xxxvi InrRopUCTION TO THE MAKERSTOUN OBSERVATIONS, 1845 anD 1846. 
TABLE 4.—continued. 
ees Are at |Number| Time | Tempe- mays Are at |Number| Time 
Araneae Com- of of one pains cottage Com- of of one | rature 
i mence-| Vibra- | Vibra- of hs mence-| Vibra- | Vibra- of 
ment. tions. | tion. | Needle. 
dad. h. dad. oh. r 8. @ 
1845. 1846. : 
June 10 10 |) 4:3 30 8-27 | 63:0] Feb. 4 23 4:3 18 6-63 | 41-7 
June 12 8 3-7 25 9-17 | 74-3 | Feb. 22 23 || 3-9 . 
June 13 9 || 3-7 | 20 | 9:22] 74.9 | Mar. 18 22 | 3.7 
June 17 1 4-2 20 7-90 | 64.0 ] Mar. 25 1 4-1 
June 27 22 |) 3-5 20 7-33 | 54.0 | Apr. 26 22 | 3-5 
July 717|| 36 | 20 | 8-05] 64.3] May 123] 46 
July 11 23 2-9 15 7-48 | 57.4] May 18 22] 4.2 
July 14 21 3-8 20 7-35 | 55-2 | May 21 9] 4.5 
July 20 22 3-6 20 7-17 | 56-0] May 25 8 4-1 
July 29 22 3-6 20 7-36 | 56.3 | May 26 22 4:0 
May 27 22 || 3.7 
3:7 
3-1 
3-1 
3-5 
4-0 
48. lst, It has been concluded from Table 5, Introduction 1844, that after the 
needle has been vibrated by any means through a large arc, its time of vibration 
has been increased ; this will be apparent from the observations of vibration be- 
fore and after April 304 74, July 24¢ 184, July 26% 3, November 54, and November 
84 215, 1844. On all these occasions the needle was vibrated through large ares, 
either from the accidental approach of iron, or from the removal of the box for a 
short period.* 
49. 2d, It is obvious, from the observations for 1844, 1845, and 1846, that 
the time of vibration depends upon the temperature of the needle, a change of +1° 
of temperature causing a change of from +0505 to 0°10 in the time of one vibration. 
* See Transactions of the Royal Society, Edinburgh, vol. xvi., p. 69, Table I. 
