188 



The time at my disposal was scarcely sufficient to test the ther- 

 mometers supplied to the Arctic Expedition so completely as I should 

 have wished. The mercurial thermometers were after their gradua- 

 tion compared incidentally at two or three different temperatures, 

 and found to agree generally to 0°' I Fahr. They were all placed in 

 melting ice, when it was found that four of them read exactl}'' 32°, 

 the other three, viz. Nos. 34, 46, 47, were about 0°T too low. In 

 a few of these thermometers the column of mercury could be 

 readily broken : when this column was moved to different portions 

 of the scale, it was found to occupy precisely the same number of 

 divisions. This was the case with four of the instruments ; the other 

 three not having been tested in this way. 



The five spirit thermometers were compared at four different tem- 

 peratures with a standard mercurial thermometer. The comparison 

 at 0° being taken in ice and salt, is not very trustworthy. Their 

 errors were as follows : — 



Temp, by 

 mer. stand 



. S. 2. 



S.4. 



S. 6. 



S. 7. 



S. 8. 



Mean of 

 errors. 



o 



65 



+ 0-8 



o 



-0-3 



o 



-0-2 



o 



+ 1-3 



o 



-0-1 



+ 0-30 



52 



+ 0-8 



-0-2 



-0-3 



4-1-4 



0-0 



4-0-34 



32 



-1-0-8 



-OT 



-0-3 



4-1-4 



-0-3 



4-0-30 







+ 0-6 



0-0 



0-0 



4-1-7 



4-0-2 



+ 0-50 



The numbers in the column " Mean of errors " seem to indicate 

 little error of a systematic nature. In the case of Nos. 2 and 7, the 

 index error is very large : this, it is believed, is owing to some of the 

 vapour of alcohol having become condensed in the upper portion of 

 the^^tube before the fixed points were determined, and having escaped 

 my notice ; in fact the greatest attention is required to avoid errors 

 from this source. These spirit thermometers cannot by any means 

 be considered as standard, although they are doubtless more trust- 

 worthy than most of those usually made. The limited time at my 

 command for the completion of the instruments, prevented the pos- 

 sibility of rectifying any blunders into which I might have fallen, 

 owing to my inexperience in such work, and the intricacy of the 

 problem. 



John Welsh. 



Kew Observatory, April 21, 1852. 



2. The Reply of the President and Council to a Letter addressed 

 to them by the Secretary of State for Foreign Affairs, on the subject 

 of the cooperation of different Nations in Meteorological Observa- 

 tions. Communicated by direction of the President and Council. 



Somerset House, 10th May 1852. 



Sir, — I have the honour to acknowledge the receipt of your 

 letter of March the 4th, transmitting, by direction of the Earl of 

 Malmesbury, several documents received from foreign governments 

 in reply to a proposal made to them by Her Majesty's Government, 

 for their cooperation in establishing a uniform system of recording 

 meteorological observations, and requesting the opinion of the Pre- 



