There are two points connected with clouds on which I wish to make a few remarks. The first is on the classification of clouds, and the second on the manner in which certain forms of clouds are produced. It may be as well to remark at the outset that the observations are those of an “outsider,” being in a department of meteorology to which the writer has given but little attention, and they have been written with the view of calling the attention of specialists, and getting their opinion on the subject.

It appears to me that in classifying clouds they ought first of all to be divided into two great classes. In the one class should be placed all clouds in the process of formation, and in the other those in the process of decay. The two classes might be called Clouds in Formation and Clouds in Decay. We may take Cumulus clouds as an example of the former, and Nimbus of the latter. My observations made in the clouds themselves have shown that there is a difference in the structure of these two classes of clouds. In clouds in formation the water particles are much smaller and far more numerous than in clouds in decay; and while the particles in clouds in decay are large enough to be seen with the unaided eye when they fall on a properly lighted micrometer, they are so small in clouds in formation that, if the condensation is taking place rapidly, the particles cannot be seen without the aid of a lens of considerable magnifying power.

The following experiments were performed with normal human gastric secretion. After thoroughly washing out the stomach of a healthy man, several ounces of a dilute solution of Caffyn's liquor carnis were introduced into it. After the lapse of an hour the contents of the stomach were drawn off, filtered, and used instead of the pure acid solutions in former experiments. The acidity of the gastric fluid was due to inorganic acid and amounted to 0·15 per cent. hydrochloric acid.

This experiment shows that, in the stomach, with an acidity of the contents less than that even normally present in the gastric secretion, the action of ptyalin is wholly restrained.

Was the ferment merely inhibited from action by the acid, or was it destroyed ?

To determine this, I took equal volumes of this gastric fluid, 1 per cent, starch solution, and saliva, and having mixed them, carefully neutralised the mixture with a solution of caustic potash, using very delicate test-papers to show the neutral point.

On examining the mixture shortly after neutralisation, the whole of the starch was found to have undergone conversion. It reduced Fehling's solution strongly, and contained 0·22 per cent. of reducing substance. This demonstrates that, with an acidity equal to 0·05 per ′cent, hydrochloric acid, the action of ptyalin is restrained.

I performed similar experiments with the gastric fluid from a case of chronic gastric catarrh, the acidity of which was equal to 0·067 per cent. hydrochloric acid.

This inquiry embraces the seventeen years beginning with 1878 and ending with 1894, the material utilised being the weekly mortality returns published by the Registrar-General for Scotland. Particulars are given in these returns of the number of deaths from small-pox, measles, scarlet fever, diphtheria, whooping-cough, diarrhœa, fever, croup, laryngitis, bronchitis, pneumonia, and pleurisy. Some of the diseases are classed together, viz., typhus and typhoid fever, croup and laryngitis, and bronchitis, pneumonia, and pleurisy. The data discussed also embraces returns of deaths from all causes, deaths of infants under one year of age, and of persons aged sixty years and upwards. The deaths have all been entered as having occurred during the calendar weeks in which they were registered, but as notification usually follows decease by several days, a slight element of error is introduced. Since the returns do not give any information as to the duration of the illness, we are unable to ascertain whether specific weather types are in casual relationship to disease. There are every week a number of deaths from uncertified and unspecified causes. These omissions are subsequently rectified, but their presence in the returns does not affect the general results of the investigation. It is our intention merely to discuss some of the broader results of the inquiry, the chief object of which is to give a first approximation to the seasonal death-rate of the diseases under review. In discussing the relation between weather and disease, it is well to keep in mind the fact that different diseases exhibit varying degrees of sensitiveness to weather influences, and that climatic changes take some little time to affect the human subject.

In addition to the authorities quoted in the first part of the paper, memoirs by Clerk-Maxwell and by Lord Rayleigh are referred to, also a passage in the Beiblätter zu den Ann. d. Physik. (1895, p. 289), which cites Hélie, Traíté de Balistique.

The Author then considers the more obvious defects of the rudely approximate solution of the differential equations which is given in Part I., especially the omission of the direct gravitational effect on the speed, and shows how to take account of the effect of the observed gradual diminution of the angular velocity of the projectile. An improved solution of the problem of § 8 of the paper is also given.

The Author stated that lie had occasionally succeeded in obtaining the kink spoken of in Part I., the projectile being a humming-top made of very thin metal. He had also occasionally obtained a cusp, thus exhibiting the paradoxical result of a projectile's path which is at no point concave downwards.

It is singular to observe the comparative ease with which elementary propositions in attraction can be proved by one of the obvious methods, while the proof by the other is tedious.

Thus nothing can be simpler than Newton's proof that a uniform spherical shell exerts no gravitating force on an internal particle. But, so far as I know, there is no such simple proof (of a direct character) that the potential is constant throughout the interior.

On the other hand the direct proof that a spherical shell, whose surface-density is inversely as the cube of the distance from an internal point, is centrobaric is neither short nor simple. (See, for instance, Thomson and Tait's Elements of Natural Philosophy, § 491.) But we may prove at once that its potential at external points is the same as if its mass were condensed at the internal point.

I use the word “liquid” for brevity to denote an incompressible fluid, viscid or inviscid, but inviscid unless the contrary is expressly stated. A finite portion of liquid, viscid or inviscid, being given at rest, within a bounding vessel of any shape, whether simply or multiply continuous; let any motion be suddenly produced in some part of the boundary, or throughout the boundary, subject only to the enforced condition of unchanging volume. Every particle of the liquid will instantaneously commence moving with the determinate velocity and in the determinate direction, such that the kinetic energy of the whole is less than that of any other motion which the liquid could have with the given motion of its boundary. This proposition is true also for an incompressible elastic solid, manifestly ; (and for the ideal “ether” of Proc. R.S.E., March 7, 1890; and Art. xcix. vol. iii. of my Collected Mathematical and Physical Papers). The truth of the proposition for the case of a viscous liquid is very important in practical hydraulics. As an example of its application to inviscid and viscous fluid and to elastic solid consider an elastic jelly standing in an open rigid mould, and equal bulks of water and of an inviscid liquid in two vessels equal and similar to it. Give equal sudden motions to the three containing vessels: the instantaneous motions of the three contained substances will be the same.

The sarcastic criticism which M. Bertrand (Comptes Rendus, May 4 and 18, 1896) again bestows on Clerk-Maxwell's earliest solution of the fundamental problem in the Kinetic Theory of Gases, together with Prof. Boltzmann's very different, but thoroughly depreciatory, remarks (ib., May 26), have led me to reconsider this question, already discussed by me at some length before the Society. Both of these authorities declare Maxwell's investigation to be erroneous:—but, while Prof. Boltzmann allows his result to be correct, M. Bertrand goes further, and bluntly calls it absurd. He had, in his Calcul des Probabilités, (1888), already given Maxwell's proof as an example of illusory methods. I have the misfortune to agree with Maxwell, and to hold that his reasoning, though not by any means complete, is (like his result) correct. (Trans. R.S.E., vol. xxxiii. pp. 66 and 252.)

I have not found anything in these communications of mine (so far at least as the present question is concerned) which I should desire to retract; but they can be considerably improved; and I think that, by the introduction of the Döppler- (properly the Römer-) principle, the true nature of a part of the argument can be made somewhat more immediately obvious. Also I will venture to express the hope that Prof. Boltzmann may at last recognise that I have, in this matter at least, not deserved the reproach of having reasoned in a circle.

Some little time ago a preliminary note upon Phoronis was read before the Eoyal Society, and therein it was stated that a study of the anatomy of this group had led one to believe that its nearest phyletic allies were to be found in the Hemichorda, a group comprising a few species with primitive chordate characters.

In attempting to class Phoronis with these, an important difficulty presented itself. It has been usual to define the Chordata as having three essential characters in common, either temporarily in ontogeny or permanently throughout life, i.e., a dorsal nervous system, paired gill-slits, and a notochord.

With regard to these features, there can be no doubt that the nervous system of Phoronis is dorsal in position, and its arrangement is exactly comparable to that of Balanoglossus; but, on the other hand, there are no gill-slits in the adult Phoronis, and the notochord is as certainly absent.

In the case of the gill-slits, we find upon critical examination that they are extremely variable in extent of number and position in the different Chordata, and in one species, Rhabdopleura, they are, according to present knowledge, entirely absent. For these reasons it is well not to insist on the presence of gill-slits as an essential character. With respect to the notochord a different condition prevails-the hypoblastic origin and vacuolated character of this organ mark it out from all other skeletal structures, and it figures more or less prominently in all the Chordata.

A preliminary demonstration on photography and fluorescence was given. A description accompanies the report on the communication made on 4th May 1896.

When Professor Röntgen's results were first made known the greatest attention was paid to the photography of objects which had previously been considered beyond the range of human vision. It is clear, however, that the discoverer did more than present us with a new photography by a force differing, in many respects, from day or artificial light. In his first paragraph he describes fluorescence on a prepared screen, and in the second he shows how one may see shadows of the bones within a faint dark shadow of the hand itself. The obvious advantage of being able to throw shadows of the deep-seated structures of the body upon screens cannot be over-estimated for medical and surgical purposes. The following experiments were undertaken with a view of contributing something to the work in this direction.

With regard to the salts employed, screens were prepared of potassium-platino-cyanide, barium-platino-cyanide, lithium-rubidium-platino-cyanide, calcium tungstate in its crystalline form (Edison), sulphide of calcium, magnesite, fluorspar, &c. In my experience it may be said at once that the potassium and bariumplatino-cyanide salts were found to be the best, although the lithium-rubidium-platino-cyanide gave an excellent picture. The fluorescence of the potassium salt is probably in advance of all others, but occasionally one seems to get at least a more pleasant picture of the deep-seated structures of the body with the barium screen, particularly when the latter has a thick coating.

The first series of photographs thrown on the screen included the different parts of the human skeleton. The second series illustrated photographs of the soft tissues, such as the tongue, larynx, heart, and diaphragm, all from the living subject. The third series were taken with a view to reduction of the time in exposure. With the fourth is given a description of some experiments upon attempts to polarise the x-rays.

The apparatus now most commonly employed was used in these experiments, viz., electricity (from the main), an induction coil giving a range of from 2 to 10 inch spark as required, a Crooke's tube having an aluminium cathodal disc, and a small plate of platinum for the positive pole. It is now known as the focus tube. Paget xxxxx-plates were used, as no particular advantage had been obtained from those specially prepared. The following points, amongst others, were found to be of great service in obtaining the best results:—Firstly, the current passing to the coil should be regulated according to the work to be done, and as little variation as possible should take place during the exposure. Primary batteries are not as satisfactory on account of this, and the best source is from the main. Lord Kelvin's cell tester and ampere gauge were used in the experiments, and any variations in the current were regulated by means of a rheostat. Secondly, the Apps or other coil or transformer must give, with the present form of tube, six inches or even more of spark when the deeper tissues of the body, such as the spine, are being taken. Thirdly, the vacuum of the tube should be carefully regulated and tested to give the maximum results.

I have, in a previous communication to the Society, given results for a number of alloys; these I propose to discuss from the point of view suggested by the title of this paper; I shall also discuss the results published by other experimenters, which relate chiefly to the behaviour of the Hall effect by constant field and variable temperature.

In attempting to explain the transverse effect, we have two things to consider. (1) The direction, and (2) the magnitude. In the following table the metals are arranged in a thermo-electric series as given by Wiedemann; and in the second column the direction and magnitude of the transverse effect in terms of the rotatory coefficient R, according to Ettingshausen and Nernst's results, are given.

Sodium mercaptide and dibromosuccinic ether, in the proportion of two molecules of the former to one of the latter, were dissolved separately in absolute alcohol, and slowly mixed. A considerable evolution of heat took place, while sodium bromide separated out. The flask was then digested for some hours on the steam-bath. The alcohol was subsequently distilled off, and the residue, on cooling, was treated with water. An oil separated out. This oil was collected by means of a separating funnel, and the aqueous layer several times extracted with ether. The oil and the ethereal extracts were added together and dried over calcium chloride. Next morning the ether was distilled off at the ordinary pressure. The remainder was distilled in vacuo. Between 50° and 60° a few drops came over, which proved to be ethyldisulphide.

The remainder came over between 150° and 170°.

This latter fraction was redistilled, and a portion of it used for analysis. The boiling point at 20 mm. pressure was 160°.

Combustion of dietthiosuccinic ether.

Weight of substance taken = ·2477 gram.

Weight of carbonic acid obtained = ·4476 gram.

Weight of water obtained = ·1702 gram.

In the following Abstract I refer to such Linear and Vector Functions, only, as correspond to homogeneous strains which a piece of actual matter can undergo. There is no difficulty:—though caution is often called for:—in extending the propositions to cases which are not realizable in physics.

The inquiry arose from a desire to ascertain the exact nature of the strain when, though it is not pure, the roots of its cubic are all real:—i.e. when three lines of particles, not originally at right angles to one another, are left by it unchanged in direction.

1. The sum, and the product (or the quotient), of two linear and vector functions are also linear and vector functions. But, while the sum is always self-conjugate if the separate functions are so (or if they be conjugate to one another), the product (or quotient) is in general not self-conjugate:—though the determining cubic has, in this case, real roots. The proof can be given in many simple forms.

We may write the electro-magnetic equations of Clerk-Maxwell as

For plane waves, running with normal velocity vα= −μ−1, we have

whence at once

[For the moment, we assume that φ and ψ are self-conjugate, so that a linear function of them is also self-conjugate. And we employ the method sketched in Tait's Quaternions, §§ 438–9.]

Eucain, like cocaine, is a methyl ester of a benzoylated-oxypiperidine, carbo-oxylic acid. It is, however, a synthetic product, while cocaine is obtained exclusively from coca leaves; only, in the exhaustion, synthesis has been introduced for the purpose of completely exhausting the cocaine in the leaves.

The formula of cocaine and of eucain is the same.

Eucain, like cocaine, is insoluble in water, or nearly so, but the neutral salts formed by combinations with acids are soluble.

The hydrochloric salt of eucain appears in two forms.

One modification crystallises from water in small shining plates, which contain a molecule of water of crystallisation, and the formula for it is

C19H27NO4HCLH2O.

It dissolves in water to the extent of 6 per cent.

The second modification crystallises from a solution in methyl alcohol in shining prisms, which contain two molecules of methyl alcohol in crystallised form.

For anæsthetic purposes the first modification crystallised from water is to be preferred. A solution of it in water differs from a solution of cocaine in water in this respect, that it remains unchanged, while the cocaine solution, after a time, undergoes decomposition.

The appellation ‘eucain’ has no meaning. It is used simply to dispense with the complex chemical nomenclature which has been mentioned.

Eucain hydrochlorate is not so expensive as cocaine hydrochlorate.

The Council has done me the honour of requesting me to open the 114th Session of the Society, and to offer some remarks that may be deemed appropriate to the occasion.

Up to a comparatively recent date, our conception of the nervous system was that it was built up of nerve cells and nerve fibres, more or less intimately bound together by a peculiar kind of tissue known as neuroglia. It was further supposed that, in the central nervous organs, nerve cells were linked together by processes passing from one cell to another, that sensory nerve fibres passed into, and were in their substance continuous with, nerve cells, and that motor fibres originated in nerve cells, and passed out to muscle fibres. It was also held that the elements of sensory organs, such as the retina or the organ of Corti, were organically connected with nerve cells in the cerebral organs. In short, the nervous system, as a whole, was held to be composed of cells and fibres closely connected together, so that the structure was like a vast web, the size of the meshes of which would vary according to the intricacy of the connections by which the various cellular elements were held together by nerve fibres. These histological conceptions were founded on the microscopical scrutiny of sections prepared by the older methods of hardening and staining, from the time of Lockhart Clarke to nearly the present day.

The notions of physiologists, as is usually the case, were more or less in conformity with, and were influenced by, these histological conceptions. Nerve cells were supposed to be excited by nervous impulses, or to originate nervous impulses, and nervous impulses appeared to pass from cell to cell.

Suppose we introduce a telephone a into the primary circuit of an ordinary induction coil, such as used in physiological laboratories, and another telephone b into the circuit of the secondary coil, and suppose the wires connecting telephone a with the primary and connecting telephone b to be many yards in length. If one observer speaks into a, another observer will hear every word if b is applied to his ear. Every one is acquainted with this fact, that the currents awakened in a induce corresponding currents in the secondary coil, which are transmitted to b. If we substitute for a a microphone-transmitter c, and speak to it, the tones are reproduced by telephone b.

Further, as I showed to the Society in February last, if we suspend a microphone-transmitter over the phonograph, when the latter is in motion and giving out tones, the variations in resistance in the microphone-transmitter produce such alterations in the current flowing through it to the coils of an electro-magnet as to make it possible, mechanically, to record these variations.

These considerations led me some months ago to try the following experiment. The microphone-transmitter was suspended over the phonograph disk, and it was introduced into the circuit of the primary coil of the induction machine along with four Obach's cells (Q type). The terminals of the secondary coil were carried to two strips of platinum foil immersed in two insulated vessels (glass beakers or shallow vulcanite troughs) containing a ·75 per cent. solution of common salt or sulphuric acid (1:10 of water).

Since my last communication on this subject to the Society, in February, my attention has been directed to perfecting a mechanism for obtaining a record of the vibrations imprinted on the wax cylinder of the phonograph, and I wish to acknowledge the great assistance derived from the ingenuity and mechanical skill of Mr Reid and Mr Kean, of the well-known firm in Glasgow known by the name of “James White.” The instrument now before you, which I shall call a phonograph recorder, traces out, on a large scale, the curves of the indentations on the wax cylinder corresponding to each vibration of sound, and it does so in a way that seems to be highly satisfactory. It is now an instrument that can be used by other workers in this difficult department of research, and I hope that some of the younger physiologists and physicists will take the matter up and apply it to an extent that, with numerous avocations and with calls to other branches of physiological research, I can never hope to overtake.

The subject of the production within Diatoms of spores, en docysts, &c., has been worked at by several observers, principally Castracane in recent years, and before him O'Meara and Rabenhorst. Some of these observers have noted ciliated, spore-like bodies, probably parasitic or casual intrusive organisms; others, notably Castracane, have recorded oval and other cysts winch have not been figured and the characters of which are difficult to realise. Miquel has made an experimental examination of the subject without being able to confirm Castracane's results. Castracane has also recorded the presence, as he thinks, of “gonids or embryonal forms” within a fossil Diatom (Coscinodiscus punctatus) in a marine deposit of miocene age. During March of this year I tow-netted near the Bell Rock a large quantity of Coscinodiscus concinnus — with many dead valves separated at the girdle. These frequently contained not only other and smaller individuals of the same species, but other species of diatoms and casual objects as well, and the observation makes one cautious about accepting evidence of the character brought forward by Castracane as to his fossil form.

Lauder, in describing forms of Bacteriastrum and Chœtoceros, observed the formation of endocysts. “At certain times, or under certain circumstances, the endochrome does not divide after the lengthening of the frustule, but secretes a siliceous envelope and becomes a gonidium or sporangium, consisting of a cell with two rounded ends, and a connecting hoop, one end being smaller than the other ….