St;', nt'tjic Iittrlli<i<:/>r, . 



in 



this Journal by Mr. Russell (xxi, 873) and by Mr. Holman 













s. f. Meteor., xiv, 426 as simply giving Xeumann's method for 

 ibrating thermometers. This' met hod is given, m the papers 







'erred to, quoted from Wild and Dorn, but tliere are also given 





lplifications and improvements of it by myself, which were 



!" 



leed not difficult to find, but are now become a matter of 





fnHolman's paper it is asserted that some of the advantages of 







fl- 



>ni taking readings with an end of the thread apparently just at 

 e line of "the scale. This method of taking readings, often rec- 









>thod nor was it adopted by myself; that will be seen from the 



ex 



am pies given in the papers quoted. In the thermometers used 







.1. 



nee of top and line, since they allow the top of the mercury to 



b< 







I shall venture to add some remarks on the methods of calibrat- 



in 



g thermometers, a matter too often disregarded, and about which 



; felt in this c 



I am acquainted with all the important and many of the unim- 

 poriunt papers on this subject, but I have never found a method 

 that i- not supeiseded by one of the three methods 1 have described 

 in the paper in Carl's Rep., viz : 



]. The method of Lambert or (i:iy-Lussa<-, the oldest and sim- 

 plest one, but not permitting very great accuracy. The method 

 proposed by flolman does not ditK-r materially from this. 2. The 

 method- of Ilaii-troin r.-'|tiiriiii: a u'reater number of ob>ervat ioti.s 

 and a more tedious i : ] answer in all ordi- 



requtring a great number of observations but giving the best 



call Hansen's method, though Hansen pro- 

 posed it for another matter) the labor of cah-uhii ion is increased 

 rather more than the accuracy; moreover, there is not always 

 occasion for employing this method and it is not easy for every - 



try of Lead '#■ ill'-. r„ /.,. ■„,/.,. 

 Rocky Mountain Di 



II. Geology and Mineralogy 

 Geological Sur 



wo colored plates. Washington. l---j. 



