"The rod armed with its point weighs 15383*7 grains, or
2 lbs. 3 oz. 2J drs. avoirdupois nearly."

All the compounds to be experimented upcm were kneaded
stiff, and as nearly aa possible to the same degree of con-
sistency, by the aid of a pestle. Those samples intended
for immersion in water were put into rather deep than broad
cups of delft or common glazed earthenware, and were
covered with pore water immediately after their preparation.
The initial set of the immerged samples were measured by
the number of days which elapsed from the instant of im-
mersion to the time when they could bear without any appre-
ciable penetration a knitting needle of *047 inch diameter,
filed to a right angle at one of its extremities, and loaded at
the other with a weight of 10 oz. 9 dra. svoirdopois.
t2

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276 SCIEIIOE AND ART OF POETLAKD CEMENT.
The machine nsed for breaking the priamB of mortar, as
shown in Figs. 34 and 35, ia very simple in character, and
Fjo. M. Fig. sa



3dbvGoOg[e



277

capable of accurately estimating the streogtli in the maimer
required. The machine must have beea steady from the
mode of applying the weight by a stream of sand, the
passage of which from the hopper to the box suspended
from the clip round the sample was even and smooth.
Fig. 36 represents a modified form of Vicat's penetrating
testing maotiine, which baa been used in America and
this country by some engineers and architects for many
years.
