all our manufacturing wealth, was seriously considered. The facts that, theoretically, a pound of coal is, by its combustion, capable of producing sufficient mechanical energy to raise ten million of pounds one foot high-that in our best constructed steam-engines only onetenth of that result is obtained—and that with our ordinary engines not even one-third of this lower amount is produced, were carefully considered; and the inference drawn that in our average steamengines thirty times as much fuel is required as would be requisite with a perfectly-constructed heat-engine.

The possible substitution of some new source of motive power was considered; the fact that we cannot obtain mechanical energy without the consumption of materials demonstrated; and that no materials could possibly be so cheap as the coal from the earth and the oxygen of the air; the latter costing nothing, and every pound of coal rendering available two and a-half pounds of oxygen as a source of power. The reason that the materials of water cannot be regarded as a source of power is that the oxygen and hydrogen are already chemically combined, and require the expenditure of a great amount of chemical energy to effect their separation.

The time when we shall utilize the natural falls of water as sources of mechanical energy was regarded as inevitably, though slowly, approaching; and one great river was stated to develope at a single plunge sufficient power to carry on all the manufacturing operations of mankind, if they could be concentrated in its immediate neighbourhood.

The waste of coal in our ordinary households was a subject of regret. In warming by open fires we consume at least five times the amount of fuel requisite in a well-constructed stove; and as one pound of coal in an efficient steam-boiler is capable of evaporating one gallon or ten pounds of water, the amount of fuel wasted in our ordinary fires may be readily inferred.

The increase of temperature below the earth's surface, as measured at the Monkwearmouth colliery to a depth of 1800 feet, was stated to agree closely with that observed in other localities, namely, to be one degree Fahrenheit for every 60 feet. This, assuming the fusing point of subterranean minerals to be 3000°, would give a thickness to the earth's crust of about 34 miles, and would from the mere increase of temperature prevent the working of mines to as great a depth as 4000 feet.

In connection with the dynamical theory of heat, the circumstance that every degree of heat (Fahrenheit) in one pound of water is equivalent to 772 pounds lifted one foot high was stated, and also that these amounts of heat and power were reciprocally convertible into one another. This led to the consideration of the explosive force of gunpowder, which first appears as heat and then takes the form of mechanical power, communicated chiefly to the shot; which force is reconverted into heat when the motion of the shot is arrested in striking an object.

After alluding to the resolutions of Mr. Tyndall on radiant heat, which have been described in our previous volumes, Sir W. Armstrong advocated strongly the introduction of the metric system of

weights and measures, and the centigrade division of the thermometer, and recommended the Association to exclude all other standards from their future publications; and concluded by a consideration of, and a qualified assent to, the Darwinian theory regarding the origin of species.

Many of the topics of the papers read in the different sections of the Association have been already mooted in the different scientific societies, and have been duly chronicled in our pages. Among the most interesting of those not noticed may be mentioned that of Mr. A. Claudet on the refractive power of the eye, by which objects that are situated in reality somewhat behind us appear as if situated to the left or right; or, in other words, that objects are pictured in the retina which are included in an angle much larger than half the sphere of which the observer is the centre.

From the refractive power of the cornea, rays passing through it are more and more refracted in proportion to the angle at which they strike its surface; the only objects seen in their true position being those whose rays enter the eye perpendicularly to its surface; rays entering at an angle of 90° are refracted 10', and appear to come at an angle of 80°.

Some curious illusions result from this law. I may suggest the following experiment. Connect two lights placed at some yards distance from each other by a strained thread, on placing the face over the centre of the thread, and looking at right angles to it, both lights are seen somewhat in advance of the body, as if forming an ́angle of 160°, and if the observer turns his back on the thread and walks away from it, both lights remain visible, so long as the angle formed by them does not exceed 200°; hence we are really enabled to see behind us whilst looking straight in front.

Mr. Claudet called attention to another effect of this phenomenon. That on placing ourselves so that the sun is on one hand and our shadow on the other, the sun and shadow do not appear connected in one line, but that they are bent to an angle of 160°, and are both seen a little before us. The intellectual observer of these phenomena need hardly be reminded that the head should not be turned to either side during these experiments.

The paradoxical and apparently impossible action of Giffard's injector, employed instead of a feed pump in charging steam-engine boilers, was illustrated in a remarkable manner by the Abbé Moigno, with M.M. Bourdon and Salleron's "Injector of Solids."

Giffard's injector consists of three tubes united at one point: one of these brings the supply of water for the boiler from any convenient source; the second is for the purpose of conveying the water into the boiler, and opens below the level of the liquid in that vessel; the third brings a jet of steam from the upper part of the boiler. This jet of steam has the power of injecting a constant supply of water into the boiler, and so obviating altogether the necessity for a feed pump, and, apparently impossible as it may appear, not only has the steam power to inject water into its own boiler, but it is capable of feeding another boiler in which the steam has a much higher pressure than itself. MM. Bourdon and

Salleron's Injector of Solids, which is capable of rendering this action visible by means of solid bodies, consists of two air vessels, with a communicating tube capable of being opened or closed at the will of the experimenter. One of these vessels is made of glass, and furnished with an aperture closed by a valve opening inwards. The other has a small air-gun proceeding from it, the barrel of which is directed against the opening in the first vessel. On condensing air into the two receivers, it is found that, even when four atmospheres are condensed into the glass vessel, and, only two in that connected with the air-gun, the bullet driven by the latter has power to open the valve closed by the pressure of four atmospheres and enter the glass receiver.

The paper read by Dr. Embleton on the Anatomy of a Chimpanzee strongly corroborated the facts brought forward by Professor Huxley and Mr. Marshall, that the brain of this animal differs only in degree—that is, in the smaller size and extent of its parts-from that of man; and that with this difference essentially the same structures, without any exception, exist in both brains.

Dr. Crawford maintained in a subsequent paper that the consideration of the material structure of the brain was of far less value than a consideration of its working or living action, and that probably there exist subtle differences between the brain of man and those of the lower animals that anatomy has not, and probably never will, detect.

Thus the brain of the wolf is anatomically the same as that of the dog, one being an untamable glutton, the other the friend and companion of man. The Australian savages tame the young of the wild-dogs, and use them in the chase, whereas the young of the wolf are not capable of complete or useful domestication. Again, the hog, with its low organized brain, is equal in intelligence to the most anthropoid monkey. The sheep and the goat have brains identical in structure, the one being a stupid, the other an intelligent animal.

Among the more singular new instruments exhibited at the meeting must be mentioned M. Soleil's Tenebroscope, for demonstrating the invisibility of light; this was shown and described by the Abbé Moigno. It illustrates the fact well-known to scientific observers that rays of light are invisible except the eye is so situated as to receive them either directly or as reflected from surrounding objects.

This is decisively shown when a beam of sunlight is admitted into an otherwise perfectly dark chamber, and received on a piece of black velvet or other non-reflective surface; when the whole chamber remains in perfect darkness, and the ray of light itself is perfectly invisible except that small portion of it which is reflected from the atoms of dust floating in the air. On powdering some small dust in the course of the beam, or by pouring a shower of water across it from a small watering can, it becomes immediately visible; and the chamber itself may be instantly illuminated by receiving the beam on any reflective surface. M. Soleil's Tenebroscope consists of a tube closed at one end, the other being open to

admit of being looked into. The interior is blackened, and there is an opening in the side to admit a strong light to pass across the tube. When looked into from the end, the tube is perfectly dark despite of the light passing across it; but on raising a small white ball into the course of the rays of light, they instantly become visible from being reflected so as to enter the eye of the observer.

NOTES AND MEMORANDA.

SUGAR FROM SERPENTS' SKINS.-M. S. de Luca obtains small quantities of sugar by chemical transformation of a substance existing in the skin of serpents, and which is isomeric with vegetable cellulose. The existence of this substance under such circumstances affords another connecting link between animal and vegetable organic bodies.

POISONOUS EFFECTS OF THALLIUM.-M. Lamy calls the attention of the French Academy to the poisonous properties of thallium, to which he ascribes pain and lassitude chiefly in the lower members, which he experienced while experimenting on that metal and its compounds. He dissolved five grammes of sulphate of thallium in milk, and offered it to two puppies, who tasted it and left it alone. Two fowls, six ducks, and a moderate-sized dog obtained accidental access to the milk. The dog was soon taken ill with sharp pains, and his hindquarters were partially paralyzed, after exhibiting convulsive movements. Iodide of potassium was administered as an antidote, but the animal died in sixty-four hours, having been affected neither by vomiting nor alvine dejections. In the evening after the milk had been swallowed one fowl and six ducks died. Four days afterwards the two puppies died. All the creatures suffered paralysis of their lower limbs. The second fowl was killed on the eighth day, having for three days been in a bad state, and unable to stretch its neck sufficiently to pick up food.

THE AUGUST METEORS.-M. Coulvier-Gravier has a short paper on this subject in Comptes Rendus. He says that "in August, 1861, he pointed out the year 1858 as terminating the descending period, since 1848, when the phenomena were at their height, and on the 9th, 10th, and 11th August 110 shooting stars appeared per hour. In 1858 the number had descended to 39·3, while in August, 1863, he noticed 667 per hour." He adds that we may soon expect the August showers to re-appear in all their magnificence.

BREAD FROM POMPEII.-In August last year a baker's oven was discovered in Pompeii, closed with an iron door, and containing eighty-one loaves of a brownish colour. M. S. de Luca, who examined some of this bread, and reported to the French Academy, found that the loaves still contained some moisture, which they parted with at 110° to 120° C. The central portion contained about 23 per cent. of water and the exterior only 19 to 21 per cent. The quantity of carbon diminished from the circumference to the centre, while the hydrogen followed an opposite rule; thus it would seem that the decomposition took place very slowly, and was not affected by sudden and strong heat. The central parts were least affected, and contained the largest quantity of the elements of nutrition.

POISONING BY NITRO-BENZOLE.-The Proceedings of the Royal Society, No.' 56, contain an important paper by Dr. Letheby on the above subject. It appears that if a dose of nitro-benzole be not too large, its poisonous action will not be immediately apparent, but it may "destroy life by a lingering illness, which shall not only defy the skill of the physician, but shall also baffle the researches of the jurist." After death the blood of animals so killed is black and turbid, and the large organs congested, and no nitro-benzole can be discovered, if sufficient time has elapsed, as it will then be converted into aniline. Such facts show the necessity of having medical men well trained in chemistry. Aniline produces symptoms very similar to nitro-benzole. The conversion of the latter into the

former takes place in a dead stomach, or by contact with putrid flesh for several

hours.

CAUSES OF COAGULATION OF BLOOD.-Professor Joseph Lister observes, in the Croonian Lecture, which details elaborate experiments, "that the coagulation of the blood is in no degree connected with the evolution of ammonia any more than with the influence of oxygen or of rest. The real cause of the coagulation of the blood when shed from the body is the influence exerted upon it by ordinary matter, the contact of which for a very brief period effects a change in the blood, inducing a mutual reaction between its solid and fluid constituents, in which the corpuscles impart to the liquor sanguinis a disposition to coagulate.-Proceedings of the Royal Society.

ATMOLYSIS.-Professor Graham gives this name to operations of dialysis conducted with gases, the molecules of which pass through tubes of unglazed earthenware, or plates of graphite, with unequal velocities, so that a separation, more or less complete, of mixed gases, can be effected by this means. He says, "the most remarkable effects of separation are produced by means of the tube atmolyser. This is simply a narrow tube of unglazed earthenware, such as a tobacco-pipe stem, two feet in length, which is placed within a shorter tube of glass, and secured in its position by corks, so as to appear like a Liebig's condenser. The glass tube is placed in communication with an air-pump, and the annular space between the two tubes maintained as nearly vacuous as possible. Air, or any other mixed gas, is then allowed to flow in a stream along the clay tube, and collected as it issues. In the gas collected, the denser constituent is thus concentrated in an arithmetical ratio, while the volume of the gas is reduced in a geometrical ratio. In one experiment the proportion of oxygen in the air, after traversing the atmolyser, was increased to 24.5 per cent., or 16.7 upon 100 oxygen originally present.”—Proceedings of the Royal Society, No. 56.

Ross's NEW COMPRESSORIUM.-Microscopists who have suffered the inconvenience inseparable from ordinary forms given to a compressorium, will thank us” for calling their attention to an entirely new pattern devised by Mr. Ross. It consists of a stout plate of brass about three inches long, having in its centre a piece of glass like the bottom of a live box. This piece of glass is set in a frame which slides in and out, so that it can be removed for the convenience of preparing any object upon it, under water if desirable. The upper moveable part, attached to a screw motion, is admirable for simplicity and efficiency. At one end of the brass plate, which forms the bed of the instrument, is an upright piece of brass, accurately grooved so as to receive a vertical plate, to which a downward motion is given by a single fine screw, surrounded by a spiral spring, which elevates the plate as soon as the screw pressure is removed, by turning the milled head the reverse way. The vertical plate carries an arm precisely at right angles to its own plane, and terminating in a square frame capable of receiving very thin or somewhat thicker glass according to desire. This is the upper part of the compressorium, and the exact amount of pressure required is completely under command by the motion of a single screw. The arm has likewise a horizontal motion, so that the upper glass, plate can be turned completely off the lower one. Should the thin upper glass be broken, it can be instantly replaced, as no cement is required. It is merely needful to remove the fragments, and slip a fresh glass in. We do not know any compressorium that is at once so accurate and so easily used. If required, a duplicate frame, carrying a thin bottom glass, can be obtained, and it would be very easy to contrive a support, as in the pattern of M. Quatrefages, by which either side of the object could be viewed. It often happens that on account of the trouble of an ordinary compressorium, a microscopist simply uses a slide and a piece of covering glass, and finds when too late that an exact means of regulating the pressure would have been desirable. With Mr. Ross's new pattern the convenience is so great that it should always be employed if there is a chance of the screw motion being advantageous.

EARTHQUAKES AT RHODES.-M. Jouanin, gerant of the French Vice-Consulate, gives an account in Cosmos of the disturbances in that island since 1860; and he likewise mentions a severe shock which occurred on 12th October, 1856, accompanied by vertical oscillations. In the year 1860 earthquakes occurred