Miseelhiih ixis Int.-ll'nj, ,i,->. 



IV. Miscellaneous Scientific Int: 



—Mr. ( 



oibert lias made :i very impoc; 









-inniti dub. iu'.s of dntnd h } t h» i UM 



though 







.ns results which air decidedly nmro accur 





1 l»y the methods now in use. The followi 





iear the prh.cipl s upon whir!, the neu me 



while r. 





be mad 



e to the origi . m. .mi, v. id, 



in this r 



espeet. Mr. Gilbert devotes ! he opening I 





iioh- to a general discussion of .! 





■reneesof altitude by means of the 1-aminrl 



tin- |.rii 



H-ij.al in ■thods now employed, and the varh 





ns <>!■ temperature, humidity and so on, wi 



for the i 



•limination of errors <lue to t'hem. This dis 



out vcr\ 



■ fully and (dearly the una \ oida ' 



determined by the spiri 



it-level) is as great, and whose horizontal 













t the third station whose "altitude is to be 



<leteri.ii.ied. No obsen 





humidity are required. 



The readings, corrected for index error 







coincident for the two 



bav nations and the new Nation. From 



these the approximate 



height (.4') of the new station, and that 



of the base line (£') i 



ire calculated as usual, but without the 



ordinary corrections, tin 



it is, assuming that the air is dry and at 





f 32° F. Then if the known true height 



of the base line is B, 



the true height (A) of the new station is 



For, the weight ( W) of the air column between the two base 



stations, determined by the barometer, is equal to the product of 

 the mean densit v u/| of the column, multiplied bv the height ( />') 

 and by a constant factor {E) 



W=dBM (2) 



