244 EANSAi^ ACADEMY OF SCIENCE. 



These paving bricks are made of shale (or shales) of the coal measures. 

 The outcrop that has become best known is at the soldiers' home, where it 

 shows from 20 to 30 feet in thickness. It forms the lowest part (a) of No. 7 in 

 the section on page 236. It is mainly a clay shale called by the workmen soap- 

 stone, but it changes into luminated sandy shales in parts of its thickness. 

 Sometimes the best results are obtained by selecting a particular part of the 

 thickness of the bed. At others the proper proportions of sand in the clay 

 are obtained by mixing all the parts of the entire stratum. The iron that 

 seems to be a necessary part of a clay for vitrified bricks is found in some 

 parts of the shales as bands of limonite nodules or concretions, which are 

 ground up with the rest of the material, but elsewhere there are no concre- 

 tions, yet sufficient iron is distributed in streaks and ocherous stains through 

 the substance of the shale. 



It is a feature of these brick shales that they contract considerably in burn- 

 ing, to the extent sometimes of one-eighth of the linear dimensions of the 

 bricks, which in the cubic contents is a diminution of bulk in the ratio of 512 

 to 343. This must be allowed for in the making of the bricks, and the heat 

 of the drying shed and the kiln must be so regulated that the contraction 

 shall be regular. The proper time for tempering the material before use is 

 also important, and the use of winter frosts for this purpose should have at- 

 tention. With care on all these points and attention to results of previous 

 experience the bricjj shales of Leavenworth will produce as good results as 

 anywhere. It seems that one of the solutions of the problem of the pave- 

 ment of the city streets is found in the use of vitrified bricks. 



The material for making them is abundant. The geologic position which 

 we will call No. 7a, is easily found, and where not eroded it is of the brick 

 shale quality very extensively. It may be seen cropping in the 



1. River bluff near the railway-yard limits, northwest of Riverside mine. 



2. River bluff under the South Esplanade, north of Home mine. 



3. River bluff near Fort Leavenworth. 



4. River bluff at Kickapoo. 



5. Santa Fe cutting south of crossing of Fourth street, near soldiers' home. 



6. Santa Fe cut northwest of Fourth street crossing. 



7. Santa Fe and Southwestern cut near linseed-oil mills. 



8. On street cut in the city on Shawnee street. 



9. On bank of Three Mile creek on West Cherokee street. 



There are places where the brick shale shows only a little, as under the 

 loess at Geiger's quarry, where going back into the hill would probably show 

 it of considerable thickness, and above Ryan's quarry, where it does not show 

 at all in the outcrop. Similar beds are found in the higher parts of No. 7 

 (c and e) which show at the railway cut on the military reservation, on the 

 flanks of Pilot Knob ridge, in the bluffs of Little Stranger and on Seven and 

 Nine Mile creeks. The shales immediately above the coal on Little Stranger 

 have great similarity to the proved qualities of brick shale. 



The experience already attained in the making of paving brick, flooring 

 tiles, curb blocks and Roman bricks from these brick shales warrants the 

 expectation of still greater successes, and that terra cotta of the best quality 

 may be made for use in ornamental architecture. At one of the brick yards 

 an improvement of the common bricks has been made by an admixture of loess 

 clay with the brick shale, and this admixture has also been made by nature 

 where the loess and the brick shales come together, a greenish clay with red 

 streaks being the result. 



