February 17, 1905.] 



SCIENCE. 



275 



can be assumed to prove that priority. If this 

 is the case, he is not justified in assuming that 

 his quotation from the edition of 1779 is iden- 

 tical in wording with the original statement 

 in the preface of 1778. This quotation is: 

 ' L'usage ordinaire a consacre le premier des 

 ces mots (cosmologie) dans le sens ou je I'em- 

 ploie.' 



Geikie's statement with regard to the 1778 

 edition is : " The proper word he admits should 

 have been geology, but he could not venture 

 to adopt it because it was not a word in use." 



Eastman, assuming that the statement in 

 the second edition was word for word the same 

 as that in the first edition, says that Geikie's 

 rendering is not justified. 



I reply that his assumption is unfounded, 

 for so prolific a writer would be more likely 

 than not to vary the wording of his phrases 

 on a second writing. But even if the assump- 

 tion were correct, Eastman's own rendering, 

 ' the word cosmology is more generally used 

 in an equivalent sense ' is as free in one di- 

 rection as Geikie's in another. 



Entirely aside from this question, which is 

 somewhat on the hair-splitting order, it is to 

 be observed that my statement was, that De 

 Saussure was the first geologist (in the mod- 

 ern sense, as Dr. Eastman kindly added for 

 me) to use the word geology in speaking of 

 his science. There is no question that De 

 Saussure was such a geologist. Let us see, 

 then, what authorities like Von Zittel and 

 Geikie think of Deluc in this regard. 



Von Zittel qualifies him as a remarkably 

 busy but flighty observer, and a fantastic 

 scribbler whose publications have, for the most 

 part, fallen into deserved oblivion. His use 

 of the term geology he says is first suggested 

 in the preface to a volume containing four- 

 teen letters addressed to Queen Charlotte of 

 England, whom he served for many years as 

 reader and traveling companion. This pref- 

 ace, he says, makes the pompous announce- 

 ment that the book will contain the ground- 

 work of a cosmology or earth history, but 

 when examined the letters are found to be 

 mostly filled with long-winded descriptions of 

 the lands and peoples visited and very little 

 of what the preface promises. 



Geikie classes him with Richardson, the 

 believer in fossiliferous basalt, Kirwan and 

 others of that ilk, and says : 



But though these men wielded great influence 

 in their day their writings have fallen into de- 

 served oblivion. They are never read save by the 

 curious student who has leisure and inclination 

 to dig among the cemeteries of geological litera- 

 ture. 



S. F. Emmons. 



SPECIAL ARTICLES. 



NOTE ON THE VARIATION OF THE SIZES OF NUCLEI 

 WITH THE INTENSITY OF THE IONIZATION. 



1. I shall use the word fog-limit, to denote 

 the difference (Bp) of pressure between the 

 outside (constant pressure) and the inside of 

 the fog-chambeir, to which sudden exhaustion 

 must be carried in order that condensation 

 may just occur in dust-free air saturated with 

 moisture. It is obvious that if the fog-limit 

 is to be used as a criterion, the result depends 

 in all cases (cset. par.) on the particular type 

 of fog-chamber used and all statements are to 

 refer to a given type. 



2. Nuclei of any size may be produced in 

 dust-fi'ee moist air by varying the time and 

 the intensity of the exposure to X-ray or other 

 similar radiation. A particular fog-limit and 

 hence a particular size of nucleus is reached 

 for each case until the fog-limit vanishes. 

 Thus in my experiments for 



Dust-free air (radium at infinity) Sp — 24.5 



Radium (10,000 X, in thin sealed glass tube) 



at 200 cm. from fog-chamber, 21.5 

 at 100 cm. '• " 20 8 



at 45 cm. " " 20.2 



Radium, do., within the fog-chamber 19 



X-ray bulb 



at 35 cm. from fog-chamber, exposure 2 min. Sp = 19 



at 10 cm. " " " 2 " IS 



at 10 cm. " " " 4 " 17 



at 2 cm. " " " 2 " l.'i.S 



at 2 cm. " " " 4 " 10 



at 2 cm. " " " 10 " vanishing 



at 2 cm. (stronger radiation) " 5 " 5 



at 2 cm. (still stronger radiation) " 5 " below 4 



To these may be added the fog-limits corre- 

 sponding to the more gradual decay of excited 

 radio-activity (radium 10,000 X> thin her- 

 metically sealed aluminum tube placed for 15 

 or 30 minutes within the fog-chamber). 



