Captain HalFs Notice of a Voyage of Research. S58 



be obvious to the least informed person, can obviate the perplex- 

 ing dilemma into which sailors are thrown by tables of longi- 

 tude, which vary amongst themselves. All the requisite accu- 

 racy, it is satisfactory to know, might be attained, and some 

 day will be attained, by the judicious employment of chronome- 

 ters, and other instruments now in the hands of every seaman. 



The absolute longitude of those places, that is to say, their 

 difference measured from the meridian of Greenwich, though 

 not so material for the immediate or daily purposes of the na- 

 vigator, is not without its share of importance in a geographi- 

 cal, as well as a nautical, point of view, and is one branch of the 

 inquiry which would employ much of the attention of an offi- 

 cer sent upon this service. Collaterally it would become an ob- 

 ject of peculiar interest to ascertain which one, of all the numerous 

 methods for solving this problem, is the most applicable to prac- 

 tice, in a given time ; and to determine with what degree of pre- 

 cision it can be obtained by the means at present in use. These 

 points are far from being settled in the way they ought to be, 

 either in the purely nautical case, where a ship is out of sight of 

 land, or on shore, at stations where the sailor may have it in 

 his power to erect a temporary observatory. 



Under this head, therefore, would fall a series of experiments 

 on the respective value of the various instruments in the hands 

 of travellers, as well as of seamen. This is the more necessary, 

 as there is at present a considerable difference of opinion amongst 

 practical men, v/hich leads to inconvenience, and ill-bestowed 

 expence, and after all the object is not attained. 



The difficulty of the longitude problem, or, to speak more 

 correctly, the degree of care requisite in its determination, for 

 there is no other difficulty in the matter, have, perhaps, by 

 giving it an undue importance, thrown some other equally es- 

 sential points too much out of sight, though in every respect 

 of as much consequence in practice. This remark applies more 

 particularly to the latitudes, and to the variation of the compass 

 in different parts of the world. It often happens, absurdly 

 enough, that, while much labour and discussion are bestowed 

 upon a single mile, or half a mile of longitude, the neglected 

 latitude is not determined within twice the amount, merely be- 

 cause it is more easily obtained. With the variation of the 



JULY OCTOBER 1826. Z 



