Proceedings of the Polytechxic Association. 733 



When required to keep, the picture is made on a film of paraffine 

 poured on glass, and covered, while still wai-m, with the powder, and 

 treated in the same maner as the albumen paper. 



Monster Furnaces. 

 The Kosedale and Ferrj Hill Iron Company's, establishment at 

 Ferry Hill, England,, which, until lately, consisted of seven iron fur- 

 naces, each about eighty-two feet high and twenty-two feet in diame- 

 ter, has been enlarged by the erection of two furnaces, each 105 feet 

 high by twenty-eight feet in diameter. One of these has been put 

 into use, and has proved itself a signal success. The air is supplied 

 by two powerful blast engines, and the material fed by two efficient 

 hydraulic hoists and one balance hoist. When all these furnaces are 

 at work, they will produce annually about 180,000 tons of pig iron. 



Durability of Buried Iron Pipes. 



A cast iron water pipe, laid by the Old Manhattan Water Com- 

 pany, at the coi'ner of John and William streets, ISTew York, sup- 

 posed to be more than forty years ago, was recently taken up, and 

 showed no corrosion whatever. It was gray iron, which confirms 

 Mr. McAlpine's opinion as to the value of this variety for pipes. 

 Mr. James B. Francis lately took up some cast iron water pipes at 

 Lowell, Mass., which were laid in 1828. With regard to the condi- 

 tion of the metal, he says : " Thirty-nine year's use appears to have 

 made but little impression upon it." 



Venation of the Umbellifers. 



An interesting paper was presented at the Eoyal Microscopical 

 Society, London, by John Gorham, which gives the results of his 

 investigations on the distribution of veins in leaves of that class of 

 flowering plants bearing umbels. He has found that one-half, if not 

 more, of the species belonging to the L'mbellifertB have a kind of 

 venation peculiar to themselves, which consists in the existence of a 

 vein at the very edge of the leaf itself, and which more or less entirely 

 fringes the whole margin. Hence this marginal vein may be said to 

 constitute a form of venation peculiar to this order, and to give a 

 character to it which does not belong to other orders of plants. Mr. 

 J. Hogg, secretary of the society, in commenting on the paper of 

 Mr. (rorham, said, although some other plants have a similar kind of 

 venation, it would be difiicult to show that a peculiar kind of yena- 



