PREFACE TO VOL. III. THE original one-volume edition of the Treatise on Mathematical Instruments having now been expanded into three volumes, this third volume is devoted entirely to the consideration of Surveying Instruments and of Astronomical Instruments, forming Parts IV. and V. of the work. The additional space thus obtained has been employed by the Author, in the first place, in describing more fully the several varieties of the instruments treated of, and in giving more detailed and comprehensive illustrations of their application; and, in the second place, in introducing entirely new chapters upon instruments for the determination of distances by observation, and upon the measurement of altitudes by the barometer and thermometer. A chapter has also been added to Part V. upon the construction and use of the Equatorial, undoubtedly the form of instrument best adapted for the examination of those phenomena of the solar orb, which now demand so much attention from the scientific world. The Author is again bound to mention his obligations to Messrs. Elliott, who have kindly supplied several of the woodcuts that illustrate the volume, and to Messrs. Parkes and Son of Birmingham, who sent him a large number of instruments for inspection, among which were the Drawing and Mining Levels, described at pp. 37, 38. To these gentlemen, and to all from whom he has derived assistance in the preparation of this and the preceding volumes, the Author begs leave again to return his most sincere thanks, and ventures to repeat the hope already expressed in the preface to the first volume, "that the skill of the workman may not appear to have been altogether inadequate to the manipulation of the materials supplied him.' 108 118 124 The Mercurial Thermometer The Standard Barometer The Syphon Barometer The Portable or Mountain Barometer The Wheel Barometer The Aneroid Barometer of Altitude Application of the Barometer to the determination of difference 3 Meteorological Phenomena denoted by the Barometer |
