466 General Notices. 



generally a clean and strong though porous gravel. The mud, therefore, 

 will puddle in, and close the pores of the bed of gravel on which it lies 

 above low-water mark, so that the filtration into the neighbouring wells, 

 the waters of which are remarkably pure, must take place below low-water 

 mark ; and Mr. Wright proposes to construct a filtering chamber below the 

 bed of the river; from which chamber a main pipe or tunnel must be made 

 for conducting the filtered water into a well on the river side, whence it 

 is to be drawn up by steam power, and distributed to the houses to be 

 supplied, by the mains and branches at present existing. . . . The filtering 

 chamber and apparatus are to be prepared by erecting a coffer-dam in the 

 river, of sufficient size to enclose the whole of the area required for that 

 purpose. This coffer-dam will require piles of 45 ft. in length. The bed 

 of the river, thus laid dry, is to be dug out, and a bed of brickwork, 

 set in cement, laid clown : a floor must then be constructed in the form of 

 an inverted segment of an arch. On the top of the walls of this floor 

 plates are to be laid, and in the enclosed area, granite blocks placed ; upon 

 these, again, the girders are to be laid, and over these the joists, which are 

 to support a first layer of large flints. Upon these, successive layers of 

 smaller flints are to be arranged, decreasing in size as they approach the bed 

 of the river. Upon the uppermost of these, a stratum of clean shingle is to 

 be deposited, and then a bed of fine and very clean gravel ; thereby form- 

 ing a filtering bed of 8 ft. in depth, the top of which will still be 4 ft. below 

 low-water mark. So that, allowing 7 ft. for the timbers and brickwork, 

 and 18 ft. for the rise and fall of the tide, the total depth,- at high water, 

 will be 37 ft." We have no doubt of the practicability of this plan ; 

 though we do not believe it would free the water entirely from impurities, 

 or remain many years in repair. To render the plan completely effective, 

 it appears to us necessary to form a general sewer on each side of the 

 Thames, and running parallel to it, for some miles above the river and for 

 some miles below it, into which all the other sewers and drains of impure 

 water might empty themselves. This would render Mr. Wright's plan 

 complete. — Cond. 



A Tub for measuring and weighing Corn. — I have lately invented a tub for 

 measuring and weighing corn, which, I think, promises to be very useful. 

 Com of all kinds is here sold by the coomb, of four imperial bushels ; 

 but though nominally by measure, yet reference is always had to weight as 

 well ; and, accordingly, in buying grain, some idea is always formed, by the 

 buyer, of its weight per coomb. If, on delivery, it falls short of this 

 estimated weight, recourse is had to the bushel, to ascertain whether the 

 quantity contracted for has been delivered. The measuring and weighing, 

 being separate processes, take up a good deal of time ; a vessel, therefore, 

 by means of which the two operations might be combined in one, became a 

 desideratum. The main difficulty consisted in the emptying after weigh- 

 ing, &c. To this end, a movable bottom appeared requisite ; and, taking 

 a hint from the water-balances in coal-pits, the valve b, in fig. 78., was 

 devised, as best adapted, by its conical form, to penetrate the body of the 

 grain in the tub, and to allow of its free egress from the same when raised 

 for that purpose. The next question was, as to the best mode of raising 

 the valve. An ingenious mechanic of this place, of the name of Robinson, 

 has effectually removed all my difficulties on this head, or, I should rather 

 say, foot, by the application of the lever d, which is put in action by the 

 pedal c, as shown by the dotted lines in fig. 78. When the foot is applied 

 to this pedal, the valve is raised, as shown in the figure, and the corners 

 of the tub being rounded (see the section, fig. 78.), the tub is emptied in 

 quick time. Of course, the tub should be suspended high enough above 

 the floor to allow the corn sufficient room to escape. To this end, a 

 platform f, something like what is here called a horsing-block, is neces- 

 sary. Up this platform the man bearing the sack of corn walks ; and, the 



