Untitled record

Application filed May 21,1889. Serial No, 311,536. (No model.) Patented in England January 5,1884, No. 806.

To all whom it may concern:

Be it known that I, THEOPHILUS GOAD, a subject of the Queen of Great Britain, residing at Forest Gate, Essex, England, have in5 vented certain new and useful Improvements in Portable Electric Safety-Lamps for Miners, (for which I have obtained a patent in Great Britain, No. 806, bearing date January 5,1884,) of which the following is a specification.

io In electric safety-lamps as hitherto constructed for use in mines the incandescent lamp has been fitted on the outside of the battery, and is consequently liable to be easily broken, when the filament will generally re15 tain the necessary heat sufficiently long· to ignite carbureted hydrogen, and consequently an explosion may ensue. Another source of danger in the present form of safety-lamps is due to the “sparking” that takes place on 20 making and breaking contact when this occurs surrounded by explosive gases.

The object of this invention is the construction of a safety-lamp which shall be free from these two sources of danger.

In carrying out this invention I arrange an incandescent lamp within a glass covering hermetically air-tight, such glass covering being held by a metal carrier suitably arranged to be connected to a battery. In the bottom 30 of the metal carrier within the glass covering is arranged a flexible diaphragm capable of being depressed by a pressure of air within the glass covering, such depression of the ., diaphragm being arranged to complete the 35 electric circuit for the lamp. Consequently on the breaking of the glass cover the pressure of the air is removed'from the diaphragm, which immediately returns to its normal position, thereby breaking the circuit and au40 tomatically extinguishing the lamp. To prevent the dangers of explosion by the sparking, I arrange that the making and breaking contact shall take place in^- a hermeticallytight chamber to which no gas has access.

These results ! attain by the mechanism illustrated in the accompanying drawings, in which—

Figure 1 is a sectional elevation’ of lamp complete; Fig. 2, a front or top view of incan50 descent-lamp chamber; Fig. 3, an under side view of Fig. 2; Fig. 4, a sectional view of Figs.

Und 3; Fig. 5, a sectional modification of part embodied in Fig. 1; Fig. 6, a detached view on larger scale in previous figure.

A is the battery-case, having a boss A'for 55 the incandescent-lamp-holding part B, to be attached by screws by aid of flange B', so as to form a chamber C between the bottom of B and front of battery-case. This chamber is made gas-tight by a washer of india-rubber 60 D. Within this chamber the leads E for the current of the battery are conducted. The bottom B has a rim B^s to hold a glass envelope F, which is made hermetically tight. Passing through the bottom of B are pegs G H, 65 which make contact with the ends of the leads E. These pegs are insulated by vulcanite I. Peg G is electrically connected to the lampsocket J, to which one of the spring-connections for the lamp is attached. In the mid- 70 die of the bottom B a recess K is made and covered over with a diaphragm L, preferably of very thin metal, to which the other connection for the lamp may be attached and arranged for contact with the top of the peg H 75 on the depression of the diaphragm, thereby completing the circuit and lighting the lamp. The depression of the diaphragm is proposed to be effected by a pressure of air introduced into the glass envelope F by suitable force- 80 pump through the passage M, the exit of which is closed by a spring-valve N. It will be readily understood· that the breaking of the envelope F will at once admit of the escape of the compressed air, which will cause 85 the diaphragm to rise to its normal position, thereby breaking the circuit and extinguishing the lamp.

To enable the lamp to be extinguished at will without letting out the compressed air, 90 the bottom B is fitted with a switch arrangement 0, consisting of a piece of vulcanite eccentrically attached to a stem and turned by outside handle, which enables the end of one of the leads Έ, normally in contact with one 95 end of the peg H, to be held off same.

Where a more yielding material than metal is used for the diaphragm L—such as indiarubber—I prefer the arrangement shown in Figs. 5 and 6. A-suitable collar P is screwed 100 through a hole in bottom B, having the

I top covered over with a yielding material Q, s

413,708 pressed up by the head of the stem R. By the spring S one end of one of the spring-connections of the incandescent lamp is carried through bottom B and attached to stem R, 5 which on being pressed down by a pressure within the glass envelope completes the circuit by coming down on contact-stud T, connected to one of the leads E. To prevent all danger from sparking when the contact is io not made and broken in a gas-tight chamber,

I coyer the contact parts of stem R and stud . T with a piece of thin india-rubber tubing U.