4 ; 
* 
J. H. Alevander on the Tension of Vapor of’ Water. 317 
for suggestions as to the plan of ob oP Brot. Loe and I beg leave to 
refer the Board to the report of Prof. Loomis, of New York 
ceived in answer. T rmer contains exposition of the 
advantages which may be derived from the study of meteor- 
ology, and done in this branch of science in 
for commencing an enterprise of the proposed kind. 1€ Citi- 
zens of the United States are now scattere “over ae | part of 
the southern and western portion of North America 2 eX- 
tended lines of telegraph will furnish a ready cats re warning 
the more northern and eastern observers to be on the watch for 
the first appearance of an advancing storm. 
S 
Arr, XXIX.—On a New empirical Formula for ascertaining 
the Tension of Vapor of Water at any Temperature; by 
J. H. Avexanper, Esq. or 
ad (Concluded from page 223.) 4 4 as 
at w the last number of this Journal, I gave the fortiiuili itself 
temperatures. Want of room excluded then what remained to 
complete this Memoir, in shewing the probable errors of the for- 
mula as compared with the principal experiments, and with the 
probable errors affecting too those different series of experiments 
themselves. Such a discussion is the object of the present paper. 
‘It was already said, in the preceding part, that the most proper 
mode of expressing these errors is by the linear scale of temper- 
ature; which both in theory is the most important, and in prac- 
tice is the most accessible and usual. In this last aspect, it is on — 
this scale too where errors of observation are the most easy 
made, and likely to occur. With this view, the formula ne 
atten here only i in its converse form, (i. e., for ascortaigi 
res en given pressures,) as under : 
© F’abr. = sage 1059-13; 
P being in nce of mercury : 
ahr, = fad 136 — 105°: 13; 
a being i in stmpephiilllec s at 3 i 
As this will have to be ‘aghensly applied fi a sPartarpotbion 
throughout the following discussion, it may be as s well to remark 
¥ 
