Of Telegraphic Communication. 
jn vol. i. of the Repertory of Arts, Old Series. For a 
nocturnal telegraph it consists of four large patent reflec- 
tors, situated in the same plane and parallel to the hori- 
zon, but sufficiently elevated above it. Each of these re- 
flectors is susceptible of being elevated or depressed at 
pleasure by means of winches, and the letters of the al- 
phabet are denoted by the changes. When this telegraph 
is used in the day, gilt balls, or any other conspicuous 
objects, are tq be used instead of the reflectors. Captain 
Pasley, of the Royal Engineers, also invented two tele- 
graphs. one of them to be used by day and the other by 
night : — for a description of these see our fourth volume, 
page 6 .* 
Two methods have generally been adopted in commu- 
nicating telegraphic information : in the one, each signal 
represents a single letter 5 in the other, a complete sen- 
tence. This last has generally been thought to possess an 
advantage over the other in point of expedition, but it is 
only partial in its application ; and we have already sta- 
ted it as our opinion, that the general elements of lan- 
guage only should be transferred, and that every real im- 
provement in the telegraphic art must tend to facilitate 
the execution of this object. 
(To he continued .) 
No. 39. 
On Signals made hy Fire, f 
(With a Plate.) 
THE subject which Polybius here treats is curious 
enough in itself ; and besides, it bears so near a relation 
to the facts I am now relating, as to excuse a digression, 
that will not be of a great length, and which the reader 
* These different forms of the Telegraph will be given in subsequent mun« 
bers of the Emporium. Ed. 
-j- Rollin’s Ancient History, v. 6, p. 3$1. 9th edit. Dundee. 
