24 



- KNOWLEDGE ♦ 



[Jdly 13, 1883. 



had been cited by the other side, was probably a pupil of 

 that school ; and certainly Benthaiii and Mill were, who 

 really spread the principles which led to the abolition of 

 excessive punishment. And those principles were only 

 the principles of science applied to morality. 



" Though he admired our ancestors of the sixteenth 

 century, he felt bound to admit that they were a brutal lot. 

 An instance of how far we have improved in point of 

 humanity is to be seen in Roderick Random. After 

 having reduced his young, amiable, and beloved hero to 

 very great straits through " dissipation," Smollett makes 

 him go to India to purchase a lot of slaves, whom he sells 

 in America at a large profit. This we should consider 

 brutal and degrading conduct, and the fact that we do so 

 consider it marks the great improvement which has taken 

 place in our morality. It is quite true that it is not 

 merely the growth of science, but the general intellectual 

 development of the country which has put a stop to cruelty; 

 but it is equally true that the growth of science is an 

 integral part of that development, and one that cannot be 

 separated from it. None of these things would have been 

 possible unless the intellect had widened ; and science has 

 helped to do this. We may hope for similar good results 

 from the application of science to other things ; for example, 

 to politics, where there is little enough of scientific prin- 

 ciples at present. 



" On the religious question I can only say this," Mr. 

 Stephen remarked in conclusion, " that you have got this 

 plain dilemma to face, which cannot be avoided. In the 

 first place, if any religion, or religious belief, is true, what 

 can the holders of it have to fear from the growth of 

 truth, which you call scientific truth ? If these beliefs are 

 destroyed, is it not a conclusive proof that they may be 

 false, or at least contain an element of untruth t The 

 religion may, indeed, have been very useful, although not 

 true, and not qualified to satisfy all the aspirations of a 

 cultivated mind. You may see, when a civilised race comes 

 in contact with a lower race, that the effect of the sudden 

 contact may be to destroy the religion and the rule of life 

 of the inferior race, without putting anything it its place. 

 Evils of that kind have been caused by modern science." 

 It is destroying inevitably many beliefs which people 

 have lived under well and happily. It is undeniable that 

 this causes pain, and that it may be injurious to their 

 morality I shall not attempt to deny. But when I am 

 asked to say that therefore science is injurious, I have to 

 come back to my original proposition — the remedy is more 

 science. The only way out of the difficulty is this ; We 

 are here, and we have got to go — forward. And the only 

 way is to apply the test of truth to all our beliefs. This 

 effects a certain amount of pain, as every other kind of 

 progress does ; but the only other way is to go on believing 

 what you know to be lies. And, without saying which are 

 true and which are false, I cannot see how any person can 

 wish to do anything else but increase the amount of truth, 

 the only satisfactory cure." 



Paper Cross -Ties. — A railway cross-tie has, says 

 Engineering, been invented in America, made of paper or 

 any other fibrous substance, such as straw or grass. This 

 is reduced to a pulp, and run out into boards. Sheets or 

 layers of this straw-board are laid one upon the other, 

 cemented and pressed into moulds to form the cross-tie, 

 which is practically fire and water proof, having been 

 manufactured under a temperature of 500 deg. It is 

 claimed that atmospheric changes have no effect upon 

 it, that it can be made as cheaply as a wooden one, and 

 will outlive five. It does not rot, and it deadens sound, 

 which would be an advantage upon elevated railroads. 



THE BRUSH DY^^AMO-ELECTRIC 

 MACHINE. 



{Concluded). 



IN the previous article on the Brush dynamo it was 

 stated that its chief feature is its armature, which, in 

 so far as it consists of a ring of iron, with projecting teeth 

 between the coils, resembles the Pacinotti ring. It has 

 comparisons also with the Gramme ring ; but the excep- 

 tional feature in it is the method of connecting the coils. 

 In the Gramme, and all the long list of closely-allied 

 machines, each coil of wire is connected to the next 

 succeeding coil. In the Brush, however, no two contiguous 

 coils are so joined, each coil lieing permanently connected 

 by one of its extremities to the coil opposite it. This 

 arrangement is shown roughly in Fig. -"i, where R R is the 

 iron ring, and S the shaft. The free ends of the coils are al) 

 connected to the commutator. Fig. 6, a diagram introduced 

 by Prof. Thompson, in his paper before the Society of Arts, 

 will help us materially in comprehending the general 

 principles upon which the generation of the current depends. 

 By referring to Fig. 1 (Knowledge, No. 81) it will be 

 seen that (as pointed out in the article) there are two pairs 

 of lirushes, pressing on four commutator rings ( Fig. 3), 

 which are represented in Fig. 6 by A A', B B'. The coils 

 permanently connected are (in Fig. 6) similarly numbered, 

 as 1,1, 2,2, (i-c. S and N represent the field- magnets, the 

 arrows indicating the direction of the current. 



As the armature revolves, each pair of coils passes 

 through the magnetic field, and is subjected, successively 

 and oppositely, to every stage of the inductive influence- — 

 ttiat is to say (associating ourselves with the coils 1,1), both 

 coils are simultaneously in the neutral zone, or the 

 region of minimum induction, this zone being at right 

 angles to the direction of the lines of magnetic force. 

 In this position, one of the brushes of the com- 

 mutator presses the insulating piece (C, Fig. 3), and 

 accordingly the circuit through coils 1,1 is disconnected. 

 The object achieved in this arrangement is of a twofold 

 nature. In the first place, the absence of a current in the 

 coils during the period of disconnection allows time for the 

 coils to get cool — an object which is also assisted by the 

 grooved form of the iron ring, currents of air being allowed 

 to pass through these grooves to carry ofl' a large quantity 

 of heat. It must not be forgotten that the resistance of a 

 metallic conductor increases with the temperature, so that 

 there are electrical as well as mechanical objections to a 

 heated machine. In the second place, the coils being in 

 the neutral zone, no useful current is being produced, and 

 if the current produced in the other coils is allowed to pass 

 through them, uot only do they perform no good office, but 

 they become a positive obstacle to the production of a 



