Sources: A Manual Of Peroral Endoscopy And Laryngeal Surgery

The simplest, best, and safest source of current is a

double dry battery arranged in three groups of two cells each,

connected in series (Fig. 8). Each set should have two binding posts

and a rheostat. The binding posts should have double holes for two

additional cords, to be kept in reserve for use in case a cord becomes

defective.* The commercial current reduced through a rheostat should

never be used, because there is always the possibility of grounding

the circuit through the patient; a highly dangerous accident when we

consider that the tube makes a long moist contact in tissues close to

the course of both the vagi and the heart. The endoscopist should

never depend upon a pocket battery as a source of illumination, for it

is almost certain to fail during the endoscopy. The wires connecting

the battery and endoscopic instrument are covered with rubber, so that

they may be cleansed and superficially sterilized with alcohol. They

may be totally immersed in alcohol for any length of time without


* When this is done care is necessary to avoid attempting to use

simultaneously the two cords from one pair of posts.

[FIG 8.--The author's endoscopic battery, heavily built for


It contains 6 dry cells, series-connected in 3 groups of 2 cells each.

Each group has its own rheostat and pair of binding posts.]