GOULD — REDUCTION OP D AGELET S OBSERVATIONS. 9 



from Bessel's tables, after reduction to the standard temperature of 100° F., and to the baro- 

 metric pressure of 29 English inches. For this purpose 0.00885 is added to all the logarithms 

 of the barometric factor, 0.04153 to all those depending on the external thermometer, and 

 0.00264 to those depending on the temperature of the quicksilver, a corresponding subtraction 

 being made from the logarithm of the mean refraction. Of course, the application of the 

 same quantities to the tables constructed for Reaumur's scale and the old French barometer 

 enables us to use Coffin's value of log R. 



Since d'Agelet made no record of the attached thermometer, we must assume that its 

 indications would have been the same as those of the external thermometer, and Bessel's 

 tables of log y and log T [Coffin's T and t] may therefore be combined in one. The following 

 tables are formed in this manner, being Bessel's log y + log T + 0.04417 for Reaumur's 

 scale, and log B -4- 0.00S85 for old French inches and lines : 



Thcrmometric coefficients for Reaumur's scale. 



Barometric coefficients for old French scale. 



The indications of the thermometer and barometer, as recorded by d'Agelet, are here 

 collected, the time appended being the supposed sidereal time of observation. The last 

 column, entitled log TB, gives the corresponding logarithm to be applied to the log R taken 

 from Coffin's tables. 



(9) 



