VITRIFIED BRICK PAVEMENT'S FOR COUNTRY ROADS. 35 



THE OPERATION OF THE TEST. 



Item 10. The trick charge. — The number of brick per test shall be 10 for all 

 bricks of so-called "block size," whose dimensions fall between from 8 to 9 

 inches in length, 3 to Si inches in breadth, and 3J inches to 4i inches in thick- 

 ness. 1 No brick should be selected as part of a regular test that would be 

 rejected by any other requirements of the specifications under which the pur- 

 chase is made. 



Item 11. Speed and duration of revolution. — The rattler shall be rotated at a 

 uniform rate of not less than 29£ nor more than 30^ revolutions per minute, 

 and 1,800 revolutions shall constitute the test. A counting machine shall be 

 attached to the rattler for counting the revolutions. A margin of not to exceed 

 10 revolutions will be allowed for stopping. Only one start and stop per test 

 is generally acceptable. If from accidental causes the rattler is stopped and 

 started more than once during a test and the- loss exceeds the maximum per- 

 missible under the specifications, the test shall be disqualified and another 

 made. 



Item 12. The scales. — The scales must have a capacity of not less than 300 

 pounds and must be sensitive to one-half of an ounce and must be tested by a 

 standard test weight at intervals of not less than every 10 tests. 



Item 13. The results. — The loss shall be calculated in percentage of the 

 initial weight of the brick composing the charge. In weighing the rattled brick 

 any piece weighing less than 1 pound shall be rejected. 



Item 14. The records. — A complete and continuous record shall be kept of 

 the operation of all rattlers working under these specifications. This record 

 shall contain the following- data concerning each test made : 



1. The name of the person, firm, or corporation furnishing each sample tested. 



2. The name of the maker of the brick represented in each sample tested. 



3. The name of the street or contract which the sample represented. 



4. The brands or marks upon the bricks by which they were identified. 



5. The number of bricks furnished. 



6. The date on which they were received for test. 



7. The date on which they were tested. 



S. The drying treatment given before testing, if any. 



9. The length, breadth, and thickness of the bricks. 



10. The collective weight of the 10 large spherical shot used in making the 

 test at the time of their last standardization. 



11. The number and collective weight of the small spherical shot used in 

 making the test at the time of their last standardization. 



12. The total weight of the shot charge after its last standardization. 



13. Certificate of the operator that he examined the condition of the machine 

 as to staves, liners, and any other parts affecting the barrel and found them 

 right at the beginning of the test. 



14. Certificate of the operator of the number of charges tested since the last 

 standardization of shot charge. 



15. The time of the beginning and ending of each test and the number of 

 revolutions made by the barrel during the test as shown by the indicator. 



16. Certificate of the operator as to number of stops and starts made in each 

 test. 



1 Where brick of larger or smaller sizes than the dimensions given above for blocks are 

 to be tested, the same number of bricks per charge should be used, but allowance for the 

 difference in size should be made in setting the limits for average and maximum rattler 

 loss. 



