28,360. Keith, J., and Keith, G. Dec. 24. [Cognate Applications No. 1994, A.D. 1908, dated Jan. 29, and No. 7541, A.D. 1908, dated April 6.] Incandescent gas lamps.-The mixing-tube H<1>, Fig. 1, of an inverted lamp is constructed with a heating-chamber A, preferably of aluminium, nickel, &c., or coated with these metals, and comprising two shallow cones arranged base to base with a diaphragm A<1>, perforated at its edges, between them. The cones may be corrugated or ribbed, and may be secured together by swivel catches &c., and the chamber A may be divided by vertical partitions when several burners are employed. The mixing-tube has a veuturian constriction, such as is described in Specifications No. 16,955, A.D. 1900, and No. 26,198, A.D. 1901, and is provided with a transverse regulating-screw H. The heavy burner-nozzle B, Fig. 3, such as is described in Specification No. 17,584, A.D. 1904, is protected at its end either by a non-conducting mantle-ring, or by a non-conducting covering carrying the mantle or mantle-ring. When using pure gas, the nozzle B is provided with perforations a<10> for burning part of the gaseous mixture under the chamber A. The upper part of the mixing- tube is enclosed in a substantially rectangular airchamber D<1>, open to the atmosphere at its lower end d<2>, Fig. 1, and arranged in the cylindrical flue D, and the lamp may be provided with an inner globe I or cylinder open at its lower end, and with an outer globe I' with inlets at the top, both globes I, I<1> being attached to a chamber F enclosing the heater. When the casing is enamelled, the screws g, Fig. 1<c>, for securing the globe or reflector, are carried by a ring G resting on a band on the casing F, and pass through clearance holes in the casing F. The lamp may be rendered wind-proof by fitting an external casing J, Fig. 1, and by extending the top cowl E downwards. The nipple N, Fig. 1<b>, is fixed to a tube n secured to a part outside the lamp in order to enable the nipple to be withdrawn from the top, and the internal air supply is filtered by a fine gauze cylinder capable of being withdrawn upwards beyond the cowl. In order to prevent overheating when the burner is started, the heating- chamber A is provided with a thermostat, consisting of two dissimilar metal strips o and provided with a perforated metal tongue for partly closing the entrance to the heater when the burner is cold, thereby allowing the long rarrow mantle to be burnt off in situ. Specification No. 6509, A.D. 1906, is also referred to.