In collecting field samples, special attention is paid to the occurrence of the stone, extent of the deposit, strike, dip, etc., and specimens are procured having their faces cut with reference to the bedding planes, in order that compressive and weathering tests may be made, not only in relation to these planes but at those angles thereto in which the material is most frequently used commercially. Attention is also paid to the results of blasting, in its relation to compressive strains, as blasting is believed to have a material effect on stones, especially on those which may occur in the foundations of great masonry dams, and type specimens of stone quarried by channeling, as well as by blasting, are collected and tested. _Clay and Clay Products Investigations._--These investigations are in charge of Mr. A. V. Bleininger, and include the study of the occurrence of clay beds in various parts of the United States, and the adaptability of each clay to the manufacture of the various clay products. Experiments on grinding, drying, and burning the materials are conducted at the Pittsburg testing station, to ascertain the most favorable conditions for preparing and burning each clay, and to determine the most suitable economic use to which it may be put, such as the manufacture of building or paving bricks, architectural tiles, sewer tiles, etc. The laboratory is equipped with various grinding and drying devices, muffles, kilns, and apparatus for chemical investigations, physical tests, and the manufacture and subsequent investigative tests of clay products. This section occupies the east end of Building No. 10, and rooms on the first and second floors have been allotted for this work. In addition, a brick structure, 46 by 30 ft., provided with a 60-ft. iron stack, has been erected for housing the necessary kilns and furnaces. [Illustration: PLATE XVI. Fig. 1.--Brick Machine and Universal Cutter. Fig. 2.--House-Heating Boilers, Building No. 21.] On the ground floor of Building No. 10, adjoining the cement and concrete section, is a storage room for raw materials and product under investigation. Adjoining this room, and connecting with it by wide doors, is the grinding room, containing a 5-ft. wet pan, with 2,000-lb. rollers, to be used for both dry and wet grinding. Later, a heavy dry pan is to be installed. With these machines, even the hardest material can be easily disintegrated and prepared. In this room there is also a jaw crusher for reducing smaller quantities of very hard material, as well as a 30 by 16-in. iron ball mill, for fine grinding. These machines are belted to a line shaft along the wall across the building. Ample sink drainage is provided for flushing and cleaning the wet pan, when changing from one clay to another.