866 THE COLLIERY GUARDIAN. May 5, 1916. ABSTRACTS OF PATENT SPECIFICATIONS RECENTLY ACCEPTED. 1105 (1915). Improvements in Tubular Steam Boilers. G-. H. Mann, of Neithrop Villa, Banbury, Oxfordshire.— Relates to steam boilers of the type described in Patent No. 21608 of 1900, and consists in the construction and arrange- ment of certain of the parts whereby the efficiency of the whole is increased. The drawing is a longitudinal sectional elevation. Several rows of smoke tubes, 6, 6a, lead from the fire box 7 to the said combustion chambers 3 and 3a, but there is only one horizontal row of tubes 2 and 2a, on each side, leading from the chambers 3 and 3a to the combustion chamber 4. This arrangement enables the combustion chamber 4 to be made comparatively shallow, and height of the fire box 7 to be increased, and a larger number of tubes 6 and Qa got into said fire box 7 without increasing the 8 6' 15- 3 diameter of the boiler 8. The end doors 9, 9c, are hollow, to act as superheaters for the exhaust steam conducted thereto through pipes 10 and 10a. Tubular receptacles 11, llu, are mounted within the combustion chambers 3 and 3a respec- tively, and steam is conducted thereto by the tubes 12, 12a, which lead from these hollow doors 9 and 9a, thus giving extra surface to enhance the superheating. On these recep- tacles 11 and Ila are mounted nozzles 13 and 13a opposite 'the ends of the tubes 2 and 2a, while at the ends of said receptacles 11 and Ila are mounted detachable plugs 14, 14a, to afford facilities for cleaning same. The outer wall of the doors 9 and 9a is hollow, to form a space or chamber 15,15a, which may be filled with non-conducting material. (Five claims.) 2964 (1915). Improvements in Lancashire and like Steam Generators. E. Warrington, of Bennett-street, Hyde, Chester.—Relates to improvements in or in connection with steam generators, and more particularly those of the Lanca- shire, Cornish, and similar types, and has reference to devices for preventing the hot gases from the flues of the boiler pass- ing between the end of the boiler and the brickwork down- take. It consists in the provision of plates and their con- taining boxes made as a complete unit, which can be built into the edges of the vertical walls of the downtake, so that the plates will readily adjust themselves to the position of the boiler during the expansion or contraction of the latter. Fig. 1 is a side elevation, partly in section, of the rear end of a boiler and flues, showing the application of one form of the invention thereto; and fig. 2 is a sectional plan. A cast iron or like box a, which can be built into the downtake wall b, is provided with a vertical plate c, which can be suspended - e- s I- ------£ in various ways within the box, so that its outer edge d always tends to keep in contact with the end e of the boiler f. One form of suspension is a pair of links g secured to the plate c at i by their lower ends, and to a pivotal point h by their upper ends, so that the outer edge of the plate will always tend to fall towards the rear end of the boiler. This tendency may be assisted by arranging the connecting point i for the link or links with the plate a little to the rear of the suspension point h. Each box a is provided at the front side and a little to the rear with vertical inwardly pro- jecting ribs p, which are preferably pointed or brought to a thin edge, the plates c, previously referred to, fitting between the ribs loosely. By making the ribs with thin edges, they tend to scrape the plates clean, and also prevent grit resting between the plate and the ribs. In some cases, each box a is made longer than the plate c, so as to leave a space q, into which grit or dirt may fall from the box and plate, and be removed through a hole at one side. (Two claims.) 3639 (1915). Improvements in Turbines, Turbo-Com- pressors and the like. E. O. Willis, of Brougham House, 92, Brougham-street, Hartlepool, Durham, legal representa- tive of the late J. B. Willis.—Relates to improvements in the design and construction of shrouded turbine blades and to axial steam baffles at root of blades for turbines, turbo- compressors, and the like driven prime movers; and con- cerns constructions of the kind wherein a radial packing fixed in each of the perimeter grooves of the cylinder or rotor is employed in combination with a shrouding fitted on the blade tips, said root packing projecting as an annular flange and providing a circular or radial surface which can be machined to form ian accurate or uniform and very fine clearance with the surface of the tip shrouding of the adjoin- ing ring of blades, which may also be machine faced, so that the annular space between'the rings of blades can thus be reduced to a small known clearance. The shrouding is attached to the blades by slotting the blade tips to form tongues, and bending over the tongues after passing same through the holes in the shrouding, to hold the shrouding in place. The shrouding is preferably formed with a rib or ribs which have the advantage of strengthening the shroud- ing and of serving as a guide for the automatic feed punch or tool employed for punching the holes in the shrouding. The drawing is a detail sectional view of sections of a turbine cylinder and rotor with shrouded blades, a a repre- sent the blades or vanes fixed in the perimeter grooves c of the cylinder and rotor, with or without distance pieces between their root portions; k represents a radial packing fixed in the perimeter grooves of the cylinder and rotor for co-operating with a shrouding h on the blades. The packing k projects as an annular flange with a plain or serrated contact surface k1, which has a projecting facing fillet h1; the annular space between the rings of blades can thus be reduced to a small known' clearance. The shrouding is applied to the blades by slotting their tips to form tongues which are passed through holes h2 punched at uniform intervals in the shrouding, and then bending over the tongues passed through the holes; r represents ribs with which the shroudings are rolled, and which allow of guiding the automatic punch or tool employed for producing the holes in the shrouding, and enable these to be punched in a straight line, so that when the blades are inserted in the holes these form a perfectly true row. a1 represent the slots in the tips , of the blades to form the tongues, and a2 a shouldered edge on the tip of the blade to accommodate the facing fillet of the shrouding. The blades or vanes can be assembled together in segments, before being fixed in the grooves, the shrouding being made in segments and the ends of the blades being inserted in the holes of the shroud- ing and bent over as mentioned, the segments being then fitted to the rotor and cylinder and the roots of the blades fixed in the grooves thereof. Also the facing fillet of the shrouding for co-operating with the machined surface of the root shrouding can be machined after assembly. The pack- ing pieces for co-operating with the shrouding are placed in position in the grooves, and may be held in place therein by the friction of the blades, or they may be sweated or other- wise fixed to the blades and to the distance pieces in any known way. The blades will be cut off to the required length, and as the slots can all be cut in the same jig all slots can be cut at the same distance from the steam edge of the blade; (Two claims.) 4675 (1915). Improvements in Mine and other Electrical Signalling Systems. Sterling Telephone and Electric Com- pany1 Limited, F. Gr. Bell, and H. W. Barclay, all of 210-212, Tottenham Court-road, London, W. .— Relates to improvements in electric bells and relays of the kind in which the operating magnet is provided with a short-circuited secondary winding, in order to diminish the sparking which usually occurs during the operation of the bell. The inven- tion is particularly intended for use in connection with signalling systems in mines where sparking may be the cause of starting explosions, and with this in view the invention aims at reducing the sparking to as small an amount as possible. The short-circuited secondary winding which serves as an eddy current or damping winding, is wound in close proximity to, turn by turn, with the main operating winding. The effect of such a winding is to resist the rate of change of flux in the core which it surrounds when the circuit of the primary winding surrounding the core is broken or closed. In this way the inductive electromotive force which tends to induce a spark at the armature contact or where the yvires touch, in the case when the invention is applied to bare wire systems, is reduced to a negligible amount. In an ordinary bell the short-circuited secondary winding may be upon the bell magnet, but in some instances, according to the invention, the bell itself is enclosed and operated by a local circuit completed through a contact made by a relay joined to the line wire, and then the short-circuited secondary or damping wire is provided on the core of the relay in order to prevent sparking between the line wires. In general, the best effect is obtained by making the coefficient of mutual induction between the usual winding and the short- circuited secondary as large as possible, and this is the object aimed at in winding the secondary coil, as mentioned above. Fig. 1 is a diagram of the invention applied to an ordinary trembler bell; and fig. 2 shows the invention applied to a bell whose circuit is closed by a relay, and is provided with enclosed contacts. In fig. 1 the bell magnet has two wind- ings. The winding 4 is the usual winding, and is connected up as usual through the armature contact 5, operated by the armature 6, and so to the terminals 7, 8 of the bell. The winding 2 shown in dotted lines has its circuit permanently closed through the short-circuit connection 3, and is wound turn by turn with and in close proximity to the winding 4. In mine signalling systems the bell may be connected to conductors 9, 10, which are bare wires stretching along the passages of the mine, and the circuit may be closed by touching them together, or by means of a bell push in the ordinary way. . In operation the bell acts as an ordinary trembler bell, but, as explained above, the effect of the wind- ing 2 is to reduce sparking owing to the effect of reducing the rate of change in the flux in the core 1. The sparking is reduced both at the armature contact 5 and between the wires 9 and 10 or the bell push. Fig. 2 shows the invention applied to an enclosed bell operated by a relay. The bell 11 has its circuit closed by the armature 12 of a relay 13 at the contact 14. The bell is joined to a local battery 16, and together with the contact 14 is totally enclosed. The relay 13 has its usual winding 17 joined to the line wires 9 and 10, which may be bare wires or otherwise, and, in addition, the relay 13 is provided with a short-circuited winding 18 shown in dotted lines. In this case, the winding 18 does not have any effect on the sparking at contact 14 or the armature con- tact of the bell 1, but this does not matter, because all these contacts are enclosed. Any spark which tends to be formed /Q /6 Z^J [ between the wires 9 and 10, however, is greatly reduced owing to the reaction and damping of the winding 18. (Two claims.) 4745 (1915). Improvements in Respirators for Protection against Noxious Fumes. Montagu Stern and Company Limited and S. Goldreich, of Finsbury-court, 18, Ropemaker- street, London.—Relates to respirators for protection against noxious and dangerous fumes, in particular that class of respirator which is treated with a liquid substance for the purpose of neutralising the evil effects of the fumes. The respirator comprises a cup-like body which contains an absor- bent screen thin enough to enable speech to be transmitted therethrough, and is adapted to fit over the mouth and nostrils of the wearer at such a distance that clear articulation is possible. The cup-like body comprises a storage receptacle which constitutes the sides of the said cup, and is mainly composed of an absorbent material of considerable thickness, protected on the outside by a covering impervious to moisture, and a screen of absorbent material of inconsiderable thick- ness, which screen is connected to the storage receptacle in such manner that liquid can be readily supplied from the said receptacle to said screen by virtue of the force of capillary attraction. The absorbent material in the storage receptacle is preferably of a spongy or felty nature, such as “ spongia-piline.’’ The absorbent material employed for the protective screen is a material of capillary nature, and is preferably a known material termed paper textile, i.e., a woven material in which one set of threads is of twisted paper, the other set of cotton. Fig. 1 is a side elevation; and fig. 2 a plan partly in section. The respirator com- prises two essential portions, a storage receptacle 1, and a neutralising screen 2. The material (“ spongia-piline ”) in the storage receptacle consists of a backing 3 of waterproof material, and an absorbent material 4 consisting of felt and sponge suitably incorporated. The receptacle is roughly annular in form, and carries at its front end the neutralising screen 2, which consists of a sheet' of paper textile. The screen 2 is so connected to the storage receptacle 1 that, as liquid is evaporated from the screen, a fresh supply of liquid is readily drawn thereto from the storage receptacle by virtue of capillary attraction. The storage receptacle and screen together form a cup-like body, which, at the rear end 5 of the storage receptacle, is adapted to fit over the mouth and nostrils of the wearer. The recess 6 (fig. 2) is made to fit snugly against the bridge of the wearer’s nose, and the lower portion 7 is adapted to fit below the wearer’s mouth. To the form of joint preferred for connecting the storage receptacle with the screen is shown in fig. 2. To make this joint, the paper textile constituting the screen 2 is sewn to the “spongia- piline ’’ at two places, 8, 9, the edge 8 of the paper being first sewn at this place, while the sleeve of “ spongia-piline ’’ 4 is turned inside out, whereupon the said sleeve is brought back to its normal position. The screen 2 will bulge outwardly owing to the diameter of the ring at 8 being less than before. Thereupon the front edge of the waterproof backing 3 of the “ spongia-piline ’’ is drawn inwardly, and sewn to the paper textile at the ring 9, and in that manner the screen 2 of paper textile is drawn up tautly, and is then flat and at right angles to the cup. By connecting the screen 2 in this manner the liquid contained in the storage receptacle 1 is readily drawn from the latter by virtue of the force of capillary attraction. Suitable bands, 10, 11, such as elastic or leather bands, are provided for enabling the wearer to