On the Sca and Land Rates of Chronometers. 125 
on being taken back again to the ship, the rate was found to be 
6” 5”; shewing a change in the ship-rate of 3” 1/. 
Another of them, by a different maker, lost anda 9” by its remo- 
val from the vessel to the shore; and a third, by another maker, still 
more. ‘The variation in the shore rates is also remarkable, that of 
the first appearing to have been 8”; of the second 6”; of the third, 
7 2/’s and of a fourth, 8”. And all these errors were noted in 
the short period of seventeen days. 
From the performance of such chronometers, it would surely be 
unsafe to draw positive inferences as to the effects of any generally 
operating causes on their rates of going. 
Mr. W. C. Bond, of Boston, in America, a gentleman well quali- 
fied for the task, has taken much pains to ascertain whether there 
is any regular and systematic tendency in chronometers to change 
their rates when put on ship-board; and, in a paper published in the 
Transactions of the American Philosophical Society, he has given 
the result of experiments on a great number of chronometers. 
When he had opportunity, he found the rate before the chronome- 
ter was sent to sea, and its rate after its return, and he took the mean 
for the shore rate; and, dividing the change in the error which had 
occurred while the chronometer was at sea by the number of days, 
he obtained the sea rate. 
The following extracts are the results from eighty seven chronom- 
eters made by us, with their different numbers, and whose rates pre- 
vious to the chronometers being placed on ship-board were accurate- 
ly determined, and the same seek their return from the voyage : 
Differ- |... Differ- [3 5 Differ- |. Differ- |_ 3 
of i} No. of om | No. of Su |No. o 
ene “ence of é Be Chron. | “Ce of so 2a] Chron. cuce of s 2s |Chron. ence of é Pad 
ie A Rate. Zag ‘ Rate. sae Rate. eae Rate s a8 
875 +0.4 96 752 +0.7 59 1100 +0.5 48 | 1146 -0.4 47 
928 0.0 56 549 -—0.1 | 388 832 +0.3 66 | 1179 0.0 55 
427 -—0.6 | 167 1035 +0.9 |. ..4 1047 -—0.3 | 231 | 1100 0.0 55 
920 +0.2 | 153 905 -0.6 5A 1142 +0.3 58 599 —0.8 56 
966 —0.3 46 871 —0.4 | 200 1184 —0.1 29 508 +0.1 | 677 
873 +0.8 53 1061 S10) 61 981 —0.5 95 981 +0.2 | 146 
981 | +0.4 55 1090 +0.1 | 109 1170 +0.1 36 521-| +03 74 
1030 —0.7 64 919 +0.1 47 1006 —1.0 37 947 —1.0. | 254 
920 +0.7 | 157 981 Oromia lle 613 -0.5 | 176 599 +01 84 
534 —0.1 63 125 —0.2 |Pacif. 430 -—0.1 | 313 873 0.0 95 
871 +0.2 | 186 Ocen. 871 +0.7 89 | 1053 0.0 61 
919 AU Wa SHU) lias. 866 —0.4 | 10L | 1246 +0.3 61 
684 AUS) Woe e 727 +0.4 28 832 +0.5 | 114 966 —0.6 | 112 
889 +0.1 |... 1030 —0.7 57 1122 -0.9 95 1 1184 +0.2 68 
1056 —0.4 52 549 —0.6 | 169 EA 0.0 53 | 1068 +0.2 60 
669 —0.5 | 294 669 +0.5 45 609 0.3 | 220 901 0.0 50 
704 +0.3 62 ele —On SZ 966 —0.3 | 120 |} 1210 +0.3 47 
832 +0.7 59 oa a he KOs) |) BSH) 1091 —0.6 77° +} 1242 —0.7 47 
1091 +0.6 50 we. | —0.5 | 294 873 0.0 27 635 | +0.3 | 102 
1079 -0.8 50 ooo | SiO yo lals 1030 +0.3 | 177 | 1100 -0.2 57 
891 —0.3 | 161 811 +0.5 | 136 1215 +07 57 
928 —0.7 65 534 —0.6 26 1030 -0.3 | 202* 
928 —0.7 90 1144 +0.5 44 | 
* 70 tons of iron on board. 
