OF AETS AND SCIENCES : FEBRUARY 14, 1865. 425 



Ride for Solid Cylindrical Cast-steel Pillars. 



According to Ilodgkinson, calling thie strength of a cast-iron pillar 

 1000, the strength of a cast-steel pillar, not hardened, of the same di- 

 mensions, is 2518. Then to find the safe weight for a solid cylindrical 

 cast-steel piiku-, find, by the preceding rules for cylindrical cast-iron 

 pillars, the weight for a cast-iron pillar of the same dimensions, multiply 

 this weight by 2.518, the product will be the safe weight for the cast- 

 steel pillar. 



Rule for Solid Cylindrical Pillars of Dantzic Oak and Red Deal.* 



According to Hodgkinson, calling the strength of a cast-iron pillar 

 1000, the strength of a pillar of the same dimensions of Dantzic Oak 

 is 108.8 and of Red Deal 78.5. Then, to find the safe weight for solid 

 cylindrical pillars of these materials, find, by the preceding rules for 

 cylindrical pillars of cast-iron, the weight for a cast-iron pillar of the 

 same dimensions ; if for Dantzic Oak, divide this weight by nine, if for 

 Red Deal, by thirteen, the quotient will be the safe w^eighffor the 

 wooden pillar. 



Rule for Solid Square Pillars of Dantzic OaJc and Red Deed. 



Find the weight for a cylindrical pillar of a diameter equal to the 

 side of the square pillar by the next preceding rule ; add one half to 

 this weight, the sum will be the safe weight for the square pillar. 



* Barlow's formula for the breaking weight of a beam supported at each end 



and loaded in the middle is, S = - — rr ; in which S is a constant to be determined 



4 a (P 



by experiment, W the breaking weight, I the length between the points of support, 

 a the breadth and d the depth of the beam, the dimensions being all in inches. 



For Dantzic oak (so called in England from the place of shipment), 



from experiments by Barlow and Moore . . . . .8=1518 



For American White Oak (Quercus alba), from experiments by 



Nelson S = 1699 



For Eed Deal (Pinus sijlvcsiris, Scotch Fir, Riga Fir), from ex- 

 periments by Barlow . . . S = 1165 



For American White Pine (Pinus strobus), from experiments by 



Nelson S = 1456 



The values of S do not necessarily give the relative strengths of different woods 

 when used for pillars; they, however, afford some indication, and we may conclude, 

 from the values quoted, that we may safely adopt the rule for pillars of Dantzic Oak 

 for pillars of American White Oak, and the rule for pillars of Red Deal for pillars 

 of American White Pine. 



