total height may be considered as divided by each floor. Otherwise, the effect of a shearing or a bending strain, however introduced, would be fatal to any walls of great height and length.

Another question is that of the effect of age upon the different varieties of brickwork. The specimens marked a in the second series were three months old, and all of those in the third series were five months old. Upon inspection of the tables of results it will be seen that, except in the case of blue bricks in cement, those built three months gave very similar results to those built five months. The difference in the case of the blue bricks is partly explained by the fact that the bricks of which the specimens 27 in. by 18 in. were built were from a stronger lot than those of which the 18 in. square were built, the samples from each delivery failing respectively at 779 and 701 tons per square foot.

In bearing.

E. face, two hair cracks in course 24, next S.E. angle.

E. face, the cracks already noticed at bottom of wall passing upwards for 3 courses.

W. face, flaking centre of top course.

N. end, courses 18 to 22 cracked at centre.

N. end, crack in centre of course 15.

W. face, crack in courses 14 to 16, 44" from S. corner.

S. end, two cracks in centre.

E. face, crack in course 8, 7" from S.E. angle.

W. face, two cracks near bottom, N. angle.

E. face, courses 20 to 24 cracked at 24" from S.E. angle.

E. face, courses 18 to 20 cracked at 24′′ from N.E. angle, and

the crack at centre of N. end opening ".

Sounds of internal cracking.

N. end, centre crack extending to course 14.

E. face, cracking and flaking at bottom, S.E. angle.

W. face, cracked from course 12 to 19, S. angle.

N. end, centre crack open":

E. face, splitting in centre.

W. face, cracking in several places. (See photograph, fig. 5.)
Pressure fell, S.E. corner fell out, next the S.W. corner, and
then the whole gave way, the mass falling towards N.
Mortar set harder than in Nos. 34 and 35, but not quite dry.

No. 38. -Red Bricks from Ellistown, near Leicester, in Lime Mortar 1 to 2.
Wall 6' 1" high; 27" x 18"; sectional area 3.375 sq. ft.
Built 29th October; crushed 31st March. Age 21 weeks.

No. 39.-Red Bricks from Ellistown, near Leicester, in Lime Mortar 1 to 2.
Wall 6' 14" high; 267" x 18"; sectional area 3.359 sq. ft.

Built 29th October; crushed 31st March. Age 21 weeks.

In bearing.

No sign of damage.

Audible crack and slight falling of mortar on E. face.

E. face, cracks in four courses near centre.

W. face, crack in course 14, 2" from S.W. angle.

N. end, cracks in five courses near centre.

W. face, crack in courses 10 to 12; also in courses 4, 14, and 17.

E. face, hair crack in course 4, 3" from S.E. angle.

N. end, the crack in centre, noted at 225 lbs., passed up through courses 11 and 10.

E. face, hair crack in centre of course 2.

W. face, several continuous cracks, courses 14 to 18.

E. face, hair crack in centre of course 20.

S. end, several cracks in centre.

19

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23

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24

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