PROCEEDIXGS OF THE POLYTECHNIC ASSOCTATIOX. 925 



three rings of enveloping brick-work bound by hoops of angle iron, 

 and are to receive, after being laid, an internal lining of brick-work, 

 bringing the diameter to twelve feet nine inches. The length of the 

 tubes, including the shore ends, will be five-eighths of a mile. The 

 first of these will soon be completed, when it will be floated down 

 the river from the* workshop to its destination. 



This floating down immense masses of iron and masonry is not the 

 least astonishing feature of the affair, and will be effected in this way ; 

 the ends of each section will' be closed by bulkheads, thus rendering 

 the air-inclosing tube lighter than its bulk of water. When it reaches 

 Hungerford, its destination, it will be, by a moderate admission of 

 water, lowered down into its final resting place on the foundations pre- 

 pared for it, in like manner with the other sections. The ends will be 

 brought together by means of guiding rods, and a close joint tube be 

 effected by an ingenious method lately devised by Mr. Kammell. 



This great enterprise may be said to be the first ripe fruit in half 

 a century from the invention of Medhurst the Dane. This project 

 once a success, it is scarcely too much to expect that the long dreamed 

 of feat of subtubing the Straits of Dover may be in time accomplished. 



The Pneumatic Railway at the American Institute Fair. 



It would be, indeed, surprising if the inventive genius of this 

 country had continued to sleep while the progressive labors above 

 detailed were going on in England. The matter of underground 

 railroads has been twice before the Legislature of this State ; and last 

 year two bills were presented, asking for the right to form a company 

 and the necessary charter to enable it to run pneumatic tubes for 

 mail dispatching purposes through this city. These bills, like many 

 others, died a permature death in Albany, but with them did not die 

 all hope in a successfnl future for the pneumatists, if we may coin a 

 short name for them for convenience sake. Charters were obtained 

 in Massachusetts, Connecticut, New Jersey and PenneyLvania, and it 

 is understood that two biUs for New York will be again presented 

 with best guarantees of success at the next session of the Legislature, 

 In thp meantime onr spirited neighbor, Mr. Alfred E. Beach, of the 

 ScientiJiG American, is the first in the field with his demonstration 

 of the practicability of pneumatic passenger locomotion, made on an 

 actual working scale. The splendid example of a pneumatic railroad 

 erci-ted at the last American Institute fair, and which M'as in suc- 

 cessful operation, is the project of that gentleman ; and it is not too 



