[2594]. Sliding door for furnaces, &c. The weight of door may be relieved by rollers at top, as shown.
[2595]. Door or manhole held up by two wedges.
S traps. D traps. These are divided chambers, or bent portions of pipes, designed to always contain a well of water so as to cut off any currents of air or gases that would otherwise pass along the pipes.
Street manholes and lampholes are round, rectangular, or oval covers, strongly made to carry street traffic, and fitted in strong cast-iron frames, so as to be easily removable, and yet practically air-tight. Those fitted over sewer manholes are frequently provided with charcoal filters to arrest foul gases.
Section 107.—FEED GEAR.
[2596]. Ink feed, for printing machines.
[2597]. Ticket feeding gear.
[2598]. Feed worm, with air blast.
[2599]. Hand or power feed gear, for a drill, boring machine, &c.