SCIENCE. 



[Vol. XI. No. 266 



to point out some disadvantages of the alternating system. The 

 advantages of the system, as allowing the distribution of incan- 

 descent lights over extended areas, are so well known, that it is no 

 more than fair that the drawbacks should be recognized, as it is by 

 the honest investigation of every side of a case that science and 

 industries advance. It was pointed out in the paper on motors re- 

 ferred to above, that the energy, being transformed, which is equal 

 to CE, the product of the electro-motive force by the current, could 

 be changed in two ways : supposing E is constant, we can either 

 change the absolute value of C, or we change the position of its 

 maximum with respect to the maximum of E. Now, if the former 

 was what actually occurred, as we decreased the work being done, 

 — turned out a number of lamps, for instance, — we would decrease 

 the current ; and the heating of the line wire, equal approximately 

 to C% R, would decrease in a still greater proportion. But this is 



not what really occurs. We have only a partial decrease of current, 

 the total decrease being partly made up by a shift of the position 

 of the curve representing C. It was pointed out that this was a 

 disadvantage, as the heating of the line was independent of the 

 position of the current curve, depending simply on its value. 

 There is another disadvantage in this, which was not mentioned in 

 the paper referred to. A dynamo cannot carry more than a certain 

 current, corresponding to its maximum capacity. Now, if there 

 were absolutely no change in the value of the current from full load 

 to no load, it would mean that all of the dynamos in the station 

 would have to be run all the time ; for, if we distributed the cur- 

 rent among a few of them, they would rapidly heat and burn out. 

 It is evident that this state of affairs would be most uneconomical, 

 since the absolute number of horse-power lost in each machine 

 varies very little with the load, and, besides these losses, we have 

 the depreciation and wear on the machinery. Of course, the en- 

 gines, supposing there were no lamps being burned, would be doing 

 very little work, running uneconomically. In practice we do not 

 have this state of affairs : the current does decrease in value as 

 lamps are turned out in the secondary circuits, but it does not de- 

 crease proportionally to the lamps turned out, and we must run 

 more dynamos than are necessary to supply the energy required in 

 the lamps ; and this at a reduced load, and therefore at a low effi- 

 ciency. There are a number of interesting points that might be 

 brought out here, but until I have calculated the results of some 

 experiments, and have from them some reliable data as to the mag- 

 nitude of the different effects, I will not push the matter further. 



From Mr. Smith's paper it would seem that the Westinghouse 

 Company have found it best to run the converters separately ; that 

 is, not to join a number of them in parallel. Now, the objections 

 to this are, ist, that it does not allow the converting system to take 

 advantage of the law of averages ; and, 2d, that as each converter 

 is only working for a limited time on full load, and as the efficiency 

 on partial loads is not great, the total efficiency is much reduced. 

 As for the first, it is well known that if the total number of lamps 

 in a certain district is, say, 2,000, the maximum capacity of the 

 station required to supply them by a direct system will be very much 

 less, say, 1,000 lamps ; this, of course, because all the houses in the 

 district will never have all of their lamps burning at once. If, how- 

 ever, we wish to supply them by converters, using a converter in 

 each house, the capacity of our converters would have to be 2,000 

 lamps, since any one house might have all the lamps burning on 

 some special occasion. If we calculate the amount of gas we could 

 burn in a month, supposing each jet were burning all the time, and 

 compare with the amount we actually do burn, we will find that we 

 use, perhaps, one-twentieth part of the maximum capacity of our 

 lights. Now, a converter working at an average of one-twentieth 

 of its capacity is not an especially economical machine. 



The above considerations must interfere with the economy of the 

 alternating system ; still it must be remembered that the system 

 is already successful in so many cases, that, in spite of these draw- 

 backs, the field before it is immense. In Mr. Smith's paper it is 

 especially gratifying to notice how the system has been improved, 

 and is still being improved. 



Mr. W. L. Church read a paper on ' Independent Engines for 

 Incandescent Electric- Light Stations,' in which he pointed out, that, 

 when the amount of energy required from an electric-lighting sta- 



tion varies within wide limits, it is better to have a number of small 

 engines to drive the dynamos than one large engine. The reason 

 evidently is, that while a large slow-speed engine is more econom- 

 ical than high-speed engines of smaller size, when both are working 

 at a maximum efficiency, yet our single large engine would only be 

 working at full load for a small part of the day, while the rest of 

 the time it would be doing only a small part of its possible work, 

 and its efficiency would be low. With a number of small engines, 

 on the other hand, when our load decreases, we can shut off 

 some of the engines and dynamos, keeping those that are left up to 

 very nearly their maximum efficiency. Another point in favor of 

 the small engines is, that they may be belted directly to the dyna- 

 mos, thus avoiding the loss in the countershafting used with the 

 large machine, — a loss that might amount to twenty per cent. 



Among the other papers read was a very valuable one on electric 

 motors by Dr. G. A. Liebig; while there were a number of others,. 

 all of considerable technical interest. 



Pres. J. F. Morrison having declined a re-election, Mr. S. A. 

 Duncan of Pittsburgh was unanimously elected president of the 

 association. 



Taken altogether, the meeting was the most important, both as 

 regards attendance and the papers read, that the association has 

 yet held. 



WASHINGTON SCIENTIFIC NEWS. 



Maj. J. W. Powell on Evolution in Civilized Man. — Ascertaining ihe 

 Density of the Earth. — Submarine Oil-Springs in the Pacific. 



Evolution in Civilized Man. 



The annual meeting of the Anthropological Society was held art 

 Tuesday evening, March 6. Maj. J. W. Powell, the retiring presi- 

 dent of the society, occupied the evening by reading a paper, the 

 sixth of a series on the same subject, on the evolution of man. 



In the opening portions of his address, Major Powell explained 

 the doctrine of evolution as taught in the philosophy of Darwin 

 and embodied in the phrases ' the survival of the fittest in the 

 struggle for existence' and 'natural selection.' "Nature," he 

 said, " gives more lives than she can support : there are more in- 

 dividuals requiring nourishment than there is food. Only those 

 live that obtain sufficient nutriment, and only those live that find a 

 habitat. Of the multitude of germs, some perish on the rocks, 

 some languish in the da.rkness, some are drowned in the waters, 

 and some are devoured by other living beings. A few live because 

 they fall not upon the rocks, but are implanted in the soils ; because 

 they are not buried in the darkness, but are bathed in the sunlight ; 

 because they are not overwhelmed by deep waters, but are nour- 

 ished by gentle rains ; or because they are not devoured by the 

 hungry, but dwell among the living. A few live because they are 

 the favorites of surrounding circumstances. In the more stately 

 phrase of the philosophy of evolution, they are ' adapted to the 

 environment.' Evolution, or progress in life, is accomplished 

 among animals or plants by killing the weaker, — the less favored, 

 — and by saving the stronger and more favored. Many must be 

 killed because there are too many, and so the best only are pre- 

 served. Those a little above the average are saved, and this is 

 called ' natural selection.' But this general statement must be fol- 

 lowed a little further, that its deeper significance may be grasped." 



Major Powell then illustrated the operation of the law of evolution 

 by showing the infinite variety of conditions presented by the earth 

 as the home of living beings, some of the ways in which compe- 

 tition for life is carried on, and the manner in which plants become 

 more perfect, and animals advanced. " The endeavor has been 

 made," he said, " to show what the struggle for existence means, 

 and the part which competition plays in biotic evolution. Compe- 

 tition among plants and animals is fierce, merciless, and deadly ; 

 out of competition fear and pain are born ; out of competition come 

 anger and hatred and ferocity. But it must not be forgotten that 

 from this same competition there arise things more beautiful and 

 lovely, — the wing of a butterfly, the plumage of the bird, and the 

 fur of the beast ; the hum of the honey-bee, the song of the night- 

 ingale, and the chatter of the squirrel. So good and evil dwell to- 

 gether." 



