26 



We commenced our triangulation in Smith's Fork Valley 

 by establishing a base-line on the top of the long ridge which 

 runs between the east and west branches of the river. This 

 line was measured very carefully. A difference of -f$ of an inch 

 only was found between the several measurements. From 

 the ends of this line our triangles stretched up the side upon 

 which our camp was situated, and across to the other side. 

 It will be seen from the triangulation map given in the report 

 that some x parts of the valley figured in the main map were 

 not reached by us ; these we were enabled to fill in from 

 sketches which we took from several points, as was our cus- 

 tom whenever it did not rain too hard. The height of No. 

 n was ascertained from the top of No. 12, which was seen 

 to be nearly on a level with it, so nearly that the small frac- 

 tion of a foot given fully covers the difference. Where it 

 was possible, we of course measured all the angles of our 

 triangles, but as we never reached the summit of No. n, on 

 account of its precipitous sides, we could not make the meas- 

 urement of the angles centering there. It formed, however, 

 a fine triangulation point, as it had a sharp, spire-like head, 

 which was situated just at the summit of cliffs rising perpen- 

 dicularly almost 2000 feet from the valley below. We expe- 

 rienced little difficulty in finding our monuments, as the air 

 was remarkably clear when we could work, and probably 

 this accounts for the accuracy of our triangles ; they closed 

 within half a minute of arc, and, as our transit only read to 

 minutes, we thought they would answer our present purpose. 

 The measurement of the triangles was always repeated three 

 times and the mean of the three readings taken. Compass 

 directions of the lines were also taken when the electricity 

 permitted. We had two camps in our work in this region ; 

 one in the little rounded valley at the head of the west 

 branch of Smith's Fork, on the left-hand bank ; the other on 

 the little hill directly at the base of No. n, on the lower side 

 of the hill, about twenty yards from the right-hand head of 

 the east branch of the same river, at a point a little above 

 the place where it joins the other head. The topography of 

 this valley we have found very hard to represent on paper 

 by means of topographical emblems on account of several 

 features which seem to be entirely peculiar to it we refer 



