280 ENCAUSTIC TILES 



of tho frame, and tho slider, 11, is thereby confined to movo up or down, with an 

 exactly vertical motion, when it is actuated by tho screw, without deviation from tho 

 vertical. 



Thus far tho machine is an ordinary screw press, such as is commonly xised for 

 cutting and compressing metals for various purposes. The tools witli which the press 

 is furnished for tho purpose of this new process consist of a hollow mould, c c, formed 

 of steel, the exterior cavity of the mould being the exact size of tho article which is to 

 bo moulded. The mould, e e, is firmly fixed on tho base, B, of the frame, so as to be 

 exactly beneath the lower end of tho piston a, or plug, /, which is fastened to tho 

 lower end of tho square slider, H, and tho plug,/, is adapted to descend into tho 

 hollow of tho mould, e e, when the slider, H, is forced downwards by action of tho 

 screw, F, tho plug/ being very exactly fitted to tho interior of tho mould, e e. 



The bottom of tho mould, e c, is a moveable piece, , which is exactly fitted into tho 

 interior of tho mould, but which lies at rest in the bottom of the mould, e e, during 

 the operation of moulding the article therein ; but afterwards tho moveablo bottom, ii t 

 can be raised up by pressing one foot upon one end, R, of a pedal lever, u s, tho 

 fulcrum of which is a centre pin, r, supported in a standard resting upon the floor, 

 and the end, s, of the lever operates on an upright rod, m, which is attached at its 

 upper end to tho moveablo bottom, n, of tho mould, e c. 



A small horizontal table, T T, is fixed round the mould, e e, and on that table a 

 quantity of powdered clay is laid in a lump in readiness for filling tho mould. 



The two detached figures, marked jfys. 836 and 837, are sections of the mould e c, 

 and the plug,/, on a larger scale thanjfy. 835, in order to exhibit their action more 

 completely. 



The operation is extremely simple : the operator, holding the handle, h, with his 

 right hand, puts it back from him, so as to tiirn back tho screw, F, and raise the 

 slider, H, and the plug,/, quite out of tho mould, e e, and clear above the orifice of 

 the mould, as shown in fig. 835. 



Then, with a spatula of bone, held in the left hand, a small quantity of tho powder 

 is moved laterally from the heap, along the surface of the table, T, T, towards tho 

 mould e e, and gathered into the hollow of the mould with a quiet motion, so as to fill 

 that hollow very completely, and by scraping the spatula evenly across over the top 

 of the mould, e e, the superfluous powder will be removed, leaving the hollow cavity 

 of the mould exactly filled with the powder in a loose state, and neither more nor less 

 than filled. 



Then the handle, h, being drawn forwards with a gentle movement of the right 

 hand, it turns the screw, F, so as to bring the slider, H, and tho plug, /, which thereby 

 descends into the mould, e e, upon the loose powder wherewith the mould has been 

 filled, and begins to press down that powder, which must be done with a gentle motion 

 without any jerk, in order to allow the air that is contained in the loose powder to 

 make its escape ; but the pressure, after having been commenced gradually, is con- 

 tinued and augmented to a great force, by pulling the handle strongly at tho last, so 

 as to compress the earthy material down upon the bottom, n, of the mould, into about 

 one-third the space it had occupied when it was in the state of loose powder. Tho 

 section,^/. 836, shows this state of the mould, c e, and the plug/, and the compressed 

 material. 



Then the handle, h, is put backwards again, so as to turn back the screw, F, and 

 raise up the slider, H, and the plug, /, until the latter is drawn up out of the mould, 

 e e, and clear above tho orifice of the mould, as in fig. 835, and immediately afterwards 

 by pressure of one foot on the pedal, R, of tho pedal lever, R, s, and by action of the 

 upright rod, m, tho moveable bottom, , of the mould is raised upwards in tho mould 

 e e, so as to elevate the compressed material which is resting upon tho bottom, n, and 

 carry tho same upwards, quite out of the mould e e, and above the orifice of the mould, 

 as is shown in fig. 837, and then the compressed material can be removed by tho 

 finger and thumb. 



The compressed material which is so withdrawn is a solid body, retaining tho exact 

 shape and size of the interior cavity of tho mould, and possessing sufficient coherence 

 to enable it to enduro as much handling as is requisite for putting a number of them 

 into an earthenware case or pan, called a sagger, in which they are to be enclosed, ac- 

 cording to the usual practice of potters, in preparation for putting them into the 

 potter's kiln for firing ; tho sagger protects tho articles from discoloration by smoke, 

 and from partial action of the flame, which, if a number of small articles were 

 exposed thereto without being so enclosed, might operate more strongly upon some 

 than upon others of those articles ; but by means of tho saggers tlw heat is caused 

 to operate with cleanness, uniformity, and certainty upon a number of small articles 

 at once. 

 After the firing is over, the articles being removed from the saggers, aro in tho 



