Testimonials. 



Director's Rooms, College of Civil Engineering, of Cornell University, 



Ithaca, N. V., April 10, /5pp. 

 C. L. BERGEK & SONS, 9 Province Court, Boston, Mass. 



Gentlemen: In answer to yours of the ;th inst., I am pleased to bear testimony to the excellence of your 

 work as instrument makers. 



We have here in our equipment a large number of transits and levels, and none of them, with perhaps one 

 exception, are superior to yours in excellence of workmanship and effectiveness in details. The exception 

 referred to is the work of an artist long since dead. 



The last dumpy level we bought of you is an excellent instrument in all respects, both as to the suitable 

 sensitiveness of the level, and the satisfactory performance of the objective. 



Very truly yours, E. A. FUERTES, Director and Dean. 



New Roche lie, N. Y., April 10, iSQQ. 

 Messrs. C. L. BERGER & SONS, 9 Province Court, Boston, Mass. 



Gentlemen: Your favor of April 6 at hand. In reply will say that the light field transit (special), 

 of the number 2 class, instrument number 2940, has been used in my field work and tested thoroughly with 

 results as follows: 



Instrument, light but very steady. 



Plates, good. Reading to 30" and not too close with the magnifiers attached. Inverting telescope, all 

 that could be desired. Decidedly prefer it to my other erecting transit telescope, the field being clearer and 

 more brilliant. 



Bearings smooth and seemingly perfect- 

 Vertical circle, with double opposite verniers, a fine piece of work, which I hardly expected would show 

 such perfect centering. 



Level on vertical circle, a great convenience in topography with stadia. 



Reversion level. Could hardly part with this now, as when vertical circle is not in use, I use the level 

 reversed, bringing it to the top of telescope and directly under the eye. I am unable to discover any error 

 in its use either above or below the telescope. The bubble is very sensitive and admits of the best of work. 



Fixed stadia wires. Under repeated tests fail to show any errors in spacing. 



Davis solar. Quite necessary on some work. Easy to attach and no extra weight. 



Striding level. Have twice purposely thrown the axis out of adjustment to test whether striding level 

 would bring same absolutely horizontal, as well as to test the rings. Each time, after bringing into adjust- 

 ment with the level, the ordinary test by sights failed to show any discrepancy. This makes the adjustment 

 simple and easy and the matter of a few minutes only. 



In the first work done with this instrument on an extended survey, twelve angles were taken and five in- 

 strument points were occupied and straight lines extended over very hilly country. Angles were all taken 

 and read on A and B verniers. Were then repeated and read on both verniers. One repetition only. A 

 vernier single angles gives ten seconds too much. Mean of A and B verniers on one repetition gave six sec- 

 onds too much. Why use larger and heavier instruments'? 



Yours truly, L. E. VAN ETTEN, Civil Engineer and Surveyor. 



ANGLE A VERNIER MEAN OF A AND B 



(one repetition) 



1 180 41'' oo" 180 41' oo" 



2 143 34 30 143 34 23 



3 161 56 45 161 56 48 



4 86 53 oo 86 52 52 



5 158 1045 158 1045 



6 169 57 30 169 57 30 



7 1 80 58 30 1 80 58 15 



8 90 14 30 90 14 23 



9 i?9 26 3 179 26 48 



10 115 20 10 115 20 15 



ii. 153 43 153 43 oo 



12 179 04 oo 179 04 07 



1800 oo' 10" 1800 oo' 06" 



U. S. Dep. Mineral Survey, 



Boulder, Colorado, April n, i8qq. 

 Messrs. C. L. BERGER & SONS, Boston, Mass. 



Gentlemen: The number 4 Mountain, Mining and Reconnaisance transit which I received from you 

 last December has been greatly admired by all the mining engineers who have seen it. You will remember 

 that I had many consultations with you and hesitated for some time before placing an order for a number 4. 



You frequently assured me that I would not regret having ordered the number 4 size; I assure you 

 that I do not regret having done so. My object was to combine lightness with accuracy in an instrument. I 

 believe I have accomplished my object. I have tested the little instrument many times over a standard line 

 and I find that it is as reliable as other makes of instrument of larger size. The graduations are clear cut 

 and can be easily read without the aid of a glass. The levels are extremely sensitive, both on the telescope 

 and on the plates. 



The main telescope has a large field ot view, and objects seen through it appear very clear cut and dis- 

 tinct. This feature has been especially noted by other engineers. The design which enables your patent 

 auxiliary telescope to be used either as a side or top telescope for vertical sighting is very simple and the 

 change from the side to the top or vice versa is easily made. 



The lightness of the instrument, together with the interchangeable auxiliary telescope, especially recom- 

 mends it for underground work. All the above features render this size of transit very desirable for an engi- 

 neer whose work covers a large section of country, and I cheerfully recommend the number 4 with the 

 attachments to all members of the profession. 



Very respectfully yours, C. A. RUSSELL, Mining Engineer 



