14 MR. JOHN GRAHAM ON CONSUMPTION 
In experiments of this nature it is difficult to raise the 
water in the cistern beyond 210°. The increasing heating 
activity of the steam towards the end, as shown by the 
above Table, may possibly be accounted for by the in- 
creased motion in the water as it came near the boiling 
point. 
Although the experiments were carefully performed with 
these small boilers, the results present a want of harmony 
among themselves, as regards the amount of water evapo- 
rated, and are not in accordance with the results obtained 
with other boilers, also of small dimensions. The effects 
produced by disturbing causes seem to be much more 
considerable when the boilers are small. At the risk 
of being tedious, I subjoin a notice of such disturbing 
causes as were recognized during the performance of the 
small boiler experiments (Zable A.) Some of these in- 
fluences appear of an unimportant character, and really 
are so in large experiments; but it would appear that 
slight disturbing causes may with small boilers produce 
greater deviations than is generally believed. It will 
also be observed that uniformity is not always attained 
even when the disturbing causes, so far as known, ap- 
pear to be nearly equal. And lastly, that such causes 
appear occasionally to give the opposite result with 
small boilers from what they give with boilers with larger 
fire-places. 
This discrepancy in results obtained in the “small way,” 
as compared with those obtained on the “large scale,” is 
well known to men of practical skill, and constitutes our 
chief difficulty in subduing science to our requirements. 
The case, for example, of dyeing “ patches,” as compared 
with dyeing “ pieces,’ may be mentioned as one where 
disturbing causes rise to an extreme. 
