22 EIGHTH REPORT — 1838. 



the tides, &c., will I have no doubt aflford very valuable infor- 

 mation, since it registers the force and direction of wind, with 

 the amount of rain for every instant in twenty-four hours. 



The observations with the barometer are complete up to June 

 last, all the observations having been reduced. I have not, 

 however, been enabled to arrange in Tables more than those ■ 

 of the year ending January 1, 1838. These observations being 

 for one year only, I have thought it undesirable to write any 

 detailed report of them. I may, however, be permitted to lay 

 before the Section, as an approximative result, the march of the 

 atmospheric pressure through one mean day, as shown in Table 

 A, Plate 9, and deduced from 8760 observations ; from which 

 some idea may be formed of the probable horary oscillation in 

 this place, a subject of singular interest in meteorology. It 

 appears by the result of the hourly observations for the year 

 1837; that the horary oscillation amounts to 0*0144 of an inch. 

 The hours of max. being 11 a.m. and 9 p.m. 

 The hours of min. being 5 a.m. and 3 p.m. 



The line of mean pressure appears to be crossed 4 times in 

 the 24 hours, viz. between 2 and 3 a.m., and between 7 and 8 

 A.M. ; between 12 and 1 p.m., and between 6 and 7 p-m- 



The deviations being .rjrvor , }-for the max. and min. a.m. 



and .Qnqf-, >ior the max. and min. p.m. 



The neg. sign indicates the depression below the line of mean 

 pressui'e, the pos. sign the elevation above it. 



The mean pressure by these observations, at 60 feet above the 

 level of the sea, and at a temperature of 55° of Fahrenheit, is 

 29-9532*. 



On the 1st of January, 1839, we shall have completed 2 years 

 of these hourly observations, when general results, entitled to 

 more confidence than those deduced from a single year, will 

 probably be arrived at. It seems therefore desirable, in order 

 to avoid too hasty generalization, not to enter further at present 

 into this question. I avoid for a similar reason any further 

 notice of the register of the hygrometric thermometer, the ob- 

 servations being in a state of progress only. 



The register of the ordinary thermometer, first contemplated 

 by the Association at York in 1831, is, I am happy to say, 

 complete for 5 years, and the observations are novv' reduced up to 

 January last. 



* A general type of the daily march of the barometer is given in Table A, 

 Plate 9. 



