Machines of Class 11 have a cylinder bed and a drop feed, and are especially designed for stitching heavy tubular shaped articles in cloth or leather. They are used in the manufacture of mail bags, coal bags, ore bags, military boots and a great variety of similar articles. Some of the machines of Class 11 are intended for making grommet holes and overseaming or zig-zag stitching in heavy fabrics. Machine 11-30 is used for stitching rubberized material in the manufacture of aeroplanes and balloons. It has two needles and simultaneously makes two parallel lines of lock stitching in gauges from to inch, as desired. Orders for the machine should specify the gauge required. For to inch gauges, the machine will be fitted with shuttles 3381 and 3229; for )4 inch gauge, shuttles 3226 and 4729; for H to inch gauges, shuttles 3229 and 3226; and for to Yi inch gauges, shuttles 3381 and 3521. This machine has two alternating presser feet and feeds the work across the cylinder. The length of stitch is adjustable up to 34 inch, and the machine will sew fabrics or rubberized material up to γς inch in thickness. This machine has a cloth plate 36 inches long by 12 inches wide and there is a clear working space of 30 inches at the right of the needle. The machine is usually operated on an iron colunm stand 56688 equipped with an electric motor. This equipment is furnished, on order, at an additional charge to the machine.