PROCEEDINGS OF SECTION H. ; 349 
starting at under 500 Ibs. per square inch at. three months they 
increase rapidly, at six months and thereafter a slow and steady 
increase, and apparently have not reached their maximum yet. 
In conclusion, there have been over 309,000 casks of cement 
used by the Board. The tests, however, that are recorded do 
not necessarily mean that the cement was accepted, but the 
‘results have been tabulated in order to arrive at an average 
result for each brand. 
3—UNITS OF STRESS AND WEIGHT IN ENGINEERING 
CALCULATION. 
By ANKETELL Henperson, M.C.E., F.R.V.I.A. 
| Abstract. } 
Tue object of the paper is to protest against low units of 
weight and stress in engineering testing and calculations, as 
they tend to waste of mental energy in unnecessary arith- 
metic, false ideas of accuracy, and, worst of all, to weakening 
of the imagination and judgment. 
The imagination is necessary to the engineer as well as to the 
architect, for it is the source of originality. Comparing the 
work of the old-time engineer and the present, the latter has 
done best for the business of the world, but has too largely in- 
creased its stock of ugliness. An exact appreciation of the 
forces at work in a unit that appeals to the imagination and 
judgment will result in better-looking work, which need not 
be less scientific. Some of the old solid structures cost less, 
and last longer than modern complexities, because of their 
simplicity. In English business, heavy goods, such as coal, 
flour, iron, &c., are quoted and sold by the ton and cwt., and 
these weights are mentally appreciated by all. Consider the 
enormous extra work if quoted by the lb., yet such extra work 
‘is done in many engineering calculations, the result being loss 
of originality and judgment, as well as loss of time. 
The assumptions as to the external forces acting on struc- 
tures, and the internal distribution of stresses, and the resist- 
ance of materials being likely to vary within 5 per cent., there 
is no necessity for a low unit, with its extra labour. 
