540 



SCIENCE 



[N. S. Vol. XXVIII. No. 721 



that is to say, the greatest amount of good 

 must come from a given expenditure of 

 energy. This makes tlie machine efficient 

 and shows that it is doing all that it is 

 possible for it to do, and when this is the 

 ease it is generally considered that the 

 engineer has successfully performed his 

 duty. If it is a question of using the force 

 or material in some other way, through 

 some other kind of machine ; then the engi- 

 neer may also be concerned and it may be 

 necessary for him to change his methods of 

 work to conform to a new demand — that is, 

 of economy. In some cases the application 

 of the force or the iise of material is not 

 economical, for reasons which are beyond 

 the power of the engineer to control, for 

 they may be economic in their character. 

 In the future, waste of raw material should 

 be abhorrent to the engineer and his aim 

 should be to conserve the materials which 

 nature has provided for his use. The agri- 

 culturist and the forester, as well as the 

 engineer, are concei*ned in the conservation 

 of the natural resources, but in a broad 

 sense all may be considered as belonging to 

 the same class. They all develop the nat- 

 ural resources of the country and prepare 

 them for the use of men. I shall speak of 

 these resources separately and try to show 

 in what way the engineer, the forester and 

 the agi'ieulturist may work for their con- 

 servation. 



FORESTS 



I have already stated that in the early 

 days of our history it was the one aim of 

 the settler to destroy the forests because 

 they were in his way. He was an agricul- 

 turist and needed to have his land cleared 

 of trees and other obstructions in order 

 that he might harvest the greatest crop. 

 As the country grew the demand for lum- 

 ber inereE(sed and then it became necessary 

 to save the trees in the forest and turn 

 them into lumber, but the supply still 

 seemed inexhaustible and only the finest 



and best of the trees were used. The de- 

 structive use of the forests thus begun has 

 continued ever since, though perhaps not 

 in so great a degree. It takes from thirty 

 to seventy-five years to grow a tree, but the 

 lumbermen only cut those which have 

 grown the straightest and cleanest and only 

 use the best parts of the tree that is cut. 

 The branches and the upper part of the 

 tree are left to decay in the forest. They 

 are not only wasted, but they are scattered 

 over the ground in such a way as to pre- 

 vent future growth, for the soil is covered 

 with a mat of material through which it is 

 hard for any living thing to penetrate. It 

 is necessary to burn this over in order that 

 a new growth may rapidly start. But the 

 burning over of the forest effectually kiUs 

 the young trees which were growing among 

 the old ones and thixs entails a further loss 

 iipon the forest and its owner. 



The demand for lumber has increased 

 enormously during the past few years. In 

 ISSO the consumption per capita in the 

 United States was 360 feet, while in 1906 

 it was 440 feet. The total amoi:nt of lum- 

 ber cut in 1906 was over 40,000,000,000 

 feet, and this yearly amount will largely 

 increase in the future, both throi;gh the in- 

 crease in popiilation and through the in- 

 crease per capita, unless some steps are 

 taken to prevent it. No accurate census of 

 the amoi:nt of timber in the country has 

 been made, but it is estimated that we have 

 now of standing timber aboiit fourteen 

 hundred billion feet. TVe are using forty 

 billion feet per year. Upon this basis the 

 present lumber supply will last thirty-five 

 years, but this does not take account of the 

 increase in the amount used per year nor 

 does it take into account the amount of 

 timber which will grow during the next 

 thirty-five years. If nothing is done to 

 increase our forest area we may suppose 

 that these two will balance each other, al- 

 though it is probable that the lumber cut 



