1 24 Daniell on a neiv Hygrometer, 



register published in this Journal has been arranged almost 

 wholly from my own experiments, except, in some few instan- 

 ces, during short absences from London, when I have been in- 

 debted to the kindness of a friend, upon whose accuracy I have 

 reason to place great reliance. In the course of the remarks 

 which I shall have to offer, I shall likewise refer to other expe- 

 riments which I have taken the opportunity of making whenever 

 favourable circumstances have occurred, or I have been enabled 

 to take advantage of an atmosphere free from the smoke of our 

 great metropolis. Before, however, I address myself to this 

 subject, I must beg leave to say a few words in reply to some ob- 

 servations with which the editors of the BihliotMque Universelle 

 of Geneva, have favoured me in their number for March, 1820, 

 and in which they have done me the honour to publish a trans- 

 lation of my paper on the hygrometer. I am the more anxious 

 to do this, as the experience which I have now had has con- 

 firmed me in the opinion that the instrument is certain in its 

 construction, and infallible in its indications ; and I should 

 therefore wish to see it made extensively useful, by being 

 generally adopted. 



In the first place, I am proud to record so strong a testi- 

 mony to the accuracy of the combination as the following : — 

 " On peut ne pas adopter toutes les theories de Tauteur ; 

 ni partager sa predeliction pour I'appareil qui fait I'objet 

 principal de son memoire ; mais on ne peut disconvenir que 

 cet appareilf tel quit est construit par Mr. Neivman, fonctionne 

 admirahUmentP The learned editors must pardon me if I en- 

 deavour, by removing their objections, or rather their predi- 

 lections, to make them absolutely partake of my preference for 

 the instrument. ** II est a presumer," say they, "que I'auteur 

 ne faisant mention nuUe part dans son memoire de I'hygrometre 

 ^cheveu defeu De Saussure, n'en avait aucune connoissance ; 

 fait assez etrange vA la reputation qu'a acquise et que merite a 

 fort juste titre, cet instrument pour toutes les recherches deli- 

 cates. 11 est pour le moins aussi sensible que celui de I'auteur ; 

 ct pour la commodite du transport, et de Tusage, soit ^ Fair 

 libre, soit en vases clos, I'hygrometre a cheveu Temporte de 



