162 GEOLOGY OF OHIO. 



the pug mill forces the clay into a space in front of the plunger, which 

 then forces the wad or ball of clay out into a mold; here it is stamped by 

 a vertical plunger and consolidated into the brick form and again 

 forced out on a carrier belt, which takes it away. The action of this 

 machine is not as clean-cut and desirable as the Tecumseh, the clay beiug 

 subjected to movement 3 times, in getting it into the mold box where 

 it is made into a brick. However, it at no time passes through a die 

 under pressure, or is acted on by an auger, so that the field of usefulness 

 of the machine in working plastic clays may be quite important. Its 

 capacity is about 2500 per day. The structure of the brick made on it 

 from plastic clays is very fair, free from the defects which would surely 

 present themselves in working the same clays by auger or plunger 

 machinery. 



A third type of machine, the invention of Mr. H. Camp of Cuya- 

 hoga Falls has been built and tested at Greentown, Ohio. It is not prop- 

 erly a combination machine as the clay is formed by a distinct plunger 

 action. But the novel feature of the machine is, that it combines the 

 manufacture of the brick, with the repressing of them, and the automatic 

 delivery on a dryer car so that one man in general charge of the machine 

 can produce 25,000 repressed bricks per day on the cars ready for drying, 

 with no assistance. While this machine has been subjected to the prac- 

 tical test of manufacturing 600,000 brick, in which it gives satisfaction, the 

 company that controls it has not made a success of the plant as a whole 

 and its use was not continued. The machine is a marvel of ingenuity, 

 and without question has the elements in it of a very great success; it is 

 likely that some alterations would be needed to adjust its action if it were 

 being introduced widely. 



Repressing. After the bricks are made and cut to length, they are 

 finished as far as their form is concerned and with no further work 

 except drying and burning. They are a marketable product. But pav- 

 ing brick manufacturers have many of them gone farther and submitted 

 their bricks to a second mechanical operation, for producing the finished 

 shape. This operation is called re-pressing, though in most kinds of 

 brick it is not properly Re-pressing, as it is th.^ first application of pres- 

 sure in a confined space. 



The purposes which makers have in view in the repressing are as 

 follows : 



1st. To give their ware new and ornate shapes and marks which 

 are not attainable by use of any die where flow of the clay is produced. 



2nd. To obliterate the rough sides or ends caused by the passage of 

 the cutting wire through the clay, and give the biick a smooth, dense 

 skin which shall assist in preventing the absorption of water. 



3rd. To produce a stronger, denser, better wearing material than 

 can be abtained by the formation of a bar of clay by passing through a 

 die. 



