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THE POPULAR SCIENCE MONTHLY 



which i)re vents the frame C from turning. E is the former or 

 profile which shapes the interior of the vesseh The lever or pull- 

 down, above the horizontal bar F, gives a transverse motion, 

 and forces the former toward the side of the mold. 1 and 2 are 

 adjustable collars which are fastened by screws ; 1 regulates the 



distance to wliich the col- 

 lar or frame C must be 

 lowered to give the prop- 

 er thickness to the bot- 

 tom of the vessel, while 

 2 acts as a stop to pre- 

 vent the frame from be- 

 ing thrown up too high. 



A " jolly " is a some- 

 what similar contrivance, 

 consisting of a table on 

 which is a revolving 

 mold with a single or 

 double pull-down. 



The construction of 

 pottery kilns has changed 

 but little in the past fifty 

 years. The glaze kiln of 

 the Tucker & Hemphill 

 factory was made on the 

 French plan. It possessed 

 six fire - boxes and the 

 same numT)er of flues, 

 eight inches in width, 

 which passed through 

 solid walls and met in 

 the center. Besides the 

 central space there were 

 two circular passages, 

 one extending around the 

 circumference of the kiln 

 and another midway be- 

 tween this and the cen- 

 ter. Modern kilns are 

 generally made about 

 fifteen to sixteen and a 

 half feet diameter inside, and measure about the same in height 

 to the crown, with usually ten fire-boxes. In some of the 

 Western kilns slight modifications have been made in the lat- 

 ter for the employment of natural gas, which is used instead 

 of coal. 



Fig. 16.—" Jigger." 



