S Utility of Mensuration to Garde?iers. 



such as cannot be waited for. Those, however, who are desir- 

 ous of instruction, will always try to provide the articles neces- 

 sary for the purpose. 



Winter is the best time for studying figures. The days, at 

 this season, are short, and the body is, consequently, less liable 

 to be so much fatigued by manual labour as to unfit the mind 

 for study ; besides which, the gardener's cares, at this period of 

 the year, are generally fewer than at any other. At this season, 

 then, the young gardener's indoor studies should be chiefly 

 directed to this useful, and, at the same time, amusing, science ; 

 and they should be continued until the practical and really 

 valuable questions of each rule can be wrought with facility. 

 Then these rules should be practically applied to measuring, 

 taking first anything easy, either solid or superficial ; else, when 

 a person begins to practise in reality, he will appear awkward, 

 and, what is worse, may commit gross mistakes. Witness the 

 acts of those who have been at school for years learning men- 

 suration, but who, previously to their beginning to practise, 

 never saw a field measured, nor a chain for measuring one. A 

 week's practical experience is worth a month's theoretical study. 

 Oral and ocular demonstrations are the life of this as well as of 

 many other things. 



When a field or piece of land which has irregular boundaries 

 is to be measured, and where offsets are required, much depends 

 on these being at right angles with their base lines ; and the 

 same of perpendiculars. Trust not to the eye, but use a cross- 

 staff. There are several modes of calculating offsets : that 

 which consists in considering them as triangles and trapezoids 

 is the best ; and all calculations of land should be made in 

 decimals. 



The measuring of round trees is a simple process by the 

 common method of a fourth of the mean girth as the side of the 

 square [whose contents are found to be adequate to those of the 

 tree] : but, simple as it is, some cannot, or rather will not be at 

 the pains to learn it ; and, of course, must always use a book. 

 Certainly foresters ought to be able to measure a tree by several 

 rules (the one to prove the other) ; by the sliding rule, and by 

 considering the tree as a cylinder. A round tapering tree, 

 measured in sections, say of three 12 ft. cuts, makes the amount 

 of the contents larger than measuring it by girthing it in the 

 middle does. Again, twice the length and one fifth of the 

 girth are data which will give the true contents of a tree ; and 

 calculating by these produces almost the same result as reckon- 

 ing from the dimensions obtained by measuring the tree as a 

 cylinder. Square logs, the sides of which are unequal, should 

 not be measured by girthing them, because the results obtained 

 by this mode are incorrect. 



