620 TRANSACTIONS OF THE 



same rock has been laid down in peculiar inverted pyramidal 

 blocks, presenting from four to six inches only on the surface, and 

 is known as the Belgian pavement. This kind of pavement has 

 proved by use to be the best that has yet been tried in this city, 

 as it avoids the principal objection against the larger blocks on 

 Broadway, which wear smooth and cause mimy accidents to ani- 

 mals, especially in wet weather, during which the surface of the 

 blocks is covered with a slippery black mud, which causes the 

 animals to slip and fall, in which the want of crevices at shorter 

 intervals in the blocks also contributes ; such is not the case with 

 the Belgian blocks, which enable the hoofs of horses to take fre- 

 quent hold, and prevents their slipping and falling. The great 

 value of the Trap Rock pavement, however, consists in its great 

 resistance of the abrasion of the wheels of vehicles, and iron shoes 

 of the horses ; the rock is much more resistant than granite, and 

 the people of the city may well congratulate themselves that it 

 occurs, and in great abundance so near to their streets. 



The streets of the city of Naples, which are paved with this 

 rock, present conclusive evidence of its greatdurability, where 

 for one thousand years the pavement has been in use, and has 

 only worn during that long period to the depth of one inch. The 

 streets of those ancient cities Herculaneum and Pompeii, were 

 paved with Trap Rock, and although it must have been used for 

 a long period prior to the destruction of those cities by the vol- 

 canic eruptions of Vesuvius, yet the pavement is now in a good 

 condition, having been exposed to view by recent excavations. 



The substitution of a friable quartz rock, which crumbles in 

 the fingers, does not appear to be an improvement upon this very 

 hard and almost incomparably resistant species of rock for paving 

 purposes, the Trap, which, if worked in the proper shape, as in 

 the case of the Belgian pavement, will answer nearly all the con- 

 ditions required of it. Certainly nothing can be gained in 

 an economical point of view, as the durability of the trap rock 

 will prove itself superior to all other kinds of pavement, availa- 

 ble to the principal cities of the United States. 



I understand it is proposed to use the quartze conglomerate, in 

 blocks of much larger size than the Russ blocks on Broadway; 



