the Barometric Formulce, t^r. 647 



I have, however, to protest against the employment of it, or of the more 

 correct one already published, without the aid and co-operation of a reliable 

 table of horary corrections, excepting at moments of the day near to sunset, or 

 two hours after sunrise, when the horary corrections, if they do not vanish 

 altogether, are comparatively but small. 



In reference to Batley's formula (as simple in form as that which I have 

 now just described), I have to remark, that in the absence of a correct table of 

 horary corrections, I advise the employment of it for observations made near 

 noon of the summer months ; because under such circumstances it contains 

 implicitly the horary corrections. It is, in fact, the formula of PoissoN, suited 

 to the Fahrenheit thermometer and English measure, which has been obtained 

 from Laplace's formula, of which the constant has been determined, as already 

 stated, from observations of Ramond, made in the Pyrenees near noon of the 

 summer months. 



I now produce Baylet's formula in juxtaposition with my own modified 

 formula, for sake of comparison. 



Bayley's Formula — Fahrenheit Thermometer. 



z = 60345-6 Eng. ft. { 1 + 0-002695 cos 20 ! j 1 + 0-002222 {^~ - 32^ j 



, ^ 



^^^iS'j 1 + 0-0001 (3-3')!" 



The following is my own modified formula, which makes correct provision 

 for the hygrometric state of the atmosphere, also for temperatures below the 

 freezing-point, in which respect the formula of Bayley is seriously faulty: — 



1 + 0-0022222 (-^- 32 J | 

 ^ = 60664-0Eng. ft. jl + 0-002695 cos 20ji and 1- 



/tA-t' 



1 -f 0-002 -^^ 32 



^^°° ^-Tr +ooooi(3-30 -^"-^-^- 



VOL. XXIIL 4 Q 



