About the same time as Lilienthal was at work the author succeeded in evolving the arched form, or dipping front edge, purely from theoretical considerations, at that time having no knowledge of the previous work of Phillips or the experiments then being conducted by Lilienthal. If the body be arranged to deal continually with the same set of particles, none being allowed to escape, then it may be supported without any continued expenditure of energy-that is to say, without any work being done. In the case of the field proper to a force of stated direction applied to a given body in a quiescent fluid, it follows from considerations belonging to hydrodynamic theory that the form of the field is unique, that is to say, its geometry is absolutely defined by the conditions. I would say, that played on my best sound-system theres sometimes just a little too much going on in there, busy-ness confusing those essential Band-style empty spaces in the music. Now the factor that must limit the thickness of this stratum is evidently the size and shape of the plane, for the more remote layers of the fluid only escape by the fact that a circulation takes place from the side of greatest to the side of least pressure, which circulation depends chiefly upon the size and shape, and but little upon the angle of the plane.
It is evident that when the layers of air adjacent to the aeroplane are diverted these will react on the neighbouring layers of air, and so on, so that a stratum of some considerable thickness will be involved. But if an up-current is encountered, impinging on the advancing edge of a loaded aeroplane, the downward momentum communicated to the air will be augmented, and may be regarded as consisting of two parts, to the sum of which the sustaining force is due, i.e., the part communicated in bringing the up-current to a state of rest and the part communicated to the air as velocity downwards. It is extremely probable that Acrae was not founded until after two obvious outposts had already been occupied-a post guarding the road to Acrae itself, and including the sacred enclosure of Apollo, which later, when it became a quarter of the city, acquired the name Temenites; and another post on the road to the north, in the upper part of the region known as Achradina.
Fig. 61.§ 110. In the Region of a Falling Plane,-Up-current.-In the foregoing discussion the subject has been treated as if the air, coming into the immediate region of an advancing aeroplane, is in a state of rest, and as if the support is wholly derived from the downward velocity imparted to it. From an external perspective it is close to a self-evident truth that the world of external objects does not exist within the cranium of the subject; but from the internal perspective, which is what we actually have as occupants of consciousness, that same world of external objects does exist as a representation within the subject. § 109. Dynamic Support.-Endeavours have been made in the past to apply the principles of the conservation of momentum-that is, the doctrine of the continuous communication of momentum (§ 3)-to estimate directly the efficiency of an aeroplane sustaining a load and the expenditure of power necessary. In both cases it will be observed that the projected particles act as carriers of momentum between the earth’s surface and the dynamically supported body, the weight of which is eventually carried down and distributed on the surface beneath; and, moreover, we are unable to conceive of any arrangement of material particles used for dynamic support, however complex, that will not eventually transmit the stress produced by the weight of the body down to the surface of the earth.
Case 2.-If, on the other hand, the particles and the surface of the earth be perfectly elastic, the former will rebound with a velocity equal to that with which they strike, and the system as a whole will not lose energy. The force of gravity in the one case can be substituted by the resultant of the force of gravity and an applied force of propulsion in the other. Such estimates generally fall short of the experimental value in the relation of about one to two. One member of the Socorro sheriff’s office told him that “hundreds of persons” on the south side of town had heard it. The day after I arrived in Basel, we went to what was going to be the last flea market in town before quarantine. II. Metaphysics as positively drawing from the results of science to illuminate the truths of Christian revelation, as a contribution to integral Christian wisdom.
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