

3 8z 



THE POPULAR SCIENCE MONTHLY. 



rhinoceros in the Regent Park Zoological 

 Garden do not suffer even in very cold 

 weather ; and that in the isle of Saghalien, 

 to the north of Japan, the reindeer is preyed 

 upon by the tiger, which crosses the ice in 

 pursuit of its victim. Hence it follows that 

 mammals are not good indicators of tem- 

 perature. Mr. Tiddeman rested his argu- 

 ment for man's antiquity in Britain on the 

 occurrence of a (supposed) human fibula 

 and two hacked bones of goats in deposits 

 older than the post-glacial. But Prof. Busk 

 objected that the " fibula " was probably 

 ursine, and, at all events, that it was alto- 

 gether too insignificant a fragment on which 

 to base any far-reaching conclusion. The 

 goat-bones, hacked as if by the hand of 

 man, were found in Victoria Cave, at the 

 depth of fifteen and twenty-five feet re- 

 spectively. But it was urged that these 

 bones really belonged to a superficial stra- 

 tum, and had fallen down to a lower level 

 while the work of excavation was going on. 

 But, even supposing them to belong to the 

 levels from which they were taken, these 

 bones are not decisive as to the age of the 

 deposit in which they were found a matter 

 which is still in dispute. Arguments pro 

 and contra were advanced by sundry mem- 

 bers of the Institute, and the various evi- 

 dences of the antiquity of man were consid- 

 ered in the light of geology, anatomy, the 

 science of language, and paleontology. But 

 no positive result was reached one way or 

 the other ; nevertheless, the conference was 

 not without fruit, inasmuch as it has done 

 much to remove misapprehensions, and to 

 indicate the proper lines of research. 



Electricity in War. Mr. H. Baden Prit- 

 chard, in one of his communications to Na- 

 ture on scientific principles involved in the 

 art of war, gives a sketch of the employ- 

 ment of electricity in military operations. 

 He says that the employment of electricity 

 for exploding charges of powder was sug- 

 gested by Franklin and Priestley ; only very 

 recently, however, have we been in a posi- 

 tion to make proper use of this valuable 

 agent as a means of firing charges at a dis- 

 tance. One of the first applications made 

 of the subtile fluid was in the removal of 

 the wreck of the Royal George at Spithead, 

 nearly fifty years ago, when the explosion 



of the charges was brought about by what 

 is termed a wire fuse, a short piece of plati- 

 num thread stretched between two copper 

 wires. The platinum bridge, having less 

 conducting power than the copper wires, 

 presents a considerable resistance to any 

 current of electricity that passes, and so be- 

 comes heated sufficiently to ignite gunpow- 

 der. " But for many purposes," remarks 

 Mr. Baden Pritchard, " the wire fuse is ill 

 adapted to the military and naval services. 

 A voltaic battery is necessary to evolve the 

 low-tension electricity required to yield suf- 

 ficient resistance and heat, and such a bat- 

 tery made up of metal plates, and involving 

 the use of acids, is a cumbersome apparatus. 

 In 1853 Colonel Verda, of the Spanish army, 

 with the aid of a Ruhmkorff coil, succeeded 

 in firing half a dozen charges simultaneous- 

 ly. Wheatstone and Abel followed in Yer- 

 du's footsteps, and while the former directed 

 his attention to the construction of a port- 

 able frictional apparatus, the latter busied 

 himself in the preparation of a fuse inclos- 

 ing a compound more easily explosible than 

 gunpowder a fuse which still holds an im- 

 portant place among warlike stores." 



Alternation of Seasons and Tree-Growth. 



The fact that the exogenous plants of the 

 preglacial epoch show concentric growth- 

 rings has been by many writers regarded 

 as proof positive that in these times the 

 earth's axis must have been inclined as at 

 present, and that there must have been then, 

 even as now, alternating seasons. But is 

 alternation of seasons necessary to the for- 

 mation of rings ? 



This question is considered by Dr. C. B. 

 Warring, in a paper read before the New 

 York Academy of Sciences, an extract from 

 which has appeared in the American Jour- 

 nal of Science and Arts. The problem might 

 be solved experimentally, says Dr. Warring, 

 if we could secure for plants a uniform 

 temperature throughout the year. The 

 nearest approach to such a condition in this 

 latitude is found in greenhouses. Exoge- 

 nous plants so placed, e. g., the orange and 

 lemon, form growth-rings as regularly as do 

 forest-trees. The author has found it dif- 

 ficult to obtain any information as to the 

 formation of these annual markings in ex- 

 ogenous plants growing in tropical regions. 



