Improvement of the Barometer. 97 



Art. VIII. — Improvement of ike Barometer; by Chxs. F. Durant. 



TO PROF. SILLIMAN. 



Dear Sir — In the frequent use of the portable barometer, I have 

 often experienced much inconvenience from air entering the tube, at 

 limes when, perhaps, great precision was necessary, not only for as- 

 certaining the altitude, but likewise for weighing the atmosphere, 

 which is sometimes intimately connected with other experiments, then 

 under a course of investigation. 



Although one of the most simple in form, the barometer is proba- 

 bly one of the most difficult instruments to construct. The frequent 

 breaking of the tubes, while undergoing the great heat which is ne- 

 cessary to exhaust the air, requires more patient care for this tedious 

 process, than most men are able or willing to devote ; and yet with- 

 out this process, and that, well and effectually performed, the air must 

 be diffused through the mercurial column, or escape to the top, where 

 it destroys the vacuum, in which case the instrument is not suitable 

 for the purposes intended, and does not deserve the name of barom- 

 eter. The manufacturer who would allow such an instrument to 

 pass from his hands to the world, is guilty of a great misdemeanor, 

 and deserves the censure of all good men ; for such imperfections, 

 have prevented the barometer from attaining the rank which it de- 

 serves in the estimation of the world. It is an insult to the memory 

 of Torricelli, who will yet be ranked among the greatest benefactors 

 to mankind. 



It is to be regretted, that so many imperfect or deranged instru- 

 ments, are in use. It destroys all confidence in the barometer, and 

 I know some persons, who deride, its well known properties of pre- 

 dicting winds, and even treat the idea as chimerical. But such men 

 could not have possessed a perfect instrument, or have devoted a 

 proper attention to the observations, as thousands can testify to its 

 efficient warnings; when, by suitable and timely preparations for the 

 predicted hurricane, property and lives have been saved from the 

 devastating elements, which would otherwise have involved the whole 

 in ruin. 



Although in the construction and repairing of my barometer, I 

 was generally fortunate in clearing the tube entirely of air, yet in use, 

 1 think I never kept it one year in that perfect condition. This re- 

 peated derangement and consequent expenditure of time, patience and 



Vol. XXVII.— No. 1. 13 



