446 
Proceedings of the Koyal Society of Edinburgh. [Sess. 
which is a commonly occurring period of duration for minor fluctuations of 
the barometric pressure. 
The maximum value of y is given by 
2/max. = « C0S x{ C0S £1 + C0S X e - ( 7r- x) tan x eh tan x}. 
Hence 
2/max. = T -7280a, 
as compared with 2 a in the outer air. If we leave out of account the sub- 
sequent fall of the microbarogram, the ratio of damping is *864. 
For the subsequent minimum we have 
g(i 2 ) = sin - sin x e _ ~ tan x e ~ ^ tan x = 0 . 
A first approximation, given by (20), is 
£ 2 = T - *062832 + *019739 - *003791 = *05311 . 
Calculating more closely, by means of the equation 
g(£ 2 ) = sin £ 2 - ‘053685e _ ' 100034 ^2 = 0 , 
we have the following table : — 
Hence 
fa 
sin | 2 
•053685e -' 100034 ^ 
0(f 2 ) 
A 
*052 
*051976 
•053405 
- -001429 
1004 
*053 
*052975 
•053400 
- *000425 
1004 
•054 
*053974 
•053395 
+ -000579 
'053423. 
For the time corresponding to the minimum we have 
w/ + T = 2tt+ *05342; 
^ = 2tt/w- -04658/rc (22). 
Hence the minimum is accelerated by 
*04658 x 300*03 = 14 sec - 
The minimum value of y is given by 
Hence 
2/min. — a cos x{ - COs£ 2 + COSxe - ( 27r ^x) tan Xe~£2tanx) > 
2/min.ii - -00177a . 
It follows that the whole range on the microbarogram is 1*7 298a, as 
•compared with 2a in the outside air. In practice this minimum would, of 
course, under ordinary circumstances be negligible. 
