0)1 the Errors hi Longilude, C^c, 24S) 



feet ! ! ! The bare statement of these facts will, I trust, furnish tha 

 best comments upon this part of the " Comparative Advantages 

 of illuminating by Gas from Oil and from Coal." 



His fifth and last head, '•' Which is most durable in a na- 

 tional point of view?" is best answered by a general axiom, That 

 that is the best source of a nation's revenue which is most lucra- 

 tive, least fortuitous, and least hazardous. That oil gas should 

 be preferred to coal gas, because it would thereby encourage 

 the Greenland fisheries as a nursery for our fleets, is a rather 

 strange doctrine, when we recollect that during war it is pro- 

 tected by law from that most disgraceful system, the impress ! 

 And we certainly have yet to learn how it can be put in com- 

 parison with the Newcastle coal trade, and that carried on along 

 our western and southern shores. As I said in my former reply 

 to the very same argument, I repeat my opinion, that where the 

 former brings up one sailor, these latter sources bring up fifty. 



We have now contemplated the Jive-point picture of oil gas, 

 which the fanciful pen of Mr. Ricardo has presented to the reader 

 of the Annals of Philosophy. Be assured, Mr. Editor, that in my 

 thus attempting to hold up the mirror of truth, in order to take 

 a fair impartial view of it, I am as free as even Mr. Ricardo him- 

 self from being " influenced by interested motives in seeking 

 publicity to it." The cause of truth and of science is alone the 

 object I am desirous to subserve: if Mr. Ricardo or any of y out- 

 numerous readers should by the aid of these reflections discover 

 that his chief points of " Comparative Advantages," highly co- 

 loured as they are, are out of all drawing, due keeping and pro- 

 portion, and that, in order to make them bear out, not a few false 

 shades have been thrown over coal gas, — then indeed shall I rest 

 satisfied that I have neither written, nor caused you to print, in 

 vain. Believe me, most respectfully, 



Your friend, 

 Derby Brewery, March 21, 1821. Gro. LowE. 



XXXVI \\. On the Errors in Longitude as determined by Chrono- 

 meters at Sea, arising from the Action of the Iron in the Ships 

 upon the Chronometers. By Gkorge Fisher, Esq. Com- 

 municated by John Bakhow, Esq, F.R.S.'^ 



J. HE determination of the longitude at sea by time-keepers, is 

 so exceedingly easy from the simplicity of the observations and 

 calculations employed, and from the general practicability of the 

 method, as to render chronometers, in the present improved state 

 of navigation, almost indispensable articles in the ec|uipment of 

 ships for foreign service; and I shall feel happy if the following 



• From the Tran«actions of the Uoyal Society for 1820. Part II. 

 Vol. 57. No. 276. J/rril 1821. i I obser- 



