wooden support entirely disconnected from the refractometer which was mounted on brick piers.
FIG. 1. — Vertical section through tubes. FIG. 2. — Plan of tubes. FIG. 3.— One end of tubes, allowing glass plate inclined to axis. FIG. 4. — Gauge for velocity at different points. FIG. 5. — Plan of refractometer.
The flow of water was obtained by filling a tank four feet in diameter and three feet high, placed in the attic, about 23 meters above the apparatus, with which it was connected by a three inch pipe. The latter branched into two parts, and each