840 PROFESSOR CHRYSTAL AND MR E. MACLAGAN-WEDDERBURN 
Taking T, = 9°00, T, = 5:06, T, = 3°54 as a basis, we proceed exactly as in the case 
of Earn, and the results are given below. 
§ 21. After the calculations had been made, it was found that the shrinkage error of 
the 6-inch ordinance map of the lake, on which the soundings were plotted, was not 
negligible. It amounted, in fact, to about °5 per cent. As the areas v were measured 
with a planimeter, and the breadths b(#) with an absolute scale, the linear error 6A/A 
enters twice into v, once into b(«), and once into A(x).* The values of a in the table 
on p. 839 are unaffected, and p=«a/a’ is also unaffected by this error. But da/a=200/, 
dh =20/A. Since the values of ¢ and c’ depend merely on p, we have (H.T.S.(45) ) 
@T/T =ea/a— 4eh/h =0r/r. (20). 
Hence, to correct for the map error, we have to multiply each of the periods obtained 
from the data of the table on p. 839 by the number i:005. 
§ 22. Uninopau Perriop or TREIG. 
| 
r ¢ a | RG+a)) HG-a) |43+a)| 43-0) | Kiel) 
eee 
9:05 | 38433] 4-0464 | 2:2616| -2384 17616 | —-2616 | —1-98857 
9:10 | 3°8012| 4:0255 | 22564} -2436 17564 | —-2564 | -1-91295 
9-15 | 3°7598 | 40049 | 22512 | -2488 T7512.) = 2519 deed oles 
a H EPs 
oie a, BR alehi He a5) | 1840) eG Sa) 02 eon 
| 
| a 
| 9-05 | -5956 | 1:8391 | 1-7098 | -7902 1:2098  -2902 75462 
910 | -5891 | 1:8320 | 1:7080| -7920 | 1-2080| -2920 ‘T5753 
9-15  -5827 | 1°8251 | 1:7063| -7937 1:2063 | -2937 "76024 
| | | 
| ) 
Det) S5e(c) Diff. 
| 9-05 —-06162 | -07299 
| 910 | +:01137 | -07962 
| 915 | +:09109 
| | 
T, = 9°093' = 9:09’, say. 
c, =3°8078 ; Cp DoOU: 
Corrected for map error, T, = 9°14’. 
* The depths were, of course, read from the map. 
