90 Mr R. A(iie''s Experiments with Thermo- and 



tin or copper swages ; or else by passing them between grooved and fur- 

 rowed rolls (of soft metal for the struck side),^' evidently implying that 

 one side would be unstruck or uncut. In factj for some time at first we 

 only attempted to cut one side of the file, and frequently now we are 

 requested to leave sometimes the concave and at others the convex sur- 

 face blank or uncut. 



We trust these crude remarks may be of interest, as giving a reason 

 for our discontinuing to cut and press these files from steel of parallel 

 thickness, and if you choose to embody any part of them in your report, 

 you are at perfect liberty. We have not the slightest objections to Sir 

 John's paper being printed in your Transactions ; and if any of our re- 

 marks are not perfectly clear, we shall be happy in giving further ex- 

 planations.* 



It must be highly satisfactory for the friends of the late Sir John Robi- 

 son (and your Society in so freely noticing it), to learn that the invention 

 is considered by eminent engineers and practical men, one of the first and 

 best improvements in file-manufacturing of the day. Always at your 

 command, we are most respectfully, Sir, your very obedient servants, 



Johnson, Cammell, & Co. 



An Account of Experiments with Thertno-Hydro-Electrical 

 Currents^ with an Examiyiation of the Metals exposed to Ther- 

 mo-Electric Action. By M. R. Adie of Liverpool. Con- 

 cluded from p. 353 of preceding Volume (Vol. XXXV.) 

 Communicated by the Author. 



19. The arrangements described (17 and 18) appeared to'me to be worthy 

 of further attention, to ascertain the variations in the amount of chemi- 

 cal action performed by two opposing therm o-electrical currents, which 

 are much influenced by climate. The experiments made with these cur- 

 rents, now about to be given, have been conducted in the midst of a large 

 town, where there are many local disturbing causes to affect the results ; 

 they should be received, then, more for shewing the general action of 

 the currents under examination, than as correct results for this climate. 

 The season through which they have extended has been remarkable for 

 passing from one extreme to another ; beginning with a very cloudy, bad 

 spring, next an indifferent summer, and then a fine autumn, the autumn 

 including six weeks, from the middle of August to the end of September, 

 of the most powerful sunshine for the season of the year ever remembered. 

 In April last a thermo-electric battery, fig. 1, was placed, with the 

 upper half exposed to sun and sky, and the lower half screened ; the vol- 

 tameter contained silver poles, and argento- cyanide of potassium in solu- 



* Messrs Johnson, Camraell, & Co., obtained the Society's Honorary Silver 

 Medal for their specimens of Files cut on Sir John Robison's method, 13th 

 November 1843. 



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