546 THE COLLIERY GUARDIAN. March 16, 1917. the heater, and 9 the passage leading to the bottom of the boiler, 30 being the passage at the top stop valve leading from the heater,-and 32 the' passage leading from the top stop valve to the steam space of the boiler. 41, 42 are the clack valves. The casing of the valve device at the lower part of the drawing comprises a part 60 screwed into the main portion of the casing, the part 60 itself comprising a portion provided with the ports 49 and a portion forming a piston chamber 61, which latter is closed by a screw cap or cover 62. The stem 48 of the valve 45 passes through the central portion of the part 60, and has secured to its outer end a piston 63 located in the piston chamber 61, the part 64 of spindle 48 being preferably enlarged and provided with packing grooves. 65 is a spring arranged between the cover 62 'and the piston 63 adapted to normally hold the valve 45 in the position shown. 66 is a passage or port in the part 60 leading into the piston chamber 61, and adapted to be connected to a pipe 67 from a steam supply controlling valve 68, 69 being the steam supply to the said valve 68, and 70 an exhaust passage and pipe. The top stop valve 36 is provided with a hollow stem 71 terminating at its outer end in a piston head 72, working in the bore or piston chamber 73 of a part 74 screwed into the main portion of the casing of valve 36, 75 being a spring between the piston 72 and the end of the piston chamber, and normally acting to hold the valve 36 in the position shown. The outer end of the piston chamber 73 is closed by a screw cap or cover 76, and a port or passage-way 77 is provided, as shown in the cap 76, leading from a pipe 78 into the piston chamber 73, the pipe 78 being Connected to the pipe 67 and to the valve device 68. 79 is the port or passage in the plug of valve device 68, and 80, 80 are exhaust holes, normally open, to, prevent compression behind the pistons 63, 72 when operated by steam, as hereinafter described. 81 is a screwed spindle, adapted to work in a tapped hole in a plug 82 m the mam casing of the lower valve device, and provided with a head 83, by which it may be operated, and a stem 84 adapted when the spindle is screwed in to engage the valve 45 -and hold it on to valve seat 46 should it be desired to mechani- cally hold the valve in that position. The spindle may also be used to mechanically or manually move the valve 45 from the position shown into position against the valve seat 46. 85 is a similar screwed spindle, working through the cap 76 at the top stop valve for mechanically holding the valve 36 on the seat 35 or for manually moving it to such a position. Means are also described for opening by steam the valve controlling the communication between the feed water supply and the heater. (Four claims.) 103793. Improvements in Couplings for Railway and like Vehicles. C. Forbes, of Rothens, Kemnay, Aberdeenshire. —Relates to improvements in couplings for railway or like vehicles of the type in which the coupling link of one vehicle is caused to ride over the inclined surface of the hook of the vehicle to be coupled thereto. The drawing is a side eleva- tion, partly in section. The coupling comprises a, hook member 1 secured to each vehicle intermediate the buffers 2, and presenting at its forward end a cam surface 3 adapted to be tracked by a loop member 4, pivotally attached at 5 to an adjacent vehicle, so that when two vehicles approach closely to one another the loop 4 rides freely over the cam surface 3, and drops by gravity into a socket 6, whereby it is latched. Straddling the hook member 1, and located in juxtaposition with the socket is a bifurcated striker 7, which is engageable with the loop 4 to move the loop into a posi- tion clear of the socket 6, such striker being associated with loaded levers 8 'arranged transversely of the vehicle and operable from one or both sides by handles 9. In practice there are fitted to each end of each vehicle a hook member and also a loop member, each adapted to co-operate with a counterpart fitted to the adjacent end of the nearest vehicle. (One claim.) 103619. Improvements Relating to Pneumatically - Operated Percussion Tools. H. Christiansep, of 80, Fahlts- kamp, Pinneberg, Germany. — Relates to pneumatically- operated percussion tools actuated by reciprocating air columns, such tools including percussion drills, pneumatic hammers, stamping tools for railways, and so forth. The drawing shows a longitudinal section of a tool with the hammer piston just striking the end of the tool proper. A reciprocating piston hammer b is driven backwards and for- wards in a cylinder a by connecting the spaces in front and behind the hammer piston b by means of ports c and d and suitable piping to cylinder spaces in front of 'and behind a power-driven reciprocating piston or pistons. The power- driven reciprocating piston and the hammer piston b operated by the air columns, moving to and fro between these pistons, therefore carry out corresponding movements. On the forward movement, the hammer piston b strikes the tool e, and transmits its kinetic energy by this impact. The tool e is guided in the tool holder g, which is mounted in the neck of the cylinder a. The tool e is provided with a collar e1, which during the forward movement of the tool, first moves freely, and then strikes against the front end of a spring i, of which the rear end is secured, for example, by being threaded on the neck of the cylinder. The spring i thus prevents the tool from being driven out in case the tool is not in contact with the work when the whole energy of the hammer piston b is expended in the acceleration of the tool e. In order to prevent the hammer piston b from striking against the cylinder cover f at the end of its return stroke, the port d opens into the cylinder d1 some distance from the cylinder cover /. The hammer piston b closes the onening d1' of the port d during its return stroke. The hammer piston is automatically stopped, in spite of the con- tinued operation of the air piston, as soon as the tool is no longer pressed against the work, and the hammer piston b automatically re-commences its operation as soon as the tool e is again pressed against the work. For this purpose the port c, leading to the front cylinder space, is provided, in addition to the opening c1 at the front end of the cylinder, with >a second opening c2 disposed somewhat to the rear. This opening c2 is disposed so far towards the rear that it is closed by the hammer piston b when the piston has still a considerable portion of its stroke to complete before it strikes the tool e. The air in front of the piston b communicates, therefore, during the last part of the stroke of the hammer piston entirely through the opening c1 with the space in front of the power-driven air piston. When the tool e rests against the work, the said tool can only be driven forwards a short distance, and the hammer piston b can only be impelled forwards through a short distance, and therefore does not expose the opening c2. If, however, the tool e does not rest against the work, then it can be driven by the piston b to a certain position. The piston b is then impelled forwards such a distance that the opening c2 is uncovered. The tool holder g is provided with a steel spring ring h, over which the cylindrical boring in the front end of the hammer piston b engages. It is then held by the spring h in such a manner that the buffer action of the spring i can no longer move back the tool e, and by. means of this the piston b. The reciprocating air columns are now no longer to provide improved means temperature of the air in is, an elevation, a is the The valves g and h are separated by the piston b, but communicate directly with one another through the port c, opening c2, the space behind the hammer piston b, the opening d1, the port d, and the con- necting piping. The hammer piston is therefore not operated, although the power-driven piston continues to reciprocate. 'Four claims.) 103780. Improvements in Self-contained Breathing Apparatus. R. H. Davis, of 187, Westminster Bridge-road, Westminster, London.—Relates to self-contained breathing apparatus of the kind employing compressed air or oxygen, a breathing bag,