308 



month was 30-370 on the 21st, and the lowest was 29-293 on the 3Uth, which 

 will allow for three vibrations. 



In July, on the 5th the pressiu-e was 30-129 ; on the 7th it was at 29-376, 

 which was at the lowest for the month, while on the 10th it rose to 30-123 ; 

 on the 14th, instead of lowering, it rose to 30-304, which was the highest for 

 the month, and the difference of time between the highest and lowest readings 

 is in this case contradictory to the generality of the oscillations previously 

 noted, their regularity being partly neutralized by others. In August, the 

 pressure ou the 7th was 30-069 ; on the 10th, 29-374, being the lowest for the 

 month; on the 14tli, 30-131; on the 17th, 29-447; on the 19th and 20th, 

 30-23, which was the highest for the month; on the 23rd, 29-937, when it 

 commenced rising till the 25th. In September the lowest reading was 29-428 

 on the 2nd, and the highest 30-446 on the 19th, this interval would allow of 

 five vibrations, while on the 24th the pressure was 29-695. 



In October, on the 13th the pressure was 29-527, then on the 18th, 30*354, 

 which was the highest for the month, while four days after we have the lowest 

 for the month, 29-279 for the 22nd. Then, six days after that, which would 

 allow of near two vibrations, the pressure was again as low as 29-466 on the 

 28th ; on the 31st it rose to nearly 30-2, and in this case continued to rise tUl 

 it attained 30-328 on the 2nd November; in which month the vibrations were 

 irregular on the whole, but it may be remarked that on the 23rd the pressure 

 was 29-727 ; on the 28th it sank lowest for the month — namely, 29-253 ; while 

 on the 1st December it rose to 29-980, and then continued to rise slightly, but 

 on the 5th it was down to 29-734 ; on the 8th it rose to 30-062 ; on the 13th 

 down to 29-727, then on the 21st and 22nd up to the highest for the month — 

 namely, 30-372 ; on the 25th down to 29-792 ; on the 27th up to 30-032, and 

 on the 29th down to the lowest reading for the month, which was 29-553. 



It may be interesting to mention a series of minimum barometrical readings 

 recently taken, which, from their regularity as regards the time of their occur- 

 rence, sufficiently prove that the atmosphere is amenable to the general laws 

 regulating the action of elastic media. On the morning of the 5th June, 1870, 

 the reading was 29-392, when, after rising to 29-935 on the 7th, it again fell 

 on the 12th to 29-250. The minimum oscillation is then apparently lost for 

 the 19th, being probably neutralized by others, but it appears again on the 

 25th, the interval being one day less than that obtained between the previous 

 oscillations, when we have a minimiim reading of 29-164. It again appears 

 on the 2nd and 3rd July, when the pressure was below 29-3. These oscilla- 

 tions have a large range, and must be considered as compounded with many 

 others, which would affect the time and range. 



It would be difficult to prove these oscillations to be the result of periodic 

 changes either of temperature or winds, although their time and range must 

 be modified thei-eby. It has been ascertained that there is less range of pres- 



