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be very considerable—though to gome extent dependent on the kind of iron used in the boiler Bib well as in the temperature—and often explosions thns ensue from the " breaking of the back " of the boiler. To keep the diameter of these boilers within bounds, the French have largely employed the compound form known as the Elephant boiler (Fig. 14). A boiler slightly differing from this in detail, but on the same principle, bears the name of the Retort boiler. Fig. 16. The next improvement aimed at economy, and gave us the Cornish boiler, Fig. 16. To obviate the weakness of the larger fined boilers of this class, Mr. Fairbairn introduced the Doublc-flued boiler, Fig. 17, about twenty-five years ago.

These boilers are very safe, and in somewhat extensive use, though by no means to the extent they merit. Considerable numbers of Butterley boilers have been constructed (see Fig. 18), but although they are economical, they are very weak against pressure, and therefore proportionately dangerous. Many minor varieties of boilers might be mentioned. One class of boiler—from its dreadfully destructive nature—claims attention, namely the class used in ironworks. These boilers, surrounded by brickwork, and exposed to the fierce flames from the puddling furnaces, would be sufficiently destructive in any ordinary situation; but, placed as they are, in the very midst of B number of men, amongst whom, when

they explode, they scatter a death-dealing shower of bricks, iron, and water, with the frequent addition of some of the hot iron from the furnaces, the carnage prodnccd is often frightful.

The Mnlti-flued boiler (see Figs. 19 and 20), demands but little notice, as it has not been found satisfactory in practice, since its economy in fuel is more than counterbalanced by its being troublesome to clean. The Multi-tubular boiler i still more economical in fuel, but also still more difficult of access for cleaning. It is also liable to leak at the bottom, and from those two causes is wanting in durability. It is particularly илsuited to foul feed-water. Amongst the improvements made in boilers of late years Adamaon's flanged joints in internal flues, and Galloway's conical tubes occupy most important places. The strength afforded by the flange joints is very great, and when the frequent collapse of long flues is taken into consideration, is very important. Galloway's tubes, Fig. 21, not only materially strengthen the flues, but they also add a most efficient heating surface, as the flame and gases strike almost at right angles to the metal, while the water rises at a slight angle from it, the best possible mud it ions for evaporation—and thns they are valuable économisera of fuel. They also cause a very brisk circulation, which further tends to economy, and to the preservation of the boiler by equalizing the temperatura of the water throughout, and so preventing unequal strains. It is probable that if inner tubes were added, as shown in Fig. 22, that the efficiency would be still greater, as such inner tubes would separate the water into two currents, upwards and downwards. All the boilers we have hitherto noticed, differing as they do largely, inter se, have one peculiarity in common, namely, that they each contain a large volume of water and steam. In case of an explosion there is, therefore, a correspondingly large supply of destructive material. Further, they are each to some extent deficient in economy of fuel, as they allow the heated gases to slide to too great an extent along their heating surfaces, not breaking up the current sufficiently; and they are also, as a rule, wanting in circulation. These last objections do not apply much to Galloway's boiler, the first does. Many attempts have been made to so construct boilers as to be free from these objections, and also to carry high pressures. Ал early labourer in this field was Dr. Ernet Alban, of Plan, who produced a very able and exhaustive treatise on boilers about a quarter of a century ago. He diseusses pressures up to 1,0001b. per inch. He was the originator of some very ingenious water-tube boilers. As these boilers have, however, become obsolete, they hardly fall within the scope of the present article. James and others proposed tubular boilers, having an extra inner tube to promote circulation. These inner tubes by no means answered the purpose for which they were intended, as the upward and downward enrrents met each other at the tops of the two tubes—inner and outer—and the circulation was far from being satisfactory. Mr. Field combatted this difficulty by splaying the top of the inner tube, which thus become trumpetshaped. That the "Field" tube answered its purpose may be gathered from the favour it enjoys and the large number—upwards of 60,000—in use. It has been found extremely applicable to fire engines, as it is a very rapid generator, so much so, that steam of 1001b. per inch has been raised from water at about 45° Fahr, in 7J minutes, in a boiler fitted with these tubes. These boilers are extremely suitable where quickness, high pressure and economy of fuel are required; and where constant and competent supervision is given to the firing and " feeding." They are not likely, however, to be generally adopted for factory and other uses where more liability and neglect exists. We have now to notice a boiler which is, perhaps, in most respects the best yet introduced. The one we allude to is Howard's Safety Boiler. This boiler possesses the following requisites of a good steam generator :—It affords ample heating surface of the very best kind for efficiency, as the flames and currents of gas are thoroughly broken up by the alternations of the vertical tubes. It offers a maximum amount of safety at high pressures; in fact, it is doubtful whether more than one tube would go at a time, even if an explosion did occur, which is very unlikely, as the tubes being small are of enormous strength, and arc further, by reason of their shape, subject to simple tensile strains only, and therefore no very extensive damage would be likely to accrue. It also acts as a very efficient superheater, thus giving the two great advantages of very high and perfectly dry steam. Inasmuch as corrosion and scaling are undoubtedly the two most serious evils which have at all times attended boilers, so must importance attach to the fact that in Howard's boiler so good a circulation is obtained as to do away with the accumulation of scale. A further great advantage lies in its non-liability to injurious strains, as its construction admits of its yielding in all directions to the expansion and contraction consequent on changes of temperature. Thie boiler is also remarkably easy to repair. The only drawback to it lies in the rapidity with which the water will riee or fall in it. This difficulty is nowadays met, to a great extent, by Giffard's injector; but it must be borne in mind that the very class of users most likely to neglect their

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boilers are also least likely to adopt so beautiful a contrivance as the injector. In fact, the writer himself some little time back took out an old feed pump and pnt an injector in its place, which gave the utmost satisfaction. Some little time after the boiler passed from under his control, when the pump was reinstated, merely on the plea that the injector was "too scientific."

As regards the future of steam boilers, we may expect that high pressures will continue to become more general as their economy is more widely appreciated. At the same time, let us hope that the increased dangers resulting may be guarded against by an efficient system of inspection and improved workmanship and materials in the boilers, with the more extended use of double lock-up safety valves and alarums, fusible plugs, and trustworthy water and steam gauges in duplicate. At the present time it is dreadful to contemplate the numbers of boilers working literally at random. The writer went a few days back to a place where they had had an explosion of a boiler, which, though fortunately unattended by loss of life, had been fearfully destructive. Yet, notwithstanding this severe lesson, they had actually pnt down an externally-fired cylindrical boiler—a most unmanageable and mischievous form—without water or steam gauge, or even a fusible plug or alarum: its sole safeguards being a float with a stuffing-box, and a most inefficient safety-valve weighted to sixty pounds. At the time of our visit the steam was blowing off furiously, so that the pressure must have been much above 601b., very likely nearer 1001b. per inch. The danger was by no means diminished by the fact that the boüer was made with lap joints, and, of course, single riveted.

If cylindrical boilers are to be used at high pressures, the bodies and flues ought to have the longitudinal joints welded, and eaoh length rolled to a truly circular shape, The transverse joints ought all to be double butt joints, and the plates thick edged, on Alton's plan. As regards rolling a tube, why should not complete bodies and flues be rolled at once? It is only a question of size of machinery and careful design. The demand for such boilers could not fail to be large.

It is very probable that far too little attention has been bestowed on the electrical influences brought to bear in corroding the iron of boilers, where the plates and rivets differ in amount of carbonization, Sze. Bessemer steel offers a very suitable material for boilers of all kinds, and of late very considerable advance has been made in its application. As a proof of this it may be mentioned that up to March, 1868— since which we have no return—three firms in Lancashire had turned out no less than 277 steel boilers, and 152 composition boilers, partially of steel.

That these numbers are far under the mark now may be inferred from the fact that the demand was then rapidly increasing. As steel of great ductility can be got capable of bearing an ultimate strain of 33 to 35 tons per square

inch, the very great superiority of such a material to iron, only capable of bearing 20 to 22 tons, needs no lengthened comments. The use of steel for boilers has been much restricted by the general impression that the steel must be drilled and not punched. That drilling is, per se, better than punching we feel convinced, but is it not just as superior for iron as steel, if the latter be afterwards annealed?

With regard to punching steel plates, we have before us the results of a very careful set of experiments carried out by the Bolton Iron and Steel Company, and, from their important bearing on the question of increased safety with high pressure boilers, we give the tabulated results. Six pieces 23in. long by 7in. broad and 6-16in. thick, were cut from the one steel plate. Three of these were prepared by punching, and three by drilling, with Jin. holes, ljin. from centre to centre, suited for single and double riveting. In a strapping machine these were then cut to the forms shown in Figs. 1, 2, and 3.

They were tested in a lever machine by dead ■ weight. The results are given in Table I. :—

TABLE I.*

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It will be noticed from this table that the punching has a deteriorating effect of 26-4 to 87-8 per cent., being an average of 33 per cent. Examination under a powerful glass revealed the cause of weakness, and led to the trial of annealing. In the following table are given the results of sixteen tests carried out at Chatham Dockyard. The results are furnished by Mr. Barnaby, Assistant Constructor of H. M. Navy.

In these experiments eight plates of steel had each four holes of 0-66in. diameter punched in them. Each plate was then cut in two, and one piece of each annealed. The plates were {in. thick. The testing was performed in an hydraulic testing machine. The average ultimate strength of the eight annealed plates rises as high as 32-839 tons per inch of section ; that of the nnanncalod plates was only 21-097 tone. Thus it will

• Extracted from Transactions of the Institution of Naval Architects, 1868.

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It is advisable in making steel boilers to uso double butt joints and double rivoting, as otherwise the rivets will sheer with far less than tho breaking strain of the plate; unless, indeed, the rivets used be so large as to- gain strength to the detriment of the plate. The proportions given by Mr. Henry Sharpe, of Bolton, aro for G-16in. plates, diameter of rivets, 9-16in., pitch, lain., double riveting; material of rivets, mild steel. With these proportions two tests gave the following excellent results, with plates taken at random from a large quantity of steel boiler plates which were being rolled to order by the Bolton Company (a), drilled plate 42*9 tons, and (ft) punched ditto, 39*11 tons per square inch of net sectional area. Mr. Sharp further experimented as follows :—

A punch of ll-16in. was used; first, in tho ordinary way, with a bod Jin. bare, producing tho hole shown in Fig. 4; then a bed, ¡in. in diameter was used, giving the result shown in Fig. 5. The plates were dressed to the form shown in Fig. 6. When tested, which was done without annealing, the taper-holed plates gave an average of 32*527 tons per square inch of net sectional area; the platee with straight holes, 26*004 tons. These taper holes must offer advantages to riveting up.

It is certain that the desire for economy will lead to the more extensive adoption of high pressures, heated feed-water, and tho super-heating of steam. As regards the heating of feed-water, we may notice " Green's Economizer " as a very efficient apparatus. Its chief peculiarity, as is well known, consists in the scrapers—which are very slowly moved up and down by simple gearing —to clear off the soot from the pipes through which the feed is passed. By this clearance the pipes are kept efficient in absorbing heat. Very considerable saving of fuel has been effected by the use of this apparatus. Waters's heater is exceedingly suitable for non-condensing engines. It possesses the advantage of thoroughly heating the water to the boiling point, and also of causing the deposit of its earthy matters as mud in the heater. With the increase of pressure, the frequency and destructivenees of boiler explosions will increase unless efficient means be taken to combat the dangers spoken of.

Any one who will read the reports of any of the very excellent boiler associations will be convinced that, if boilers were all well made to begin with, as regards workmanship, design, and material, well mounted with efficient duplicate safety-valves (locked), water-gauges, alarums, steam-gauge«, and fusible-plugs, and finally, properly inspected, explosions would be few and far between. It is to be hoped that the Bill on this subject, introduced by the hon. member for Dudley, may either become law or lead to even

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more efficient legislation. Let us hope also that the barbarous system of buying boilers at per ton may give way to an intelligent mode of valuation. When this is done, and the great value of pure feed-water recognized,' we may expect on explosion to be a rarity.

A further improvement required is the entire remodelling of "Crowner's quest-law," by which a coroner, who knows little or nothing of boilers, is assisted (?) by a jury, who usually arc chosen as though it wero desirable to get those who know "nothing of anything."

We want a competent tribunal to inquire into all explosions, accidents on railways, in mines, &c, whether actually fatal or not. At present we witness this absurdity, that a minor accident may occur by which one life is sacrificed, and two coroners set to work; on the other hand, an accident which maims hundreds for life will not move one coroner, unless some case of death should result. These are the abuses of a bygone age which have dragged on to the present.

ACCESSORIES TO THE MICEOSCOPE.

No. I.

(Illustrated an page 401.)

IN connection with the polarization of light, the crystal commonly known as selenite has played an important part, and by its aid some very remarkable effects have been produced. Microscopists have not been Blow in applying it to their pet instrument, and various arrangements have been invented to get the best effects, so that the objects viewed by its aid, might be seen to the best advantage. A short time since Mr. F. Blankley brought before the notice of the Fellows of the Boyal Microscopical Society, two forms of Belenite stages, whioh possess two great advantages: first, simplicity of construction ; and secondly, the ease with which they can be worked.

It may not be known to all our readers that different thicknesses of selenite give different colours, and that the structure of some objects can be seen much better with one colour than with another. It will therefore at once be seen how desirable it is to view eaoh object under every tint, so that the best effect may be secured.

Fig. 1 consists of a small brass stage, 3}in. long and ljin. wide, in the centre of which is an aperture through which the object is viewed. On the under part of the stage ie a dovetail groove, into which is fitted a brass slide containing three or four selenites, whioh work as freely as the investigator may desire. A small spring stops the slide when the selenite is immediately under tho aperture.

Fig. 2 represents the compound stage, which consists of a brass stage of similar dimensions to tho ono just described; and, in addition to the brass slide, has a revolving diaphragm with three selenites, each made to rotate, and a clear aperture, so that the object may be viewed with a single film if desired. In this stage each selenite is much larger than those in the small one, and is marked in quarters, so that the colours obtained may be registered and turned to at any time.

To increase the variety of colours and tints, rotate each selenite until their cleavage is at the right angle of the positive axis of those on the slide.

The positive axis of each selenite in the diaphragm is marked coincident with those in the slide. By working eaoh film as thus described, twenty-eight tints and colours will be obtained, and can be recorded for further reference. It will be observed that the whole of the changes are obtained without moving the stage or taking the object out of the field or focus, thus saving much time and trouble. They are made by Mr. Swift, 128, City-road, London, who is preparing a complete list of changes that can be effected by them.

ORGANIC LIFE. Bï H. В. Bakes, M.D., of Wenona, Mich., U.S.

THE OHDER OF CBJBATTON OF LIVING. BEINGS, FROM BIOLOGICAL EVIDENCE.

BEGINNING with the highest organism, we know that mau takes food, which Is then still further organized into the human tissues, and thus in early life he grows; and throughout life can only, through continued use of food, maintain his existence. It is also known that he is only able to assimilate matter that has been, to some extent, previously organized: and this is true not only of man, but of all animals. Even infusorial animalcvles require for their existence tho presence of

organized food, either animal or -vegetable. Certain animals require animal food, others can live without that; but some can maintain Ще without at least food derived from the vegetable kingdom.

Following down the scale of organization, we find that vegetable life and growth require the presence of matter arranged at least into binary compounds. Vegetable tissues ore made up of carbon, hydrogen, oxygen, and nitrogen, but, so far as known, these elements are always obtained by plants from matter organized or arranged in compounds such as carbonic acid, ammonia, ice.* These compounds may be, and at présent are, in part derived from the animal kingdom, though not necessarily so, for they result from the breaking down of vegetable matter, and may be naturally produced by union of their elements.

Although the animal kingdom cannot be maintained without vegetable food, the vegetable kingdom may be without animal food; and although vegetable life and growth cannot be maintained without matter arranged at least into binary compounds, these compounds which serve as food for plant-life con be formed and maintained without the aid of animal or vegetable matter. The animal kingdom is then essentially primarily supplied with food from the vegetable kingdom, and this, in torn, from binary and higher compounds. The complex compounds, chemistry teaches us, are formed by the union of simpler ones, and the simplest by the union of elementary atoms.

These seem to be universal laws, to which tbere are no known exceptions.

Food is essential to the growth of all organisms. Growth being an increase of the elements of which a body is composed, in certain definite proportions, and having the arrangement proper to the growing body, it is in fact a continuation of the procees of organization, and the food required for growth must at least be required for the first organization or creation; for the food if all organisme contain* a proper form their constituent elemente. If a crystal be placed on the solution from which it was formed, it will, under proper conditions, grow. Оно condition to its growth is the supply of its proper food, which consists of the same elements, harina the some arrangement as required for its first formation. The seed uf a plant exposed to moisture absorbs water, and sap or food is formed from the. material stored np in the seed which had been separated from the watery portion oí the sap contained in the parent plant; when its supply of matter, which by the addition of water serves as food, is exhausted, more is supplied from the surrounding air and soil. Like the crystal, so long as its proper food is not furnished, the germ of the seed romains stationary; and when again, under proper conditions, supplied with constituent matter, through the action of the organizing forces of nature, it grows. Animal tissues grow by means of a supply of blood, the composition of which differs in different kinds of animals, but is essentially the наше solution as the blood of the parent from which tue germs or eggs of each were formed. In all these cases it is not necessary that the solution of the food should contain only the constituent matter, but that most be present.

It is, moreover, important to notice that this constituent matter must bo to a certain extent previously organized. This may, perhaps, be better understood if we notice first the formation of the crystal, which may be considered as illustrating the formation of all organic germs. Crystals form from solutions having the organization proper to the crystal; tho solution must not only contain the elements of which the crystal is composed, but they must be arranged in molecules, corresponding to the crystalline compound. For instance, a solution may contain soda, chlorhydric and sulphuric acids, and crystals of chloride of sodium will not form because the constituent elements, although present, aie not combined or arranged with the proper definite relation to each other. Crystals of sulphate of soda will form from such solution, under proper conditions, because its elements are so combined.

The pollen and seeds as well as buds of plants are formed from the sap, which is the plant-food selected from the surrounidng earth and air ; it is matter organized in the manner peculiar to each plant ; it is, in fact, the germ of the plant in solntion. and seeds may in a manner be said to crystallize from it. The spermatic fluid and eggs of animals are formed and perfected in an analogous manner by compound molecules, separated or secroted from the highly organized animal fluids. The formation of the fluids from whioh these crystals, seeds, ami eggs are formed, requires the presence of the food proper to each, and it must consist of their constituent matter properly arranged.

From what is known concerning the laws which govern the maintenance of life by food, organic growth, the essential nature and constitution of food, the formation of the germs of organisms and the formation of chemical compounds, we seem justified in concluding that animal life is always

* It seems proper to state that this article was written before the writer had seen or heard of Professor Huxley's lecture on "The Physical Basis ot Life."

necessarily preceded by vegetable life; that this is always necessarily preceded by a certain amount of arrangement of elements into binary and more complex compounds; that the complex compounds arc universally formed from simpler ones, and the simplest by union of the elementary atoms. We сап thus trace back the order of creation, or evolution of living beings, to the chemical elements.

THE BEGDINrXa OP I.HI'.. ITS LOWEST TOSS, AND TUE SIMl'l.r.sr ORGANISHS.

In studying the creation of living organisms, if we start with any of the higher animals, and trace buck the life of an individual, we find it to- begin in an organized form of matter, an egg. But the egg is a complex substance, ami, although some of the conditions to its formation and development into a living being are well understood, studied by itself it is difficult to understand the creation, beginning, or Bource, of its vital force; and, if we understand from whence the force is derived, it is still difficult to see what gives direction. If we direct our attention to the vegetable seed, we meet with the same difficulties, in order that wo may understand the creation of the higher organisms, it may be well to search out the lowest, and begin the study of life in its simplest form; and, that we may be able to recognize the object of our search, we should hirve a reasonably perfect definition of the word life, and an idea of the characteristics of living beings. A complete and perfect definition is difficult, and is not assumed to be baapven; but it will be sufficient for our presea* purpose to say thut, from the word life, we receive an impreesiou of certain phenomena attendant upon changes which occur in organized bodies as results of their experiences of force. This definition is perhaps incomplete, but, in fact, any attempt at a perfect definition must necessarily be unsatisfactory so long as only the higher forms of life are considered. We cannot properly define a thing until the whole of it be somewhat understood. However, if wc bear in mind our miperfeet definition, and keep in sight the higher kinds of life which we do understand, we can search for the lowest, which we may not, and when the whole has been considered, a definition may he more satisfactory. Let us, then analyze the characteristics of the higher living beings from which we have received our first ideas of life, and learn their essential nature. By reducing these characteristics to their lowest terms, we ought to deduce an ideal lowest form of Ufe.

The prominent phenomena which characterize living beings are—1. Organization; 2. Definite Chemical Composition; 3. Definite Form; 4. Growth; 5. Continual Change; <>. Motion-, 7. Beproductive Power.

Our idea of Ufe being mainly formed from our knowledge of these characteristics, the ideal lowest form should have them in the simplest degree.

Commencing the search by considering them singly, we notice first that Uving bodies are organized.

According to the ordinary definition, an organism is a body consisting of organs, or mutually dependent parts having functions. The lowest organism should consist of the least number of mutually dependent parts, having functions of the simplest character.

The least mutually dependent number would be two—and, as the smaUest portion of matter imaginable is called an atom, nothing less than that could be conceived as having a function; and, as the funotions of two precisely similar atoms would be least contrasted, and of the simplest character, the lowest organism should consist of two equal atoms organized or arranged, so that its existence as an organism would depend upon the functional activity of each, which might consist in their mutual attraction for each other. This would be the case in a molecule consisting of two atoms of a chemical clement. And, as the atoms of an elementary substance are alike, their functions would be equal.

We notice, next, that Uving bodies have a definite composition; they consist of definite proportions of certain elements definitely arranged. Arrangement implies relation, and would require, at least, the presence of two units. The simplest definite proportions would !•<■ equal, and as the least portion of matter is the atom, a definite compound reduced to its lowest terms should consist of two equal atoms arranged with the simplest definite relation to each other.

As to form, we should expect to find the lowest life, having definite form, of the greatest simplicity.

Complexity of form results from complex arrangements of heterogeneous elements; the greatest simpUcity of form wUl result from the simplest arrangement of like elements. Simple definite forms arc found in crystals of the chemical elements, gold, copper, iron, sulphur, phosphorus, carbon, &c, which usually crystallize in simple cubes or octahedrons.

Growth is an increase of the eloments composing the body, in the proportion and having tho arrangement proper to it. The simplest requirement for growth would be the smaUest equal proportions of one element with the simplest definite atomic arrangement. This might be tho case in bodies consisting of one element.

The changes occurring in a Uving body to a cer

tain extent, result from the torcos acting upon it. As the atoms of an elementary body are alike, and, subjected to the same force, vibrate aUke, and tho atoms of different elements are unlike, and vibrate differently, few or many changes will be prodmced by a given force, according as it acts upon a body consisting of one or many different elemente. A given force should therefore produce the least number and variety of changes by combination or «*• arrangement, and by mutual reactions of constituent matter and force, will be least where atoms of only one element are present.

Motions result from force, and the greatest variety of motion wiU be produced by forces acting upon the greatest number and variety of elements. Motion of the simplest character results from the action of force upon homogeneous matter.

Reproduction consists, essentiaUy, in the generation of new bodies, and communicating to them the properties characterizing the parent, as regards both matter and its arrangement. The reproductive process should be simplest where the body to be reproduced is simplest, and we have seen that this must be the ease when it consists of the least organizante quantity of one kind of matter, viz., of two atoms of one chemical clement.

If we now sum up these several least requirements, we find that, from this analysis of the characteristics of Uving organisms, it appears that, reduced to their lowest terms, they must consist of two atoms of a chemical element arranged with the simplest definite relation to each other. This should be the beginning o/'tlie lowest form of life, and we also found this to be the lowest ideal organism. It is represented by the ultimate molecule, which may be the nucleus or beginning of a cryetal of a chemical element.

The conclusion here reached by deduction will no doubt be at first regarded with astonishment, and without inductive proof it is not expected that this view can be received except by those already prepared by a knowledge of such proof; but the evidence which the writer has seen on the subject is such as to convince him that the same conclusion may be reached by other and more satisfactory methods of research. This method of first presenting the subject has, however, been selected because it seems to show, from a study of the somewhat imperfect idea of Ufe, what is necessary to its perfection. Consideration of the subject from this stand-point first, may prepare some minds to study it thoroughly without the prejudice which might otherwise prevent ; and, finally, because the building up of any structure is greatly faciUtated by first perfecting a definite plan, so that the position and relation sustained by the component parts may be readily seen as soon as each is presented.

It is beUeved that the generalization indicated may be made and estabUshed with great advantage to the study of biology. The plan of the creation or evolution of living organisms is thereby rendered much more simple and easy of comprehension, as may perhaps be made to appear at воше future time.

The ideal lowest form of Ufe and the lowest organism we have found to consist of " two atoms of an elementary substance arranged with the simplest definite relation to each other," and we know that there are existing in nature such combinations of matter. In a provious part—" The Order of Creation of Living Beings "—it was pointed out that their creation could be traced bock to the chemical elements as its starting-point. From this lowest form of Ufe there is a constantly-ascending scale up to human life. From this simplest organism there is a constantly-increasing complexity of combination and organization up to the human organism. An attempt will be made to show that the phenomena attendant upon changos occurring in the simpler combinations which may be caUed primary organisms resomble, and are in fact similar to, those which are recognized as characteristic of Uving beings. We shall find how perfectly they accord with our definition of Ufe.

Beginning the subject inductively, let us first consider organization; that being an acknowledged characteristic of at least the higher Uving beings, and the first one mentioned in our analysis.

The word organism has heretofore, I beUeve, only been appUed to those compounds which have risible distinctions of parte; leaving out, among those wliich have not such distinctions, some whieh were nevertheless considered living. "The lowest living things aro not, properly speaking, organisms at all; for they have no distinctions of parts, no traces of organization "—(Herbert Spencer). Before the microscope revealed its world of Uving beings, the general idea of organisms probably included only those whose organs or distinctions of parts were visible without its nse; some minute moving bodies were no doubt by some considered living, although their organs could not then bo distinguished. Afterward, with the aid of the microscope, tbeir organs were plainly Been, as wore also myriads of other organisms. With the microscope other minnto moving bodies have been brought to view, and are now considered Uving, although their organs cannot be distinguished. We have again reached a point where a still higher vision is required to enable us to see a mutual dependence and distinction of

parts, and again show that the lowest Uving things ore organisms.

This higher view is furnished us through a knowledge of chemistry, which teaches that there is a mutual dependence of parts which extends to the molecules, ami even to the ultimate atoms, of all definitely com&ined matter. A definitely chemical compound consists of definite proportions of matter definitely «wanted. For instance» albumen is composed of carbon, hydrogen, oxygen, and nitrogen, m certain proportions, and arranged in a certain manner: if either the proportion or the arrangement be destroyed, the matter no longer constitutes albumen. The several elements of which it is composed may be considered as organs performing essential functions, their mutual dependence being absolute; fur, if one be removed, the compound is destroyed. Probably the presence of each atom of each element is essential to the existence of the compound, so that a molecule of albumen may be considered on organism, although not in accordance with the idea heretofore entertained. The same may be said of a molecule of water or of any other such group of atoms definitely arranged. Albumen was selected as an example, because the lowest living things revealed by the microscope cannot, by tke aid of the highest magnifying power, bo tlietingnished from mere minute particles of albumen.

Whether the lowest Uving things can be properly called organisms, will depend upon the definition of the words organism and organ. According to tho ordinary definition, an organism is a body consisting of mutually dependent parts having functions, and an organ is one of snoh parte. The word organ, as appears from the above quotation, hoe ieretoforo been appUed only to visibly distinct parte having functions, Av., although the definition; in our standard dictionary is similar to the onu given above, and lias no such requirement.

The standard definition wUl allow ef it* use in the extended sense that I wish, via., to denote any mutually dependent parts of definitely-combined matter having separate fonctions, whether or not the part or function be capable of demonstration to the single sense of vision. It ie essential to a right understanding of scientific problems, that the terms employed should have a precise meaning. If the words organ, organism, and organized, cannot appropriately be used in connection with all definitelycombined matter, and must, on account of old associations, be restricted to such compounds as have visible distinctions of parts, then it would seem to he advisable to invent new terms which shall, in a word, or as concisely as possible, embrace all such compounds, and thereby render easy this comprehensive and general view. But if this bo doue, the old words left as heretofore, there is then no weU-morked limit or beginning of organization, for what is visible to one, under certain circumstances, may not prove so to others, and again the limit would vary with the magnifying power used. If however, the old terms (organism, itc.) be retained and thus defined, itwillstUlbe easytooÚetinguieh between visible and invisible organs; the invisible organization may be denominated primary, as i! undoubtedly is, to vegetable and animal organization, lu my opinion, the science of biology will at present be best faciUtated by thus extending and denning the words used. The important reason for wishing thus clearly to define and extend their meaning is to coUect under one general view the prominent phenomena attendant upon matter arranged in definite compounds. At present certain highly-complex, definite compounds ore called organisms; oertaiit others, less complex, Uving things, but are not considered organisms, because not Inning visible organs; others, nearly as complex as these last, are called organic, because heretofore only found in organisms; others st ill complex, are called inorganic chemical compounds. The prominent fact connected with all these structures is, their definite composition and definite atomic or molecular arrangement: and the certain and regular phenomena attendant upon their experience of certain conditions are beUeved to be in consequence of this definite composition. This broader generalization seems to me to be useful, taking in as it does nil definite combinations, and distinguishing them from amorphous, non-arranged, or, according to my view, unorganized matter. If this he done, as heretofore indicated, the beginning of the simplest organization will be where the first two atoms unite with a certain or definite relation to each other, to form a definite compound. In accordance with the foregoing view», Ufe ш conceived to be manifested by all organized matter, tho kind of Ufe depending upon the character of the organization.

Ainoug scientific men, at the present time, the tendency is to look for the lowest organization and the beginning of Ufe among the protean compounds; and protoplasm is the name given to what many now consider as the connecting lmi. between inorganic matter and living organisms. It seems to me, however, that they are not searching deep enough; that protoplasm is about midway between amorphous matter and the highest organisms, and cannot profitably be considered as the beginning of Ufe or of organization, although it may be, as the beginning of the two highest organic kingdoms—the

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vegetable and animal. I prefer to consider the diamond as one of the lowest organized forms, and with my mental vision distinctly see the beginning of organization and the conditions for life, where, through certain conditions of force, the first two elementary atoms are enabled to manifest their mutual attraction, and affectionately and definitely embrace.

We have, however, considered only one of the characteristics of living beings; we have still to consider, in this connection, definite chemical composition, form, growth, continual change, organic motion, and reproductive power.

Definite Composition of Organisms, and Consequent Definite Function.—Proximate analysis of the higher organisms shows them to be composed of various compounds, such as water, sugar, starch, fats, albumin, fibrin, &c, which are called proximate principles. Ultimate analysis of these proximate principles shows them to be definite chemical compounds, essentially the same in all organisms of a kind; but, to a certain extent, peculiar to each kind, either in quality or proportion.

Water b» essential to the composition of all the higher organisms; each kind of organism having, within certain limits, its own peculiar, definite proportion, which is essential to its existence as an organized form.

Although free, uncombined water is always the same under the same conditions, the properties of organisms, formed by its combination with other substances, in great measure depend upon its proportion and manner of union.

The sugars, as existing in various organisms, are more or less peculiar to each. Sugars derived from the maple, cane, grape, or beet, can usually be distinguished from each other, and from those derived from other sources, by their obvious characters. It is generally possible, by observing the flavour, to tell the source from which honey has been collected. Animal sugars, no doubt, differ, although, as yet, they are not as well understood. There is doubtless, much to be learned concerning the various kinds of sugar, but chemical examination has demonstrated that many of these different kinds have different chemical composition.

The grains of starch, from different organisms, may generally be distinguished by viewing them through a microscope: their forms being different, they have, at least, a different arrangement of elements.

These simple compounds, consisting of few elemenU, can, consequently, have few modifications. Water, consisting of quite simple proportions, of only two elements, is always water, and we know of only one kind of pure water. Sugar and starch, consisting of several atoms each of three elements, exist nndcr several modifications of composition, as regards proportion and arrangement of elements. ( To be concluded next week.)

Some new minérale composed of oxides of lead and antimony have been discovered. И. Descloineaux is engaged on the study of their crystallography

MECHANICAL MOVEMENTS.

(Continued from page 448.)

cu ? A Diaphragm forcing pump. A flexible fj~i: • diaphragm is employed instead of bellows, and valves are arranged same as in preceding.

255. Old rotary pump. Lower aperture entrance for water, and upper for exit. Central part revolves with its valves, which fit accurately to inner surface of outer cylinder. The projection shown in lower side of cylinder is an abutment to close the valvee when they reach that point.

256. Cary's rotary pump. Within the fixed cylinder there is placed a revolving drum, B, attached to an axle, A. Heart-shaped cam, a, surrounding axle, is also fixed. Revolution of drum causes sliding-pistons, с, c, to move in and out in obedience to form of cam. Water enters and is removed from the chamber through ports, 1. and M; the directions are indicated by arrows. Cam is so placed that each piston is, in succession, forced back to its seat when opposite E, and at same time other piston is forced fully against inner side of chamber, thus driving before it water already there into exit-pipe, H, and drawing after it, through suction-pipe, J . the stream of supply.

257. Common mode of raising water from wells of inconsiderable depth. Counterbalance equals about one-half of weight to be raised, so that the bucket has to be pulled down when empty, and is assisted in elevating it when full by counterbalance.

258. The common pulley and buckets for raising water; the empty bucket is pulled down to raise the full one.

259. Reciprocating lift for wells. Top part represents horizontal wind-wheel on a shaft which carries spiral thread. Coupling of latter allows small vibration, that it may act on one worm-wheel at a time. Behind worm-wheels are pulleys over which passes rope which carries bucket at each extremity. In centre is vibrating tappet, against which bucket strikes in its ascent, and which, by means of arm in step wherein spiral and shaft are supported, traverses spiral from one wheel to other, so that the bucket which has delivered water is lowered and other one raised.

260. Foirbairn's bailing-scoop, for elevating water short distances. The scoop is connected by pitman to end of a lever or of a beam of singleacting engine. Distance of lift may be altered by placing end of rod in notches shown in figure.

261. Pendulums or swinging gutters for raising water by their pendulous motions. Terminations at bottom are scoops, and at top open pipes; intermediate angles are formed with boxes (and flap valve), each connected with two branches of pipe.

262. Chain pump; lifting water by continuous circular motion. Wood or metal discs, carried by endless chain, are adapted to water-tight cylinder, and form with it a succession of buckets filled with water. Power is applied at upper wheel.

263. Self-acting weir and scouring sluice. Two leaves turn on pivots below centrée; upper

leaf much larger than lower, and turns in direction of stream, while lower turns against it. Top edge of lower leaf overlaps bottom edge of upper one and is forced against it by pressure of water. In ordinary states of stream, counteracting pressures keep weir vertical and closed, as in the left-hand figure, and water flows through notch in upper leaf; but on water rising above ordinary level, pressure above from greater surface and leverage overcomes resistance below, upper leaf turns over, pushing back lower, reducing obstructions and opening at bed a passage to deposit.

264. Hiero s fountain. Water being poured into upper vessel descends tube on right into lower; intermediate vessel being also filled and more water poured into upper, confined air in cavities over water in lower and intermediate vessels and in communication tube on left, being compressed, drives by its elastic force a jet up central tube.

265. Balance pumps. Pair worked reciprocally by a person pressing alternately on opposite ends of lever or beam.

266. Hydrostatic press. Water forced by the pump through the small pipe into the ram cylinder and under the solid ram, presses up the ram. The amount of force obtained ie in proportion to the relative areas or squares of diameters of the pumpplunger and ram. Snppose, for instance, the pumpplunger to be one inch diameter and the ram thirty inches, the upward pressure received by the ram would be 900 times the downward pressure of the plunger.

267. Robertson's hydrostntic jack. In this the ram is stationary upon a hollow base, and the cylinder with claw attached slides upon it. The pump takes the water from the hollow base and forces it through pipe in the ram into the cylinder, and so raises the latter. At the bottom of pipo there is a valve operated by a thumb-screw to let back the water and lower the load as gradually as may be desired.

268. Flexible water main, plan and section. Two pipes of 15in. and 18in. interior diameter, having some of their joints thus formed, conduct water across the Clyde to Glasgow Waterworks. Pipes are secured to strong log frames, having hinges with horizontal pivots. Frames and pipes were put together on south side of the river, and, the north end of pipe being plugged, they were hauled across by machinery on north side, their flexible structure enabling them to follow the bed.

(To be continued.)

A NEW PHOTOMETER.—A photometer, invented by M. Nagent, is based upon the formation of a column of liquid partially opaque, which may be drawn out until the length i« such that the light from an illuminatin« body ceases to be visible through the liquid. Tb» length of the column, which completely obscures the light, starting from the point where the colnnm U thinnest, gives a measure of the intensity of the light under examination.

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