Phrenology taught us that the mind thinks by means of the brain, is liable to become fatigued by too long attention, as the locomotive muscles are by too much walking; and I therefore proposed to them to take a brief rest.
The same practice was continued every evening through the whole course, and with the same success. Many individuals expressed their gratification at having discovered such simple means of relieving the tedium of a long discourse.
I called their attention also to the absence of all means of ventilating the hall, remarking that, as we had already breathed the air which it contained for a full hour, it must have lost much of its vital properties and needed to be renewed.