172 THE POPULAR SCIENCE MONTHLY. 



We might make a distinct and legitimate study of numerous 

 forms of sounding apparatus, constructed on the theory of the 

 whistle, whose peculiarities consist in the manner in which the 

 air is sent over the tongue, the vibration of which produces the 

 sound. Thus, we have the pedal-horn, and the India-rubber bulb 

 whistle of tramways and omnibuses, the various systems of 

 horns that give notice of the approach of fire-engines, the alarm 

 whistles of steam-engines, "howler" whistles, and locomotive 

 whistles ; the last of which are sometimes tuned to nearly a dis- 

 tinct tone for each line. Much that is interesting might also be 

 said concerning the variations in the engineer's whistle for his 

 different calls, upon the signal-man, for the clearance of the 

 track, etc. But this would take us away from our topic. 



Modern common whistles are infinite in their variety, and 

 new kinds are appearing every day, as the fancies of amateurs 

 bring them forth. They are made of wood, bark, metal, horn, 

 shell, glass, and even of sugar. While the form of the apparatus 

 and the manner of using it change from time to time, as the 

 fruitful imaginations of fanciers devise new patterns, the prin- 

 ciple of the construction is invariable. Some conception of the 

 capabilities in design of the instrument may be gained from a 

 glance at Fig. 4. Among the whistles here represented, we 

 find the scholar whistle (3), the fireman's whistle (5), which gives 

 mi when the u^iper hole is open, and do when it is closed with 

 the finger ; the Belgian whistle (15), of inelegant shape ; the 

 square whistle with two holes, giving two notes (7) ; and the 

 Baduel army regulation whistle (9), Of a quite different type 

 is the Swiss whistle for railroad-station agents (2), in which 

 the column of air is broken upon the summit sphere and a 

 part is swallowed up, while another part is thrown outside. 

 The marine regulation whistle (6) is of a similar structure ; but, 

 like the American whistle, there is a secret in manipulating 

 it. In order to produce a sound, the upper end of the pipe and 

 the adjacent sphere must be shut up in the hand. A variety 

 of movements are necessary for the execution of different modu- 

 lations, which make a whistling - school on the quarter-deck 

 the analogue of the schools of the trumpet and the drum in 

 regiments. There are also whistles with three or four openings, 

 like the horn whistle and the railroad whistle. In the former 

 (13) the extremities A and D may be regarded as mouths, and 

 the sounds are also modified by closing alternately or in succes- 

 sion the openings B and C. In the second (13), by leaving all 

 open, we obtain a quite characteristic mixed and false sound. 

 Special modifications are obtained with the roulette whistle (1) 

 and the bird whistle, with which the songs of various birds are 

 imitated. Fancy has run rife in devising typical whistles, like 



