FRAGMENTS OF SCIENCE. 



855 



hours. The lamps are said to work equally 

 well with either alternating or direct cur- 

 rents, and there is no vacuum necessary. If 

 this lamp proves a success as a commercial 

 apparatus, it will be but another example of 

 how slight a matter may make all the differ- 

 ence between success and failure. There 

 have been numerous experimenters trying 

 for the last ten years, and in fact ever since 

 the appearance of the arc lamp, to utilize in 

 an electric lamp the great light-giving power 

 of the refractory earths in a state of incan- 

 descence; but, owing to their high resistance 

 at ordinary temperatures, no results were ob- 

 tained until Professor Nernst thought of heat- 

 ing his thoria rod, and this simple procedure 

 seems to have solved the whole difficulty. 

 It is claimed that the Nernst lamp is a much 

 more economical transformer of electricity 

 into light than the present incandescent 

 electric lamps. An apparatus called a kaolin 

 candle, which has been suggested as an an- 

 ticipation of Professor Nernst's lamp, was 

 constructed by Paul Jablochkoff in 187*7 or 

 18*78. It consisted of a strip of kaolin, 

 along which ran a " match " of some con- 

 ducting material. The current was passed 

 through this " match " until the kaolin strip 

 became heated sufficiently to become a con- 

 ductor itself. The lamp did not, however, 

 prove a commercial success. 



Laws of 4' I i malic Evolution. — The prob- 

 lem of the laws of climatic evolution was 

 characterized by Dr. Marsden Manson, in a 

 paper read at the British Association, as one 

 of the grandest and most far-reaching prob- 

 lems in geological physics, since it embraces 

 principles and laws applicable to other plan- 

 ets than ours. After presenting a formula- 

 tion of those laws, the author pointed out 

 that in consequence of their working, a hot 

 spheroid rotating in space and revolving- 

 about a central sun, and holding fluids of 

 similar properties to water and air within the 

 sphere of its control, must pass through a 

 series of uniform climates at sea level, grad- 

 ually decreasing in temperature and terminat- 

 ing in an ice age, and that this age must be 

 succeeded by a series of zonal climates grad- 

 ually increasing in temperature and extent 

 The conclusions thus reached were that in 

 the case of the earth zonal distribution of 

 climates was inaugurated at the culmination 



of the ice age, and is gradually increasing in 

 temperature and extent by the trapping of 

 the solar energy in the lower atmosphere, 

 and that the rise has a moderate limit ; that 

 the ice age was unique and due to the phys- 

 ical properties of water and air, and to the 

 difference in specific heat of land and water ; 

 and that prior to the ice age local formation 

 of glaciers could occur at any latitude and 

 period. Dr. Manson then observed that Ju- 

 piter was apparently in a condition through 

 which the earth has already passed, and 

 Mars was in one toward which the climatic 

 evolution of the earth was tending. 



Poisonous Plants. — Statistics in regard 

 to poisonous plants are lacking on account 

 of a general ignorance of the subject, and it 

 is therefore impossible to form even an ap- 

 proximate estimate of the damage done by 

 them. Besides the criminal uses that may be 

 made of them, there are some other prob- 

 lems connected with them that are of general 

 public interest. The common law of Eng- 

 land holds those who possess and cultivate 

 such plants responsible for damages accru- 

 ing from them ; and a New York court has 

 awarded damages in a case of injury from 

 poison ivy growing in a cemetery. In order 

 to obtain information on the subject, the bo- 

 tanical division of the Department of Agri- 

 culture arranged to receive notices through 

 the clipping bureaus of the cases of poison- 

 ing recorded in the newspapers. Thus 

 through the persons named in the articles or 

 through the local postmaster it was put in 

 correspondence with the physician in the 

 case, who furnished the authentic facts. A 

 large number of correct and valuable data 

 were thus secured. It is proved by these 

 facts that all poisonous plants are not 

 equally injurious to all persons nor to all 

 forms of life. Thus poison ivy has no ap- 

 parent external effect upon animals, and a 

 few of them eat its leaves with impunity ; 

 and it acts upon the skin of the majority of 

 persons with varying intensity — on some 

 hardly at all, while others are extremely sen- 

 sitive to it. A similar variability is found in 

 the effects of poisonous plants taken inter- 

 nally. In some cases often regarded as of 

 that kind, death is attributable not to any 

 poison which the plant contains, but to im- 

 moderate or incautious eating, or to mechan- 



