562 MR JOHN ALLAN BROUN ON THE HORIZONTAL FORCE 
the action of spiders :—1844, June 3 to 26, December 11 to 16; 1845, January 
12 to 14, March 27 to April 13, June 3 to 9, October 27 to November 2. Besides 
these dates, there are some others in which it is extremely probable, that spiders’ 
threads were attached to the magnet; but as this could not be proved, no altera- 
tion has been made in these cases. 
136. SiveaporEe.*—On comparing the Singapore bifilar observations with those 
at Trevandrum, &c., the daily mean scale readings were found to have altered 
suddenly on different occasions; the corrections for these changes were determined 
as follows :— 
137. 1842, January 20.—A sudden change occurs ;— 
By Trevandrum bifilar means (Jan. 20, 21, 24, 25, 26) minus (Jan. 12, 13, 14, 17, 18) = — 2-87 
By Singapore a - = + 5:06 
Correct Singapore means before January 20 by 5 : . : 5 +742 
138. 1842, February 2.—A change occurs in this foes 
By Trevandrum bifilar means atesen 7-10) minus (Jan. ie ieeaes = —2°55 
By Singapore sar = + 3°69 
Correct Singapore means before February 2, by : - ; + 6:24 
February 2, is interpolated from Trevandrum. 
TABLE XXXVII.—CuHaAnGEsS or Daity MEAN BiFitarR SCALE READING, May 13, 1842, 
k = 0:00014. 
Corrected minus 
Date 1842. Hobarton. | Trevandrum. | St Helena. Singapore. 




Observed. 
Sc. div 
May 15 minus May 13 + 0:92 ag 
Gis 15 —11:77 a 
1 aes 16 + 6°59 + + aie 
18 YE) 17 + 453 = AF + 
LO 5 18 — 0:50 - = a 
20 es; 19 + 2°69 + + = 
22 20 + 2°39 + aL 4 
23° 95; 22 + 0°75 _ + =e 
2 23 — 0°65 + + =f 
Oe 24 — 0-41 — — se 
260 25 — 0-66 — a 
2 ode 26 + 0°52 + = 
29) 27 + 0:12 _ ot 
30 ames 29 + 0:25 ae = 
Bile Gt 30 + 0-16 + ae 

* Lat. 1° 18’ 32” N., Long. 64 55™ 46s HE. Height above the sea, a few feet. Observatory of 
the East India Company ; Director, Captain C. M. Exxtot, F.R.S. The observations in manuscript 
are, it is believed, in the archives of the Royal Society. Copies of some of the observations are also 
in the Library of the Trevandrum Observatory. The observations have also been printed, but not 
published as yet. 
+ It is not improbable that there is an error in the mean for May 20 of 10 se. div. (k= 0001946), 
or 18°9 se. div. of the table. 

