64 On the Electric Telegraph of Prof. Morse. 
Such being the capabilities of the telegraph, and such the sim- 
plicity of its details, its frequent erangement becomes an object of 
wonder, and it would seem that the invention might be made more 
reliable. The most thorough experience proves, that, setting 
aside natural difficulties, the requisites for reliability are ‘few au 
simple. Firm structure, good instruments, efficient battery, com- 
petent human skill, but especially, thorongh insulation. A want 
of any of these destroys reliability at once. The first, structure, 
have been generally incompetent, the poles so weak and small as 
to make it sometimes doubtful whether, in relation to. the wire, 
it supported or was supported, the wire so badly secured as to 
break often without any violent external cause. If not broken, 
each of the ductile wires has been sSaeuale hable to contact 
with its support or its fellow cord. Let us trace the effect of such 
contact. As the ground is used asa seat conductor, as a wire 
of the tenuity of “Wollaston’s platina thread would be sufficient 
to conduct the current, and as the capacities of conductors vary 
with their size, defects in insultation become conductors to the 
earth. Suppose a line erected as our ordinary lines with a bat- 
tery however at but one end. 'T'he current passing from the pee 
tive pole proceeds through the miles of conducting wire to the 
ina 
certain proportion to its length, a connection with the earth at 
some point between the two stations would be preferred to 
at the distant station. Thus a certain part of the battery current 
would be returned at the point of non-insulation, the force of ne 
battery would be unequally distributed, the magnets on the 
tery end having a preponderance in proportion to the extent ak 
relative position of the non-insulation. The best non-conductors 
we Be Bue are insufficient for perfect insulation. Ona dong jine, 
the Re ary i though the insulation be practically entire. The 
want of a few glasses makes a difference quite perceptible. The 
crossing of wires acts as described above, throwing upon the 
wire used, the aggregate non-insulation of the two. Did defec- 
tive insulation act as a constant quantity, less difficulty would 
be experienced, but its effects are highly inconstant and_ vari- 
able. They are often such as might be attributed to the violent 
* agi tation, contact and separation of the wires, in a gale of wind. 
“Slight variation of current exists almost always—generally | 
ae than during theday, and beiug more prevalent on long than 
‘Gircuits, they may be attributed to the electricity of the at- 
no 2; doubtless the wire in its passage through 500 miles of 
p same is exposed to very different electrical states of the atmos- 
az ascity ying. time it was supposed imbosnibie to A Sia two 
. 
Oe eh aie a, a ie ta 
