ffmplements. 39 



about an inch in diameter, pointed at one end to admit of 

 insertion in the ground. If they are used to locate long 

 straight lines or at a great distance, a piece of white or red 

 cloth is put on the top ; they will be best seen if painted 

 red and white alternately. It is clear that when a line has 

 to be staked out on the ground the operator needs an 

 assistant to place the staff in the right position; he is 

 directed to the right or left as the case may be by motions 

 of the hand. 



The water-level is a handy instrument for placing grade 

 stakes and for levelling small g U 



plots of land. It consists of a A rl 



simple tube of brass or zinc with | '" jj 1||| 



two vertical arms in which glass 

 tubes have been placed. In filling the 

 instrument the water rises to the same 

 level in the two glass tubes and it needs 

 therefore no adjustment. Now supposing 

 we desire to measure the grade and alti- FIQ. ^.-WATER-LEVEL. 

 tude of the knoll represented in Figure 13, we first stake 

 out the line A-B, putting stakes in the places indicated by 

 the figures. Placing the instrument at A, the assistant 

 holds a levelling rod in the first station (1), we now sight 

 along the surface of the water in the two tubes and 

 read the height in feet and inches on the levelling rod. 

 This done the assistant goes to the second station, the 

 height of which is read and noted in the same manner. 

 The instrument is then shifted to B, and after reading the 

 height of the two stations 2 and 3, the instrument is again 

 shifted to c, and so on. The field-notes are taken in the 



