41 8 Progress in Science. [July> 



one over the Santee River, on the North-Eastern Railroad, built in 1855 ; and 

 the other over the Great Pedee River, on the Wilmington, Columbia, and 

 Augusta Railroad, built in 1857. The air-lock used in sinking these piles was 

 invented by Alexander Holstrom. It was a cast-iron cylinder, 6 feet in 

 diameter and 4 feet high, closed at top and bottom by cast-iron plates, through 

 which were man-holes, opening downward for entrance, and bull's-eyes of 

 glass for light. Two goose-neck pipes passed through the sides and bottom — 

 one for introduction of air, and the other for the discharge of water, when it 

 would not escape through the material underneath the pile. A windlass was 

 attached for raising the earth within the pile, all of which was removed by 

 hand. There were four air-pumps set in a single frame. Construction of the 

 pneumatic pile piers for a bridge over the Savannah River, on the Charlestown 

 and Savannah Railroad was begun in the fall of 1859. The air-lock used was 

 6 feet instead of 4 feet high, and the cylinders were of wrought- instead of 

 cast-iron. In order to overcome certain defects which made themselves appa- 

 rent, an air-lock was made of less diameter than the pile, so that an annular 

 space was left between the two, in the plate covering the top of the latter, into 

 which bull's-eyes were introduced. Through the side of the air-lock was a 

 pipe or trap, inclined at an angle to discharge readily any material put into it, 

 and arranged for closing at either end ; the outer end being closed, the trap 

 was filled with material, the inner end was then closed, the compressed air 

 thus cut off from the air-lock liberated, and the outer end opened, when the 

 material would pass out. By reversing the process the trap was made ready 

 to receive material again. By this means nearly twice as much work was 

 done in the same time as with the Holstrom air-lock. It was soon found that 

 the sandy material through which these piles were sunk could be raised by the 

 escaping compressed air through a discharge-pipe, and delivered outside in a 

 continuous stream ; for this the mouth of a flexible tube, fitted to the lower 

 end of a fixed pipe, was thrust into the wet sand, and moved from place to 

 place as the material disappeared. The ratio of work done to that with the 

 whole air-lock, which before was as 28 to 10, now became as 28 to 1. 



The Rigi Railway.— On the 29th of April last Dr. William Pole, F.R.S., 

 read a paper, before the Institution of Civil Engineers, on the Rigi Railway. 

 The object of this railway is to convey passengers to the top of the Rigi, there 

 being no carriage-road thither, the only means of ascent having hitherto been 

 either by walking or by horses, or by chaises a parteurs. The summit of this 

 mountain is 4500 feet above the plain, and an unusually steep gradient of 

 about 1 in 4 was necessary. The line commences at Vitznau, on the Lake of 

 Lucerne, and is about 4 miles long. The works are mostly formed by cutting 

 and benching on the rocky slope of the mountain ; there is one short tunnel, 

 and but one iron bridge over a ravine. The gauge is 4 feet 8$ inches, and the 

 rails are of the Vignoles shape, weighing 34 lbs. to the yard. The ascent is 

 made by means of a rack and pinion arrangement, similar to that proposed 

 and constructed by Mr. Blenkinsop in 181 1. The rack is placed midway be- 

 tween the rails, and is formed of two wrought-iron cheek-plates, having 

 wrought-iron teeth inserted between them and rivetted on each side. The 

 pitch of the teeth is nearly 4 inches. The locomotive weighs about 12 tons, 

 and is supported on four wheels. The boiler is vertical, and its axis is inclined 

 to the base line, so as to be nearly upright when running on the steep gradient. 

 The crank-shaft is worked by gearing on the main axle, on which the cog- 

 wheel is placed. The speed on the incline does not exceed 3 or 4 miles per 

 hour, either up or down : the danger of getting off the rails is met by clips 

 fastened to the vehicles, which pass under the rack bar, and would, if the 

 wheels should run off, prevent the carriages from getting away. Clip-brakes 

 are provided which embrace drums on the cogged wheel-axles, so that when 

 these clips are tightened the cogs are held fast in the rack, and thus support 

 the weight of the vehicle, preventing it from running down the incline. 



Dynamometers. — A paper has recently been read, before the Franklin Insti- 

 tute, on the Francis Dynamometer, by Mr. Samuel Webber. The principle of 

 the dynamometer is that of obtaining the " horse-power," on weight moved 

 1 foot per second, by suspending that weight to the end of a steelyard, which, 



