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62.

reached, whereas the meteor enters the earth's atmosphere with an enormous initial velocity.
  
If it is considered, for any reason, desirable to dispense with a sufficiently large parachute, the retarding of the apparatus may be accomplished to any degree by having the rocket consist, at its highest point of flight, not merely of instruments plus parachute, but of instruments together with a chamber, and considerable propellant material. Then, after the rocket has descended to some lower level, let us say, to the upper limit of [[underline]] s [[/underline]] [[subscript]] 6 [[/subscript]], this propellant material can be ejected, so that the velocity is considerably checked before the apparatus reaches as low an altitude as say, 5,000 ft. For the cases in which the effective velocity, c(l-k), is as large as 7,000 ft/sec. there is little inconvenience in increasing the mass in this way. But for the case in which c(l-k) = 3,500, this method can hardly be as satisfactory as the parachute method; for if the "final" mass to be elevated is made a number of pounds, let us say [[underline]] n [[/underline]], the "total initial mass" (which is large even for one pound final mass) will be [[underline]] n [[/underline]] fold larger, and the apparatus correspondingly more expensive.

[[underline]] APPLICATIONS TO DAILY OBSERVATIONS [[/underline]].

Before leaving the subject of the attainment of high altitudes within the earth's atmosphere, it will be well to mention briefly another application of the method herein discussed; namely, to the sending daily of small recording instruments to [[underline]] moderate [[/underline]] altitudes, such as five or six miles. As is already understood, simultaneous daily observations of the vertical gradients of pressure, temperature, and wind velocity, at a large number of