377 



SCIENTIFIC SIDE-LIGHTS 



Law 



able, producing always precisely and neces- 

 sarily the same effects that is, provided it 

 is worked under the same conditions. But 

 then, if the conditions are not the same 

 the invariableness of effect gives place to ca- 

 pacities of change which are almost infinite. 

 It is by altering the conditions under which 

 any given law is brought to bear, and by 

 bringing other laws to operate upon the 

 same subject, that our own wills exercise 

 a large and increasing power over the ma- 

 terial world. And be it observed to this 

 end the uniformity of laws is no impedi- 

 ment, but, on the contrary, it is an indis- 

 pensable condition. Laws are in themselves 

 if not unchangeable at least unchanging, 

 and if they were not unchanging they could 

 not be used as the instruments of will. If 

 they were less rigorous they would be less 

 certain, and the least uncertainty would 

 render them incapable of any service. No 

 adjustment, however nice, could secure its 

 purpose if the implements employed were 

 of uncertain temper. 



The notion, therefore, that the uniformity 

 or invariableness of the laws of Nature can- 

 not be reconciled with their subordination 

 to the exercise of will, is a notion contrary 

 to our own experience. ARGYLL Reign of 

 Law, ch. 2, p. 58. (Burt.) 



1844. LAW OF CONSTANCY OR 

 CONTINUITY Exemplified by Action of the 

 Voltaic Battery Effect Exerted at a Dis- 

 tance from the Cause. Before you is an in- 

 strument a small voltaic battery in which 

 zinc is immersed in a suitable liquid. An 

 attractive force is at this moment exerted 

 between the metal and the oxygen of the 

 liquid, actual union, however, being in the 

 first instance avoided. Uniting the two 

 ends of the battery by a thick wire, the at- 

 traction is satisfied, the oxygen unites with 

 the metal, zinc is consumed, and heat, as 

 usual, is the result of the combustion. A 

 power which, for want of a better name, we 

 call an electric current, passes at the same 

 time through the wire. Cutting the thick 

 wire in two, let the severed ends be united 

 by a thin one. It glows with a white heat. 

 . . . Suppose in the first instance, when 

 the thick wire is employed, that we permit 

 the action to continue until 100 grains of 

 zinc are consumed, the amount of heat gen- 

 erated in the battery would be capable of ac- 

 curate numerical expression. Let the action 

 then continue, with the thin wire glowing, 

 until 100 grains of zinc are consumed. 

 . . . The amount of heat generated in 

 the battery . . . will be less by the pre- 

 cise amount generated in the thin wire out- 

 side the battery. In fact, by adding the 

 internal heat to the external, we obtain for 

 the combustion of 100 grains of zinc a total 

 which never varies. We have here a beauti- 

 ful example of that law of constancy as re- 

 gards natural energies, the establishment of 

 which is the greatest achievement of modern 

 scientific philosophy. By this arrangement, 

 then, we are- able to burn our zinc at one 



place, and to exhibit the effects of its com- 

 bustion at a distance. In New York, for 

 example, we may have our grate and fuel; 

 but the heat and light of our fire may be 

 made to appear at San Francisco. TYNDALL. 

 Lectures on Light, lect. 1, p. 6. (A., 1898.) 



1845. 



Suddenness in 



Na ture Lightning Chemical Combination. 

 The same ultimate conceptions, and no 

 other, appear to constitute all the truth 

 that is to be found in a favorite doctrine 

 among the cultivators of physical science 

 the so-called "Law of Continuity." This- 

 phrase is indeed often used with such loose- 

 ness of meaning that it is extremely diffi- 

 cult to understand the primary signification 

 attached to it. One common definition, or 

 rather one common illustration, of this law 

 is said to be that Nature does nothing sud- 

 denly nothing " per saltum " [literally, by 

 a leap]. Of course, this can only be 

 accepted under some metaphorical or tran- 

 scendental meaning. In Nature there is such 

 a thing as a flash of lightning, and this is 

 generally recognized as sufficiently sudden- 

 . . . The action of chemical affinity is al- 

 ways rapid, and very often even instantane- 

 ous. Yet these are among the most common 

 and the most powerful factors in the mech- 

 anism of Nature. They have the most inti- 

 mate connection with the phenomena of life, 

 and we know only too well that in these the 

 profoundest changes are often determined in 

 moments of time. For many purposes to 

 which this so-called "Law of Continuity" 

 is often applied in argument no idler dogma 

 was ever invented in the schools. ARGYLL 

 Unity of Nature, ch. 4, p. 83. (Burt.) 



1846. LAW; OF DEATH Natural 

 Tendencies to Dissolution Life a Tempo- 

 rary Resistance of Disorganizing Forces. 

 There is in every living organism a law of 

 death. We are wont to imagine that Na- 

 ture is full of life. In reality it is full of 

 death. One cannot say it is natural for a 

 plant to live. Examine its nature fully, 

 and you have to admit that its natural tend- 

 ency is to die. It is kept from dying by a, 

 mere temporary endowment, which gives it 

 an ephemeral dominion over the elements 

 gives it power to utilize for a brief span the 

 rain, the sunshine, and the air. Withdraw 

 this temporary endowment for a moment 

 and its true nature is revealed. Instead of 

 overcoming Nature it is overcome. The very 

 things which appeared to minister to its- 

 growth and beauty now turn against it and 

 make it decay and die. The sun which 

 warmed it withers it; the air and rain 

 which nourished it rot it. It is the very 

 forces which we associate with life which, 

 when their true nature appears, are discov- 

 ered to be really the ministers of death. 

 DRUMMOND Natural Law in the Spiritual 

 World, essay 2, p. 92. (H. Al.) 



1847. LAW OF GROWTH IN STRUC- 

 TURE OF THE EARTH Formerly men 

 looked upon the earth as a unit in time, as 



