PREFACE. 



fTlHE Instruments enumerated in this Catalogue, and described in the Manual, 

 are all of our own design and regular manufacture. Full supplies of Engineers' 

 and Surveyors' Instruments will be kept on hand. The demand, however, 

 is at times so great as to exhaust our supply. To secure an instrument in season, 

 it is best to order it from four to eight weeks in advance of its intended use. In- 

 struments vary ing from our customary designs, or those of rare inquiry, will be 

 made to order only. 



While the illustrations given represent the instruments as they have been made 

 by us, we nevertheless make changes from time to time, as experience and the 

 progress of engineering show them to be desirable. 



Our long experience in the manufacture of Engineering and Astronomical 

 Instruments, enables us to unite in our Instruments the high accuracy and finish 

 of the European makers, with the lightness combined with strength, steadiness^ 

 practicability and portability required by American engineers. 



Having three well-equipped automatic dividing engines, with circles 2, 2, and 

 3 feet in diameter (the last-named built by the late J. H. Temple, of Boston, 

 Mass.), we are enabled to make graduations of rare excellence. We also have a 

 machine for engraving the figures, etc., on our circles and plates. Our adjusting ap- 

 paratus, consisting of nine collimators, for the purpose of testing our lenses, and foi 

 correcting and adjusting the telescopes, etc., and instruments of our manufacture, 

 marks a new epoch in the manufacture of accurate Engineering and Surveying 

 Instruments. With the aid of this, we can test our instruments in so thorough a 

 manner as only the most rigid tests in the field could reveal. In the possession of 

 an apparatus of this kind, we believe, we stand entirely alone, here or abroad. It 

 is the invention of Mr. C. L. Berger of this firm. 



A careful selection of skilled workmen, increased iacilities of steam power, and 

 the application of the most approved tools and machinery, enables us to offer at a 

 moderate cost a very superior article. We make no pretence at manufacturing 

 cheap Instruments, our prices are as low as is consistent with thoroughness of 

 workmanship and the best material. 



IMPORTED INSTRUMENTS. We have made and do make Scientific Instru- 

 ments, such as Cathetometers, Spectrometers, etc., but owing to the somewhat 

 limited demand, and the fact that their manufacture entails chiefly the employ- 

 ment of hand labor, for this reason we find that we cannot produce them of equal 

 quality and completeness at prices prevalent with best makers in Europe. In 

 order, therefore, to enable customers and scientific institutions to procure these in- 

 struments at the lowest prices, we are giving our special attention to their impor. 

 tation. We refer more particularly to those used in the higher branches of 

 Geodesy and Astronomy. When a greater demand for such instruments exists, jus- 

 tifying the introduction of special tools and machinery for their manufacture in 

 numbers, we will make our own designs and improvements, and incorporate them 

 in our regular line of manufacture. These instruments we can import to the 

 order of schools and colleges free of duty. Approximate cost will be given on 

 application. 



C. L. BERGER & SO^S. 



