Fig. 8.

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speedily close up and obstruct the passage of every floating particle. When this food running soccurs, it may collected in a separate vessel and again filtered. In this apparatus I do not claim as my invemion all the different parts of it taken separately, neither do I claim any exclusive privilege of the application of the pressure of a column of liquid in the operation of filtering. My invention consists in the method of placing the leaves in the ground sockets, and of carrying off the purified liquor, therefore, by means of separate pipes and stop cocks, so that each leaf becomes a distinct filter, and may be worked singly or altogether, so that any accident Occasioning foul runnings from one, will in no ways impede the action of the rest, as the operation of the foul leaf may be put an end to by stopping its stop cock. In witness whereof, &c.

A Machine to prevent Accidents in descending Mines.
By Mr. G. PRIOR, of Howard's Green, City Road,
With an Engraving.

The Silver Isis Medal was voted to Mr. G. PRIOR for this
Communication.

From the TRANSACTIONS of the SOCIETY for the Encouragement of ARTS, MANUFACTURES, and COMMERCE.

IN consequence of the late misfortunes which have

happened in this part of the country, by the breaking of the ropes by which men and coals are let down and brought up at coal-pits, I have been induced to visit them, and see if I could not discover some method or VOL. XXXV.-SECOND SERIES f other

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other by which such misfortunes could be preventeds #1 find the coal-pits have an upright sliding frame, made of wood, cased with iron from top to bottom, supported in different parts by beams across the pit, on which a frame slides, made very strong of iron, to prevent the rope from untwisting when a weight is applied at the end of itadel have represented a coal-pit in the model inclosed, with the sliding piece or frame which supports the corve or bucket as they are used; to which is added an invention by which I hope such accidents will in future be prevented, where it may be applied.

It is not at all necessary for me to give any explanation of the machine, on account of its simplicity of construction, as its advantages will appear by hanging on the weight to the frame which slides on the upright pieces which go down into the pit, and hooking on the string at the top, which will allow it to be raised or lowered without any obstruction. By slipping the ring from the hook at the top of the frame which supports the weight, the effect will be the same as if the rope had actually broken; and you will find the instant the rope is let loose, two powerful clicks, with centres of motion on the side of the moving frame, are brought into action: the arms of these clicks go through holes cut in the sides of the frame, and meet each other in the iniddle in such a manner that a bolt may pass through them, and at the same time through a block which is astride the bar which holds the frame together: at the top of this block is a hook to which the rope is fastened. When in use, the rope bearing the sliding frame with the corve or bucket, pulls the heads of the clicks close up to the bar which is over them, and draws their ends from the sides of the sliding frame which goes down to the bottom of the pit, which

is armed with strong iron pieces driven or screwed into them at some small distances.

In case of accident by the rope giving way, the clicks instantly present themselves to the sides, by the elasticity of the springs which are under them, screwed fast to

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their frame, which may be made very strong, as there is

no danger of their breaking, being required only to bend so little. Elasticity being much quicker in its action than gravity, the frame with the corve or bucket is sure to be stopped by the first bolt they meet with, and will remain suspended in the pit until another rope can be procured, by which means the lives of the men in the bucket will be preserved. If by the concussion at any time the bolt which passes through the joint of the click › should break, the sides of the frame will instantly become the fulcrum, and will not in the least prevent the click from action, but will in fact press it tighter against the upright pieces to which the bolts are affixed. The clicks, when the rope is attached, have not any weight to support on their joints, as their heads through which the bolt passes in the block support or rest themselves against the beam which combines the sides of the frame Logether.

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REFERENCE TO THE ENGRAVING.

geg, Figs. 2 and 3, (Plate XIII.) represent the iron dfraine to which the corves or basket is attached; hh is the upright slide fixed on the inside of the coal-pit shaft, which fitting into a groove in the frame g, Fig. S, serves to direct the motion of the frame as it is raised or lowered."brow BC <di

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gabb, Figs. 1 and 2, is the book by which the frame is suspended to thecrope.This hook is shown more, in detail, Fig. 7, in which the upper eye receives the cross bar of