Thermometrical Diary kept abroad. 499 



ing the daily observations, and to understand the compara- 

 tive abstract of the temperatures subjoined hereto. 



The hours which I selected for observation were ten o'clock 

 in the morning and ten o'clock at nighty nol because they were 

 the best adapted for taking the differences of the day's tem- 

 perature in general, but because I soon found from experience 

 that they were the most convenient, and those on which I could 

 rely with the greatest certainty for being able to continue un- 

 interruptedly similar registries. In making the morning's 

 observation, I, as carefully as the situation would allow, sus- 

 pended the thermometer to the north, or most shady spot, 

 and at such a height above the ground as to prevent any 

 effect from reflected heat, or from the influence of the rays of 

 the sun being increased by any closely adjacent wall, or roof, 

 or water, &c. If, however, as it sometimes happened, it was 

 either too much past the stated hour, or I could not meet 

 with a proper situation at that exact hour, I preferred en- 

 tirely omitting such observation, rather than make one which 

 would have been manifestly incorrect ; hence, where a va- 

 cancy occurs in the 1st or 2nd columns of the annexed por- 

 tion of my Diary, it shows that I was prevented from correctly 

 observing the thermometer, for either one or both of these 

 reasons. 



I have added in the 3rd and 4th columns similar observa- 

 tions made with Fahrenheit's thermometer in England, for 

 the sake of comparing the difference between the atmospheri- 

 cal temperature of the place where I then was, with that of 

 the English metropolis upon the same day. This statement 

 I have taken from the " Meteorological Diary, by W. 

 Gary," London, published monthly in the ' Gentleman's 

 Magazine.' The editor of that able periodical has kindly 

 informed me, " that Mr. Gary made his thermometric obser- 

 vations three times daily, in the Strand, in the years 1824, 

 1825, 1826; that the thermometer was out of doors, and in 

 nearly a due north aspect." (See Gent.'s Mag. for March, 

 1836, vol. V. No. III. p. 218.) Although, as it will be seen, 

 Mr. Gary made his mornings observation two hours earlier^ 

 but that of the 7iiglit one hour later^^ than I had been wont 

 to do with mine ; yet, upon the whole, they come the nearest 

 to my own hours of any of the London registers of the ther- 

 mometer with which I am acquainted ; for those of the Royal 

 Society, as at present published in the Transactions of that 



* But of course I need scarcely say, that there will be some variation 

 as to the corresponding hours according to the difference of longitude 

 which, however, can easily be ascertained. 



2T2 



