Page:Popular Science Monthly Volume 5.djvu/267
"The pneumatic tube extends from the London and Northwestern Railway Station at Euston Square, to the General Post-Office in St. Martin's-le-Grand. The central station is in Holborn, where is also the machinery for effecting the transit of the trains. Here the tube is divided, so that in effect there are two tubes opening into the station, one from Euston to Holborn, and the other from the Post-Office. The length of the tube between Holborn and Euston is exactly a mile and three-quarters. The tube is of a flattened, horseshoe section, 5 feet wide and 4 feet 6 inches high at the centre, having a sectional area of 17 square feet. The straight portions of the line are formed of a continuous cast-iron tube, the curved lengths being constructed in brick-work, with a facing of cement. The gradients are easy; the two chief are 1 in 45 and 1 in 60; the sharpest curve is that near the Holborn station, which is 70 feet radius. The tube between Holborn and the Post-Office is 1,658 yards in length, and is of the same section, and similarly constructed to the first length. Two gradients of 1 in 15 occur on the Post-Office section, but this steep inclination is in no way inimical to the working of the system. The Holborn station is situated at right angles to the line of the tubes, which are therefore turned toward the station into which each opens. All through-trains, therefore, have to reverse there, and this is effected in a simple manner by a self-acting arrangement.
"The wagons, or carriers, as they are termed, weigh 22 cwt., are 10 feet 4 inches in length, and have a transverse contour conforming to that of the tube. They are, however, of a slightly smaller area than the tube itself, the difference—about an inch all round—being occupied by a flange of India-rubber, which causes the carrier to fit the tube exactly, and so to form a piston upon which the air acts. The machinery for propelling the carriers consists of a steam-engine having a pair of 24-inch cylinders with 20-inch stroke. This engine drives a fan 22 feet 6 inches in diameter, and the two are geared together in such a manner that one revolution of the former gives two of latter. The trains are drawn from Euston and the Post-Office by exhaustion, and are propelled to those points by pressure. The working of the fan, however, is not reversed to suit these constantly-varying conditions; it works continuously, the alternate action of pressure and exhaustion being governed by valves."
Dr. James McNaughton, President of the Albany Medical College, and Professor of the Practice of Medicine, is supposed to be the oldest medical lecturer now in active service. He has delivered fifty-three annual courses of lectures, and, during this half-century of work, has not missed a dozen lectures or been confined to the house a week by sickness. He is seventy-seven years old, and is hale and active.
The white-willow, it is said, has been used very successfully in Iowa for fencing. C. B. Mendenhall, of Marshall County, has about thirteen miles of white-willow fence, of from three to seven years' growth, of which above half will turn cattle. He has also a grove of white-willows, set out about six years ago, which is considered to be worth about $500 per acre.
A Western paper reports that a spaniel, named Curly, performs the duties of mail-carrier between Lake of the Woods, Dakota, and the Minnesota line, twelve miles distant. Letters and papers are placed in a sack and tied about the dog's neck; he is told to go, and never fails to reach his destination. On his arrival, the mail is over-hauled, the dog is treated to a good dinner, and started back again.
Philadelphia possesses a very energetic Zoological Society of about 500 members. Thirty-five acres of ground in Fairmount Park have been assigned to them for a zoological garden, though for the present they will occupy but ten acres. Within the last six months the society has laid vulcanite walks through the garden, built a monkey-house, and made other provision for a large number of beasts and birds from all parts of the world. A small collection has already been made, which will this summer be added to by importations from Africa, Asia, and Australia. There will be a large aquarium, and it is intended to institute courses of popular lectures on Natural History.At a meeting of the Philadelphia Academy of Sciences, Mr. Meehan exhibited a