86 On a Uniform System of 



commend any modification, but to leave to each nation to 

 continue its scales and standards as heretofore, except with 

 regard to the thermometers, which it was agreed should, in 

 addition to the scale in use in any particular service, have 

 that of the centigrade placed upon it, in order to accustom 

 observers in all services to its use, with a view to its final 

 and general adoption. 



" The advantages of concert of action between the meteor- 

 ologist on land and the navigator at sea were so obvious, 

 that, looking forward to the establishment of a universal sys- 

 tem of meteorological observation upon both elements, it 

 was thought that the consideration of scales could, with 

 greater propriety, be left for that or some such occasion. 



" As to the instruments to be recommended, the conference 

 determined to add as few as possible to such as were in 

 common use in vessels of war ; but, regarding accuracy of 

 observation as of paramount importance, the conference felt 

 it to be a matter of duty to recommend the adoption of ac- 

 curate instruments, of barometers and thermometers espe- 

 cially that have been carefully compared with recognized 

 standards, and have had their errors accurately determined, 

 and that such instruments only should be used on board 

 every man-of-war co-operating in this system, as well as on 

 board any merchantman, as far as it may be practicable. 



" The imperfection of instruments in use at sea is notorious. 

 The barometer having hitherto been used principally as a 

 monitor to the mariner, to warn him, by its fluctuations, of 

 the changes in prospect, its absolute indication of pressure 

 has been but little regarded, and makers seldom, if ever, de- 

 termined the real errors of these instruments, or, if known, 

 still more rarely ever furnished the corrections with the in- 

 struments themselves. 



" That an instrument so rude and so abundant in error as 

 is the marine barometer generally in use, should, in this age 

 of invention and improvement, be found on board any ship, 

 will doubtless be regarded hereafter with surprise ; and it 

 will be wondered how an instrument so important to meteor- 

 ology, and so useful to navigation, should be permitted to 

 remain so defective, that meteorologists, in their investiga- 



