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FORESTRY AND IRRIGATION. 



March, 



THE EFFECT OF ICE STORMS ON TREES. 



By Herman H. Chapman. 



ON the night of Friday, February 

 2 1 , a storm swept over the Atlan- 

 tic seaboard, accompanied b^^ rain which 

 froze as it fell, forming a coating of ice 

 on every exposed surface. The effect 

 of this storm on trees in some localities 

 w^as so severe as to be worth study, as 

 such storms are not infrequent and oc- 

 cur even as far inland as Kansas. Ob- 

 servations taken on the north shore of 

 Staten Island showed sound limbs up to 

 four inches in diameter broken from 

 ^Elm, Beech, Tulip, Poplar, and Black 

 Oak. Birch trees up to eight inches 

 thick were bent over to the ground. 

 White Oak alone resisted serious dam- 

 age by the great strength of its branches. 

 In many cases all the limbs of a tree 

 were broken and the crown reduced 

 fully 90 per cent. The greatest damage 

 was done in culled timber, where the 

 old trees had been left isolated. Much 

 of this was rotten and did not stand the 

 test, unsound limbs up to a foot in di- 

 ameter being torn from the trunk. The 

 damage was greatest where the wind 

 had a sweep. 



To calculate the forces which caused 

 such destruction, a number of twigs 

 were cut transversely and diagrams 

 made of the thickness of the twig and 

 the ice incrustation. The ice is of about 

 the same weight as the wood of a green 

 twig. Calculating from the relative 

 area in cross-section, it was found that 

 twigs one-eighth of an inch thick were 

 carrjdng from thirty to forty times their 

 weight of ice, those one-fourth of an 

 inch thick twenty times their weight. 



and those one-half of an inch thick five 

 times their weight. While the exact 

 calculation would be rather difficult, it 

 is safe to say that branches one-inch 

 thick were called on to support a weight 

 over ten times as great as usual and 

 possibly twice this much. 



In addition to this enormous burden, 

 the surface of the crown or branches 

 was increased over fivefold, thus multi- 

 plying the effect of the wind by that 

 factor. The wonder is that any limbs 

 were left. 



Forest trees depend very largely on 

 one another for protection from such 

 unusual conditions. Where the trees 

 grew thick and undisturbed, the protec- 

 tion from the wind was so complete that 

 much fewer and smaller branches were 

 broken; but where man had stepped in 

 and ' ' improved ' ' the woods, by cutting 

 out the underbrush and saplings and 

 leaving only the ' ' grand old trees in 

 their majestic beauty," Nature took es- 

 pecial pains to point out the error of 

 his ways, and most of these grand old 

 trees are now more fit for scarecrows 

 than for shade. That wind and ice are 

 not the only enemies that ' ' improving ' ' 

 gives a chance was shown by the fact 

 that nearly all the limbs broken off 

 showed rot in their interior. The dry- 

 ing soil, the grass, and the exposure 

 following thinning had already gotten 

 in their deadly work, and it needed only 

 the storm to reveal it. If man wants a 

 park, let him keep the whole wood, or 

 raise a new one. "Improvements" 

 are seldom accepted by Nature. 



PUMPING WATER FOR IRRIGATION. 



THIRD PAPER. 



THE arrangement of windmills for 

 pumping water for irrigation is 

 illustrated in the drawing accompany- 

 ing, which gives a view of an earth 

 reservoir built nearly circular in form. 



The two windmills which suppl}' the 

 water are placed upon opposite sides, in 

 order that the pumps ma}- be as far 

 apart as possible. In many instances 

 three or even four mills, each of mod- 



