Remarks on Self -Registering Thermometers. 301 



more effective. The principle may briefly be stated as fol- 

 lows : — That by the expulsion of the mercury from the tube 

 into a convenient receptacle till the temperature reaches its 

 maximum, the orifice of the tube shall become a zero of move- 

 able value, whose value shall be determined by adding the 

 space left unoccupied by mercury (expressed in degrees) to 

 the temperature of the time of observation observed on a com- 

 mon attached thermometer. I think it is above two years 

 since I contrived a plan perfectly identical with that of Mr 

 King ; but as I never mentioned it to any one, it is obviously 

 impossible that Mr K. should have borrowed his instrument 

 from mine ; but what I think it just to state is, that my plan 

 was suggested by Mr Blackadder's thermometer in this Jour- 

 nal, No. ix. p. 92, which, though it was only meant for regis- 

 tration at a particular moment of time, is on a principle nearly 

 approaching that above defined. My motto is " palmam qui 

 meruit, ferat ;" and it is one which I have before now sup- 

 ported in this Journal, and to which you, Sir, have ever been 

 particularly attentive. My wish is therefore merely to remark 

 on the originality of Mr Blackadder's idea, and the feeling 

 which experience must necessarily have produced on my mind, 

 that Mr King has borrowed the idea without that acknowledg- 

 ment which the candour of science seems to require ; for my 

 part I have no wish to oppose to him my hitherto unpublished 

 claims to the instrument, and with this I drop the question of 

 priority of invention. 



With regard to the merits of this register thermometer, when 

 I first thought of the plan several practical imperfections oc- 

 curred to me, which prevented me from having it executed. 

 One of these, which regarded the determination of the indica- 

 tions of the instrument, proved on an attentive consideration 

 to be unfounded ; but there are defects which I suspect would 

 prove hurtful both to the accuracy and the general adoption 

 of the instrument. The first occurs from the essential prin- 

 ciple of the adjustment of the instrument at each observation. 

 It is obvious from Mr King's description above referred to, 

 that after the mercury in the tube has been made by the heat 

 of the hand to join the quantity in the reservoir at the top, 



VOL. IX. NO. II. OCTOBER 1828. U 



