4 BULLETIN" 246, U. S. DEPARTMENT OF AGRICULTURE. 
inches in cross section, and the brick are formed by cutting through 
the column, by means of an automatic device, at intervals of about 
3^ inches. For "end-cut" brick the column has a cross section 
approximately 4 inches by 4J inches and is cut into sections about 
10 inches long. 
Paving brick, whether end or side cut, have. usually in the past 
been re-pressed. This process smooths the surfaces, rounds the cor- 
ners, and forms on one side of each brick small lugs which serve 
to produce uniform spacing between the successive courses of the 
pavement. Suitable lugs may also be formed at the time the brick 
are cut, and the process of re-pressing is then omitted. Much dis- 
cussion has taken place as to which of these methods produces the 
better brick, and each method has many advocates. Entirely satis- 
factory pavements have been made from both re-pressed and unre- 
pressed brick under widely different conditions, and it is very doubt- 
ful if the failures which have been observed in connection with either 
type could rightfully be attributed to this particular feature in the 
process of manufacture. 
Special shapes, such as nose brick for use next to car tracks, and 
hillside block, which have one side thicker than the other and which 
are used on steep grades in order to give the pavement a rough sur- 
face, may be made either by special die or special re-press molds. 
The next step in the process of manufacture consists in drying the 
brick. In a properly systematized plant the brick are stacked upon 
drier cars as they leave the presses in such manner as to permit a 
free circulation of air between them. The loaded cars are imme- 
diately run into a tunnel dryer, the temperature of which is main- 
tained at about 100° F. at the entering end. As cars containing 
"green" brick enter one end of the tunnel, which is usually more 
than 100 feet long, other cars containing dry brick are being removed 
at the opposite end. Air circulation in the dryer is effected by means 
of fans or high stacks. During drying the brick lose an amount of 
moisture equivalent to from 15 to 20 per cent of their own weight. 
The brick leave the dryer ready for burning, which is the last and 
undoubtedly the most important step in the process of manufacture. 
Upon the burning depends largely the quality of the finished product, 
and it requires the greatest skill so to regulate the temperatures and 
firing periods as to obtain the best results from a given material. 
Experience alone can demonstrate the manner in which the burning 
must be modified in order to suit varying sets of conditions. The 
kilns in which the burning is done are made of brick and are provided 
with numerous furnaces. The brick are placed in the kilns so as to 
permit a free circulation of the gases of combustion and the heated air. 
