376 Description of a Camp Telegraph . 
counts preferable to any other, I was unwilling to aban- 
don them entirely ; but resolved to take the precaution of 
always trying them before I should apply them to use. 
The mode I adopted was, to lay them upon a slice of 
cork sufficient to make them float upon water, and I was 
in hopes that out of a considerable number I might be 
able to select sufficient for my purpose ; but to my sur- 
prise, out of many dozens which I tried in this manner, I 
could not select one that had not polarity. Some of them 
had it but in a weak degree, and not more than one or 
two, out of the whole quantity, appeared to have it so 
strong as the one which gave birth to these experiments 
and to the present paper, which is perhaps more prolix 
than could be wished : but the subject appeared to be 
not uninteresting, and I hope the remarks I have offered 
will not be altogether useless, as every thing that can 
tend to add to the perfection of time-pieces, or to remove 
any cause that operates against their perfection, is of 
some importance.— &c. &c. 
S. Varley. 
No. 47, 
Description of a Camp Telegraph , invented by Knight 
Spencer, Esq, Secretary to the Surry Institution .* 
Sir— The important advantages resulting to the naval 
service from the introduction of the telegraph by sir 
Home Popham, now universally adopted, are too well 
known to be here insisted upon. 
That telegraphic signals have been productive of great 
advantages to land armies, for more than 3000 years, is 
very easily proved. 
* Tilloch* vol. 36. p. 321, 
