LEVELLING. 



299 



LEVELLING. 



used for the same purpose, and for deter- 

 mining the level of drains, &c. The 

 diagram exhibited in Fig. i. and the 

 accompanying remarks are taken from 

 Loudon's " Self- Instruction for Young 

 Gardeners." 



"Suppose," he says, "it were required 

 to run a level through the ground indi- 

 cated, AB, from the point A. Provide a 

 few staves proportioned in length to the 

 work in hand, and let them have cross 

 pieces to slide up and down ; then, having 

 firmly fixed the staff, to which the quadrant 

 is attached, in the ground, at the point A, 

 set the instrument in such a position that 

 the plumb line should hang exactly parallel 



5 feet 6 inches down the second, 5 feet 

 9 inches down the third, &c., &c. The 

 dotted line AD would then represent the 

 line parallel to the bottom of the intended 

 drain." 



Where elevations or mounds are to be 

 thrown up, stakes should be inserted of 

 the desired height, and a line stretched 

 across their tops to show the conformation 

 of the surface, as in Fig. 2. These stakes, 

 in all garden operations, should range 

 from 10 to 20 feet apart, 15 being a good 

 average ; they are not only necessary for 

 ascertaining the levels, but enable the men 

 to perform their work with the utmost 

 ease and certainty as to the result. In the 



or fttr 



15 



20 



30 

 ^ 



FIG. I. LEVELLING GROUND WITH QUADRANT. 



to the perpendicular limb of the quadrant ; 

 the upper limb will then be horizontal. 

 This done, direct the eye through the 

 sights, and, at the same time, let an assistant 

 adjust the slides on each staff so as exactly 

 to range with the line of vision. Then 

 suppose the height AC to be 5 feet down- 

 wards from the upper side of the slide 

 upon each staff, so shall the dotted line 

 AB represent the level line required. Sup- 

 pose the operation had been to determine 

 a cut for a drain, to have a fall of 3 inches 

 in every 20 feet, the distance between each 

 staff in the above figure may be supposed 

 to be 20 feet, then 5 feet 3 inches would 

 have to be measured down the first staff, 



illustration of this method of producing the 

 outline in section of an artificial mound or 

 elevation by means of stakes and a cord, 

 the stakes a to m are driven into the 

 original surface, AB, which for convenience 

 is supposed to be level, and the cord is 

 hen stretched from top to top, as shown 

 by the solid line abcdefghklm* The cord 

 should be drawn as tight as possible, and 

 notches for its reception should be cut 

 in the tops of the stakes. The outline 

 afforded by the cord is approximate only, 

 and consists in a series of straight lines 

 from top to top of adjacent stakes. The 

 outline that the soil will take when placed 

 in position is indicated by the dotted line 



