122 Report on Trials of Plows. 



"Referring to diagram Fig. 6, the diagonal lines Ff^- and g f^ 

 will be found. On the line IlJ el divide the space between tlie 

 points of its intersection with the arc, 7^, and the line M m into 

 eight equal parts, and from each of the points of division I draw 

 lines parallel with the base to intersect the arc, h, and these points 

 of intersection I mark from 4 to 12, as the divisions are marked 

 on the arc, /^, of the second division; and I then draw diagonal 

 lines, /^, f^^ p, f^, f^, /^°, f^\ passing through points of the 

 divisions correspondingly numbered on the arc, h, of the second 

 division, and on the arc, k, of the third division, and project them 

 until they intersect the first division. On Fig. 5, I measure the 

 height from the base where the line F f^'^ intersects the line D d 

 or plane of the first division, and transfer that distance or height 

 on the line A a or plane of the land side. In like manner, on 

 Fig. 5, I measure the distance or height from the base where tlio 

 line g f^ intersects the line D d or plane of the first division, and 

 transfer that height on to the line A a, of Fig. G, from the base, 

 and draw a line, N n^ parallel with the base until the said line 

 intersects the diagonal line, g y^, and this point of intersection 

 will be found to be at the same distance from the line A a, Fig. 1, 

 as the point of its intersection of the said line g f^ with the line 

 D d or plane of the first division is distant from the plane of the 

 land side, so that these several points of intersection on these 

 several figures prove each other. I then strike an arc, o, of the 

 same radius as the arc k (forty-eight inches), so that it shall inter- 

 sect the point Avhere the line F f^"^ intersects the line A a, and 

 also the point where the line ^n intersects the diagonal \u\e g f^; 

 and the distance between the lines F f^~ and N n, where these 

 lines cut the said line A a, 1 divide into eight equal parts, and 

 from these divisions I draw lines parallel with the base, and these 

 several lines will be found to cut the several diagonal lines, /'^ to 

 jf^^', inclusive, where they intersect the arc o, which points of 

 intersection on the said arc, o, are numbered from 5 to 11, as tlio 

 corresponding divisions are marked on the ares, h and /,■, of the 

 second and third divisions. 



" From the several points of intersection on the said arcs o and k 

 of the first and third divisions, numbered from 4 to 12 inclusive, 

 I draw lines perpendicular to the base, and cutting the said base 

 lines; and the divisions thus obtained on the base line of Fig. 6 

 I then transfer to Fig. 4, transferring the divisions obtained from 

 the arc o on to the line 1) d, or tii'st division, and begiinu'ng with . . 



