Daniell's Meteorological Essays. 223 



hygrometric instruments. Did it furnish us only with an easy 

 and certain method of ascertaining the quantity of moisture 

 present, at any given time, in the atmosphere, it would be of 

 the utmost importance in keeping registers of the weather, 

 with a view of comparing the climate of different countries, and 

 seeking for those causes of atmospheric phenomena which are 

 yet hidden ; and it would, when joined to observations of the 

 barometer, furnish the most certain indications of the proba- 

 ble state of the weather, so important to those engaged in 

 many of the active pursuits of life. But in addition, it gives 

 us a measure of the force and quantity of evaporation ; a ques- 

 tion that has never yet received a satisfactory solution ; and 

 which, when settled, could at once be applied advantageously 

 to many practical cases ; and it supplies the desideratum that 

 has hitherto prevented the complete success of the barometric 

 measurement of heights. 



It is to be recorded, to the disgrace of European science, 

 that this instrument, so simple in theory, and so beautiful in 

 its practical application, has, from causes of local jealousy, 

 not yet received the notice and distinguished approbation to 

 which it is entitled. In Edinburgh, Professor Leslie, bigoted 

 to his own inventions, and full of his views of applying his 

 differential thermometer to this, among a variety of other 

 uses, has, in his article on meteorology, in the supplement 

 to the Encyclopedia Britannica, entirely passed over the in- 

 vention of Mr. Daniell; and, after stating casually the principle 

 on which it is founded, contented himself with saying, that it 

 might be of value could it be " easily and nicely reduced to 

 practice." In Switzerland, the editors of the Bibliotheque 

 Universelle affect to think that Mr. Daniell could not have 

 been acquainted with Saussure's hygrometer, or he would not 

 have thought it necessary to construct a new one ; although 

 Saussure's papers may be quoted as the evidence of the im- 

 perfections of his own instrument. The philosophers of France, 

 with a blindness of national prejudice, almost equal to that 

 manifested by the mathematicians of England, when, for a 

 quarter of a century, they disdained to profit by the brilliant 

 inventions of Laplace and Lagrange, have passed Mr. Daniell 

 and his discoveries without notice ; while in London he has to 

 contend with the whole weight and influence of the President 

 and Council of the Royal Society, in consequence of hishavino- 

 pointed out the extreme negligence with which the meteorolo- 

 gical register, published under the sanction of their authority, 

 was kept. Mr. Daniell has, however, had the good fortune 

 to meet with a coadjutor in his interesting experiments, who, 

 lor scientific- acquirements, and skill as an observer, ranks se- 

 cond 



