20 The Laryngoscope. 
fuse of any kind, which in coal reaches from seven to over 
sixteen per cent. of the whole amount. In the ability to 
command a forced fire almost instantly, without a forced 
draught, which, under some circumstances at sea, is of vital 
importance. In dispensing with the numerous class of coal 
heavers, stokers, &c., and all the inconvenience of raising 
clinkers and ash from the furnace rooms; and finally the 
diminished space occupied in the storage of the fuel 
THE LARYNGOSCOPE. 
LL really useful discoveries seem to have been long 
foreshadowed before they actually appeared ina perfect 
form. It is interesting to follow that gradual development of 
ideas, which ultimately results in a new means of prosecut- 
ing scientific inquiry, and the disputes to which this 
frequently gives rise form an amusing episode in our 
scientific progress. These remarks will be aptly illustrated 
by our sketch of the history of the laryngoscope—an 
instrument which, asits name implies, enables us to see the 
interior of the larynx or wind-pipe, as well as some other 
parts hitherto hidden from the sight. The instrument 
itself is very simple, and the principle on which it depends 
easily understood. It is in fact, neither more nor less than 
the employment of a small looking glass to reflect light 
into the dark cavity. Take a tube of any kind, an ordinary 
bottle covered with paper, a wax vesta box, or a piece of 
paper rolled up and set upright on a table, will answer the 
purpose. This represents, for the time being, the human 
wind-pipe. Drop into it any small articles. - These cannot 
be seen so long as the eye remains ona level with them. 
Now take a small piece of looking-glass, fix this to a rod, 
a pen-holder will do well. By holding the mirror over the 
tube in such a way as to allow the light to fall directly 
upon the mirror, the small articles you have dropped into 
the tube, will be seen clearly. We have often seen much 
amusement produced by the offer to discover the nature of 
anything dropped into a tube of this kind by another 
person. At first it seems almost incredible—the readiness 
with which things are detected. 
Now, this simple contrivance is an exact representation 
of the laryngoscope, and shows us how we may employ 
reflected light to study the movements in the throat, by — 
