On the Horary Oscillations of the Barometer at Rome. 113 



lavity. The principal hints on the subject which I have seen 

 are contained in Nos. iv. and viii. of The Edinburgh Jour- 

 nal of Science, and in Mr Daniell's admirable essays, particu- 

 larly the last edition. 



In the course of the hourly observations which I made at 

 Rome on the 15th of January last, and formerly transmitted 

 to this Journal, the horary changes which took place on the 

 mercurial column that day led me to believe these oscillations 

 to be much more regular and better defined than the sequel 

 proved to be the case. 



Stimulated by this conviction, in the beginning of Febru- 

 ary I commenced a series of observations to be made each day 

 as frequently as convenience would allow, which I continued 

 every subsequent day of my residence in Rome. Those who 

 do not travel with a professedly scientific aim too often find 

 their limited residence in any particular place so much occu- 

 pied by the new scenes daily presented to them, that no time 

 is left, even if they had the inclination, to institute any thing 

 like a series of regular experiments ; and hence, to the detri- 

 ment of science, we find that little or nothing is derived from 

 those who, enjoying the advantages of visiting various cli- 

 mates and latitudes, might make the most important physical 

 investigations. As a traveller, then, I must make this my 

 apology for whatever barrenness may be found in these obser- 

 vations, made during a limited residence in the ancient mis- 

 tress of the world, where so much tends to divide our atten- 

 tion and withdraw it from abstract speculation. At Rome 

 my business was to mahe the observations which lay by for re- 

 duction at a future period. During fifty-four days of residence 

 in February, March, and April, about 470 observations have 

 been made with the data of thermometrical correction for 

 each. When on my return to Scotland, I reduced all these 

 results with the utmost accuracy into the form of tables ; and 

 when I came to determine the value of the several quantities, 

 I regretted to find that the sums were considerably irregular, 

 and did not rise and descend with the same steadiness from 

 hour to hour as any one day's observations within the tropics 

 might have exhibited ; and I was led to believe that the num- 

 ber of data I proceeded on was not sufficiently great or regu- 



VOL. Viri. NO. 1. JAN. 1828. ' ' .B ' 



