Among other makes of shedding machines the common dobby or witch machine may be mentioned. It is of earlier invention than the Keighley, patents having been taken out for it at varying dates from 1830 to 1850. In it the knives slide vertically; there are two lattices, all the odd picks being on one side, the even ones on the other, and a peg indicates a faller—contrarily to the Keighley.
A sketch of a double-lift machine on this system, called by the makers a Blackburn dobby, is shown at [Fig. 51].
The connection of the jacks with the lifting knives is made by hooked wires, 2 wires to each jack. Where there is no peg these hooks are in position over the knives; thus, whichever knife should lift, the jack will be lifted by one of the two hooks. Where there is a peg, however, the wire is pressed back slightly, sufficiently so as to remove the hook at the top of the wire away from the knife; and there is no lift for the jack to which the wire is attached.
The pegging for a Blackburn dobby of pattern [Fig. 32] is shown in [Fig. 52], which represents six jacks and four lags on each side of the machine, a lag in the Blackburn dobby only carrying the pegs for one pick. The large figures indicate the picks and the smaller ones the jack pegged for the picks against which they stand.
FIG. 52.
The Keighley is generally preferred by practical men for its strength and less liability of getting disarranged or broken. Other makes of dobbies are made, resembling in principle one or other of the types given.
Cloths Woven on the Dobby
Include all makes from plain to 40-shaft patterns. Stripe patterns of the character described on page 101 are frequent; indeed, this shedding motion is useful for stave work of all kinds, including:—