Abstract: The invention provides that a sewing machine is used for sewing the adjacent edges of a flat felt web which is folded to bring the edges together. The web moves past the sewing machine, and the sewing machine is mounted so as to reciprocate in a forward stroke in the direction of the web during the stitching, and to move rearward back to an initial position to effect the next stitch. The drive mechanism of the sewing machine is such that from the commencement of the forward stroke the machine is accelerated up to the speed of the web the needle penetrates the web and effects the stitch, the needle is removed from the web, and then is decelerated to zero before completing the backstroke. The invention also relates to an optical sensing mechanism for examining the presence of stitches.

Abstract: The manufacture of flexible tubes of two or more layers of a material such as felt which can absorb synthetic resin comprises feeding a first web in the direction of its length and folding the web so that its edges came face-to-face and are sewn together by stitches which loop round said edges, the second layer being wrapped around the first and its edges sewn in a similar manner, the looped stitching being such that when the tube is inflated to circular form the extremities of the edges in the stitching loops in each layer come into butting contact, whereby there are no regions where the layer has a double thickness of material.