78 TECHNOLOGY. 
the lap-roller is turned ; and thus the winding of the lap takes place with 
entire regularity. A weight is hung upon each end of the roller w, for the 
purpose of giving firmness to the lap. 
With this machine first commences the determining of the fineness of the 
thread to be spun. As this fineness depends upon the weight of a given 
length of thread, the manufacturer must keep himself informed in the whole 
course of his operations of the length produced in each step of the process 
by a certain quantity of cotton. This comparison must commence with the 
lap-machine. | 
The cotton is spread upon the feeding apron, a, not only with great regu- 
larity, but care must be taken that a specified weight of cotton be distributed 
upon a certain length of cloth. To the accomplishment of this end the 
cloth is divided into equal lengths by red and black lines, and the cotton is 
weighed in small portions as it comes from the first blowing-machine, so 
that an equal quantity of cotton is always distributed upon an equal distance 
of the apron. When a number of such portions of the apron requisite to 
fill the lap-roll have passed a division is left empty, that the laps may be 
separated from each other as they come out of the machine. 
Carding is the next operation to which the cotton is subjected; its object 
is to draw out the imperfectly opened fibres, to lay them parallel with each 
other, and to cleanse the cotton more perfectly. The operation consists in 
the mutual action of two contiguous surfaces, both furnished with hook- 
formed elastic teeth of hardened iron wire, of the form seen on pl. 17, jigs. 
8 and 9. These wires are bent and placed in the eard-plates by machinery, 
the utmost regularity being requisite in both operations, otherwise an 
uneven fabric would be the result. American ingenuity has given birth to 
the most beautiful automatic machines for making these cards. Mr. Ellis’s 
machine has been justly characterized by an English writer on the subject 
as ‘one of the most elegant automatons ever applied to productive industry.” 
The leather and wire are furnished to the machine in rolls; the former is 
shaved to a uniform thickness and pierced with the requisite holes to 
receive the wire, which is cut into proper lengths, bent, and passed through 
the leather, and the strips of card cloth leave the machine completed. 
Suppose @ and b (pl. 1%, jig. 11) to be two cards whose teeth are set in 
opposite directions, and whose surfaces are parallel and at a short distance 
from each other; suppose a bunch of cotton to lie between them; let a 
move in the direction of its arrow, whilst > remains stationary or is moved 
in the opposite direction ; the teeth of a tend to carry the cotton with them, 
whilst those of } retain it, or carry it in the opposite direction. Each of the 
cards takes a portion of the cotton, the small bunches are all drawn apart, 
and the fibres laid in a parallel direction. If the cards are placed as in 
pl. 17, fig. 10, the teeth pointing in the same direction, and a be moved in 
a direction contrary to that indicated by its arrow, whilst 6 remains station- 
ary or moves slower than a, then a will comb the wool out of the teeth of 6, 
since the hooks of } have in this position no power of retaining it. By con- 
sidering these two relative positions of the cards, which take place in hand 
cards simply by reversing one of them, any person will be able to under. 
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