SCIENTIFIC SUMMARY. 
435 
or attaclied to any part of his person. The flow of the escaping air from 
the helmet through the lamp gives a bright flame, enabling the diver to see 
in all directions, rendering the employment of the expensive electric light 
no longer necessary. 
A Pneumatic Sewing-machine. — An apparatus of this description has 
been lately patented by Mr. J. E. Holmes. It consists of a sewing-machine 
having, below the table, a train of gear-wheels and an air-pump, operated 
by a crank, the pump being used to exhaust the air from a cylinder, under- 
neath a piston which traverses the cylinder. The exhaustion of the air 
causes the piston to descend and drive the sewing-machine. If a vacuum 
equal to 14 lbs. to the inch can be obtained, the piston being nine inches in 
diameter, the pneumatic pressure on the piston will be 890 lbs., equal to a 
weight of that amount falling say three feet, the height of the sewing- 
machine table under which the piston is placed. 
Improved Raihoay-carriage Brakes. — These have been described to the 
Society of Engineers by Mr. W. H. Fox, C.E. His conclusions are that 
every engine and carriage should be fltted with brake apparatus capable of 
reducing it from a speed of sixty miles per hour to a state of rest in a dis- 
tance not exceeding 220 yards on a level, in ordinary weather; that a 
retarding force of 18 per cent, of the weight of the train is sufficient to do 
this ; that cast iron is generally more suitable than wood as a material for 
brake-blocks ; and that experiment shows that a pressure of 2|- tons is re- 
quired to be applied to the cast-iron blocks fltted to each of the four wheels 
of a carriage weighing 10 tons, and 1-8 ton if wooden blocks be used in like 
manner. The author considers that the atmospheric brake complies with 
nearly all the conditions necessary to be fulfilled by a perfect continuous 
brake. See also Scientific American.” 
An Instrument for bringing up Portions of the Ocean-bed has been dis- 
covered by a blacksmith on board the ship Hydra. The Challenger, the 
exploring ship now on a voyage of discovery round the world, is supplied 
with a number of these instruments. The machine consists of a hollow 
metal rod, fitted with valves, and on which are rove cast-iron weights 
of 100 lbs. each, one for every 1,000 fathoms of estimated depth. The 
whole is so adjusted that the weights detach themselves on striking the 
bottom, and only the rod, with the soil within it, is recovered. When the 
Challenger started on her voyage, some months ago, she had thirty of these 
weights, which will probably have to be replenished before she has com- 
pleted her work. A much better instrument (in the opinion of the 
Scientific American ”) for deep-sea sounding is that invented by Sidney 
E. and G. L. Morse, brother and nephew of the late Prof. S. F. B. Morse, 
patented in New York in 1866. This machine consists of a rod containing 
a series of hollow glass balls, by means whereof (the number of balls being 
increased or diminished) any desired degree of buoyancy may be imparted 
to the instrument. Bags of sand or stones are attached, by which the rod 
is carried down, and the lower end made to scoop up a portion of the ocean 
bottom. The sand-bags become detached when the rod strikes bottom, 
and the rod then rises with amazing velocity to the surface, shooting up 
into the air as if discharged from a gun. This instrument is also provided 
with glass-pressure chambers and mercury, so arranged that the pressure 
F F 2 
