390 LATROBES OBSERVATIONS 



that is over it. This is very inadequately done by timbers lying 

 at distances from each other only on the inside of the work. 

 Where there is such a foundation, it is infinitely better to com- 

 bine the strength of all these timbers, and, laying them in the 

 trench, to cover them well from the access of air, and build 

 the wall upon them. But piling is always the best thing that 

 can be done even if no very hard bottom can be reached. — 

 Bond timbers ought never to be depended on. 



I have already extended my remarks to a length which I 

 did not intend or foresee — and yet I cannot avoid adding to 

 them what I think necessary to meet the inclination, supported 

 by our Italian prejudices, which the very clear and able man- 

 ner in which Mr. Jones has described the Hindoo method of 

 constructing terraces might excite, to make further experiments 

 on the construction of flat roofs for our American houses. 



In crowded cities, where the court yards are generally small 

 and buried from the light and air by tall houses, terraces on 

 the roofs are almost necessary, for the view and enjoyment of 

 the heavens, and for many domestic purposes. But they are 

 every where, excepting beyond the region of frost, the most 

 difficult and precarious part of the construction of the house. 

 Lead, copper, sheet-iron, tarred and sanded paper, calcareous 

 cements, all have been tried, all have had temporary success, 

 all have produced permanent inconvenience. The range of 

 the expansion and contraction of lead, together with the range 

 through 100 degrees of Fahrenheit's thermometer, to which our 

 climate is subject, renders lead an improper metal for the pur- 

 pose of a terrace. It is liable to be torn to pieces by its own 

 motion. — Copper is very expensive, and is soon corroded by 

 verdigrease. Iron requires constant painting, is sooner corroded 

 by rust, but is otherwise the most convenient material and the 

 cheapest. — Sand, tar, and paper, succeed better to the north- 

 eastward, than in the middle and southern States, but is not easily 

 or securely to be connected with gutters, and is a dirty sort of 

 covering. — Calcareous cements have in no instance as yet suc- 

 ceeded, and the smallest crack, admitting water in winter, 

 during the frost, is fatal to them. 



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