PROCEEDINGS OF THE POLYTECHXIC ASSOCIATION, 531 



inteTlock we only have a stitch double the length, but it does not 

 ravel. He showed the result of the single thread chain stitch 

 ripping ; also, the result of a stitch missed. A seam having 

 been formed, it may be raveled like a stocking by pulling the 

 end of the thread at the close of the seam ; or, if a stitch was 

 missed, it might be raveled without breaking the thread. He 

 thought these facts alone sufficient to prohibit it from being 

 brought into general use. 



The double thread chain stitch is formed as follows : A loop 

 of the thread is thrust through the fabric, and held open until a 

 loop of the lower th^-ead is thrust through it. This loop of the 

 lower thread is held open until a loop of the upper thread is 

 thrust through the fabric and through that loop, which loop, in 

 its turn, is held open until a loop of the lower thread is put 

 through it. At each stitch the two threads are interlooped, a 

 loop of the lower thread passing through a loop of the upper, 

 and vice versa. One objection to its use is a ridge which ig 

 formed on the lower side. This is considered so great, that 

 manufacturers refuse to have work done by this stitch. Pucker- 

 ing is caused by the three threads on the lower side contracting 

 more than the cloth. Three threads contract more than one. 



Another defect is the enormous waste of thread used in the 

 formation of the stitch. In Douglass and Sherwood's, a day's 

 work of ten hours for one person with the lock-stitch machine, is 

 estimated at 1,000 yards of seam, ten stitches to the inch, and 

 use in its formation 3,000 yards of cotton thread, while the 

 quantity consumed by the double thread chain-stitch sewing 

 machine would be 7,500 yards. The cost of 3,000 yards of cot- 

 ton thread would be fifty cents at wholesale, and the cost of 

 7,500 yards would be $1.25, making a difierence of 75 cents a 

 day in this item alone, or $200 a year. In shirt and collar 

 manufacture, where the stitch is much finer, the difference per 

 day is only about 25 cents in favor of the lock-stitch machine. 

 In a manufactory like that of Winchester and Davies, where 400 

 lock-stitch machines are used, the saving is $100 a day. In 

 quilting, where silk is used, the difi*erence would be more than 

 $1 a day on each machine. A single yard of silk will stretch- 

 five inches. He exhibited some specimens of work done by the- 

 double-thread chain-stitch, which to his mind were not favorable,, 

 and ought not to have been exhibited by Mr. Lansey at the last 

 meeting, as on stretching it the stitches cracked and broke. He 



