_Exposed Thermometer_ (United States Weather Bureau pattern), with brass support, $2.75. _Maximum and Minimum Thermometers_ (United States Weather Bureau pattern), mounted together on one board, $6.25. _Wet- and Dry-Bulb Thermometers_ (United States Weather Bureau pattern), mounted on one board, complete with water cup, $6.50. _Sling Psychrometer_ (designed by Professor C. F. Marvin, of the United States Weather Bureau), consisting of two exposed mercurial thermometers, mounted on an aluminum back, and provided with polished, turned hard-wood handle and brass trimmings, $5.00. _Sling Psychrometer_, consisting of two cylindrical bulb thermometers, mounted one a little above the other upon a light brass frame, with a perforated guard to protect the bulbs while swinging, but which can be raised (by sliding upon the frame) for the purpose of moistening the linen covering of the wet bulb. Much less liable to be broken than the Weather Bureau pattern, $5.00. _Rain Gauge_ (United States Weather Bureau standard), 8 inches in diameter, complete, with measuring stick, $5.25. _Rain Gauge_, 3 inches in diameter, with overflow and measuring stick, $1.25. _Wind Vane_ (United States Weather Bureau pattern), $10.00. _Anemometer_ (United States Weather Bureau pattern), with indicator, aluminum cups, and electrical attachment, $25.00. The same, with painted brass cups, $23.00. _Anemometer Register_ (United States Weather Bureau pattern), with pen and ink attachment, $35.00. The same, with pencil attachment (old style), $24.00. _Aneroid Barometer_ (for meteorological work), $14.00-$16.00. NOTE.——Much cheaper aneroids can be purchased, and may be used to some advantage in the simpler observations in schools. _Mercurial Barometer_ (Standard United States Weather Bureau pattern), complete with attached thermometer, vernier, etc., $30.00-$33.00. NOTE.——The above instruments, as used by the United States Weather Bureau, are made by H. J. Green, 1191 Bedford Avenue, Brooklyn, N. Y. The prices are those given in Green’s latest catalogue. _Mercurial Barometer._ New improved form, especially designed for school use. Mounted on mahogany back. Scale engraved on aluminum. Divisions of scale on metric and English systems. No vernier, $5.75. (L. E. Knott Apparatus Co., 14 Ashburton Place, Boston, Mass.) _Thermograph_ (designed by Dr. Daniel Draper, of New York). Consists of a bimetallic thermometer in a case which carries a disk, with a chart upon its axle instead of hands like the ordinary clock. A pen (resting on the face of the disk) registers the fluctuations of temperature as the chart is carried around. Sizes, 14 × 20 inches, $30.00; 10 × 14 inches, $15.00. This instrument may be purchased of H. J. Green.