208 



SCIEJSrCE. 



[Vol. YIII., No. 187 



carried too far. It has been of gi'eat value, though 

 it may now fail to meet new demands. Electric 

 thermometry is receiving especial investigation at 

 tlie signal office, particularly from the meteoi-o- 

 logical stand-point, with some promising results. 

 Professor Mendenhall reported the progi-ess which 

 had been made in the study of atmospheric 

 electricity during the past year. It is not time to 

 begin to think of the origin of atmospheric elec- 

 tricity. The problem is its distribution and the 

 relation, if there be any, to weather changes. 

 Some very interesting results have been reached. 

 In ordinary weather the electrical condition is un- 

 dergoing constant and rather wide variations, 

 which are very local, as two collectors only a few 

 feet apart may give curves differing considerably, 

 thougli similar in their wider variations. When 

 an electrical storm occurs, the curves over a wide 

 area may be similar in general outline. 



Professor Mendenhall also noted a phenomenon 

 entirely new to him ; namely, tliat resistance coils, 

 after a current is passed through them for some 

 time, upon short-circuiting, will yield a reverse 

 current for hours. This phenomenon can no 

 doubt be classed under the general head of polari- 

 zation, yet by simple polarization it would be 

 difficult to account for persistence of ciirrent, 

 Tliis makes caution necessary in the use of resist- 

 ance coils, in order that any effects of this kind 

 may be carefully noted. In one instance the ap- 

 parent resistance of a coil was found to increase 

 fourfold when the current was reversed. 



Prof. W. A. Anthony reported the results of 

 experiments showing an increase in the torsional 

 elasticity of metallic wires. In the case of a cer- 

 tain phosphor-bronze wire, it has been increasing, 

 at a decreasing rate, for nine months. Various 

 metals have been investigated. Steel is scarcely 

 better than brass and other substances, and they 

 all show a much wider change than the bronze. 

 To determine whether the phenomenon is depend- 

 ent upon the age of the wire and the condition 

 to vihich it is subjected, a piece of wire was 

 freshly drawn. A portion forty centimetres long 

 was used in a torsion pendulum. The period 

 changed from 9.575 seconds to 9.526 seconds in 

 four days. The curve representing the time of 

 vibration shows that the change occurred less 

 rapidly each day. Another piece of the wire, 

 which had been drawn at the same time, and 

 which had been subject to no strain of any kind, 

 was then tested. The curve for this wire was not 

 a duplication, but was almost an exact continua- 

 tion of the former curve, showing that the same 

 changes had been going on in the two wires. The 

 temperature co-efficient seems to change with the 

 change in torsional elasticity. 



The following papers were also presented : 

 ' Counteracting the effect of change of level of the 

 torsion balance,' by Prof. Wm. Kent ; ' Time of 

 contact between the hammer and the string in a 

 piano,' by Prof. C. K. Wead ; and ' Registering 

 small variations of speed of machinery,' by Prof. 

 W. A. Anthony. 



PARIS LETTER. 



M. Pennetier, at a recent meeting of the Acad- 

 emy of sciences, gave the results of experiments 

 of fourteen years' duration concerning the revivifi- 

 cation of small animals, such as rotifers and An- 

 guiUulatritici, after a protracted state of apparent 

 death due to dehydration. The results are the 

 foUovring : Anguillulae, which M. Pennetier had 

 kept, year after year, in a state of apparent death 

 and in great numbers, have ceased to be subject to 

 reviviUcation, upon being put in moist conditions, 

 after fourteen years. Up to this date, they re- 

 gained movement and life easily enough, but after 

 it none of them could be brought back to life. M. 

 Vulpian remarked, d propos of M. Pennetier's ex- 

 periments, that he had noticed that every year the 

 number of dehydrated animals that can be recalled 

 to existence decreases regularly, and that most 

 likely the process of desiccation works in the ani- 

 mals some progressive alterations of an unknown 

 nature, which lead to results incompatible with 

 life. M. Vulpian argues also that it cannot be 

 death that desiccation induces; it can only be some 

 sort of lethargy during which life-phenomena and 

 manifestations are at the lowest. This conclusion 

 will be indorsed by most biologists. 



This question of the revivification of desiccated 

 animals was treated in a very interesting manner 

 some twenty-five years ago by Broca. Leuwen- 

 hoeck was the first who noticed the fact, and 

 Needham and Henry Baker (1743), Spallanzani and 

 Fontana, soon followed. During the present cen- 

 tury, Doyere, Pouchet, and Davaine investigated 

 the subject with great care. They found that the 

 facts were quite true ; but while Pouchet, follow- 

 ing Leuwenhoeck, believed that there was no real 

 death in the case, and that it was only a very good 

 imitation of it, Doyere, following Spallanzani, be- 

 lieved that the desiccated animals were really 

 dead, and that their revivification was a real re- 

 suscitation, a new creation of life. In 1860 a 

 committee was appointed by the Societe de biolo- 

 gie for the purpose of investigating the question. 

 Brown-Sequard, Balbiani, Berthelot, Dareste, and 

 Eobin were members of this committee : Broca 

 had charge of summarizing the results and draw- 

 ing up the report of the committee. This report 

 was published in 1860, and it remains one of the 



