344 Histary of Mechanical Inventions and 



may be proper at the bottom of the ramrod. Fig. 2 can barely convey the 

 idea that it is a bore carried down through a solid rock of two inches in 

 diameter, and to the depth of nine feet, yet at C we may easily conceive 

 that it will assume the figure, as represented by the dotted line, and at D, 

 some conception may be formed of the lesser bore that has been before-men- 

 tioned. Fig. 3 represents the steel cone, which must be made in propor- 

 tion to the size of the bore, and, with respect to itself, five times the dia- 

 meter of its base in length to the apex is to be the length of the cone, but at 

 the apex a fifth part is to be cut off, being of no use. Fig. 4 is intended 

 to show the bore down through the rock, with the cone let into it as far 

 as the lower or small bore. Fig. 5 shows the proposed plan of a jumper 

 for producing a circular bore through the whole extent or depth of the 

 tube ; and Fig. 6 is another for the same purpose, either of which may be 

 used according to the workman's fancy of their utility. 



2. Description of a Selj-Generuiing Gas Lamp. Communicated by the 



Inventor. 



The oil vessel of this lamp is represented at A, Plate VIII. Fig. 3. B is 

 the tube by which the oil is admitted, C is the generator, D is a hollow 

 vessel, where the heat from the burners F, underneath, is collected, the 

 dotted lines are projecting ridges on it, within the generator, to prevent 

 the oil running down and collecting at the bottom of the generator. E is a 

 circular piece of iron to collect and retain the heat. Gare tubes to conduct 

 the gas from C to F. L is a tuhe to supply the vacancy in A with gas, as 

 the oil is discharged into C. H is a metal heater to fit into D. 



To use the lamp, fill A partially with oil, alcohol, or any fluid from 

 which gas is produced, and having made the metal-heater H red-hot, place 

 it in the bulb D ; after it has continued a minute or two, turn the stop- 

 cock I, allowing the fluid to drop slowly on the heated bulb D, below, by 

 which it will be converted into gas. When it is found to escape in sufficient 

 quantities from the burners at F, set it on fire, remove the heater, and a 

 beautiful bright flame will be supported by its own heat as long as there 

 is oil in A. 



It may be found necessary to replace the first heater by a second, when 

 the lamp is used for the first time, to expel more effectually the atmo- 

 spheric air from the generator and tubes. The heat collected in D will be 

 found sufficient to generate gas to a third burner if required, as it is an 

 indisputable fact, that most bodies in a state of combustion give out much 

 more heat than is requisite to support an equal body of flame, and it is quite 

 evident by fire spreading so rapidly in all combustible substances, if not 

 checked. x. x. 



3. On the Composition of the Mosaic Gold, or Or-Molu, discovered by 

 Messrs Parker and Hamilton. 



The resemblance of this alloy to pure gold has attached to the discovery 

 of it an importance of no ordinary kind. Although it is an alloy of zinc 



