AMERICAN INSTITUTE. 183 



seams of small radius. The " rough surface feed," with the " yield- 

 ing spring pressure," invented by Mr. Wilson, secured the desired 

 results. It consists of a wheel with the surface roughened, or of 

 a reciprocating bar furnished with a toothed tongue, as in the 

 Wheeler & Wilson machine, above described. The reciprocating 

 bar is superior to the wheel, inasmuch as its operation upon the 

 cloth is intermitted while the needle penetrates the cloth, and 

 constitutes a point on which the fabric may be turned. With the 

 wheel feed the fabric is continually pressed upon the wheel, and 

 hence not so readily turned. The yielding spring presser, as 

 represented in the machine above illustrated, is valuable, as the 

 fabric is not only held but the presser yields to the varying ine- 

 qualities in any seam. 



Another excellence is embodied in Mr. Wilson's invention, 

 inasmuch as the fabric is always held firmly to the plate by the 

 threads, which prevents any play, and hence, secures a succession 

 of stitches in a regular line. In his shuttle machine, a stitch 

 having been completed the lower thread was slightly slackened, 

 affording a chance for the fabric to be moved laterally, and pro- 

 ducing a zig-zag irregularity. It will be seen from the foregoing 

 illustration of Mr. Wilson's invention, that neither thread is ever 

 left loose. The rotating hook is continually drawing upon the 

 loop of the upper thread directly, and holding the lower thread 

 taut by friction with the metallic bobbin. Thus the fabric is held 

 steady, and the regular succession of stitches secured. 



The equalization of the tension of the two threads, was a great 

 difficulty with which Mr. Wilson had to contend in his shuttle 

 machine. The lower thread from the shuttle must be unrolled 

 by jerks at each movement of the shuttle. Were the brake upon 

 the bobbin iu the shuttle too strong the thread would be broken; 

 were it too weak too much would be unrolled. It would vary 

 also by the different velocities of the shuttle. This defect would 

 not be so obvious on thick fabrics, as it would not be evident 

 whether the lock of the thread were in the centre of the fabric or 

 near the surface, except by the looseness of the thread upon one 

 side — still the sewing would be fair. The great difficulty was 

 with thin fabrics, where the " lock" must be in the centre of the 



