Care must be taken, not to press the pieces hard to the gums; this either hinders us from perceiving the convulsion, or prevents it. I find too, that one rod, whether zinc or silver, is sufficient for the communication, and even bringing the two pieces together, will do as well, or perhaps better. But the rods are easier in the management.
Asking pardon for the liberty I have taken, without having the honour of your acquaintance, I am,
With great regard,
SIR,
Your most obedient
Humble servant,
JOHN ROBISON.
F I N I S.