TO THE PRACTICAL READER. 



How often, in farming, do we wish that 'we could know, 

 on the spot, how to estimate the weight of hay in various 

 conditions in the mow ; the weight of cattle by measure- 

 ment ; the capacity of a grain bin ; the weight of a piece of 

 timber, or of a load of manure ; the distance apart to which 

 to set trees or plants in order to get a certain number 

 within a certain space ; the size of an irregular field. How 

 often in mechanics do we need to know the strength and 

 measurement of masonry ; the contents of cisterns and 

 small vessels ; the area of circles ; the quality of cements ; 

 the power value of fuel ; the weight of bar iron, or of lead 

 pipe ; the fusing heat of metals ; the strength of materials ; 

 or the board measure of scantling. 



And, worst of all, how sadly we accustom ourselves to get 

 along without knowing these things ! How much we lose 

 by guessing instead of knowing ! 



The object of this book is to put it within the power of 

 every practical man to know these details ; to leave less to 

 guessing, and to enable him to guide his daily operations by 

 the light of positive knowledge. If it accomplishes this 

 purpose, neither Mr. Courtney nor I will have worked in 

 vain. 



In addition to the many tables and statements of valu- 

 able facts with which the book abounds, I have thought it 

 advisable to review very carefully all of its " agricultural " 

 matter, and to add what I could, in the space allowed to 

 me, that might be of interest to those farmers who care to 

 look a little beyond the mere question of dollars and cents 



