184 Barometei' and Thermometer Tables. 



Here, to find the degrees of Fahr. we subtract 1°.3 from 9°.5, because thej 

 have opposite signs, one being + and the other — : In the other two cases, 

 we add, because the signs are alike, being both — . 



ExAMP. III. Convert + 13°.2 Fahr. into degrees of R. and Cent. 

 By Table II. + 13°.0 Fahr. = — 8''.4 R. = — 10°.« Cent. 

 + 0.2 = + 0.1 R. = + 0.1 



+ 13°.2 Fahr. = — a°.3 R. = — 10°.5 Cent. 



ExAMP. IV. Find the degrees of R. and of F. corresponding to — 6°,8 Cent. 

 Bv Table III. _6°.0 Cent. = _4°.8 R. = + 21°.2 Fahr. 

 — 0.8 =_ 0.7 =— 1-4 



— C'.8 = — 5°.5 = + 19°8 Fahr. 



ExAMP. V. Find the degrees of R. and F. corresponding to + e^.S Cent. 

 + 6°.'0 Cent. = + 4°.8 R. = + 42°.8 Fahr. 

 + 0.8 = + 0.7 = + 1.4 



+ 6°.8 Cent. = + 5''.3 R, = + 44°.2 Fahr. 



II. BAROMETER TABLES. 



TABLE IV. p. 139. 



1. It is required to expi-ess in metres and English measure the given 

 height 27 inches 3.5 lines Paris measure, of the mercury in the barometer. 

 We look in the first column, Paris measure, for 27 in. 3.5 lines, and find 

 opposite, in the column metres, and English measure, the equivalents, which 

 are 0.739 metres, and 29 ui. 1.0 lines English mea^sure. 



2. If tenth parts of Paris lines are given, that do not occur in the Table, 

 the surplus above tenth or 5 tenth is added to the English line. For the 

 metre, on the contrary, we take the number immediately preceding the Paris 

 line given. Thus, for example, we obtain for 319.2 Paris lines, in the first 

 place, in the column English measure, for 319 Paris lines, 



28 in. 3.9 lines. 

 the surplus is + 0.2 



28 in. 4.1 lines English measure, which is equiva- 

 lent to 319 lines Paris measure. 



Next we obtain from the column metres, for the number that immediately 

 precedes 319.2, viz. 319.0 = 0.728 metres. 



TABLE V. p. 140. 

 If it is required to give the barometric height of 0.740 metres in Paris and 

 English measure, we look in the column metres for 0.740, and in the corre- 

 sponding columns Paris and English measure, we find 27 in. 4.0 lines Paris 

 measure, and 29 in. 1.6 lines English measure. 



TABLE VI. p. 141. 



1. If it is required to give the mean barometer height of 366 English linps 

 in metres and Paris measure, we look in the column of lines of English mea- 

 sure, and wiU find the numbers 35C.0, and opposite it in the columns Paris 

 measure and metres, 27 in. 10.1 lines Paris, and 0.753 metres. 



2. If tenths of a Une English measure are given, that do not occur in the 

 Table, we proceed as in 2. under Table IV — Suppose it is required to give 

 the metres and Paris measure corresponding to 28 in. 3.8 lines of EngUsh 

 measure ; we look first for 28 in. 3.5 lines in the column English measure, 

 and opposite, in the column Paris measure, is 26 in. 6.6 lines, 



the surplus, + 0.3 



26 in. 6.9 lines Paris mea- 

 sure, which is equal to 28 in. 3.8 hnes English measure. 



Secondly, 3.8 is near 4.0. We therefore, for 2^ in. 4 lines English mea- 

 sure, find opposite in the column of metres 0.720^ 



