"Defcfipthn of a portable Barcmeter. 365 



tions with portable and comparative inltrunients, and witla 

 which the level of the whole furface of France might be taken 

 without any fenfible error, and without having recourfs to 

 long and tedious operations. The fociety of Manheim fent 

 mereorological initrumcnts to various dirtant obfervers ; but 

 the conrtniftiou of them rendered this excellent plan fruit- 

 lefs ; as the barometers, when they arrived, weie all broken 

 or deranged. 



Would it not be of advinitage to fctcnce, if the French go- 

 vernment would fend to all the fchools, learned foe eties, and 

 other eftabliliiinents, barometers, by means of which com- 

 parative meteorological tables might be conllruAed ; by 

 which the height ^of the mountains and ditierent politionS 

 might be afcertaincd, and valuable obfervations made, which 

 have been omitted in moft topographical furveys, or have; 

 been made fo badly, in confequence of the inaccuracy ot the 

 barometers, that no dcpendance can be placed on them ? 



The advancement of phi'ofophy and natural hiftory is the 

 object I propofcd in publifhing thefe relleclions. Compara- 

 tive obfervations might render the Rudy of meteorology lels 

 drv and more agreeable. The want of corred obfervaiions is 

 the caufe of our being as yet fo little acquainted with the 

 extent of the variations'in the atmoipherc, the point of their 

 maximum or minimum, fcc. &c. There is reafon to think 

 that fuch data would increafe the proba!)ility of meteorologi- 

 cal procrnodication, and render more inierefting a branch of 

 naturaf philofophy yet little known. The correfponding 

 heights of mountains and plains might be of great lervice to 

 the~geologift, and enable him to reiblve the molt curious 

 problems. 



P. S. I have learnt, from C. Dolomieu, that profelTor Pic- 

 tet employed a barometer nearly funilar to that here dc- 

 fcribtd. But as I am unacquainted with that inftrument, and 

 have ufed mine in journeys for four years without its being 

 deranged, i pubiifh this 'dcfcription of it with confidence, 

 being perfuaded that it may be of ufe to philolbphers and na- 

 turalilts. 



LIX. Ana' 



