Glass lenses, 58
Furnace for cementing Steel, 183
""obtaining Potassium, 212
Apparatus for trying Strength of Timber, 234
Diagram illustrating Halley's theory of Trade Winds, 270
Ground plan of Mine of Spathic Iron in New Milford, Conn., 313
Section of do., 317
Improved Surveyor's Compass, 338
Tusk of a Mastodon, found near Rochester, N. Y., 359
Singular impression in Marble, 361
Henry's large Electro-magnet, 408
Vol. XX.–Plates.
1. W. C. Redfield's Chart of the Atlantic Ocean, with track of a storm of August, 1830, 17
2, 3, 4. Aldini's Apparatus for Protection against Fire, 96
5. Transition Rocks of the Cataraqui, 74
Organic Remains, (trilobites,) &c., 78
Coal plant, (Crotalus? of A. Eaton,) 122
6. Tullia pycnanthemoides, 343
Wood Cuts.
Sketch of the Aurora Borealis, March 9, 1831, 263
Lenses for Microscopes, 265, 266, 267
Wilder's Geometrical Diagram, 285
Safety Apparatus for Steamboilers, 321
Henry's Apparatus for Reciprocating Motion by Magnetic Attraction and Repulsion, 342
Apparatus for manufacturing smoking Sulphuric Acid, 349
Apparatus for filling barometer tubes in vacuo, 365
Vol. XXI.–Plates.
1. Curves of Vaporization, 71
2. Prof. Joslin's Electro-magnet, 87
3. Section of Strata through a part of Connecticut, from Killingly to Haddam, on Connecticut River, by W. W. Mather, 94
4. Portrait of Eli Whitney, 201
5. Tomb of ""264
6. Rotascope by Walter R. Johnson, 265
Diagrams to E. F. Johnson's paper on the Epicycloid, 280
7. Geological and Mineralogical Map of a part of Orange Co., New York, by Drs. Young and Heron, 1831, 321
Wood Cuts.