This instrument has been devised for exploring different regions of the brain and also as a means of instituting permanent ventricular drainage in cases of internal hydrocephalus, on the service of Dr. William Sharpe.
It consists of a dull-pointed ventricular puncture needle, 15 cm. long, with two eyelet openings near the end; a forked stylet 15 cm. long; a casing 6 cm. long; and a probe 15 cm. long; all are graduated in centimeters. When the ventricular cavity is entered, the stylet is removed, allowing the fluid to escape. If a permanent drainage is desired, the depth of the cavity is ascertained, Stylet 3 is removed, and the outer casing, 1, 6 cm. long, and also graduated in centimeters, is inserted over the puncture needle, 2, to the desired depth. There the casing is held in the proper position by means of the handle, and the puncture needle is now