DESCRIPTION OP A NEW ESCAPEMENT. • 251 



of containing. But if it be proved that oil and mercilry are ca^ 

 pable of conducting caloric, it will be admitted as fufficiently 

 probable that other fluids muft have a fimilar power. Of 

 thefe two, mercury it is probable, from thefe experiments, is 

 the beft conductor, as the rife of the thermometer took place 

 m it much more rapidly than in the oil. That the temperature 

 did not rife higher in it than in the oil, feems to have been 

 owing partly to its greater mobility, by which its parts would 

 move towards and from the ice with more celerity, and partly 

 io its better conducting power, by which it would give out its 

 caloric more quickly to the large fuperficies of ice with which 

 it was furrounded. It was accordingly obferved, that the 

 fides of the ice cylinder were more excavated in the experi- 

 ments with the mercury than in thofe with the oil. 

 Edinburgh, Feb. 27, 1802. 



II. 



Defcription of a nezv Efcapement for WatcheSj invented by Mr, 

 John DeLafons *. 



JL HE inventor ftates, that fince the perfection of chrono- The perfection 

 meters confifts more in the equality of impulfe given to the of chronometers 

 balance than to any other caufe, he has contrived the prefent o^the Equality 

 efcapement for giving fuch an impulfe ; with the additional of the impulfe* 

 qualities of locking the wheels without fpring work perfectly balance t & 

 fafe, and unlocking them with lefs confumption of power than 

 in any other efcapement he knows, becauie the wheels do 

 not bear againfi the locking with more than one tenth part of 

 the whole preiTure from the main fpring, which laft eircum- 

 fiance he conceives to be perfectly new. 



He remarks, that the equality of impulfe has been effected Efcapements of 

 with great ingenuity by Mr. Mudge and Mr. Haley; but at J* u j|B e ™* 

 the fame time he objects to the efcapement of the former, on 

 account of its extreme difficulty and expence, and to that of 

 the latter, for its very compound locking. And he alfo re* 



* From the Trcmfactions of the Society of Arts. 1801. A pre- 

 mium of thirty guineas was given by the Society to the inventor; 

 I have not copied the letter prefs, as I wiflied to render the defcrip- 

 tion rather more minute than was neceffary m that place.— N. 



plies 



