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transmitted to the next generation, and, if the unfavourable conditions continue, is aggravated in it -, and thus a morbid variety of the human kind, which is incapable of being a link in the line of progress of humanity. Nature puts it under the ban of sterility, and thus prevents the permaent degradation of the race. Morel has traced, through fonr generations, the family history of a youth who was admitted into the asylum at Rouen iu a state of stupidity and semi-idiocy ; the summary of which may fitly illustrate the natural course of degeneracy when it goes on through generations.

First generation :—Immorality, depravity, alcoholic excesa, and moral degradation, in the great-grandfather, who was killed in a tavern brawl.

Second generation :—Hereditary drunkenness, maniacal attacks, ending in general paralysis, in the grandfather.

Third generation :—Sobriety, hut hypochondriacal tendencies, delusions of persecutions, and homicidal tendencies, in the father.

Fourth generation :—Defective intelligence. First attack of mania at sixteen ¡ stupidity, end transition to complete idiocy. Furthermore, probable extinction of the family ; for the generative functions were аз little developed as those of a child of twelve years of age. He had two sisters who were both defective physically and morally, and were classed as imbeciles. To complete the proof of heredity in this case, Morel adds that the mother had a child while the father was confined in the asylum, and that this adulterous child showed no signs of degeneracy.

When epilepsy in young children leads to idiocy, as it often does, we must generally look for the deep root of mischief in the family neurosis.

No one can well dispute that in the case of such an extreme morbid variety as a congenital idiot is, we have to do with a defective nervous organisation. We are still, however, without more than a very few exact descriptions of the brains of idiots. Mr. Marshall has recently examined and described the brains of two idiots of European descent. He found the convolutions to be fewer in number, individuallv less complex, broader, and smoother than in the apes ; " in this respect," he says, " the idiots' brains are even more simple than that of the gibbon, and approach that of the baboon.'' The condition was the result neither of atropy norof mere arrest of growth,âbnt consisted essentially in an imperfect evolution of the cerebral hemispheres or their parts, dependent on an arrest of development. The proportion of the weicht of brain to that of body was extraordinarily diminished. We learn, then, that when ft aan is born with a brain no higher—indeed lowe.—than of an ape, he may have the convolutions fewer in number, and individually less complex, than they are in the brain of a chimpanzee and an orang; the human brain may revert to, or fall below, that type of development from which, if the theory of Darwin be true, it has gradually ascended by evolution through the ages. _ With the defect of organ there и a corresponding defect of function. But there is sometimes more than a simple defect. A curious and interesting fact, which has by no means yet received the consideration which it deserves, is that, with the appearance of this animal type of brain in idiocy, there do sometimes appear or reappear remarkable animal traits and instincts. There is a class of idiots which may justly be designated theroid, so like brutes are the members of it. The stories of so-called wild men, such as Peter the wild boy, and the young savage of Aveyron, who run wild in the woods, and lived on acorns, and whatever else they could pick up there, were certainly exaggerated at the time. These degraded beings were evidently idiots, who exhibited a somewhat striking aptitude and capacity for a wild animal life. Dr. Carpenter, however, quotes the case of an idiot girl, who was seduced by some miscreant, and who, when she was delivered, gnawed through the umbilical cord as some of the lower animals do.

Jn the conformation and habits of other idiots, the most careless observer could not help seeing the ape. A striking instance of this kind is described by Dr. Mitchell, Deputy Commissioner in Lunacy for Scotland. "I have never," he »ays, "seen a better illustration of the ape-faced idiot than iu this case. It is not, however, the face alone that is ape-like. He grins, chatters, and screams like a monkey, never attempting a M »und in any way resembling a word. He puts himself in the moat ape-like attitude in his hnnts after lice, and often brings his mouth to help bis

hands. He grasps what he brings to his month with an apish hold. II is thumbs are bnt additional fingers. He has a leaping walk. He has heavy eyebrows, and short hair on his cheek or face. He is muscular, active, and not dwarfish. He site ,on the floor in ape fashion, with his genitals always exposed. He has filthy habits of all kinds. He may be called an idiot of the lowest order; yet there is a mischievous, brute-like intelligence in his eye. His head is not very small, its greatest circumference being twenty inches and a half, but in shape it strongly exhibits the ape-form of abnormality."

Pinel has recorded the case of an idiot who was something like a sheep, both in respect of her tastes, her mode of life, and the form of her head. She had an aversion to meat, and ate fruit and vegetables greedily, and drank nothing but water. Her demonstrations of sensibility, joy, or trouble, were confined to the repetition of the ill-articulated words be, ma, bah. She alternately bent and raised her head, and rubbed herself against the belly of the girl who attended her. If she wanted to resist or express her discontent, she tried to butt with the crown of her head; she was very passionate. Her back, her loins, and shoulders were covered with flexible and blackish hairs, one or two inches long. She never could be made to sit on a chair or bench, even when at meals ; as Boon as she was placed in a sitting posture, she glided on the floor. She slept on the floor in the posture of animals.

Dr. Crichton Browne has now under care in the West Riding Asylum, a deformed idiotic girl, who in general appearance and habits has points of resemblance to a goose; so much so, that the nurses who received her describes her as just like "a plucked goose." Her father died in the asylum, and ber mother's sister was also a patient in it atone time. She is 4ft. 2in. in height, has a small hand, and thin and scanty hair, so that the crown of the head ie partially bald. The eyes are large, round, prominent, and restless, and are frequently covered by the eyelids, as if by a slow forcible effort at winking. The lower jaw is large, projecting more than one inch beyond the contracted npper jaw, and possesses an extraordinary range of anteroposterior, as well as lateral, movement ; the whole configuration of the lower part of the face having a somewhat bill-like appearance. The neck is unusually long and flexible, and is capable of being bent backwards so as actually to touch the back between the scapulae. The cutis anserina is generally over the body, but is most marked on the back and dorsal aspects of the limbs, where it looks exactly as if it had been just deprived of feathers. The inferior angles of the scapulas stands prominently out, and, moving freely with the movements of the arms, have precisely the appearance of rudimentary wings. The girl utters no articulate sounds, but expresses pleasure by cackling like a goose, and displeasure by hissing or screeching like a goose, or perhaps like a macaw. When angry, she flaps her arms against her sides, and beats her feet upon the floor. She knows her own name, and understands one or two short sentences, such as " Come here," and "Put out your hand." She recognises the persons who attend upon her and feed her, and is much agitated if touched by a stranger. She cannot feed herself, bnt swallows voraciously all that is put into her mouth, showing no preference for one article of diet over auother. She is dirty in her habits, and no amount of attention has improved her in this respect. She is very fond of her bath, cackling wheu she is put in, and screeching when she is taken out of it.

(To be continued.)

CHAPTERS ON CURIOUS CATERPILLARS.—JUNE. By J. R. S. Clipford. гТШЕ thoughtful observer of Caterpillar life -*• can hardly fail to be impressed with the endless varieties of shading and colouring, and the numerous variations in form, which occur amongst these creatures, even if we confine our attention to our native land. Looking upon the imago, the butterfly or moth, as the true embodiment of the form of each species, we might have said that it would have mattered very little what appearance it had in this or any preparatory stttge ; and had we no knowledge to the contrary, we might have expected to find all cater

pillars very much of the same colour—perhaps of a uniform green or brown. Instead of this, we bavo sometimes displayed as much beauty as in tho perfect insect—iu some cases more—while there are very few caterpillars indeed that are of a uniform colour. It is singular, though, that in very few cases is there any resemblance between the markings exhibited by the caterpillar and those which adom the wings of the imago produced therefrom. Discernment is sadly at fault here amongst those non-entomologists who, from the circumstance that they work in gardens or fields, come into contact with many different kinds of caterpillars. As a rule, they notice no differences amongst them, but class them all together as "green varmint" or "blight," and regard them a« things to be squashed out of existtence as speedily as possible. So that of many a gardener we might say, parodying the poet's lines, that all he notices is—

A blight upon the shrubs or trees,
Some common blight, 'tis all he sees—
To hira 'tis nothing more.

Well, in these times, the schoolmaster is abroad and we will hope that such being the case he will look a little beyond his books, and getting a good insight into Nature and its operations himself, he will be the better fitted to make "the rising generation," the "coming men," rather wiser in these matters than we can expect to find those who are now too old to be apt pupils of natural history lore.

A host of caterpillars is feeding in June, especially in the early part of the month ; towards the close, however, a good part will have become pupte, and await the change to the imago, or perfect state. There is some difference in each year, according to the weather and the state of the vegetation ; this present year (1870) has as yet retarded insect life, and many species are a fortnight or three weeks behindhand. In some of our woods, more particularly in the south of England, the caterpillar of that handsome and remarkably agile butterfly known as the Silverwashed Fritillary, may be detected by a very careful search in its food plant, the violet. This caterpillar, besides feeding on the species of violet, is also said sometimes to be found on the wild raspberry, but this is extremely doubtfnl. As such lowgrowing plants cannot be " beaten," the best plan is to crouch down and turn over the leaves, disregarding the stiffness in the back thereby produced, and keeping in view the fact that the caterpillar has the trick of falling off the plant at a very slight touch, doubling itself up partly. The parent butterflies deposit their eggs in July or August, and as these hatch shortly after, and the caterpillars are not adult until the beginning of June, they thus pass about nine months in this state. The ground colour is black; down the back are two yellowish stripes, with a black stripe between them ; along the sides in a triple series are delicate lines of a rust colour. On each segment are six spires, which give off fine bristles; on the second segment there are two out of the six, which project over the head of the caterpillar, and hive black tips. (See Fig. 1.) Suspending itself against some twig or stem, when it has ceased to eat, the caterpillar's akin is cist off and the chrysalis state assumed, and in this case the name is really correct, for the shell of the chrysalis is decorated with spots and dashes of gold.

In the early part of the present century, the singularly-formed Comma Butterfly ( Vanessa С Albura) was taken pretty freely near the metropolis ; it has now disappeared, nor does it apparently occur in the southern and eastern connues of England. In Herefordshire, Mr. Newman reports it as still occurring, and in the Lake District, and a few other localities, individuals are seen on the wing most seasons. During 1864, an entomologist obtained the caterpillar of this species, and it is one of some singularity, feeding, as far as observed, only upon the bop-vine. As it is sluggish in its movements, and a day-feedei, it might probably be obtained by beating this climber. It is also supposed to feed on the currant anil ou nettles. Like the preceding, it has two processes projecting in front of the bead, but in the caterpillar of the Comma they actually spring from the head, and are of a horny nature ; these are black, as is the head and the next segment of the body, though the general colour of the remainder is grey, chequered with fulvous ; from tie seventh to the twelfth segment there is a white stripe down the back;on the sides and back are seven rows of branched spines; the eyes, ns may be observed by a magnifier, are crowded to

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KlG. 1.

gethor. The chrysalis is suspended, head down wards, from 9omc leaf-stalk, and has a few silver blotches, on an umber ground; it is also marked with fine black lines. The butterfly emerges in August and September; it is also found in the spring of the year, and individuals then on the wing have possibly lived through the winter.

Common in most parts of Britain, and occuring also in Ireland, is the moth known as the Beaded Chestnut. (Anchocelis Pittacina.) The caterpillars emerge in the spring from eggs laid the previous autumn, and as they feed on the buttercup and other meadow plants growing amongst the grass; they may be conveniently taken by sweeping the grass which is growing for the hay crop, but not during the middle of the day. They fall into the net rolled up closely, but soon relax and march off briskly, and present, as they move, an odd appearance, for, at the interstice of each'segment is a fold of skinof yellow colour, and these folds appear and disappear, looking like yellow rings. The body is velvety and cylindrical, apple-green in tint, with an extremely slender white stripe down the back, and

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Egg Eh Catebpillar.-Described in No. 260. broader one along the sides -, there are also a few dots sprinkled along the back. Early in June, these caterpillars enter the earth, and beneath it form compact cocoons of grains intermingled with silk. It has been noticed by Mr. Newman that they remain some weeks unchanged, but ultimately become chrysalides, which produce moths in September and' October. An instance how certain species simulate the appearance of tho plants on which they feed is furnished by the caterpillaroftheMallowMoth. (Eubvlia Cervinaria.) When the Common Mallow is shaken, and there are any of these citerpillars feeding upon it, they roll themselves into rings, the legs, head, and claspers being bidden, and resemblo the seed of the plant, well-known to all country children as " cheeses ; " also when not disturbed they extend themselves along the stalks, to which they assimilate in colour, and thus again escape notice. The whole body is covered with minute wart», each tipped with a tiny bristle; these are white, while the general colour is dull green; down the back is a darker line, showing the course of the alimentary canal ; the legs are curious, being very pale and nearly transparent. These caterpillars иге full grown in June.

The caterpillar of the Small Chocolate Tip ( Cloitera Recluta-), may be beaten off dwarf sallows in many places throughout England in thi« month. It is slightly hairy, marked with grey and yellow, the under surface, legs, and claspers being smoke-coloured, and the head black. The cocoon isepun amongst the leaves, and the moth flies forth in August, giving birth to another brood of caterpillars in September. A much handsomer caterpillar than that of Recluse is its congener, the Scarce Chocolate Tip. (C anaclioreta), which, however, no entomologist is very likely to find at large, as it is of exceeding scarcity. Nevertheless, spcoimens of the moth are common enough in collections, nearly all of which are the descendants of some caterpillars found at Folkestone, a few years since. It is a species which will breed in confinement, and by this means an abundance of the caterpillars have been got year after year. The general hue of the body is velvety black, mottled with smoky-grey; a stripe of dingy white runs down the back, and when the caterpillar is crawling, we can perceive that this apparent stripe is composed of square markings, which are connected by lines running between the segments; a double series of similar markings runs along the sides, one row above the spiracles, the other below them ; there is a hump of chestnut-brown on the fifth and twelfth segments ; that on the fifth is surrounded by a white patch ; in addition there are smaller prominences on three other segments; the head is black, and also the legs; the claspers of the smoky hue. Towards the end of June, or early in July, this caterpillar (at least, when in captivity) has reached its full size; and spins itself a cocoon between the leaves of the food-plant; it apparently thrives best on sallow or poplar.

A truly ferocious caterpillar is that from which the rather elegant moth, the Dun Bar (Cosmia Trapezina), is developed. So eager for prey is he that, when he is beaten into the net or umbrella, ere he has hardly recovered from the shock, he begins to crawl with rapidity after some unfortunate (.mailer caterpillar that may be at hand, especially preferring that of the Common Winter Moth; and Mr. Newman points out the curious fact, that the caterpillar of the Dnn Bar does not seize its prey by the extremity,should that be nearest, but advances until he can grasp the neck of the victim. He rarely devours the body entirely, though his appetite is considerable, preferring, after awhile, to look after a fresh victim. This caterpillar is found on oak and hornbeam, the leaves of which it probably eats occasionally, though most partial to animal food. In appearance it is of a dull green colour, the body plump, and the head rather narrower, and shining ; there are five pale stripes running from head to tail, and it is also freckled over with numerous small warts, which are black, surrounded by the white ring. The under side, legs, and claspers are of a delicate green. It is adult about the middle of June, and changes to it chrysalis on the surface of the ground ; the moth appearing a few weeks after.

A not very common moth is known as tho Lilac Beauty (Pericallia Syrinjaria), and it deserves the name it bears, tor the wings, which are of a lustrous grey, are tinged with red and yellow, mingled with white and brownish markings. The caterpillar feeds on lilac and other shrubs in this month; when of full size, it is rather of the rose-coloured hue generally, though sometimes grey, along the back is a pale line, and there are two singular processes, like hooks, on the ninth segment, and four rather conspicuous warts on the sixth and seventh segments. The chrysalis is enclosed in the silken cocoon of slight texture, and it displays numerous brown stripes and spots. I believe this species is partial to woodlauds—at least, this appears to be the case in the south of England.

REGENERATIVE HOT BLAST FURNACES.

AT a recent meeting of the Institution of Civil Engineers a paper read was " On Recent Improvements in Regenerative Hot-blast Stores for Blast Furnaces," by Mr. E. A. Cowper.

The Author stated that when, in 1828, the late Mr. J. B. Neilson (M. Inst. CF..) introduced the plan of heating the air employed as blast, by means of iron placed in or near a fire, the increase of temperature was at first only from 60 deg. to 100 deg. Fuhr. Subsequently. Mr. Neilson obtained a temperature of U0O deg. or G."<0 deg., and the pipe stoves had since been urged up to 900 deg., and in a few cases to 1000 deg. The wear and tear, however, with such temperatures of blast were considerable, there was great loss of heat by conduction, and the pipe stoves were, as a rule, worked in a leaky condition, necessitating the expenditure of engine power for blowing air uselessly.

The improvements described in the paper were based upon Mr. Siemens' regenerative furnace. Each stove of a pair consisted of a wrought-iron cylindrical casing, lined with fire-brick, and provided with a central shaft or flue, which extended to within a few feet of the brick dome forming the top. Around this shaft there were a number of compartments, or boxes, formed of brielca » placed that those in one course were not exactly coincident in position with those in the courts either above or below, though a passage v» left open from the bottom to the top of the me of brickwork. This wrought iron casing No provided with several valves, three being f ortfe admission of cold blast, of gas, and of air by combustion, and two being for the exit of tk hot blast and of the products of combustion When a stove had been at work heating blast, ad it was wanted to re-heat it, the first thing to try done was to put another stove in operation, then to shut the hot and the cold blast valves, allowing the air in the stove to be blown out at a small valve to reduce it to atmospheric pressure. The gas, air, and chimney valves were next opened, and the gas, igniting as it entered, gave a large volume of flame right up the central shaft and over and into the regenerator, thus heating the top course of brickwork considerably, the next course rather less, and so on, the products of combustion passing away to the chimney at a temperature of about 30Ó deg. In the course of a few hours, a large amount of caloric was stored up in the bricks forming the regenerator, a good red heat penetrating nearly to the bottom, when the stove was again ready to heat the blast to a temperature of 1400 deg. or 1500 deg. In these stoves the cost of dust catchers was avoided, and the expense of producing gas was also saved, as the gas was used direct from the top of the blast furnace, and the stoves could be cleaned out with the greatest facility. The construction of the regenerator in oompartments or boxes, connected together vertically but not horizontally gave the power of applying the blast with efficiency (inasmuch as the whole force of the blast was confined to the one passage that was being blown at the time), and admitted of the brush being passed up or down the boxes to remove the dust. The form and proportion of the passages had been found, after numerous experiments to produce an excellent effect in mixing the air, thereby ensuring B rapid and perfect conduction of heat from the brick to the air, or rice rerta, from the products of combustion to the bricks.

The results obtained by Messrs. Cochrane from the adoption of these stoves at Ormesoy, as regarded the quality of iron, the increased make and the saving of coke in the blast furnace, had been most satisfactory. Thus there was a saving of i cwt. of coke per ton of iron produced, by the use of the regenerative stoves for heating the blast, when compared with good cast-iron pipe stoves, and the saving was still more over ordinary pipe stoves. With a large furnace, producing 475 tons a week, the first cost of these stoves was somewhat less than the cost of pipe stoves, while the expense of working was less, so that the profit, taking every thing into account was estimated to amount to about £iU>>- » year.

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barnacle belongs to the same class of animals that includes the crabs, shrimps, and lobsters. It a piece of rock is put into a large glass full of sea water, many things may be seen on it which are of a white colour, and whose shape is something like that of a thimble with the top battered in. If they are examined it becomes evident that the conical outside is formed of several little bits of TM*i shell joined together very carefully, and that the top has a valve in it. When the water is quite clear and quiet, a small flapper is forked out through the valve, and ie moved to and fro with the motion like that of opening and shutting the fiiigers. The flapper has some long bristles attached to it, and they are beautiful, feathery-looking things when examined under a microscope. The movement goes on for hours, and ceases upon the least alarm. Then the flappers are withdrawn, the val vc closes, and the barnacle—for such is the creature—looks again like B conical piece of stone The rappers are the lungs as well as the hands of the barnacle, and minute living creatures are entangled by them and passed by a current of water into the mouth, which is within the shell. When the barnacle produces its eggs, it ejects them with a stream of water, and they float about in the sea, being very minute things. They soon become hatched, and then it is that the reason becomes clear why barnacles and crabs are placed by zoologists in the same class. The yonng barnacle is just like a shrimp, withjs(¡long body, many long

legs close to its hoad, and a large tail ; it has eyes, and swims about most vigorously. It appears to be constantly in movement, and although actively employed in swimming, and in crawling, it does not care to seek for food. After a while the young free-swimming creature rests upon a piece of rock, or wood, or even on the back of a fish, and then a wonderful alteration takes place, The long legs and feelers near the head grasp the substance on which the creature is to live for the future, and a gummy substance comes from a gland which has been growing for some time close to the head. The gum sticke the legs and the feelers to the substance, the eyes diminish in size and are no longer seen, the tail and the hind legs grow into the feathery flappers already noticed and the shell of many pieces encloses all. The barnacle is then fixed for life, head downwards, and it loses its organs of sight, and receives a mouth and stomach, which it had not before, whon in the free-swimming state. All barnacles do not undergo this change, for the males of some kinds live inside the conical house which holds the female, and never have houses of their own, for they remain in the free-swimming state. All the animals of the crab class have to undergo a change of form before arriving at maturity, and the common shore crab, when it is first hatched, is a long thing with a great head, and legs fitted for swimming, and not for crawling. As it grows the body shortens by curling the tail end underneath, and

the legs and claws grow out of the swimming apparatus. Some of the barnacles that live on coral reefs are very beautiful, and their shells are ornamented in imitation of the flower-like polypes of the stony madrepores.

The accompanying illustration will give the reader a good idea of the appearance which a family of barnacles presents, clinging to the under surface of a floating log,-- Scientific American.

NOTES ON RECENT DISCOVERIES IN SCIENCE, AND THEIR PRACTICAL APPLICATIONS.*

Poisonous Properties Op New Dyes.

A FURTHER step has been made in the investigation of the reputedly poisonous properties of some of the new dyes. There can be no doubt that cases have occurred in which intensely irritating effects have been produced by a few of these colours, but they have been rare relatively to the frequent use of articles, such as stockings, dyed with them. The researches of M. Guvot go to show that these dyes are poisonous or not according as they are pure or impure. Thus, it is said that azuline, the bine, is poisonous if it contains an excess of aniline. The same colour also produces irritation of the skin when prepared with coralino containing excess of phenol. The coralline red, as we have mentioned before, is the colour which in most cases produced the effects which caused the alarm on the subject. It is not necessary to say more on the matter, for, as the manufacture of the dyes improve, the effects now seen but rarely will never be observed.

Electrolysis oír Nitric Acid. When a very dilute acid is operated upon, hydrogen only is evolved at the negative pole, and no secondary product is found in the liquid contained in the negative compartment. With a less dilate acid, that is, an acid with about 125 equivalents of water, hydrogen is first given off, then a little nitrogen, and the liquid is found to contain traces of ammonia. In the case of a stronger acid with only 15 equivalents of water, while oxygen is freely given off at the positive pole, no hydrogen for some time escapes at the negative, all that gas re-acting on and combining with the acid in the compartment, theliqnid assuming a distinctly blue colour. After some time, however, hydrogen mixed with some nitrogen comes off, but soon gives place to an evolution of binoxide of nitrogen . which in its turn ceases, and hydrogen again appears. In the end a good deal of ammonia is found in the negative liquid, and also much nitrous acid, Nitric acid with two equivalents of water gives off at first only binoxide of nitrogen, then hydrogen. Thus we вее that the reducing action of hydrogen on nitric acid, according to the strength of that acid, produces nitrous acid, binoxide of nitrogen, nitrogen, and ammonia.

Logwood In Wine. A very easy way of detecting logwood colour in wine has been published in France, which, if good for anything, will be useful in discovering the adulteration of port. We have only to moisten a strip of paper with a strong solution of neutral acetate of copper, and dip it into the suspected vinous finid, which, if it contains logwood, will give a blue colour to the paper. If, however, the colour of the wine be the natural product of the grape the paper changes to a grey shade.

Tension Of Liquids. An observation has been made which has resulted in the discovery of a new mode of estimating the strength of alcohol. M. Ducaux has been experimenting on the superficial tension of liquids with an apparatus which exhibits the variations of it in a very remarkable way. A dropping tube, for instance, if arranged to let fall in air 100 drops a minute. If, now, the experiment be repeated in air saturated with vapour of alcohol, instead of 100 drops, 110 will fall in the minute. This is caused by the solution of some alcohol in th water, by which the superficial tension of tb liqnid is diminished. Further experiments led t the discovery that the strength of alcohol could be exactly determined by ascertaining how many drops would fall in a minute from a given orifice.

To Dye Linen With Aniline Black. A simple process is given in the Oerman Dycrt Journal, which is said to produce a very deep and beautiful black on linen goods by means of ani

• From the Mechanic*' iJagatine.

line. The goods aro first immersed in a bath con-
futing of a solution of acetate of aniline "II doir.
Baume, to which is also added 4 per cent, of sal
ammoniac, 4 per cent, of chlorate of potash, ^ per
cent, of nitric acid, and 1 per cent, of eulphate of
copper. The goods are then wrung out, and are
taken moist to an oxidising chamber and exposed
to moist warm air. After two or three days the
black is fully developed, and the goods only re-
quire to be rinsed in a weak solution of ammonia,
and finally in weak soap and water. The result
is said to be an extraordinarily beautiful colour.

To Detect The Adulteration Op Rice
Flour.

Bice Sour ia said to be often adulterated with wheaten, rye, and maize flour, as well as cheaper materials. The detection of these depends upon *.Ьз recognition of cerealine, or, if pea or some other meals have been used, leguminosin. Picric acid has the property of precipitating these substances, aud thus becomes an important agent in the detection of the above adulterations, it is employed in the following way :—The suspected flour is first digested with cold wator for an hour or two, the mixture being frequently stirred. Then the liquor is quickly filtered, and the filtrate is gradually mixed with about an equal volume of a cold saturated solution of picric acid. Any precipitate produced shows that the rice flour has been adulterated with one of the above-named substaucee. Two per cent, of most of them may be detected in this way.

A Useful Cement.
We mentioned a year or two ago that an ex-
cellent cement for fixing iron or stone was made
by mixing together commercial glycerine and
ground litharge. To-day we read of many other
applications of this compound, which seems to be
extremely useful. As a cement for joining che-
mical apparatus, it offers many advantages, for it
is unaffected by chlorine, hydrochloric aoid, sul-
phur vapour, sulphurous acid, nitric acid, and,
indeed, resists most corrosive vapours. Further
than this, it withstands the solvent action of
alcohol, ether, sulphide of carbon, and all hy-
drocarbon vapours. It hardens in from ten to
thirty minutes if mixed of the consistence of
a thick dough, and sets under water as quickly as
in air. Moreover, it will stand a very much higher
temperature than any oil cement. The composition
may be also employed for moulds for electrotyping.
For this purpose glycerine must be stirred with
the litharge until a mixture of the proper consis-
tence is obtained. The article to be copied must
bo smeared with dilute glycerine before the mix-
ture is poured on, and plenty of time most bo
given for it to set

Action Op Heat On Diamonds.
A jeweller at Marseilles had a couple of dia-

^^ mond shirt studs sent to him for the purpose of "^havifig the gold setting enamelled. Not being able to remove easily the stones from the setting he determined to leave them. Not having any charcoal, moreover, he heated his muffle furnace with coal. When the studs were taken from the muffle he found that the enamel was perfect, but to his surprise the diamonds were black. Vain were his endeavours to restore the brillianoy of the stones. Bubbing only made them shine like black lead. The stone of the lapidary, however, cut away the black layer, and then it was found that the weight of the stone had not been diminished. This curious result induced M. Morren to make some experiments on the behaviour of diamonds exposed to heat under different conditions. First, he heated one to a white heat in a' current of coal gas, and obtained exactly the same result as the jeweller. The stone appeared to be covered with a layer of plumbago, which could not be removed by friction, and the stones were found to have increased in weight. M. Morren succeeded in burping the black deposit away by

mmmJjjm^^hefttiflg' the stone to redness in the air, uftcrwhTSÍPlt was as brilliant as before. Heated in hydrogen the diamond remains completely unaffected, even at the température at which platinum melts. In carbonic acid, however, it loecs brilliancy and also weight if the exposure to heat is prolonged. M. Morren tells us that it is often difficult to burn diamonds, which is a matter of little consequence, since it is what people seldom wish to do. If anyone, however, desires to indulge in the expensive amusement he may be glad to know that in mott coses it is sufficient to :• like the stone white hot on platinum, and plunge into oxygen, when it is quietly consumed with

out blackening, remaining brilliant to the last. M. Morren telle us further the diamonds have different crystalline structures, revealed by the appearance of half-burnt specimens.

A Modification Op Smee's Galvanic Battery. A Frenohman, M. Figuier, has succeeded in producing, but with considerable trouble, a cheap battery on the вате principle as Smee's. Instead of a simple platinum plate he makes plates of retort coke, paints them over with a strong solution of chloride of platinum, dries and then reduces the metal upon the coke by heating it in the fire. Silvered carbon may, however, be used, instead of platinised, bnt these plates are obtained with more trouble. The carbons are first done over with a solution of nitrate of silver, and are then, while moist, exposed to hydrochloric acid gas. In tbis way, a coating of chloride of silver is procured which may be fused into the coke by heating. The silver will be reduced upon the carbon by the first action of the battery. Plates made in eitherof these ways, M. Figuier says, are superior to the platinised silver or platinum plates hitherto need in a Smee's battery, the irregular surface promoting the escape of the hydrogen. The author details a method of giving a rough su г face to the cut plates of retort coke. It consists in spreading the plates over with a mixture of diluted white of egg or blood albumen and syrup, and then carefully burning them until smoke is no longer given off. The process being repeated two or three times, myriads of pointa, the débris of minute vesicles, remain firmly attached to the original carbon plate. The plates thus made must be welt washed in a large quantity of water, to remove any loose particles whloh might otherwise fix themselves accidentally upon the zinc, and set up local action. These carbon platea are very durable, the author having had some in use for three years. They are comparatively cheap if troublesome to make, and the simplicity of the arrangement of the battery will, no doubt, recommeud this modification.

ON STAB-GBOUPING, STAR-DRIFT, AND STAB-MIST.»

NEARLY a century has passed since the greatest, astronomer the world has ever known—the Newton of observational astronomy, as he has justly been called by Arago—conceived the daring thought that he would gauge the celestial depths. And because in his day, as indeed in our own, very little was certainly known respecting the distribution of the stars, he was forced to found his researches upon a guess. He supposed that the stars, not only those visible to the naked eye, but all that are seen in the most powerful telescopes, are suns, distributed with a certain general uniformity throughout space. It is my purpose to attempt to prove that—as Sir Wm. Herschel was himself led to suspect during the progress of his researches—this guess was a mistakeu one; that but a small proportion of the stars can be regarded as real suns; and that in place of the uniformity of distribution conceived by Sir Wm. Herschel, the chief characteristic of the sidereal system is infinite variety.

In order that the arguments on which these views aro based may be clearly apprehended, it will be necessary to recall the main results of Sir Wm. Herschel's system of star-grouping.

Directing one of his 20-feet reflectors to d i Herein, parte of the heavens, he counted the stars seen in the field of view. Assuming that the telescope really reached the limits of the sidereal system, it is olear that the number of stars seen iu any direction affords a means of estimating the relative extension of the system in that direction, provided always that the stars are really distributed throughout the system with a certain approach to uniformity. Where many stars are seen, there the system has its greatest extension; where few, the limits of extension must be nearest to us.

Sir Wm. Herschel was led by this process of star.grouping to the conclusion that the sidereal system has the figure of a cloven disc. The stars visible to the naked eye lie far within the limits of this disc. Stars outside the relatively narrow limits of the sphere, including all the visible stars, are separately invisible; but where the system has its greatest extension these orbs produce col

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lectively the diffused light which forms the Milky Way.

Sir John Herschel, applying a similar series of researches to the southern heavens, wag led to a very similar conclusion. His view of the sidereal system differs chiefly in this respect from his father's, that he considered the stars within certain limits of distance from the sun to be spread less richly through space than those whose united lustre produces the milky light of the galaxy.

Now it ia clear that if the supposition on which these views are baaed is just, the three following results are to be looked for.

In the first place the stars visible to the naked eye would be distributed with a certain general uniformity over the celestial sphere; so that if an the oontrary we find certsin extensive regions ovar which snch stars are strewn much more riohly than over the rest of the heavens, we mutt abandon Sir Wm. Herschel's fundamental hypothesis. and all the conclusions which have been based upon it.

In the second place, we ought to find no sign» of the aggregation of lucid stars into streams or clustering groups. If we should find such associated groups we must abandon the hypothecs of uniform distribution, and all the conclusion founded on it.

Thirdly, and most obviously of all, the laid stars ought not to be associated in a marked manner with the figure of the Milky Way. To tajan illustrative instance. When we look through a glass window at a distant landscape, we do not find that the specks in the substance of the glass seem to follow the outline of valleys, hills, trees, or whatever features the landscape may present. In like manner, regarding the sphere of the lucid stars as in a sense the window through which we view the Milky Way, we ought not to find these stars, which are so near to ns, associated with the figure of the Milky Way, whose light comes from distances so enormously exceeding those which separate us from the lucid stars. Here again, thon, if there should appear signs of such association, we must abandon the theory that the sidereal system is constituted as Sir Wm. Herschel supposed.

It should further be remarked that the three arguments derived from these relatione are independent of each other. They are not as three links of a chain, any one of which being broken the ohain is broken. They are as three strands of a triple cord. If one strand holds, the cord holds. It may be shown that all three are to be trusted.

It is not to be expected, however, that the stare as actually seen should exhibit these relations, since far the larger number are bat faintly visible; so that the eye would look in vain for the signs of law among them, even though law may be there. What is necessary is that maps should be constructed on a uniform and intelligible plan, and that in these maps the faint stars should be made bright, and the bright stars brighter.

The maps exhibited during this discourse have been devised for this purpose amongst others. There are twelve of them, but they overlap, so that in effect each covers a tenth part of the heavens, There is first a north-polar map, then five maps symmetrically placed around it ; again, there is a goHth-polar map, and five maps symmetrically placed round that map ; and these five so fit in with the first five as to complete the enclosure of the whole sphere. T,n effect every map of the twelve has five maps symmetrically placed around it and overlapping it.*

Since the whole heavens contain hut 5932 stars visible to the naked eye, each of the maps should contain on the average about 593 stars. But instead of this being the case, some of the maps contain many more than their just proportion of stars, while in others the number as greatly falls short of the average. One recognises, by combining these indications, the existence of a roughly circular region, rich in stars, in the northern heavens, and of another, larger and richer, in the southern hemisphere.

To show the influence of these rich regions, it is only necessary to exhibit the numerical relations presented by the maps.

The north-polar map, in which the largest part of the northern rich regions fall, contains no less than 093 lucid stars, of w¡hich upwards of 400 fall within the half corresponding to the rich region.

* It Till be understood that ; the description here, and all which immediately follows, replaces portions of the discourse which would only be intelligible /when illustrated by means of the diagrams and illuminated mfeps actually employed.

Of the adjacent maps, two contain upwards of 500 «tar?, while the remaining three contain about 400 each. Passing to the southern hemisphere, we find that the south-polar map, which falls wholly within a rich region, contains no loss than 1132 stars! One of the adjacent maps contains 831 stars, and the four others exhibit numbers ranging from 557 to 595.

It is wholly impossible not to recognise so unequal a distribution as exhibiting the existence of special laws of stellar aggregation.

It is noteworthy, too, that the greater Magellanic cloud falls in the heart of the southern rich region. Were there not other sigos that this waiadcrful object is really associated with the sidereal system it might be rash to recognise this relation as indicating the existence of a physical connection between the Trabecule Major and tho southern region rich in stars. Astronomers Ьате indeed so long regarded the Nubecula: as belonging neither to the sidereal nor to the nebular nystem?, that they are not likely to recognise тегу readily the existence of any snch connection. Yet how strangely perverse is the reasoning which has led astronomers so to regard those amazing objects. Presented fairly, that evidence amounts simply to this :—The Magellanic clouds contain stars and they contain nebula; ; therefore they are neither nebular nor stellar. Can perversity of reasoning be pushed farther? Is not the obvious conclusion this, that since nebulae and stars are вес*» to be intermixed in the Nubecula:, the nebular and stellar systems form in reality but oae complex system.

As to the existence of star-streams and clustering aggregations, we have also evidence of a decisive character.* There is a well-marked stream of stars running from near Capella towards Monoceros. Beyond this lies a long dark rift altogether bare of lucid orbs, beyond which again lies an extensive range of stars, covering Gemini, Cancer, and the southern parts of Leo. This vast system of stars reeembles a gigantic sidereal billow flowing towards the Milky Way as towards some mighty shore-line. Nor is this description altogether fanciful; since one of the most marked instances of star-drift presently to be adduced refers to this very region. These associated stars are urging their way towards the galaxy, and that at a rate which, though seemingly slow when viewed from beyond so enormous a gap as separates us from this system, must in reality be estimated by millions of miles in every year.

Other streams and clustering aggregations there are which need not here be specially described. But it is worth noticing that all the well-marked streams recognised by the ancients seem closely associated with the southern rich region already referred to. This is true of the stars forming the River Eridanus, the serpent Hydra, and the Btreams from the water-oan of Aquarius. It is also noteworthy that in each instance a portion of the stream lies outside the rich region, the rest within it; while all the streams which lie on tho same side of the galaxy tend towards the two Magellanic clouds.

Most intimate eigne of association between lucid stars and the galaxy can be recognised,— (t.) in the part extending from Cygnus to Aquila; C>i.) in the part from Perseus to Monoceros; (iii.) over the ship Argo; and (iv.) near Crux and the /eet cf Centauras.

Before proceeding to the eubject of Star-drift, three broad facte may be stated. They arc, I believe, now recognised for the first time, and seem decisive of the existence of special laws of distribution among the stars :— First, the rich eouthern region, though covering f n *1(Ь part of tne he*vens, contains one-third •J all the lucid stare, leaving only two-thirds for the rtanajning five-sixths of the heaven.

•Secondly, if the two rich regions and the Milky

Way be considered as one part of the heavens,

the rest as another, then the former part is three

times as richly »trewn with lucid stars as the

second.

Thirdly, the southern hemisphere contains one thousand more lucid «tare than the northern, a fac'wbioh o»nnot but be regarded as most striking when it is remembered that the total number of lucid stare in both hemispheres falls ehort of 6000.

Two or three years ago, the idea suggested itself to me that if the proper motions of tho stars were examined, they would be found to convey — respecting the existence of

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variety of structure, and special laws of distribu-
tion within the sidereal system.

In the first place the mere amount of a star's
apparent motion must be regarded as affording a
means of estimating the star's distance. The
nearer a moving object i?, the faster it will seem
to move, and vice versa. Of course in individual
instances little reliance can be placed on this indi-
cation; but by taking the average proper motions
of a set of stars, no untrustworthy measure may
be obtained of their average distance, as compared
with the average distance of another set.

For example, we have in this process the means of settling the question whether the apparent brightness of a star is indeed a test of relative nearness. According to accepted theories the sixth-magnitude stars are ten or twelve times as far off as those of the first magnitude. Hence their motions should, on the average, be correspondingly small. Now, to make assurance doubly sure, I divided the stars into two sets, the first including the stars of the 1st, 2nd, and 3rd, the second including those of the 4th, 5th, and 6th magnitude. According to accepted views, the average proper motion for the first set should be about five times as great as that of the second. I was prepared to find it about as three times as great; that is, not so much greater as the accepted theories require, but still considerably greater. To my surprise I found that the average proper motion of the brighter orders of stars is barely equal to that of the three lower orders.

This proves beyond all possibility of question that by far the greater number of the fainter orders of stars (I refer here throughout to lucid stars) owe their faintness not to vastness of distance, but to real relative minuteness.

To pass over a number of other modes of research, the actual mapping of tho stellar motions, and the discovery of the peculiarity to which I have given the name of star-drift, remains to be considered.

In catalogues it is not easy to recognise any instances of community of motion which may exist among the stars, owing to the method in which the stars are arranged. What is wanted in this case (as in many others which yet remain to be dealt with) is the adoption of a plan by which suoh relations may be rendered obvious to the eye. The plan I adopted was to attach to each star in my maps a email arrow, indicating the amount and direction of that star's apparent motion in 36,000 years (the time-interval being purposely lengthened, as otherwise most of the arrows would have been too small to be recognised). When this was done,soveral well-marked instances of community of motion could immediately be recognised.

It is necessary to premise, however, that before the experiment was tried, there were reasons for feeling very doubtful whether it would succeed. A system of stars might really be drifting athwart the heavens, and yet the drift might be rendered unrecognisable through the intermixture of more distant or nearer systems having motions of another sort, and seen accidentally in the same general direction.

This was found to be the case, indeed, in soveral instances. Thus the stars in the constellation Ursa Major, and neighbouring stars in Draco, exhibit two well-marked directions of i-lrift. The etars j8, y, c, t, and Z, of the Great Bear, besides two companions of the last-named star, are travelling in one direction, with equal velocity, and clearly form one system. The remaining stars in the neighbourhood are travelling in a direction almost exactly the reverse. But even this relation, thus recognised in a region of diverse motions, is full of interest. Byron Madler, the celebrated German astronomer, recognising the community of motion between Z Ursœ and its companions, calculated the cyclic revolution of the system tobe certainly not less than 7000 years. But when the complete system of stars showing this motion is considered, we get a cyclic period so enormous, that not only the life of man, but the life of the human race, the existence of our earth, nay, even the existence of the solar system, must be regarded as a mere day in comparison with that amazing cycle.

Then there are other instances of star-drift where, though two directions of motion are not intermixed, the drift character of the motion is not at once recognised, because of the various distances at which the associated stars lie from the eye.

A cose of thie kind is to be met with in the stars forming the constellation Taurus. It was here that Mädler recognised a community of

motion among the stars, but be did not interpret this as I do. He had formed the idea that the whole of the sidereal system must be in motion around some central point; and for reasons which need not here be touched on, he was led to believe that in whatever direction the centre of motion may lie, the stars eeen in that general direction would exhibit a community of motion. Then, that be might not have to examine tbe proper motions all over the heavens, he inquired m what direction (in all probability) the centre of motion may be supposed to lie. Coming to the conclusion that it must be towards Taurus, he examined the proper motions in that constellation, and found a community of motion which led him to regard Aloyone, the chief star of the Pleiades, as the centre around which the sidereal system is moving. Had he examined farther he would have fonud more marked instances of community of motion in other parts of the heavens, a circumstance whioh would have at once compelled him to abandon his hypothesis of a central sun in the Pleiades, or at least to lay no stress on the evidence derivable from the community of motion in Taurus.

Perhaps the most remarkable instance of stardrift is that observed in the constellations1 Gemini and Cancer. Hero the stars seem to set bodily towards the neighbouring part of the Milky Way. The general drift in that direction it too marked, and affects too many stars, to be regarded as by any possibility referable to accidental coincidence. It is worthy of note that if the community of star-drift should be recognised (or I prefer to say, when it is recognised), astronomers will nave the means of determining the relative distances of the stars of a drifting system. For differences in the apparent direction and amount of motion can be due bat to differences of distance and position, and the determination of these differences becomes merely a question of perspective.*

Before long it is likely that the theory of stardrift will be subjected to a crucial test, since spectroscopic analysis affords the means of determining the stellar motions of recess or approach. The task is a very difficult one, but astronomers havo fnll confidence that in the able hands of Mr. Huggins it will be successfully accomplished. I await the result with full confidence that it will confirm my views.

(To be concluded next week.)

MECHANICAL MOVEMENTS.
(Continued from page 221.)

Ш Compensation balance, t a t' is the
main bar of balance, with timing
screws for regulation at the ends, t and t' are
two compound bars, of which the outside is brass
and the inside steel, carrying weights b h . As
heat increases, these bars are bent inward by the
greater expansion of the brass, and the weights
are thus drawn inward, diminishing the inertia
of the balance. As the heat diminishes, an oppo-
site effect is produced. This balanoe compensate!»
both for its own expansion and contraction, and
that of the balance-spring.

120. Endless chain, maintaining power on going-barrel, to keep a clock going while winding, during which operation the action of the weight or main-spring is taken off the barrel. The wheel to the right is the " going-wheel," and that to the left the " striking-wheel." P is a pulley fixed to the great wheel of the going part, and roughened, to prevent a rope or chain hung over it from slipping. A similar pulley rides on another arbor p which may be the arbor of the great wheel of the striking part, and attached by a ratchet and click to that wheel, or to clock-frame, if there is no Btriking part. The weights are hung, as may be seen, the small one being only large enough to keep the rope or chain on the pulleys. If tbe parr. Ь of the rope or chain is pulled down, the ratchet • pulley runs under the cliak, and the great weight is pulled up by с without taking its pressure off the going-wheel at all.

121. Harrison's "going-barrel.'' Larger ratchet-wheel, to which the click К is attached, is connected with the great wheel G by a spring S S'. While the clock is going, the weight acts upon the great wheel G through the spring; but as soon as the weight is taken off by winding, tha

• Here no account is taken of the motions of the stars within the svstem; such motions must be minute compared with the common motion of the system.

t Extracted from a compilation by Mr. H. T. Brown Editor of the American Artisan.

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