The report of this second investigation, made by Professor Orton, as well as of the reports of tests made with the rattler designed by Gomer Jones, were submitted in January, 1900, to a committee consisting of Messrs. D. V. Purington, J. L. Hegley, H. A. Wheeler, Gomer Jones, Edward Orton, Jr., J. B. Johnson, and A. N. Talbot, which committee had been authorized to discuss these reports for the National Brick Manufacturers Association. In the Jones rattler a few brick were clamped edgewise in pockets around the inside surface of a cylindrical rattler and cubes of cast-iron were used for the impact and abrading material. The report -of Professor Orton's tests showed that the device of Mr. Jones embodied several objectionable features and the committee concluded that while the machine might appeal to the public as in a sense representing conditions of wear in the street and while the reports show that the machine is distinctly more sensitive in indicat ing the softer grades of brick, the variable amount of surface exposed on the brick and the discordant results coming from variations in sizes, as well as other defects of the machine, rendered it less satisfactory as a general matter of testing than the rattler already in use. The series of tests with the standard rattler reported by Professor Orton enabled a comparison to be made between the National Brick Manu facturers Association method in which brick alone were placed in the rattler and the method recommended by the writer which involved the use of cast-iron shot of two sizes. The investigation included the effect of variation in quality of brick, the effect of a change in the amount of shot, the effect of a variation in the proportion of small and large shot, the effect of the speed of the rattler and the effect of size of the brick themselves. The committee in their report advised the National Brick Manufacturers Association to abandon the old N. B. M. A. test and to adopt in its place the test with cast-iron shot of two sizes, definite pro portions of small and large shot and of the total charge being adopted. This report was presented to the association in February, 1900, and the association changed its standard method of test to conform with the specifications recommended by the committee. It also accepted the
recommendation that further tests and investigations be made.
The idea of clamping the brick in position seemed a promising one and soon after this the writer constructed a rattler in which the brick were securely held around the circumference of a cylinder, their inner thereby forming the surface of the cylinder. This machine will be described under the head of "Talbot-Jones Rattler Test." During the first months of 1901, Professor Orton experimented with this machine and reported the results of the tests together with the results of tests made with the standard rattler to a committee consisting of J. B. Johnson, W. K. Hatt, A. Marston, and A. N. Talbot, in August, 1901. This committee reported and recommended a continuance of the standard adopted in 1900, on the grounds that it is somewhat cheaper and simpler than the ordinary rattler in general use, and that the find ings by the new N. B. M. A. standard tests are in accord with the results of other tests and with the results of the use of the paving brick in actual service. The committee on Technical Investigation of the National Brick Manufacturers Association accepted this report and by virtue of the authority vested in them by the association reaffirmed the method of tests adopted in February, 1900, as the standard rattler test of the National Brick Manufacturers Association.
National Brick Manufacturers Standard Rattler Test.—The specifica tions for the present National Brick Manufacturers Association stand ard rattler test thus finally adopted are here given in full. It•will be seen that they include requirements for the dimensions of the rattler chamber and the number of its sides, for the composition of the charge in the number of the paving brick or blocks and the amount of the cast iron shot and the sizes and form of the shot to be used, for the speed of the rattler, for the number of revolutions for a test, for the con dition of the brick, and for the method of calculation of the results.