSTON ON HAMPSTEAD FOSSIL PLANTS AND ON NEUROPTERIS RECTINERVIS. On, del. MiFaclane & Erskine, Lith® Edin? NEUR. PLICATA, Sternd. 2-4, NEUR. RECTINERVIS, Hidston.».s. 5-7, CARDIOCARPUS MEACHEML, Atdston, n.s ~ WARPOLITHUS OVOIDEUS, Gépp.4 Berger: 9,WALCHIA IMBRICATA. 10, SIGILLARIA MAMILLARIS, Brongé . ll, SIGILLARIA RENIFORMIS, Brongt. i ' . ., : a7 x 4 A : = ~ . ° ~ > (337) VII.— Experimental Researches in Mountain Building. By Henry M. Cape. of Grange, B.Sc., F.R.S.E., H.M. Geological Survey of Scotland. (Read 20th February 1888.) PART I. A. On the Behaviour of Strata when thrust over an Immovable Surface. B. On the Origin of Thrust-Planes and “ Fan Structure.” C. On the Relation between Folding and Regional Metamorphism. D. General Summary of Results. Introduction. Among most of the geologists who had of late years been engaged in investigating the structure of the North-West Highlands, and especially among those who did not concur in Murcuison’s explanation of the phenomena exhibited there, it was a growing belief that great overthrusts had been largely instrumental in producing the remarkable strati- graphical relations of the rock masses of that region. After a most careful detailed examination of the ground by the Geological Survey, the existence and importance of such thrusts was not only placed beyond a doubt, but a variety of additional remarkable structures were discovered, which open up new fields of investigation to the physical geologist.* lt occurred to some of my colleagues and myself, after studying these great problems in the field, that experiments might be made to throw light on the work by seeking to imitate in the laboratory the processes we believed to have been in operation in our wild North-West Highlands at an ancient geological period. With the approval of the Director-General of the Geological Survey, I accordingly instituted a series of experiments on these lines. They were conducted at different times during the last two years at Grange, in Linlithgowshire, where all the requisites for the work were ready to hand. The researches, which differed in several particulars from those of former experi- menters in this department, were attended with marked success. The structures obtained in the experiments showed a striking similiarity to those observed in the field, and as the results are otherwise new and important, I now submit them to the Royal Society of Edinburgh. The first part of the following paper will be devoted to a description of the principal experiments, and the structures to which they gave rise. As the results obtained are * Since this paper was read, a detailed account of the structure of the North-West Highlands has been published in the “ Report on the Recent Work of the Geological Survey in that region, based on the Field Notes and Maps of Messrs B. N. Peach, J. Horne, W. Gunn, C. T. Clough, L. Hinxman, and H. M. Cadell” (Quart. Jour. Geol. Soc., August 1888, pp. 378-441). VOL. XXXV. PART 7. 38K 338 MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. far-reaching in their application, not only to the mountains of Scotland, but also to the Alps and other systems of mountains of elevation, I shall postpone the second or theor- etical part of the paper till I have better studied the problems in mountain building to which the experiments seem to afford in some measure a solution, and confine any remarks on the experiments to a bare enumeration of some of the more obvious inferences from these results. DeEscRIPTION OF EXPERIMENTS. In experimenting on the behaviour of stratified rocks when subjected to horizontal pressure, it has been usual to regard great rock masses as practically plastic, and to imitate their plications with correspondingly plastic substances. Sir James HAtt, the father of experimental geology, describes, in an early volume of this Society’s Transac- tions,* how he imitated the foldings of the Silurian strata on the Berwickshire coast by compressing pieces of cloth or layers of clay. Prof. A. Favre,t to whose interesting experiments allusion will afterwards be made, produced miniature alpine ridges with laminee of fine clay, and Prof. F. Prarrf{ tried the effect of horizontal pressure on layers of loam and papier-maché pulp. Davsris,§ the greatest living exponent of experimental geology, departed, however, from the old paths by using a prism of wax which was flexible within certain limits only, and snapped on the application of greater pressure, producing a series of little reversed faults. MErLiarD Raps, in his recent valuable work on the Origin of Mountain Ranges, describes a variety of experiments, some of which resembled those of Prarr’s, and yielded somewhat similar results. He used strata of clay with lubricated surfaces. When the correct interpretation of the structure of the North-West Highlands was arrived at, however, it soon became evident that the rocks in that area had in many cases behaved like brittle rigid bodies, which, instead of undergoing plication when subjected to horizontal compression, had snapped across and been piled together in great flat slices like so many cards swept into a heap on a table. To imitate such phenomena, it was therefore necessary to employ materials of such a kind that they would, when compressed horizontally, snap and give way in definite directions rather than bend into folds like plastic bodies. The idea occurred to me that plaster of Paris, interstratified or mixed with layers of sand, might satisfy the requirements of the case. After several failures, this plan was successful. The dry stucco powder was spread in thin layers between thicker beds of damp sand of different colours, and in a few minutes it had absorbed enough moisture from the porous strata to permit of partial hydration. It “set” into hard brittle lamine, which usually snapped under strain, but in some instances permitted folding to take place. In some of the experiments black foundry loam was used, and when well damped and packed together, proved an excellent material with which to imitate rock-strata, as * Trans. Roy. Suc. Edin,, vol. vii. p. 85. + Nature, xix. p. 108, t Mechanismus der Gebirgsbildung, p. 23. § Géologie expervmentale, p. 321. MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. 339 it was stiff enough to resist much bending, but not too rigid to prevent some interstitial movement throughout the mass. Clay was also used in some cases, usually in associa- tion with less plastic strata. The experiments were of three distinct kinds, The first series (A) was designed to explain the behaviour of different types and arrangements of strata when pushed horizontally over an immovable surface. The object of the second series (B) was to ascertain if possible how gently-inclined “ thrust-planes” may have originated, and to trace their connection with ‘“ fan structure” and other phenomena observed in mountain systems of elevation. The third series (C) was conducted on principles suggested by the experiments of Favre, who placed layers of clay on a stretched india-rubber band, and on allowing it to contract, produced miniature mountain ridges by the wrinkling of the surface of the clay. I extended Favre’s experiments by removing the upper layers of the wrinkled clay, and observing the effect of the contraction on the deep-seated portions of the miniature mountain system. A. Thrusting over an Immovable Surface. The strata were formed in a rectangular box 6 or 8 inches broad and 3 to 5 feet long. One end of the box was movable, and could be pushed in so as to compress longitudinally the strata inside. At the beginning of the experiments, the sliding end piece, which may be called the pressure board, was pushed in, either by hand alone, or if the force required were considerable, with the help of a lever. In the last and most complete series of experiments, the pressure was applied by means of a strong screw running in bearings bolted to the prolonged sole of the box. The sides could be removed at pleasure, when it was desired to examine the section of the distorted strata inside. The figure on the following page gives a general idea of the size and nature of the whole apparatus. In proceeding with the experiments, after the pressure board had been pushed in far enough to produce some marked change in the internal structure of the mass, the side of the box was removed, and the vertical section thus exposed was pared along the edge with a sharp knife, to reveal the beds clearly and remove all traces of friction with the wood. If the results were of interest the section was accurately sketched, traced, or in most cases photographed, a measuring tape having previously been attached alongside of the section to show the scale of the operations in feet and inches. If it were desired to continue the experiment, the side was replaced, and the pressure board pushed further in, after which the new section was examined and recorded as before. In several of the experiments the process was repeated four or five times to indicate the successive steps in the formation of the ultimate structure of the mass. The accompanying figures, selected from some sixty drawings and photographs of the sections obtained in the experiments, tell their own tale, and require but little description. In some cases the section, although easily understood in the laboratory, is much less effective when seen in photographic form. In such cases, to make the meaning clear and 340 MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. bring out the structure effectively, a diagrammatic section from the photograph itself and from notes made at the time it was taken is exhibited alongside. Experiments in Mountain Building. In nearly every instance the pressure was exerted from the right, and the pressure board is seen in the figures supporting that end of the section. The thin white streaks pe A MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. 341 are the edges of the plaster of Paris laminz separating thicker layers of damp sand. These white beds were often so hard as to offer much resistance to the paring knife, and great care was required to avoid tearing the material out in cakes, and leaving cavities between the softer sand beds. In this experiment (fig. 1) the strata had a thickness of about 4 inches, and consisted of damp sand with three thin bands of stucco. As soon as pressure was applied, the material immediately in front of the pressure board began to swell up into an anticline in exactly the same way as Prarr’s strata of loam and papier-maché pulp were observed to do. The right limb of the anticline being pressed in, gradually assumed a vertical position parallel to the face of the pressure board. At this stage the pressure from the right was uniformly distributed from the crown of the arch downwards. But the resistance on the left was only exerted as far up as the level of the surface of the undisturbed strata, so that the part of the arch above this level was free to travel forwards. It did so for a short space, and produced the monocline at the top of the section. Had the upper strata been more rigid, they would not have become bent into such a form, but would have snapped at once, and formed a reversed fault, as has indeed been done in the thin bed immediately at the surface. It was, however, impossible for the upper part of the anticline to move far forward with an increase of pressure from the right, since all particles in the same vertical plane were subjected to equal pressure from that quarter. In the lower part of the section, the horizontal pressure from the right was met by the horizontal longitudinal resistance of the strata combined with the vertical statical resistance of the sole, so that the resultant force tended to shear the strata obliquely along a series of planes inclined towards the right. The stiffness of the beds now came into play, and prevented this shearing strain from being distributed throughout the mass. Instead of this, the brittle strata snapped at one point, and all the movement was concentrated along the line of weakness thus produced. The whole mass above this thrust- plane moved obliquely upwards and forwards, and all interstitial .movement ceased. The thrust-plane or reversed fault did not start directly from the bottom of the pressure board, but met the fixed sole a short distance in advance. As soon, how- ever, as the front of the pressure board reached the point of the wedge of undisturbed 342 MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. strata below the fault plane, the shearing ceased, and the forward motion was temporarily arrested. The photograph taken at this stage is reproduced in fig. 1. Hisw2, A new mass of strata was now brought under the influence of the pressure. In this — case the beds were subjected to a certain amount of vertical pressure due to the heaping up of the strata on the slope of the wedge, in addition to the horizontal thrust from the right. The resultant shear plane might therefore be expected to meet the fixed sole at a slightly lower angle than before. An inspection of fig. 2 will show that this has been the case. The upper reversed fault is slightly steeper than the lower. Much importance is, however, not to be attached to this difference in hade, as the weight of the piled-up strata in such experiments is small in comparison with the horizontal force, and slight differences in the hade of successive reversed faults might be due to other causes. Fig. 2a is a dia- orammatic representation of fig. 2, which is not very clear. Fig. 3a. In this case (fig. 3) the depth of strata was only 12 inches. The breadth was 8 inches, and the section was pressed in from an original length of 44 inches to a space of 15 inches. The same process went on here as in last experiment, but the cumulative effect is better dis- played. A small overfold produced at the beginning of the experiment may be seen at the top of the section, but afterwards the strata underwent a process of piling up in separate slices by slightly-inclined reversed faults. The back part of the accumulating mass slipped vertically up the face of the pressure board as each new wedge was driven under the base of the slope in front. Fig. 3a is a diagrammatic representation of this structure. These structures are almost identical in character with the structures found in advance MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. 343 of the great thrust-planes in Sutherland, where a similar process of heaping up of Silurian quartzites, shales, and limestones has at places given these strata an abnormally thick appearance, which, before the discovery of the thrust-planes, was quite inexplicable. For this arrangement of strata I would propose the name of “ wedge structure.” Fig. 4a. These strata (fig. 4) had originally a length of 44 feet and a depth of 45 inches. The brittle beds are near the bottom of the section, while the upper layers consist of damp sand, whose particles could undergo some interstitial movement, and thus allow it to behave like a partially plastic body. On compressing the end 8 inches, the surface was observed to swell up in front of the pressure board. ‘To all outward appearance, the result did not differ from that obtained in the experiments of Prarr already alluded to, and figured in his Mechanismus der Gebirgsbildung, p. 23. In examining the section, however, the brittle beds below were seen to have snapped as in former experiments, and given way along a single shear plane, without any folding. Towards the surface this line of shear is seen to split up, till the movement, which was confined to one plane below, has become so distributed throughout the mass that the underlying thrust-plane is lost ina great fold above, and never appears at the surface. The main point of interest here is the passage of a fault below into an anticlinal fold at the surface of the ground. Fig. 5. Fig. 5c. On continuing the push 4 inches farther, the anticline was slightly compressed, and a second reversed fault was started in advance of the first (fig. 5), just as was observed to take place in figs. 1 and 2. 344 MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. The strata hitherto subjected to thrusting were horizontal, but to ascertain if the same system of reversed faulting could originate with beds at different inclinations, I arranged a series of beds dipping away from the pressure board (fig. 6). The structure produced differed in no respect from that exhibited in fig. 8. The inclined shear planes can be readily traced crossing the inclined beds nearly at right angles. The figure is reduced from an accurate tracing of the section obtained. In fig. 7 the beds dip towards the pressure board, and the thrust-planes run in direc- tions nearly parallel to those of the bedding planes, and have the effect of “staving” the strata together in such a way as to increase their apparent thickness. On the right the ends of the beds next the pressure board show a tendency to become drawn out at the expense of their breadth. The attenuated strata take a wavy form as they are crushed in and made to assume a steeper inclination than when undisturbed. These little undulations are also seen on the right limb of the anticline in fig. 4, and originate as soon as the strata next the pressure board begin to roll backwards and approach verticality. The tendency of each wave is to break and pass into a small normal fault, as seen in this figure and in fig. 12 below. Fig. 8. A syncline was formed in the box, and the edges were covered unconformably by beds of sand. On applying pressure, the thrust-planes cut both sets of strata indiscriminately as in previous cases (fig. 8). These experiments, relating to different arrangements of strata of the same rather MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. 345 brittle consistency, evidently prove that (1) horizontal pressure applied at one end of the section does not throw the mass into folds from end to end, but only influences the Fig. 10. Fig. 11. Strata a short distance in advance of the compressing surface ; (2) the pressure prefers to find relief in a series of gently inclined thrust-planes, whose direction of inclination VOL. XXXV. PART 7. 2 , 346 MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. depends on the direction of pressure, and is practicably ipdepeniiet of the direction of dip of the beds. A bed of soft tenacious clay (figs. 9-11) was arranged below brittle strata of damp sand mixed with a little stucco powder, and a bed of black foundry loam well packed together. The object of the experiment was to test the behaviour of brittle beds on a thoroughly plastic base when compressed longitudinally. The three figures show the structure at as many different stages of compression. The result is certainly surprising, as in each ease the plastic clay, as well as the stiffer beds above, has undergone faulting. It is to be observed, that as the compression proceeds the thrust-strata on the left of the anticline bow forward, and tend to approach verticality, while the thrust-planes originally inclined to the right are bent over to the left also. The experiment also shows how folds are built up of interstitial displacements which may at places become divided out along a few lines. At each stage, when the section was examined, about an inch was pared off the edge, so that each figure shows the section a short distance further along the strike of the beds than in the preceding figure. In fig. 10, the left limb of the anticline is built up of many small distinct thrust-planes; but in fig, 11 the same member is shown as a single curve, proving that folding may pass into faulting a short distance along the strike of the distorted strata. : LF les Fig, 12. In fig. 12 the tendency of the thrust-planes and beds to bow forward on advancing is well exhibited. This is due to the resistance in front caused by friction below, coupled with the staving together of the materials in more immediate proximity to the pressure board. There is, in short, evidence of a continued attempt at the formation of an anticline just in front of the region of maximum pressure, As in former experiments, the beds on the right limb of the incipient fold are attenuated very considerably, and show the wavy faulted structure already alluded to. The bending down of the thrust beds on the left, it need scarcely be said, is thus a deceptive appearance, as the front has remained quite stationary, while it is the back portion which has been wedged up. In all the experiments of this series there was a tendency on the part of the pressure board to rise and move obliquely forwards and upwards as the heaping up progressed. In next experiment, instead of holding the pressure board in a constrained vertical position, with its lower end against the fixed sole, a cushion of sand ‘was substituted for it, and the push applied behind, The result, as was anticipated, showed — | MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. 347 the whole mass to rise and glide forward over the lower and less disturbed beds along a mayor thrust-plane, inclined at a very slight angle to the horizon. During the forward Ye, . movement the friction tended to retard the front more than the back of the advancing mass, and make the inclination of the thrust parts of the section still greater. Had the experiment been continued, the originally horizontal parts of the thrust mass would no doubt have reached verticality, and then begun to bend in towards the major thrust- plane below, just as the fingers of an outstretched hand, when pushed along a table, tend to turn in and fold back on the palm.* Figs, 12 and 18 are taken from photographs. Yj ¢ LMU MMMM Jl™#™#™ y Fig. 14 is a sketch of a very characteristic section which was not photographed. After continued piling up, such as is shown in fig. 3, the heap of strata rose and slid forward over a major thrust-plane, against which the smaller thrusts are all truncated. It is obvious that beds repeated in this way in nature, without inversion or folding, might come to have an appearance of enormous thickness, and thus greatly mislead the field geologist. It might indeed be almost impossible to arrive at a correct conclusion as to the thickness of such a formation, were the underlying major thrust concealed, and nothing but the edges of the upper beds exposed to view, ‘This structure is now known to be of common occurrence in the North-West Highlands, and these experiments show clearly on what mechanical principles many of the extraordinary and remarkably deceptive relationships of the rocks of that region may be explained. This experiment shows that underneath a series of beds, repeated and heaped together by small thrusts, inclined perhaps at considerable angles, there runs in the majority of cases a major thrust or * This has often taken place in nature. See sections through Ben More, Assynt, &c., figs. 15, 16, 17, Quart. Jour. Geol. Soc., 1888, pp. 421, 423, : 348 MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. “sole,” inclined at a lower angle, along which the whole mass may have travelled for considerable distances. It is almost unnecessary to say that the existence of such major and minor thrusts has only been discovered within the last three years by the Geological Survey. But I have no doubt that, when other mountain systems come to be examined in the light of the researches by my colleagues and myself in the North-West Highlands, and in the laboratory, these structures will prove to be of common occurrence.”* B. Origin of “ Thrust-Planes” and “ Fan Structure.” : It had been my belief that the great thrusts of the west Sutherland area, the effects of which have just been noted, must be connected with deep-seated folds, due to lateral compression of this part of the earth’s crust. Although there were no distinct traces of such folds to be seen on the surface, it seemed impossible that the great thrust-planes could be prolonged indefinitely downwards, at the same low inclination as they exhibited wherever exposed, and the only reasonable explanation of their origin that suggested itself was this, that each major thrust at a certain depth changed its angle, and bending downwards gradually disappeared, the break in the strata being finally represented by a single great deep-seated synclinal fold. To produce folding below, and study its results at the surface, the strata were arranged on a flexible and inextensible band of ‘stout waxcloth about 3 feet long and 7 inches broad, the extremities of which were nailed to blocks of wood, which took the part of the pressure board in former experiments. The waxcloth and end pieces were laid between the high sides of the box used before. The left end piece was fixed to the sole of the box, and the screw was applied to the right end piece in such a way as to throw the waxcloth into a series of undulations or folds, shown in figs. 15-17. 0 A ye EO Ae ES A layer of tenacious clay was formed on the waxcloth, above which were spread strata of damp sand, stucco, and foundry loam. When pressure was applied from the * Compare fig. 14 with the horizontal sections in the Survey Report, loc, cit. A MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. 349 right, the waxcloth buckled up into an anticline a short distance from the end. While the underlying clay bent round conformably with the pliable sole, the more brittle beds above behaved exactly as in former experiments, and gave way along a slightly inclined reversed fault, the right portion being thrust for some distance horizontally over the left. Fig. 16, This experiment confirmed my theory, and clearly showed on what mechanical principles it is possible for a horizontal thrust to bend down and pass into an ordinary fold below. Tee On continuing the push, the anticline was further compressed, and the pressure being increasingly felt on the left limb of the fold, a second anticline (fig. 16) appeared on that 390 MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. side of the section. As in the former case, the brittle beds at the surface showed signs of giving way without folding. | All the strata to the right of the new fold were now in motion, and movement along the first thrust-plane ceased. The pressure found relief along the second thrust only, and the anticline beneath was squeezed together till the sides nearly met (fig. 17). Had the waxcloth been longer, a third anticline would have arisen in advance of No. 2, and so on for others, each giving rise to a thrust at the surface of the section. This I conceive may explain how thrust-planes are found across great stretches of country, all lying at the same angle and dipping in the same general direction. In this experiment (fig. 18) the beds were of sand, with brittle stucco lamine between. The waxcloth was compressed from both sides equally, but to prevent complications, three small anticlines were started by wedging it up at the centre and near the sides, The section is interesting, as showing clearly the anatomy, so to speak, of the structure. The fold at the right shows the beds becoming increasingly curved from below upwards, till they have no longer been able to bear the strain, but have snapped, and as before found relief along a thrust-plane. It is to be noted that the upper beds underwent thrust- ing simultaneously with the foldmg below. According to Prof. A, Hrrm’s well-known theory, that reversed faults are produced by monoclinal folds giving way along the middle limb, we should have expected to find traces of a fold having first been formed not only below, but all along the line of shear. These and former experiments show that Hetm’s theory, which is no doubt true in many cases, is by no means of universal appli- cation. Thrust faults may originate at once, without passing through an initial stage of overfo]ding. The section is also interesting as showing how one thrust-plane may overlap another running in the opposite direction. In the right half of the section, two thrusts are seen overlapping in this way, so as to repeat the upper dark layer three times in the same vertical line. Figs. 19-22a show the results of experiments designed to imitate the type of mountain building found at many parts of the Alps, and known as “ fan structure.” As a symmetrical section was desired, the strata on the waxcloth, which consisted of sand and stucco lamine, were slightly raised in the centre. When pressure was applied, this arch rose up into a single anticlinal-fold. As the side pressure was continued, the limbs of the anticline were squeezed together till the beds slightly passed the vertical, and began to dip inwards at high angles, exhibiting, the’ desired fan-like arrangement. MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. 351 The horizontal thrust, however, caused the upper part of the folded strata to snap at Fig. 19a, the right side, as was to be expected after former experiments. Had there been a screw Fig. 20a. 352 MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. at both sides, the structure would have been quite symmetrical. In another experiment a perfectly symmetrical section was obtained. On each side the beds snapped, and a pair of thrust-planes were produced, which buried themselves in the monoclinal folds of which the whole fold is composed. After the limbs of the central anticline had been compressed till they met, a pair of smaller arches were started by wedging up the waxcloth at either side. ‘The central fold was, on the application of the screw, squeezed upwards, and the beds becoming more compressed exhibited the fan structure more conspicuously (figs. 20 and 20«). Fig. 21. On continuing the pressure, the three folds were still further compressed, and the core of the central anticline was drawn upwards and considerably attenuated. A pair of thrust-planes were formed on each side, and the beds forming the haunch of the main arch were forced inwards above the lines of shear, so as to dip in an inverted position towards the axis of the fold (fig. 21). Fig. 22.. At this last stage of compression the development of a second and larger fan out- side the first is clearly seen (fig. 22). Along the outer limbs of: each of the folds the ai 4 ® MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. 353 lower portions of the strata are drawn out in a highly attenuated form, and dip inwards as in last experiment. At these places thrust-planes tend to originate above, and three such faults have been formed on the left side. The thrust-plane on the right, formed at an earlier stage, has disappeared, as the section has now been so pared away that the front is several inches farther along the strike than at the start. The thrust m question did not extend more than one or two inches inwards along the strike, and gave place to the overfold now exposed. The compression has been so great that the bed immediately resting on the waxcloth has been nearly nipped out altogether at the crest of the central fold. Now it is clear, that when strata or rocks of any kind are thus squeezed together and drawn out in a particular direction, the original character of the rock will become changed. If the distortion be small, the alteration may not be at first noticeable, but when, as in the figure, the thickness of any member is notably diminished, and its particles forced to flow along certain planes for any considerable distance, just as the puddle bar in a rolling-mill is rolled out to a great length and attenuated to a corres- ponding extent, it is clear, that as the particles of the iron, when in a pasty condition, . s. are thus made to arrange themselves along the flow lines, and give the wrought bars a fibrous structure, so in the rock the particles assume a new arrangement along the planes of movement, and produce a foliated or schistose structure in the mass. In this minia- ture mountain system, the particles in the bed next the waxcloth have all been made to flow upwards to such an extent that, had the mountains been real ones, they would have exhibited vertical schistosity at the core. I would here throw out the suggestion that this experiment may explain how it is so common to find a core of foliated rock in many of the larger alpine masses, the original crests of which have been removed by denudation. I hope to repeat this experiment, and endeavour to obtain still better results, as the subject is one of great importance ; and in the second part of the paper | hope to discuss at greater Jength the physical problems on which it has a bearing. CG. On the Relation between Folding and Regional Metamorphism. These experiments are merely modifications of the interesting experiments of Prot. A. Favre of Geneva. VOL, XXXV. PART 7. 3M 354 MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. A band of the most elastic quality of india-rubber, 7 inches broad and a quarter of an inch thick, was grasped at the ends between vertical pieces of wood bolted together. The left end of the band was fixed to the sole of the box in which former experiments were arranged. The pair of bolts on the right projected through the wood, and passed through an iron plate fixed about an inch from the outer face of the block, as shown in the figures, In the centre of the plate, between the bolts, a hole was drilled large enough to admit the free end of the screw-shaft. This end of the shaft was fitted with a collar, which worked against the inside face of the plate, and prevented the shaft being drawn through, but permitted of its free rotation in the hole. The other end of the screw remained in its old bearings attached to the sides and bottom of the box. By turning the screw in a left- handed direction the elastic band could thus be stretched through any desired distance. Fi g. 23. The part of the elastic band measuring 2 feet between the blocks was stretched to a length of 3 feet. In Favre's experiments the sheet of caoutchouc was extended in the same proportion, A layer of very tenacious clay was then plastered over the roughish surface of the elastic band and covered with a sheet of brown paper. A second and thicker clay bed of a “shorter” and stronger consistency was lastly laid over the paper. The depth of the whole section was about 14 inch. . On slacking the screw and allowing the elastic band to contract to its original length, the upper bed of clay above the brown paper was observed to swell up into little waves, just as the surface of the clay in Favre’s experiments was observed to do. These are well shown in fig. 23. MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. 3955 On the suggestion of my colleague Mr B. N. Peacu, who helped to carry out this last series of experiments, the upper folded clay bed was stripped off, and the surface of the lower bed laid bare. It was found covered with a series of minute sharp corrugations transverse to the direction of movement and parallel to the main ridges above (fig. 24). Fig. 25. A similar experiment was made with somewhat thicker strata, but instead of all the beds being plastic, the upper layers were of brittle materials like those used in the first and second series of experiments. On permitting contraction to take place, the upper brittle beds broke into cakes, which were at places thrust over one another for short distances (fig. 25). On removing the upper strata, the tenacious bed adhering to the caoutchoue was found : as before covered with minute corrugations (fig. 26). On stretching the band slightly, the corrugations were not flattened out, but the clay _ split along a series of vertical cracks, parallel to the minute puckerings on its surface. _ The sides of these little fissures were observed to be covered with minute vertical striations, and had the appearance of slicken-sided faults, along which vertical movement had taken 3096 MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. place. In this case the horizontal pressure being uniformly exerted from particle to particle along the band, and not at one point as in former experiments, had produced a Fig. 27. general “staving together” throughout the mass, causing the particles to move upwards along vertical planes transverse to the line of greatest pressure (fig. 27). In this experiment we have a possible explanation of the origin of great areas of vertically cleaved rock known to exist at the roots of old mountain systems. The bed below has undergone what appears to be cleavage, while that at the surface has been thrown into folds without any considerable interstitial movement. If the folded surface of the clay be taken to represent the waxcloth in series B, the theory of a uniformly contracting sole might explain not only regional metamorphism, but the phenomena of fan structure, thrusting, and wedge structure as well. D. General Summary of Results. 1. Horizontal pressure applied at one point is not propagated far forward into a mass of strata. | 2. The compressed mass tends to find relief along a series of gently-inclined “ thrust- planes,” which dip towards the side from which pressure is exerted. 3. After a certain amount of heaping up along a series of minor thrust-planes, the heaped-up mass tends to rise and ride forward bodily along major thrust-planes. 4. Thrust-planes and reversed faults are not necessarily developed from split overfolds, but often originate at once on application of horizontal pressure. 5. A thrust-plane below may pass into an anticline above, and never reach the surface. 6. A major thrust-plane above may, and probably always does, originate in a fold below. 7. A thrust-plane may branch into smaller thrust-planes, or pass into an overfold along the strike. 8. The front portion of a mass of rock being pushed along a thrust-plane tends to bow forward and roll under the back portion. MR CADELL ON EXPERIMENTAL RESEARCHES IN MOUNTAIN BUILDING. 357 9. The more rigid the rock the better will the phenomenon of thrusting be exhibited. 10. Fan structure may be produced by the continued compression of a simple anticline. 11. Thrust-planes have a strong tendency to originate at the sides of the fan. 12. The same movement which produces the fan renders its core schistose. 13. 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