343 
Mr Harvey on the Rates (^'Chronometers. 
I 
in the before-mentioned paper, with XII pointing to the south, 
when the mean of six days’ observations gave an average rate of 
-{- 7".3 ; but on turning the time-keeper a quadrant, so as to bring 
XII to the west, the daily aberration for seven days became 
— 3".6 ; and on turning it through another quarter of a circle, 
it received the large increment of 28". 4, the rate for five days 
in this position being -|- 24".8 ; and on moving it through a 
fourth quadrant, it underwent a decrement of 19".8 ; the rate 
in this last position being + 5".0. Of these changes, the most 
remarkable is that which resulted from placing XII to the north. 
The variations of rate are recorded in the following Table. 
Situation of the Chronometer. 
Daily Rate. 
Detached. 
+ 2".0 
XII S. 
-f 7".S 
XII w. 
— 3" 6 
XII N. 
-h 24".8 
XII E. 
+ 5" 0 
Another considerable alteration of rate took place,, by re- 
moving the time-keeper from the surface of the magnetized 
plate, and applying it to the edge, with the hour of X in con- 
tact with the north pole ; the rate, under this new circumstance, 
changing from -f 5".0 to — 6".8 ; but on turning the chronometer 
a quadrant, so as to bring VII into contact with the pole, the 
daily variation amounted to +7".9; and on continuing the 
movement through another quadrantal space, making the hour 
of IV touch the pole, the rate became -f 2".3. 
The next experiment was with the time-keeper G, which be- 
ing placed on the surface of the same magnetized plate, with 
XII to the north, altered its rate from — 4".l, its daily change 
when detached, to 4- 0".l, On turning the chronometer a qua- 
drant, in order to bring XII to the east, the rate declined to 
— 8".6 ; and by moving it through a like space, to cause XII 
to point to the south, the rate became — S".7 ; and through an- 
other similar arc, making XII point west, — 4".4. On re- 
storing the time-keeper to its first position, i. e. with XII di- 
rected north, the rate became -f- 2".2 ; and on returning it to 
