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Thermometer and Barometer Tables. 



In perusing foreign scientific works, many of our readers must 

 no doubt have experienced considerable trouble in reducing the 

 degrees of the scales of Reaumur and Celsius or the centigrade, 

 which are generally used in continental works, to degrees in 

 Fahrenheit's scale, which has been universally adopted in this 

 country. Similar difficulties will also have been experienced in 

 reducing barometrical measurements in the French measure to 

 equivalent measurements in the English scale. With the view, 

 therefore, of obviating these difficulties, we have been induced 

 to present our readers with three Tables, by which any given 

 degree in the scales of Reaumur or the Centigrade may be re- 

 duced to corresponding degrees in Fahrenheit's scale, or vice 

 versa, by simple inspection. The other three Tables are for 

 reducino- French barometrical measurement to English measure, 

 or the reverse. 



Directions Jbr using the Tables. 



I. THERMOMETER TABLES. 



1. If it be required to convert a whole number of degrees of any one of 

 the three scales into each of the others, it is done at once by simple inspec- 

 tion of that Table in which the proposed scale to be converted stands in the 

 first column. Thus, to convert — 20^ of Reaumur into degrees of Fahren- 

 heit, also of the Centigrade scale ; — by inspection of Table I. we find, that 



— 20° Reauni. = — 13°.0 Fahr. = — 25°.0 Centigr. 

 Again, to convert 4- 36° of Fahrenheit into degrees of the other two scales, 

 we see in Table II. that 



+ 3C° Fahr. = + 1°.8 R. = + 2°.2 Cent 

 Lastly, to convert — 28° Centigrade into degrees of Fahrenheit and Reau- 

 mur, we find, by Table III. that 



— 28° Cent. = — 22°.4 R. = — 1 8°,4 Fahr. 



2. If there be tenths in addition to the whole number of degrees to be 

 converted : these must be changed by the supplementary Tables of Propor- 

 tional Parts, and added, observing the rule for the addition of quantities with 

 like or unlike signs : that is, when the signs are like, the sum is to be taken, 

 and the common sign prefixed; but when unlike, their difference, and the 

 sign of the greater prefixed. 



Note The increments or decrements for the decimal parts have always 



the same sign m all tlie three scales. 



ExAMP. I. Convert + 37°.7 R. into degrees of Fahr. and also of Cent. 

 By Table I. + 37°.0 R. = + 115°.2 Fahr. = + 4G°.2 Cent. 

 + 0.7 = + 1.6 = + 0.9 



The answer is, + 37''.7 R. = + 116°.8 Fahr. = + 47°.l Cent. 



ExAMP. II. Convert — 10'.6 R. into degrees of Fahr., also of Cent. 

 By Table I. — 10°.0 R. = + 9°.5 Fahr. = — 12°5 Cent. 

 — 0.0 = — 1.3 = — 0.7 



— 10°.6 R. = + 8°.2 Fahr. = — 13°.2 Cent. 



