5o6 



POPULAR SCIENCE MONTHLY. 



their appearances on photographs are 

 due to some chemical action which 

 takes place in the gelatin film." 



"Warming XTp." — "Warming up" 

 is the expressive term of general cur- 

 rency, which Dr. E. G. Lancaster adopts 

 to denote the process in which one start- 

 ing on any work in a little while suf- 

 fers a short period of fatigue, from 

 which he soon recovers, to go on with 

 new and increased vigor. This occurs 

 in the course of walks, with students 

 engaged in earnest reading or in writ- 

 ing, and in animals, as in dogs on the 

 chase, tlie animals pursued, and race- 

 horses. " It is said of two famous trot- 

 ters, each of which has reduced the 

 world's record within a few years, that 

 the period of warming up was very 

 characteristic. . . . Athletes, especially 

 ball players, realize the importance of 

 practice just before the games, to be 

 followed by a slight rest. A pitcher 

 would hardly enter the box till he had 

 got his arm in working order by a few 

 minutes' practice. Orators often are 

 dull at first, but warm up. It is said 

 that Wendell Phillips was often hissed 

 for his slow, uninteresting speech, but 

 rallied to the occasion at such times 

 with his masterly oratory." Dr. Lan- 

 caster has experimented on the phenom- 

 ena, using a method like those of Mosso 

 and of Lombard in the psychological 

 laboratory at Clark University, and 

 publishes the results, with details and 

 curves, in the papers of the Colorado 

 College Scientific Society. He tried ten 

 or twelve subjects, experimenting on 

 the middle finger of the right hand, and 

 gaining most of his results from four or 

 five persons. He finds that warming 

 up is general, but not universal. One 

 subject always did his best w^ork first. 

 He likewise showed no warming up in 

 his mental work. The phenomenon 

 called " second mind " is closely allied 

 to warming up, but is not the same. 

 The author is of the opinion that the 

 importance of this process is greatly 

 misunderstood. 



Sixty Years' Improvements in 

 Steamships. — A review of what has 

 been accomplished in sixty years in the 

 improvement of transatlantic traffic, 

 given by Sir William H. White in his 

 address at the British Association on 



Steam Navigation at High Speeds, 

 shows that speed has been increased 

 from eight and a half to twenty-two and 

 a half knots an hour, and the time of the 

 voyage has been brought down to about 

 thirty-eight per cent of what it was in 

 1838. Ships have been more than trebled 

 in length, about doubled in breadth, and 

 increased tenfold in displacement. The 

 number of passengers carried by a 

 steamship has been enlarged from about 

 one hundred to nearly two thousand. 

 The engine power has been made forty 

 times as great. The ratio of horse 

 power to the weight driven has been 

 quadrupled. The rate of coal consump- 

 tion per horse power per hour is now 

 only about one third what it was in 

 1840. Had the old rate of coal consump- 

 tion continued, instead of three thou- 

 sand tons of coal, nine thousand would 

 have been required for a voyage at 

 twenty-two knots. Had the engines 

 been proportionately as heavy as those 

 in use sixty years ago, they would have 

 weighed about fourteen thousand tons. 

 In other words, machinery^ boilers, and 

 coal would have exceeded the total 

 weight of the Campania as she floats to- 

 day. " There could not be a more strik- 

 ing illustration than this of the close re- 

 lation between improvements in marine 

 engineering at high speed. Equally true 

 is it that this development could not 

 have been accomplished but for the use 

 of improved materials and structural ar- 

 rangements." 



American. Advances in Forestry. 

 — The Department of Agriculture hav- 

 ing determined to prepare a book for 

 the Paris Exposition, reviewing what 

 has been accomplished in scientific ag- 

 riculture in the United States, the Divi- 

 sion of Forestry will contribute to it a 

 short history of forestry in the United 

 States, with an account of the efforts of 

 private landholders to apply the prin- 

 ciples of forestry. Much more has been 

 accomplished in the United States in 

 the way of forestry than has been sup- 

 posed. Mr. Pinchot, the forester of the 

 division, holds that wherever private 

 owners have made the effort to use the 

 merchantable timber on their woodland 

 without injuring its productive power, 

 and to establish new forests, there has 

 been the intention of true forestry. The 

 methods may have been imperfect, but 



