SECT. II.] 
PROPERTIES OF STEAM. 
67 
It will appear from this, that there is a greater difference between the results of 
different trials, than between the numbers found by our rule and those results ; and 
hence it may be presumed to be sufficiently exact. 
98. For the further satisfaction of the reader, the principal results of Dr. Ure’s 
experiments shall be given, and his simple and elegant mode of making the experi 
ments described; as, in the event of any other species of fluid being found better 
adapted than water for furnishing vapour, the same mode might be usefully 
adopted to try its force. 1 
Fig. 11. 
Fig. 12. 
Fig. 13. 
The preceding figure (fig. 11.) represents the construction employed for tempe 
ratures under and a little above the boiling point. Figures 12 and 13 were used 
for higher temperatures ; the latter is the more convenient of the two. It was 
suspended from a lofty window ceiling, and placed with the tube L D in a true 
vertical position by means of a plumbline. One simple principle pervades the 
whole train of experiments, which is, that the progressive increase of elastic force 
developed by heat from the liquid, incumbent on the mercury at /, is measured 
by the length of column which must be added over L, in order to restore 
the quicksilver to its primitive level at l. These two stations, or points of 
departure, are nicely defined by a ring of fine platina wire twisted firmly round 
the tube. 
3 Philosophical Transactions for 1818.