Chronometrical Arrangement. 215 



But it may be asked, is it not to be expected that a chro- 

 nometer which shall in one position keep a better rate than 

 twenty others, will retain its superiority under every other 

 circumstance ? To this 1 unhesitatingly reply, no. A chrono- 

 meter may go well whilst horizontal, and ill whilst vertical ; 

 and vice versa, or it may go well )vhilst in a state of quiescence, 

 and ill when put in motion ; it may go well when placed in an 

 atmosphere which is temperate, and ill when exposed to ex- 

 tremes of heat or cold. 



An instance occurred to me three years ago in a box chro- 

 nometer, made purposely for me by one of our first artists, 

 which, while it remained horizontal, kept its rate remarkably 

 well ; but when placed vertical its rate was so much altered, 

 that further trials of it till it had been returned to the maker 

 were altogether useless. Again, the same chronometer was inca- 

 pable of sustaining considerable alterations of temperature, 

 although slight differences produced no sensible effect: again, 

 on its retui'n to me, the motion of a carriage occasioned some 

 deviation from its rate, an evil which its maker afterwards com- 

 pletely remedied. But in these instances just alluded to, the 

 defects were removed ; in another instance, however, the 

 attempts have not been so successful ; in the early part of last 

 year a gold pocket chronometer was made for me by the 

 same person, and although, whilst horizontal and quiescent, it 

 would even under severe alterations of temperature dispute 

 the prize with most, still would not bear alteration of position 

 without altering its rate; it has on this account been twice or 

 thrice returned to the maker for correction ; but, notwithstand- 

 ing all his pains and labour, he has not succeeded, for he 

 informed me two or three days ago that it was still imperfect ; 

 and he is apprehensive that, to enable it to satisfy the only con- 

 dition wanting, (for it is in every other respect an invaluable 

 instrument), will probably for ever baffle his endeavours. 



Again, during the last spring two pocket chronometers were 

 placed under my care, by Major-General Sir Thomas Brisbane, 

 K.C.B. The one of them was of gold, the other of silver ; 

 the former was an old favourite, the latter was deemed of 

 no value, and considered scarcely to merit the name of a 

 chronometer; they were included in their respective boxes, and 

 their rates ascertained daily by comparisons with my transit 

 clock ; the gold one kept on the same second for a fortnight 

 or three weeks, but the silver one did not ; at this time being 

 occasionally employed in inquiries into the differences of lon- 

 gitude of my observatory and that of Greenwich, the gold one 

 amongst some others was deemed suitable for the purpose, 

 its error as also those of its co-LravcUers were well ascer- 

 tained before they were dispatched hence, and immediately on 

 their return home comparisons were again made ; on con- 



