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Mr. T. Roberts. 



[Jan. 31, 



They were made according to my directions by tlie well-known 

 machine makers, Messrs. Henry Pooley and Sons. Each lever was 

 capable of weighing with great accuracy from one pound weight to 

 1800 lbs., advancing one pound at a time, by a sliding weight, 

 which was caused to run along the graduated edge of the lever by 

 the pulling of a cord. The woodcut on page 236 shows the levers and 

 the other adjuncts placed in position for weighing. The upper figure 

 shows the machine for weighing lateral pressures, and the lower 

 figure that for weighing vertical pressures. Both levers were tested 

 by me with standard weights up to 800 lbs., and half a pound weight 

 would clearly move the lever when any part of the 800 lbs. was 

 applied to the machine. I now proceed to describe the methods of 

 weighing. 



The bottom of the bin was formed 4 feet above the basement floor 

 of the warehouse, and an opening 3 feet square was made in it 

 centrically. Beneath this opening a slide was placed which could be 

 forced through the grain by means of a powerful screw-jack, or be 

 withdrawn from beneath the grain by means of ropes and pulley- 

 blocks as might be required. Beneath this slide were grooves into 

 which a frame could be inserted, and when so placed it would be con- 

 centric with the 3-ft. aperture already described in the bottom of 

 the bin. Three frames were made to fit into these grooves, with 

 apertures of 1 ft. by 1 ft., 2 ft. by 2 ft., and 3 ft. by 3 ft. respectively. 

 Beneath any one of the apertures when placed in position in the 

 grooves, was the board which formed the top of the weighing- 

 machine, and the arrangements were such that a column of grain 

 measuring 1 ft., 4 ft., or 9 ft. superficial area, and of any height, up 

 to 51 ft. 9 ins., could at any time be weighed upon the lever of 

 the machine, without the necessity of emptying the bin to insert 

 the aperture frames after each weighing had been completed. It 

 was also necessary, in order to insure accuracy, that all pressure 

 should be taken off the machine before proceeding with each succes- 

 sive weighing, and these conditions were attained by opening and 

 closing the slides in manner already referred to. 



The weighings of the lateral pressures were accomplished in 

 manner slightly different from those of the bottom or vertical. The 

 lever of the machine was placed at right angles with the side of the 

 bin, in the way shown on the figure. The pressure-receiving top 

 of the machine, and its bracket, were suspended by a chain from 

 their common centre of gravity, and when placed in their position for 

 weighing, they just touched (without; exerting any pressure) the 

 knife-edged fulcree of the lever, and a pressure equal to less than 

 one pound weight would always be indicated by the lever rising off 

 its rest. 



Three apertures of the respective areas of 1 ft., 4 ft., and 9ft., 



