Boy 
STATE GEOLOGIST. ri) 
of blocks now manufactured of which the Palmer hollow block is a good 
illustration. The simplicity with which these blocks are molded and the 
latitude of design obtained upon the one simple machine leaves little more 
to be desired. The machine covers but small space, is fairly light, is 
readily moved from place to place and is easily prepared for molding 
different shaped or sized blocks. Four men, two mixers and two tampers, 
will make from 100 to 125 blocks a day. The usual size for the blocks are 
32 inches by 9 inches by 10 inches. The sides and ends of the machine 
swing out and down upon hinges. The hollow places in each stone are 
formed by metal wedges or cones raised into place, through the base plate 
by means of a cog and ratchet attachment. ‘The side plates can be readily 
changed so as to substitute smooth, quarry faced, or ornamental facing for 
the stone as desired. 
Fig. 23.—Palmer Concrete Hollow Block Machine. 
The concrete is tamped into the machine, upon thin iron base plates, 
so that as soon as the block, which is made of rather dry concrete, is 
finished, the sides are let down, the hollow centers lowered and the block 
is lifted out on this base plate and allowed to remain upon it until firmly 
