JANUABT 27, 1911] 



SCIENCE 



151 



little better than chaotic, many species being 

 Tin known or else grouped under a specific 

 name mostly noteworthy because of its com- 

 prehensiveness. We think all will agree that 

 Professor Theobald has done a large amount 

 of valuable pioneer work, though we may not 

 adopt all of his taxonomic views. The British 

 Museum is to be congratulated upon having 

 published such an admirable work, of which 

 the volume under consideration forms only a 

 part, consisting of five good-sized volumes, il- 

 lustrated by a large series of figures, there 

 being over 1,200 text illustrations and 88 

 magnificent plates, and characterizing prac- 

 tically all the known species in this important 

 family. It is perhaps needless to add that this 

 monograph on the Culicidffi, possibly not even 

 yet completed, must be the major foundation 

 for all subsequent studies in this group and 

 therefore nearly indispensable to the systema- 

 tist. 



E. P. Pelt 



J 



SPECIAL ARTICLES 



NEW PHENOMENA OP ELECTRICAL DISCHAEGE 



At a meeting of the Academy of Science of 

 St. Louis on December 5, the writer gave 

 further results of work on electrical discharge. 

 It had been previously shown that oscillations 

 of widely varying frequency, attended by 

 musical tones, could be brought about, by 

 means of small spark gaps of variable length, 

 in the lines leading from the terminals of an 

 influence machine to the main gap across 

 which the discharge is to pass. In a former 

 paper it had been suggested that the striss in 

 a vacuum tube were in the nature of waves in 

 an organ pipe. 



These results suggested the idea of im- 

 posing resonance vibrations in a column of 

 air contained in a glass tube, which also con- 

 tained terminals from the influence machine. 

 The air vibrations were produced by means of 

 a blast of air from a pressure tank, which was 

 directed across the mouth of another tube. 

 It has been found that with very careful ad- 

 justments, the electric discharge across a 

 small gap in the glass tube could be ailected 

 in a marked way by the impressed sound 



waves. A luminous discharge was apparently 

 converted into a dark discharge. 



The line within the tube containing this 

 gap was in multiple with another line contain- 

 ing an adjustable gap. This system was in the 

 positive side of a circuit which contained a 

 long discharge gap. Placed transversely in 

 this gap was an insulated sheet of copper, 

 which served to prevent disruptive discharges. 

 Attempts are now being made to cause an 

 organ pipe to sound a musical tone by means 

 of periodically varying electrical stresses 

 within the air-column. The response of the 

 air-column is not as marked as when the vibra- 

 tions are produced in the ordinary way. 

 Some effects have however been secured, and 

 there is every reason to believe that the at- 

 tempt will meet with success. These results 

 can only be considered as preliminary.' 



Several friends have suggested that the term 

 drainage column as applied to the positive or 

 luminous end of a discharge, was another 

 name for an ionized mass of air. If we say 

 that air is ionized by X-rays passing through 

 it, this term does not represent the conditions 

 at either terminal of an influence machine. 



In a mass of air ionized by X-rays, the 

 average charge of a molecule is the normal 

 charge. Those which have a greater than 

 normal charge mingle with those which have 

 a less than normal charge. Such a mass of air 

 will respond to the demands of an electrometer 

 placed within it, whether its leaves have a 

 greater or a less than normal charge. The 

 supercharged molecules will deliver the excess 

 to those whom they have robbed, or to any 

 others which may be in a like condition. A 

 similar statement may be made concerning the 

 molecules which have less than the normal 

 charge. But such a mass of air is not a drain- 

 age column. It is in a condition which pro- 

 motes the formation of a drainage column, if 

 the terminals of some " source " of electricity 

 like an influence machine are placed within 

 the ionized mass of air. This mass of air is 

 then made a part of the conducting circuit, 

 by the starting of the machine into action. 

 The fact that it behaves differently from the 

 rest of the circuit is incidental to the fact 



