Expansion and contraction of coping stones

Expansion and Contraction of Coping Stones.

865

their object, were, I believe, never made public. The form of the shell dilth,'ed from that of Col. Miller, as well as that of the recent patentees.

Expansion and Contraction of Coping Stones. T o 1',I~ m3ITOiX o r TI~E ; r o v x t z c a r o r T ~

rlt.~,~IeLIz~- IZCSTIa'tlTr.

Sn~,--Observing in your number for July, 18S~, that the contraction and expansion of coping stones had been attended with unpleasant consequences in the opening of the joints, I take the liberty of handing you the annexed sketch tbr the joints of coping stones, which has been tbuud sufficient to protect the wall from the drip at the joints. If the joints are made as in the sketch the water can never injure the wall through them.

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It is necessary that the water should pass through tile joints A, B, C, to get to the wall, but this is etti~ctually prevented by the inclination of the joint B. It is more expensive than the common method, but needs no cement, and tile ordinary contractions and expansions can ~ever injure it. I am, sir, respectfully, Your obedient servant, W.

T.