42 TRANSACTIONS OF THE [DEC. 17, 
of the material used and a want of care and skill in putting it 
down. ‘The material is almost without exception the trap-rock 
(diabase) of the Palisades. This is exceedingly tough and dura- 
ble and makes a very lasting pavement, but it is wrought with 
great difficulty, and the blocks have therefore not been made of 
uniform size, nor smoothly dressed, so as to fit closely to each 
other. Asaconsequence there are wide, i irregular spaces between 
them, which become filled up with street rubbish that can never 
be removed by ordinary processes of street-cleaning. ‘The trap 
also, by wear, becomes exceedingly smooth and slippery, and as 
the blocks are on an average five inches in diameter, their sur- 
faces give an insecure foothold to horses, and many falls are the 
result. From its great strength and durability, the trap makes 
a good pavement for those portions of the city that are much 
crowded with heavy, slow-moving trucks, but it is quite unfit 
for paving streets lined with residences and traversed by swiftly 
moving vehicles. 
A better pavement than that of trap is formed by the 
granite which has recently been laid in Fifth Avenue; but this 
is faulty in that the blocksare too large, their surfaces becoming 
smooth and slippery, and the joints, by the crimping of the 
edges, being large and filled with filth. A good pavement may 
be made from granite blocks, but they should be carefully 
dressed and fitted together, and be much smaller Be those in 
use here, 
In the Old World, the selection and pr eparation of the paving 
blocks are scarcely more than half the work of properly paving 
a street ; for there the roadway is most carefully prepared, and 
the blocks, whether stone or wood, are laid in concrete and are 
therefore of uniform height, producing a relatively smooth sur- 
face. 
Repeated inspections of the pavements in use in the large 
cities of Europe have shown me a gradual improvement in ma- 
terials and methods which has finally brought the art of street 
paving toits highest possible development. In my student days, 
when I lived in Paris, all the streets were paved with cubes of 
Fontainebleau sandstone; these were carefully laid and formed a 
serviceable but noisy pavement. Partly to correct this latter 
characteristic, and partly to get rid of materials specially adapted 
to the formation of barricades, the block pavement was removed 
from the principal streets and replaced with a kind of asphalt 
Macadam. Now, Paris is chiefly paved with wood and with 
Seyssel asphalt, both carefully laid and equally liked for their 
cleanliness and stillness and the easy draft of vehicles over them. 
The pavements of Berlin are partly stone and partly asphalt; 
both, like the pavements of Paris, being well laid and illustrating 
