238 REFLECTING LEVEL AND GONIOMETER. 



3. SiSi" ch.G'2 links to the centre of a gap. 



1 " 2-1 '' to an iron wood. 



4. 267° 1 " 31 " to a large beech, convex outward ten feet. 



5. 266° " 45 " to centre of a gap. 



1 " 45 " to a sugar tree near a spring. 



2 " 14 " to a beech. 



A NEW Reflecting Level and Goniometer. By 

 Prof. Locke. 



This instrument consists of a small spirit level, set in a brass 

 tube, with plane sights, and having a small diagonal reflector 

 placed over the bubble. 



It is used without a stall', tripod, or other special support, being 

 raised or lowered by hand, like a pistol, the eye ranging along 

 the sights, until the bubble at the same time seen in the reflector, 

 passes across the central opening, or remains stationary in the. 

 field of view, when the range is presumed to be level. In lev- 

 elling up a hill or ravine, I adopt the following method : Stand- 

 ing at the bottom, and ranging towards the hill, I mark some 

 object, as a stone, a stick, leaf, or a stake, at the horizontal point, 

 of course on a level with the eye. Next, advancing to the above 

 named mark, and standing with my feet upon it, I repeat the 

 same operation with regard to a second mark, (k:c., keeping tally 

 of the number of observations. In this operation, my own alti- 

 tude to the eyes, five feet five inches, is tlie unit of measure, and 

 answers the purpose of the target rod of the engineer. The 

 number of observations multiplied by this altitude in feet, obvi- 

 ously reduces the whole perpcndiculm- altitude to that denomi- 

 nation. 



If necessary, I examine geologically each unit, or fathom, by 

 itself, and make a corresponding entry in my note book. In 

 descending a hill, a mark or station may be levelled by back 

 sights, varying the position either backward or forward until the ' 

 proper altitude shall be attained by trial. This instrument I have 



