Jl XE 14, 1895.] 



SCIENCE. 



663 



100 hours of their use. It had beeu very 

 generally assumed that a glow-lamp was at 

 its best, uuder lixed conditions of pressure, 

 at the very beginning of its life and that it 

 would deteriorate from that time on. The 

 authors of this paper appear to have 

 found, however, that this is not the case 

 and that, on the contrary, the light is 

 increased from the beginning through a 

 certain considerable part of the life of 

 the lamp, after which it slowly fails. One 

 form in which this conclusion is put is 

 that if a grouj) of glow-lamps, such as were 

 examined in this case, being the Edison- 

 Swan Lamps, marked 100-S and run at a 

 pressure of 100 volts, be kept continuously 

 in operation by putting in a new lamp of 

 the same chai-acter whenever a filament 

 breaks, and never replacing the lamps liy 

 new except for a broken filament, the light 

 given out by the group will never lie as 

 small as at the beginning. Some reference 

 •is made to the proljable cause of the rise in 

 candle power bj- use, and the explanation 

 given a year or two ago by Mr. Howell, at 

 a meeting of the American Institute of Elec- 

 trical Engineers, (. e., that such a rise in 

 caudle power is due to an improvement of 

 the vacuum of the lamp during the early 

 part of its life, is commented upon. Some 

 of the earlier examinations of the increase 

 in candle power and improvement in vacuum 

 by the authors of this paper seem decidedly 

 to confirm this explanation by Mr. Howell; 

 but subsequent tests, referred to in the addi- 

 tion to the paper made in January, isit.j, 

 are not so favorable to that hypothesis. 

 The authors suggest that the rise in candle 

 power may possibly have beeu due to a 

 change in the surface of the filament caus- 

 ing the emissivity for heat to decrease, since 

 that would raise the light emitted, as well 

 as the number of caudles per watt; but they 

 declare that they have not yet discovered 

 whether such change in heat-emissivity 

 takes place. The methods of carrying on 



the investigation, both electric and photo- 

 metric, are exphxiued in sufficient detail, and 

 the whole is a valuable coutrilnition to the 

 subject. T. C. M. 



NOTES AKD SEWS. 

 EXTOMOLOGV. 



Dr. T. A. Chapm.\.x has beeu publishing 

 in the Entomologists' Record of London, 

 and has now completed, a paper of no great 

 length l)ut of much importance, on the clas- 

 sification of butterflies, based on the struc- 

 ture of the pupie, and a comparison of the 

 same with the pup;e of the lower lepidop- 

 terous families. He places special empha- 

 sis on two points hitherto entirely neg- 

 lected : The relative freedom of motion of 

 the middle joints of the abdomen, and the 

 relation of the parts on the head on dehis- 

 cence. His conclusions are that the Pa- 

 pilionidte (excluding the Pierinre) are the 

 nearest relatives of the Hesperida' (which 

 agrees witli all latest researches), but fur- 

 tlier that the Lyctenids '• sliould no longer 

 be regarded as in any way intermediate be- 

 tween the Papilionids and Xymphalids ; 

 rather should the Lemoniida> and Lycieuidie 

 be regarded as a branch which developed 

 from the primaeval butterfly (above the 

 Hesperids) in one direction, whilst tlie Pa- 

 pilionids arose and branched to the Pierids 

 and Xymphalids (juite independently. An- 

 other point is that the Pierid seiwrated 

 from the Pajiilionid at a verj- earlj- stage of 

 the evolution of tlic latter, and that the 

 Nymphalid almost immediately thereafter 

 separated from the Pierid." These conclu- 

 sions are Ijorne out by manj- facts in the 

 structure of the other stages and especially 

 render the position of the LiM-theime less 

 anomalous. 



Bruxxer vox "Wattexwvl has just pub- 

 lished his Monographic der Pseudophylli- 

 deu, the last large group of Orthopteni that 

 lias specially needed monographic treat- 



