144 On a new Hygrometer or Dew-point Instrument. 



grometer of the late Professor Daniell, partly on the ground of 

 its less liability to accident. The other grounds I have not been 

 able to make out. The passages distinctly made out are as 

 follows : — 



" Malta, July 19, 1854. 



" I have been using it (the hygrometer) on board and 



found it to answer beautifully, till I broke the thermometer the day 



before yesterday by the slightest possible slip of the finger 



The superiority of your instrument over Daniell's is, that you can 

 make the 



Therm. Wet-bulb. Dew-point. Barom. 



12th July, Gibraltar, Noon . 70 65-9 60 30-164 



3 p.m. 72 68 



13 77 72 68 



14 76 72 69 



I have no hesitation in pronouncing your instrument as superior to 

 that of Daniell, inasmuch as it is stronger and less liable to accident, 



while it admits of a thermometer of 



If yours can be constructed as cheap as Daniell's, there can be no 

 doubt of its preferability. 



" Ever yours, most truly, 



" Geo. Buist." 



In one part of the letter which I could not fully decipher, 

 Dr. Buist appears to make some suggestions for strengthening 

 the thermometer against the risk of accident in travelling, as he 

 mentions that it had been broken in a short journey in the 

 neighbourhood of London, although subsequently repaired. It 

 appears to me, however, that there must have been either some 

 defect in the packing of the thermometer in the case which Dr. 

 Buist had obtained, or that it had been accidentally exposed to 

 some unusual violence ; the result of my own experience being, 

 that it is in all respects quite strong enough to stand all the 

 ordinary concussion of travelling. I carried several of the instru- 

 ments, with their thermometers, during last summer from this 

 place to London, and afterwards to Hastings and back again here, 

 a distance in all of more than 1000 miles, without any thermo- 

 meter or any part of the instruments being broken ; and during 

 the whole journey they were simply placed in their proper cases 

 in my portmanteau, and underwent the usual not very gentle 

 handling of the railway officials. I have also made repeated 

 innocuous journeys between this and Edinburgh with the in- 

 strument. 



It may, however, be a very proper precaution for anyone going 

 to a distance from a town where good instrument makers are 

 to be found, to carry with him one or more spare thermometers 

 duly packed in their proper cases. One or two spare ivory 



