Although an extensive literature is available on ocular manometry and tonometry, there are few reports concerning the flow of aqueous humor from an open eye. The earliest reference to the measurement of such a flow was made in 1702 by Hovius,1 who measured the escape of fluid when the anterior chamber was opened. In more recent years the determination of the actual rate of formation of aqueous humor has been attempted by numerous workers. The methods of investigation have given rise to two opposing schools. Leber2 and his followers employed a filtration manometer, by which means the pressure in the eye was kept at a constant level. Any increase in the aqueous humor then forced an equal amount of fluid into a graduated outlet tube. These investigators obtained the following values :3 The conclusions of Leber and his students have been opposed by Weiss,3 Troncoso4