STANDARD TIME IN THE UNITED STATES. 177 



represents the danger which the merchant-ships of Liverpool actually 

 were subjected to for many years on account of erroneous running of 

 their chronometers, and because the sea-rates varied from the shore- 

 rates. It must also be remembered that from this table all cases of 

 vessels which were shipwrecked (on this and other accounts) are 

 omitted, so that, no matter how impossible it may at first sight seem 

 to be that such enormous errors existed, it is yet a matter of fact that 

 the errors are under and not over stated. 



Table showing Error of Longitude in Geographical Miles on the 

 Equator, deduced from 1,700 Chronometers. 



LENGTH OP VOYAGE. 



Average 

 Average 

 Average 

 Average 

 Average 

 Average 

 Average 

 Average 

 Average 

 Average 

 Average 



error from 1,700 chronometers 



error from the best 10 in 100 



error from the second best 10 in 100. 

 error from the third best 10 in 100 . . 

 error from the fourth best 10 in 100.. 

 error from the fifth best 10 in 100. . . 

 error from the sixth best 10 in 100. . 

 error from the seventh best 10 in 100 

 error from the eighth best 10 in 100. 

 error from the ninth best 10 in 100. . 

 error from the worst 10 in 100 



a 

 o 



u 



3 



o 



33 



1 



4 



8 



13 



17 



22 



28 



36 



61 



143 



Examining the table in detail, it becomes necessary to recollect that 

 it is a matter of record that these actually were the errors of chro- 

 nometers carried on a large number of ships sailing out of Liverpool. 

 The average errors derived from no less than 1,700 chronometers 

 are enormous, being as great as thirty-three miles for a voyage of four 

 months. 



Among the many vessels carrying these instruments were a large 

 number going on long voyages to India, Australia, and South America, 

 and in many cases these vessels would necessarily be between three 

 and four months or more on the voyage, often without sighting land. 

 It appears from this table that the average error to be expected on such 

 a voyage, and with such chronometers as they had (up to 18G3), was 

 no less than thirty-three miles ! It is plain that no such errors are to 

 be found in the chronometers used by our own naval vessels, nor were 

 American merchant-vessels during the same period so badly provided 

 for, but it is certain that English vessels were provided on the whole 

 with extremely poor instruments. 



It is plain that several causes were here acting. The chronometers 

 furnished to these ships were on the average very poor. This fault 



VOL. XI. 12 



