CLAY WORKING INDUSTRIES. 213 



The pipes as fast as they are made are cut to length and deposited 

 on wooden pallets of appropriate size ; if the pipes are small they are 

 then set on end on a platform truck until it is loaded and are then 

 wheeled away and set on the dry floors. 



Large pipes are transported to their destination on pronged trucks 

 which enable the workmen to raise the pipe and pallet an inch or two 

 off from the floor and run with it at a good speed. 



After the pipes have been stiffened in the warm air for a few hours, 

 they are trimmed and sponged and finished up smooth and any incipient 

 cracks are mended. 



The drying of sewer pipe has been explained and discussed in con- 

 nection with brick drying, as many brickworks use this plan of drying. 

 There is no question as to the great benefits of this plan of drying, as 

 to economy and safety, but even with the use of all the room that is 

 needed, sewer pipe men frequently have great trouble from cracking of 

 the pipes. This is likely to be due to faults of the structure of the pipe 

 or using clay fresh from the mines as much as to any thing else. How- 

 ever, any hollow ware is more difficult to dry safely than any kind of 

 solid ware, and as a rule, the use of only the slowest and most natural 

 processes will suffice to dry without considerable loss. 



The burning of sewer pipe is accomplished in all respects like the 

 burning of paving brick except that much less time is required owing to 

 the thin section of clay to be vitrified. When burning a kiln of fireclay 

 pipe in which there are many large pipe or double strength pipe, the 

 burning is much slower, often lasting five, six or even seven days. 



For kilns containing no double strength pipe and mostly small sizes, 

 four days is usually sufficient. Shale pipes require somewhat less time 

 than fireclay and are never made in double strength ; for a long time it 

 was asserted that they could not be made more than the usual thickness, 

 but it is now admitted to be possible to make them, while it is not done. 



The kilns for this class of work have been described in connection 

 with paving brick; the round down draft kiln is the standard every- 

 where. The contents of a kiln of pipe is estimated by its list value ; for 

 instance, the average size of the round kilns used for this work is 27.3 

 feet. A kiln of this size would hold an average of pipe about $1,600 to 

 $1,800 list value; if a large • number of handmade fittings were put in, 

 the value of the contents might easily be made much larger, but the aim 

 is to burn a regular proportion of fittings to every kiln, so as to make 

 the loss as small as possible in event of too much or too little heat. 



The surface finish of sewer pipe is a matter of much importance to 

 the manufacturer; the requirements of the market are very severe and 

 even unjust. Sewer pipe seems to find a very small and unprofitable 

 market, and yet the slightest defect, even of color, is frequently enough 

 to condemn the pipe. 



The glaze which is imparted to the surface of the pipe is a matter 

 of much importance; it not only beautifies the color and appearance, 



