December 10. 191S 



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Wrecking with Saw on Wheels 



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WHEN THE WRECKERS UKCA.X 



THE OIJI POXTOOX ANCHORED IX THE MISSISSIPPI WAITIXd 

 TO BE CIT IXTO SAW TIMBERS READY FOR THE MILL 



The pontoon bridge of the Chicago, Milwaukee & St. Paul Rail- 

 way Company across the Mississippi river between North McGregor, 

 Iowa, and Prairie du Chien, Wis., is believed to be the largest pon- 

 toon bridge in the world. The Mississippi has two channels both 

 used by navigation at this point and two draws are operated in the 

 pontoon. The immense boats, first put into service about forty years 

 ago, have to be replaced about every tifteeu years. Within the 

 last two years a new pontoon has been built and placed in position 

 in each draw. 



The old pontoons were offered for sale. The.v contained an 

 immense lot of hardwood. Last summer ths Ed P. Eberhard Lum- 

 ber Company, manufacturers of hardwood lumber at Guttenberg, 

 Iowa, bought one of the pontoons and towed the great structure 



TRAVELING SAW AT WORK 



PROCESS OF CUTTIXG AX EXORMOUS POXTOOX IXTO PIECES TO 



FACILITATE THE SALVAGE OF THE HARDWOOD 



TIMBERS IT CONTAINS 



down to its mill, about twenty miles south of McGregor. The 

 jiroblem then was how to saw it up. The pontoon was 408 feet long 

 and forty feet wide. The stringers that held the bottom were 

 spaced two feet apart and it was impossible to use an ordinary 

 cross-cut saw and too expensive to use a hand saw. The company 

 solved the problem by building the machine shown in photograph. 

 A small gasoline engine furnished the power. The machine was 

 mounted on four wheels and two by fours were used for tracks for 

 it to travel on. The machine could be moved anywhere and cut the 

 bottom in small enough pieces so that they could be handled without 

 trouble. The saw frame works on hinges so that it can be worked up 

 and down easily. It suits its purpose well and is not difficult to 

 handle. 



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Beech and Maple Flooring Compared 



Much more flooring is made of maple than of beech, but the latter 

 wood is largely used, and by some it is claimed to be the equal of 

 maple. For some kinds of flooring it is perhaps equal and possiblj 

 superior to maple, but in most physical qualities, maple rates higiier. 

 The maple under consideration is supposed to be sugar maple. The 

 soft maples are not often used for flooring, and when so used, they 

 are inferior to beech in wearing qualitios. 



Hardness is an essential property of flooring. Tests show that 

 sugar maple rates 2,000, and beech 1,400. That is considerable dif- 

 ference in favor of maple. The test is made with a steel ball of 

 specified size. It is laid on the wood and force is applied to sink it 

 a specified distance into the wood. If 2,000 pounds will sink it into 

 maple, it can be sunk an equal distancs into beech by a pressure of 

 1,400 pounds. 



That is the meaning of the figures in this test of hardness. But 

 it makes some difference whether the steel ball is forced into the 

 end or into the side of the wood. The above figures represent side 

 hardness, perpendicular to the grain. That is the test which a 

 floor is expected to stand. But sometimes blocks are laid on end 

 to form tloors, and then it is important to know the hardness when 

 tested by end pressure. Comparing maple and beech in that way, 

 maple is 1,430, and beech 1,190. Maple is the harder, but it may be 

 observed that neither maple nor beech is as hard by end pressure 



—24— 



as by the side. It is a common belief that the end of a piece of 

 wood is harder than the side, but tests do not show such to be the 

 case. When laid as a floor or as a pavement, if the end grain is 

 exposed to wear, it may last longer than if the side grain is the 

 wearing surface; but that result is not due to hardness alone. 

 When end grain receives the wear, little splintering occurs; but 

 the exposure of the sido may lead to splintering and rapid wearing. 

 This may often be observed in factory and warehouse floors where 

 usage is hard. 



Qualities other than hardness are essential to a good floor. 

 Strength must be sufficient. A comparison of the strength of 

 maple and beech does not show much difference, but what little 

 difference there is, is in favor of maple. The strength of beoch is 

 rated at 15,000 pounds to the square inch, that of maple at 15,800 

 pounds. 



Color is often given consideration and is of more or less import- 

 ance. Maple is much whiter than beech, the latter wood being red- 

 dish. But the sapwood of beech is nearly as white as maple. The 

 sapwood of beech is not thick enough to be worked into flooring 

 advantageously. The line separating maple heart and sap is not 

 prominent and contrast is slight. It is not very important that 

 sap and heart be kept apart in grading or selecting maple flooring; 

 (.Continued on page 33) 



