402 Intelligence and Miscellaneous Articles. 



To prepare the gauze cap, a disk 4 centimetres in diameter is made 

 of iron- wire gauze of 170 to 200 meshes to the square centimetre ; 

 this is heated, and by means of a cylindrical piece of wood of smaller 

 diameter than the tube, with a hemispherical end, the disk is pushed 

 into the tube, where it is held tight by friction. The top of the 

 wire is about level with the top of the tube. 



The sheet-iron pipe which is to be sounded is held by a stand in 

 a vertical position, with its lower end about 30 millims. higher than 

 the top of the burner (200 millims.), so that the lighted and regu- 

 lated burner can be brought under the tube by means of wooden 

 blocks, and raised in the tube to such a height that the flame is 5 to 7 

 centimetres above the bottom. The lower part of my stove-pipe, of 

 1*8 metre in length, is provided with a glass cylindrical addition, of 

 1 1 centimetres in length, so that the name can be seen ; the tube 

 gives the lowest F sharp of my harmonium, corresponding to ninety- 

 four vibrations in a second. 



Regulating the burner requires a little practice ; at first gas is 

 allowed to flow freely ; it is lit, and the burner allowed to become 

 properly hot ; the flow of gas is then regulated by means of the tap 

 on the burner, or better by one further off, until the flame is only 2 

 centimetres in height. By this means a green cone of light which 

 at first occurs in the interior of the flame gradually sinks, and is 

 seen as a green ring of light between the gauze and the end of the 

 tube. (Sometimes the burner now begins to buzz, and it does so 

 without fail if the supply of gas is reduced.) If the burner is now 

 brought into the pipe, the tube immediately begins to sound; if not 

 at once, the tone certainly comes when the flat hand has been held 

 for a short time at the bottom of the tube. Instead of the hand, a 

 pasteboard disk might be placed under the tube of the burner ; but 

 the tone becomes thereby somewhat rough. 



With a little practice in the delicate adjustment of the gas-supply, 

 it is always possible to produce this tone and keep it constant for any 

 length of time, even without the disk. With a normal tone the gauze 

 is permanently incandescent ; in the dark it looks like a strawberry 

 which is surrounded by a green ring of light ; a pencil of pale violet 

 light rises a few millimetres above the tube. 



The tone thus produced, owing to the number of accompanying 

 harmonic upper tones, is richer than that produced by almost any 

 other musical instrument. The simple tone of the siren is dull and 

 thin in comparison. It can scarcely be heard without suggesting 

 the question whether a gas-organ could not be constructed on this 

 principle. There could scarcely be a more powerful mouthpiece 

 for sounding a vertical open tube than such a burner ; but the cer- 

 tainty of starting or introducing the burner is not great enough ; the 

 buzzing of the burner outside the tube may also be disturbing. Yet 

 I think that by simultaneous intonation of three large pipes tuned in 

 harmony, a powerful effect would be produced. 



2. If the vibrating flame be observed in the dark in the rotating 

 mirror, or in one which is rapidly moved backwards and forwards in 

 the hand, the incandescent gauze gives a dark-red band, in which 



