Mr. Nixon on Barometrical Registers. 1 5 



Being partly aware of the transverse strength from the for- 

 mer experiment, the time used for applying the first part of 

 the load was shortened ; but towards the conclusion the ad- 

 ditions were cautious and slow, and the whole time occupied 

 in the experiment was 57j minutes ; the breaking weight was 

 50G pounds, which gives 59,950 pounds per square inch, for 

 the cohesion, or in round numbers 60,000 pounds, and the 

 mean of both 60,500 pounds. Yours truly, 



Leighton, Dec. 11, 1826. B. Bevan. 



P.S. I have lately seen in the public papers, under the title 

 of Curious JVeatker-gauge, an account of a machine invented 

 by Mr. Donovan, capable of showing the commencement and 

 termination ofeveiy shower, and the rate of raining, with the 

 quantity fallen. 



I beg leave to say, that I have several rain-gauges of such 

 a nature as to exhibit all these particulars ; one of which has 

 been in constant use for fifteen years. — Further particulars I 

 perhaps may give at another time. 



V. Table and Formulce for reducing Registers of the Height 

 of the Barometer to the Standard Temperature and Level. 

 By Mr. J. Nixon. 



To the Edito?-s of the Philosophical Magazine and Annals. 



Gentlemen, 

 /^NE of the many obstacles to the advancement of the de- 

 ^^ graded science of Meteorology, is confessedly the difficul- 

 ty of an immediate comparison of the pressure of the atmo- 

 sphere, as registered at places differing in elevation and tem- 

 perature. So intolerably irksome to the man of genius, anxious 

 to devote his talents to this obscure branch of philosophy, 

 must be the unintellectual toil of rendering a vast number of 

 similar registers comparable with each other, that the true 

 lover of the science cannot but indulge in the wish, that the 

 editors of scientific journals would invariably decline the in- 

 sertion of meteorological registers unreduced to the standard 

 level and temperature. 



To render the task thus imposed on the observer as easy 

 and brief as is compatible with the requisite accuracy, I have 

 taken the liberty of transmitting you the annexed Table, de- 

 rived from the following formula;: in which //denotes the 

 observed height of the barometer corrected lor the varying 

 height of the surface of the mercury in the cistern, and for 

 the effect of capillary attraction ; T the heigiit of the detached 

 thermometer (or temperature of the mercury) ; a tlie elevation 



of 



