PREFACE. 



. Efficiency, as a distinct branch of contemporaneous activity, has 

 its origin in the complexity of modern life, in the diminishing 

 margin of natural resource and the relentless crusade against time 

 wasted in unprofitable results. It demands honest effort, intelli- 

 gent interpretation and a replacement of tradition with obviously 

 better methods. 



Greater refinement of method characterizes not only the larger 

 engineering projects of to-day but dominates policy in the manu- 

 facture of the better grades of equipment. All logical enterprises 

 meeting a natural demand have an upward tendency a constant 

 trend toward progress and evolution. 



In the manufacture of Surveying Instruments, the problem of 

 producing parts to pre-determined standards of accuracy is a 

 matter of systematic insistence. Inferiority is the inevitable 

 response to a demand for quantity in preference to quality, and 

 precision instruments have never been manufactured upon the 

 basis of lowest unit cost or maximum output. 



All engineering work is founded upon an effort to utilize power, 

 materials and equipment without preventable waste and to bring 

 actual performance up to the level of an accepted standard of com- 

 parison. Such investigations require a critical study of the nature 

 and source of error as well as logical conclusions as to their relative 

 importance. 



In linear measurement the origin and magnitude of errors are 

 reasonably tangible quantities; but in angular measurement the 

 effect of natural, instrumental and personal influences tends to 

 modify accuracy. On the rational and commonly accepted 

 assumption that the absolute value of an angle is never known, we 

 can corollate the proposition that instrumental errors can be fairly 

 compensated by the systematic process of reversion, repetition and 

 equalization; but where the result is affected by personal 

 inefficiency there is no ground for discussion . 



On the other hand, the more confidence an engineer reposes in 

 his own capabilities, the more critical and exacting he becomes 

 concerning each inscrutable detail of construction for which the 

 maker alone is responsible. The instinctive tendency in every 

 high class man is toward higher class results, partially accomp- 

 lished at least through the elimination of time or patience lost in 

 unstable instruments. 



To extend the boundaries of popular knowledge on this sub- 

 ject, to provide a ready reference in relation to instruments of our 

 own manufacture and to give our customers the best there is in 

 value and treatment without their insistence, is the excuse and 

 necessity for the publication of this, the ninth, enlarged and 

 revised edition of the Saegmuller Vest Pocket Handbook. 



B. & L. O. CO. 



Rochester, N. Y. 

 |1915 



