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I wrote earlier:
"Here's an article published in 1847 discussing the uses..." 

And Alex, you asked:
"Where, "here"?" 

It was the body text of the message. Since it wasn't especially long, I'm 
copying it into this message (apologies to anyone annoyed by seeing it 
again):
"By Capt. John S. Sleeper, Editor of the Mercantile Journal.
Few instruments hove ever been invented, that are more ingenious or useful 
than the chronometer, and the improvements introduced into its manufacture 
within the last quarter of a century, are such as to make it an almost 
perfect measurer of time. The difficulties caused by the expansion and 
contraction of metals in different degrees of temperature, after a long 
series of experiments, have been almost entirely overcome�and by means of 
this little instrument, the longitude of a place may be determined with the 
greatest ease and almost perfect accuracy. The advantages of this instrument 
in navigation are of course immense, and begin to be generally appreciated 
by the mercantile community. It must be evident that the safety of a ship, 
and the time occupied in a passage, must in a very considerable degree 
depend on the knowledge which the master may have of the position of his 
ship from time to time. This, it is well known, cannot be determined with a 
sufficient degree of accuracy by dead reckoning�and before chronometers were 
introduced, no other means were ordinarily used at sea for this purpose than 
lunar observations�the process of working which in those days was 
exceedingly tedioue and laborious, and required much care to avoid error. 
The process, however, which is now used, is much more simple, and requires 
fewer figures than the former mode. 

But the great advantage which the chronometer possesses over the sextant, in 
determining the longitude at sea, is, that it may be used at all times when 
the sky is so unclouded that an altitude of the sun in the morning or the 
afternoon may be observed. It is not unfrequently the case that no 
opportunity will occur during a long voyage to Europe, of measuring the 
distance between the moon and the sun, or a star�while an altitude of the 
sun in the forenoon or afternoon, may be obtained on almost every day during 
the passage. Hence a chronometer on board our European traders, is not only 
an article of great convenience, but should be regarded as an instrument 
which cannot he dispensed with. 

Some of our West India traders also find it of great value. With a 
chronometer on board, a vessel with a perishable cargo can be navigated 
directly towards the port to which it is bound, instead of proceeding so far 
to the eastward that it will require several days to run down the latitude, 
as is too often the case. When it ie considered that a few days' difference, 
in a passage to the West Indies will sometimes make a difference of 
thousands of dollars in the sale of a cargo, the great advantage of having a 
chronometer on board will be at once perceived. We were once informed, by an 
intelligent ship-master, that he was bound to a port, St. Pierre, in one of 
the Windward Islands, and in the latitude of 28�, was steering due south, 
having already arrived to the eastward of his destined port. At this time he 
fell in with a lumber-loaded vessel from some port in Maine, bound to the 
same place, which was steering S. E. by E., the captain of which was 
exceedingly anxious to get far enough to windward. Our friend reached 
Martinico in safety, after a very short passage.�discharged his cargo, 
received another on board, and was in the act of leaving the harbor, when 
the vessel which he had previously spoken arrived! 

We conceive chronometers to be of much greater service in voyages to Europe 
and the West Indies, than in voyages to the East Indies,-although in the 
latter case it is well known that they are exceedingly useful. In East India 
voyages, during a very considerable portion of the passage, the sky is 
generally so unclouded that a sextant may be used, and the longitude 
ascertained with great certainty by means of lunar observations. When a 
sextant is not on board, or is out of order, a good quadrant will supply its 
place. In the year 1825, while on a voyage from this port to Batavia, we 
ascertained to our great regret that our sextant, a new one, and 
high-priced, was a worthless instrument. There was no chronometer on board, 
and we at first anticipated some difficulty in ascertaining the longitude, 
but we soon found that by measuring distances of objects on each side of the 
moon, with a quadrant, and by taking the mean of the observations, in this 
way the longitude could be determined, as often as was necessary, with 
almost perfect accuracy �this was proved in running for the Islands of Cape 
de Verd, the Islands of Trinidad, St. Paul, and Java Head�and so far from 
occupying unusual time in performing the voyage, as we apprehended might be 
the case, when we first discovered the worthlessness of the sextant, the 
whole voyage to Batavia and back to Boston, with full cargoes both ways, was 
performed in a space of time unprecedentedly short�being only seven months 
and eighteen days. 

The greatest objection to the use of a chronometer is, that the instrument 
being of delicate construction, is easily affected by injuries�and will 
sometimes lose its rate, and may thus deceive the navigator, and lead him 
into danger. This should be guarded against with the utmost care; and where 
a vessel is furnished with only one chronometer, it should never be 
implicitly relied on. Every opportunity should be seized to test its 
correctness�particularly by lunar observations. 

In European voyages, where, as we have before stated, an opportunity for 
taking lunar observations seldom occurs, two chronometers, or a chronometer 
and a well-regulated watch, will be found of incalculable value. So long as 
there is no essential difference in the Greenwich time indicated by these 
instruments, the navigator may run boldly, relying, with the aid of a good 
look-out, upon the correctness of his longitude�but should a variation 
occur, he will immediately perceive it, be upon his guard, and enabled to 
escape dangers which might otherwise befall him. " 

If you want a copy of the original, jus hit googlebooks and search for any 
unique phrase. 

 -FER

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