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XXV. On the Construction of Meteorological Instruments, so as 

 exactly to determine their Indications during Absence, at 

 any given instant, or at successive intervals of Time. By 

 HENRY HOME BLACKADDER, Esq. Surgeon, MED. STAFF 

 H. P. 



(Read May 2. 1825J 



I T is universally admitted, that, in the present advanced stage 

 of Meteorological Science, nothing would be more desirable 

 than complete and accurate registers of the indications of Me- 

 teorological Instruments, more especially of the Thermometer, 

 Barometer, and Hygrometer, such registers being cotempora- 

 neously kept at numerous places, and at various elevations on the 

 earth's surface. Many are the obstacles, however, which have 

 been found opposed to such an acquisition. 



There are probably but few of those at all conversant with 

 meteorological pursuits, who have not been induced, at one time 

 or other, to commence keeping a register. But the necessary 

 regular inspection of instruments at certain fixed hours of the 

 day, and for many months or years in succession, has, in most in- 

 stances, been found to become so irksome, so liable to unavoid- 

 able interruptions, and so apt to interfere with other equally 

 important avocations, that few, indeed, have been able to perse- 

 vere for such a length of time as was necessary to arrive at any 

 very decided results. As to most of those registers to be found 

 in circulation, it is well understood, that little or no dependence 

 can be placed on their accuracy. But, even in those instances 

 in which accuracy may be expected, if we advert to the great di- 



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