1. On a New Hygrometer, or Dew Point Instrument

Extract

This instrument consists essentially of a little spherical bottle of thin brass, polished externally; a small exhausting syringe; a thermometer with ground brass stopper; and a brass clamp. The bottle has a diameter of 1 3/20 inch, and is capable of holding half an ounce. Its neck is attached to the syringe by means of a lateral screw, and is three-fourths of an inch high, and about three-tenths of an inch wide. The syringe is about five inches long, and has a diameter of eight-tenths of an inch. The stopper attached to the thermometer fits air-tight into the upper part of the neck of the bottle. The clamp is intended for securing the instrument to the sill of an open window, or to a table or other fixture in a room. Three drams of ether are then slowly introduced into the little bottle, and the thermometer inserted.