On the Sea and Land Rates of Chronometers. 121 



Art. XXII. — On the Sea and Land Rates of Chronometers ; by 



Parkinson & Frodsham. 



(Republished in this Journal by request/) 



TO THE EDITOR OF THE NAUTICAL MAGAZINE. 



Sir — An article in your Magazine for May, entitled " Magnetic 

 experiments on Chronometers," by Messrs. Arnold and Dent, has 

 appeared to us, and to several others of our distinguished contem- 

 poraries in the profession, to require some notice, as its effect may 

 be, to lead persons unacquainted with the subject to form very erro- 

 neous notions as to the degree of perfection which the art of chro- 

 nometer-making has reached. Indeed, if chronometers in gener- 

 al, as sent from the hands of respectable makers, were the imper- 

 fect sort of machines which those appear to have been on which 

 your correspondents have experimented, they would ill deserve the 



I 



confidence which nautical men have long seen reason to place in 

 them. 



We remark in the first place, on the striking change of rate which 

 your correspondents represent as caused by the (we presume care' 

 ful) removal of chronometers from London to Greenwich, amount- 

 ing to as much as two seconds per diem, that it is not at all in accor- 

 dance with our experience. We are constantly in the habit of taking 

 chronometers from our house of business in town to our private resi- 



* 4 'Change Alley, London, December 20, 1833. 



TO PROFESSOR 8ILLIMAN. 



Dear Sir. — We respectfully take leave to enclose you a paper entitled Land and 

 Sea rates of Chronometers, which we have thought it necessary to publish in answer 

 to a paper which appeared in a periodical entitled Nautical Magazine, and contained 

 to our ideas very erroneous opinions. 



As it is a subject which we believe concerns every maritime nation and none more 

 than your own — we have to request that you will do us the favor of inserting it in 

 your valuable Scientific Journal. Our object in wishing to give this paper the most 

 extended circulation, is, that we believe it might destroy the confidence of the Nau- 

 tical man in one of the most important inventions for the benefit of Navigation; and 

 we feel assured that many hundreds of your most intelligent navigators from their 



experience can bear witness that our Chronometers are not subject to the change 

 of sea and land rates (which would render them useless for navigation) as stated to 

 exist in the Chronometers of Messrs. Arnold & Dent. 



We remain sir, your very obedient servants, 



for Parkinson & Frodsham. 



John Frodsham. 



Vol. XXVI.— No. 1. 16 



