necessaries and most of our luxuries. And now-adays even the farmer, for the correct laying out of his drains, has recourse to the level—that is, to geometrical principles. When from those divisions of mathematics which deal with space, and number, some small smattering of which is given in schools, we turn to that other division which deals with force, of which even a smattering is scarcely ever given, we meet with another large class of activities which this science presides over. On the application of rational mechanics depends the success of nearly all modern manufacture. The properties of the lever, the wheel and axle, &c., are involved in every machine—every machine is a solidified mechanical theorem; and to machinery in these times we owe nearly all production. Trace the history of the breakfast-roll. The soil out of which it came was drained with machine-made tiles; the surface was turned over by a machine; the seed was put in by a machine; the wheat was reaped, thrashed, and winnowed by machines; by machinery it was ground and bolted; and had the flour been sent to Gosport, it might have been made into biscuits by a machine. Look round the room in which you sit. If modern, probably the bricks in its walls were machine-made; by machinery the flooring was sawn and planed, the mantel-shelf sawn and polished, the paper-hangings made and printed; the veneer on the table, the turned legs of the chairs, the carpet, the curtains, are all products of machinery. And your clothing—plain, figured, or

VALUE OF MECHANICAL SCIENCES.

47

printed—is it not wholly woven, nay, perhaps even sewed, by machinery? And the volume you are reading—are not its leaves fabricated by one machine and covered with these words by another? Add to which that for the means of distribution over both land and sea, we are similarly indebted. And then let it be remembered that according as the principles of mechanics are well or ill used to these ends, comes success or failure—individual and national. The engineer who misapplies his formulæ for the strength of materials, builds a bridge that breaks down. The manufacturer whose apparatus is badly devised, cannot compete with another whose apparatus wastes less in friction and inertia. The ship-builder adhering to the old model, is outsailed by one who builds on the mechanically-justified wave-line principle. And as the ability of a nation to hold its own against other nations depends on the skilled activity of its units, we see that on such knowledge may turn the national fate. Judge then the worth of mathematics.

2 Pass next to Physics. Joined with mathematics, it has given us the steam-engine, which does the work of millions of labourers. That section of physics which deals with the laws of heat, has taught us how to economise fuel in our various industries; how to increase the produce of our smelting furnaces by substituting the hot for the cold blast; how to ventilate our mines; how to prevent explosions by using the safety-lamp; and, through the thermometer, how to regulate innumerable processes. That

division which has the phenomena of light for its subject, gives eyes to the old and the myopic; aids through the microscope in detecting diseases and adulterations; and by improved lighthouses prevents shipwrecks. Researches in electricity and magnetism have saved incalculable life and property by the compass; have subserved sundry arts by the electrotype; and now, in the telegraph, have supplied us with the agency by which for the future all mercantile transactions will be regulated, political intercourse carried on, and perhaps national quarrels often avoided. While in the details of indoor life, from the improved kitchen-range up to the stereoscope on the drawing-room table, the applications of advanced physics underlie our comforts and gratifications.

Still more numerous are the bearings of Chemistry on those activities by which men obtain the means of living. The bleacher, the dyer, the calicoprinter, are severally occupied in processes that are well or ill done according as they do or do not conform to chemical laws. The economical reduction from their ores of copper, tin, zinc, lead, silver, iron, are in a great measure questions of chemistry. Sugar-refining, gas-making, soap-boiling, gunpowder manufacture, are operations all partly chemical; as are also those by which are produced glass and porcelain. Whether the distiller's work stops at the alcoholic fermentation or passes into the acetous, is a chemical question on which hangs his profit or loss; and the brewer, if his business is sufficiently

d

CHEMISTRY AND AGRICULTURE.

49

large, finds it pay to keep a chemist on his premises. Glance through a work on technology, and it becomes at once apparent that there is now scarcely any process in the arts or manufactures over some part of which chemistry does not preside. And then, lastly, we come to the fact that in these times, agriculture, to be profitably carried on, must have like guidance. The analysis of manures and soils; their adaptations to each other; the use of gypsum or other substance for fixing ammonia; the utilization of coprolites; the production of artificial manures—all these are boons of chemistry which it behoves the farmer to acquaint himself with. Be it in the lucifer match, or in disinfected sewage, or in photographs—in bread made without fermentation, or perfumes extracted from refuse, we may perceive that chemistry affects all our industries; and that, by consequence, knowledge of it concerns every one who is directly or indirectly connected with our industries.

And then the science of life—Biology: does not this, too, bear fundamentally upon these processes of indirect self-preservation? With what we ordinarily call manufactures, it has, indeed, little connexion; but with the all-essential manufacture— that of food—it is inseparably connected. As agriculture must conform its methods to the phenomena of vegetable and animal life, it follows necessarily that the science of these phenomena is the rational basis of agriculture. Various biological truths have indeed been empirically established and acted upon

cess.

by farmers while yet there has been no conception of them as science: such as that particular manures are suited to particular plants; that crops of certain kinds unfit the soil for other crops; that horses cannot do good work on poor food; that such and such diseases of cattle and sheep are caused by such and such conditions. These, and the everyday knowledge which the agriculturist gains by experience respecting the right management of plants and animals, constitute his stock of biological facts; on the largeness of which greatly depends his sucAnd as these biological facts, scanty, indefinite, rudimentary, though they are, aid him so essentially; judge what must be the value to him of such facts when they become positive, definite, and exhaustive. Indeed, even now we may see the benefits that rational biology is conferring on him. The truth that the production of animal heat implies waste of substance, and that, therefore, preventing loss of heat prevents the need for extra food—a purely theoretical conclusion—now guides the fattening of cattle: it is found that by keeping cattle warm, fodder is saved. Similarly with respect to variety of food. The experiments of physiologists have shown that not only is change of diet beneficial, but that digestion is facilitated by a mixture of ingredients in each meal: both which truths are now influencing cattle-feeding. The discovery that a disorder known as "the staggers," of which many thousands of sheep have died annually, is caused by an entozoon which presses on the brain;