5i 
Experiments upon Heat. 
meter ; and, lastly, the thermometer being introduced farther 
into the tube, and being brought into its proper place, that 
part of the substance which, being introduced last, remains in 
the cylindrical tube above the bulb of the thermometer, is 
pushed down into the globe, and placed equally round the 
bulb of the thermometer by means of a brass wire which is 
passed through holes made for that purpose in the stopple 
closing the end of the cylindrical tube. 
As this instrument is calculated merely for measuring the 
passage of heat in the substance whose conducting power is 
examined, I shall give it the name of passage-thermometer, 
and I shall apply the same appellation to all other instruments 
constructed upon the same principles, and for the same use, 
which I may in future have occasion to mention; and as this in- 
strument has been so particularly described, both here, and in 
my former Paper upon the subject of heat, in speaking of any 
others of the same kind in future it will not be necessary to 
enter into such minute details. I shall, therefore, only men- 
tion their sizes, or the diameters of their bulbs, the diameters of 
their globes, the diameters of their cylinders, and the lengths 
and divisions of their tubes, taking it for granted that this will 
be quite sufficient to give a clear idea of the instrument. 
In most of my former experiments, in order to ascertain the 
conducting power of any body, the body being introduced into 
the globe of the passage-thermometer, the instrument was 
cooled to the temperature of freezing water, after which, being 
taken out of the ice water, it was plunged suddenly into boil- 
ing water, and the times of heating from ten to ten degrees were 
observed and noted ; and I said that these times v/ere as the 
conducting power of the body inversely ; but in the experi- 
H 2 
