rforations about an inch in diameter, for the transmission
of the current to the feet. 1 1/4" pine plank is the most suitable wood
to use in the construction of the tub. This is preferable to any of the
hard woods, because of the greater facility of fitting in the electrodes
etc. It is also the most economical.

(_b_) _The electrodes and connections._ These consist of two carbon
plates, two brass binding posts, and insulated wires to connect the
carbons with the binding posts, and these with the battery. The carbons
are such as are ordinarily employed in the construction of galvanic
batteries, and can, as well as the wire and binding posts, be procured
from any house that deals in telegraph material. Their size is to some
extent optional; the dimensions I have given above however answer very
well.

The inside of the tub having received one or preferably two coats of
paint, the carbons are now fitted in the receptacles provided for them.
The next step is the attaching of the binding posts. These should be of
the kind known as "single" binding posts with "wood screws." The most
convenient location for them will be found on the coping covering the
horizontal portion at the head of the tub. Here the coping, as it has to
cover not only the upper edge of the head of the tub, but that of the
back-rest also, is of necessity much wider than at any other portion,
and thus affords most room for the binding posts.

Having marked out then a site for the binding posts, say in the centre
of the coping at the head of the tub--which should now be placed in
position--and about two inches apart, the posts are laid aside to be put
in place when the wires are all _in situ_, and the coping fastened down.

In order to facilitate the description of the placing of the wires by
means of which communication is to be established between the electrodes
and the binding posts, I shall term the end of the wire that is to be
attached to the electrodes the distal, that which is attached to the
binding posts the proximal end. A gimlet hole sufficiently large to
admit of the passage of one wire should be made half an inch outwards
from the centre of the site of each binding post. The best wire to use
is about No. 16 copper wire, coated with gutta percha or rubber. The
site of the posts being as above suggested, it will be found that the
wire which is to connect the head electrode with one post requires to be
about 18 inches long, that which runs from t