Popular Lectures on Science and Art: Delivered in the Principal Cities and Towns of the United States, Τόμος 2Greeley & McElrath, 1846 |
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Άλλες εκδόσεις - Προβολή όλων
Συχνά εμφανιζόμενοι όροι και φράσεις
air-pump angle apparent magnitude appear applied atmospheric air atmospheric pressure attached axis axle beam body boiler boiling point bottom bulb called cause centre of gravity cock combustion communication condenser conductor constellation constructed continued crank cylinder degree descend diameter diminished direction distance double star downward effect elastic electricity engine equal experiments explained feet fluid force fulgurites greater heat inch inclined plane increased instrument latent heat length lever light liquid lower machine magnet magnitude manner mass mechanical mercury meridian metal motion moving power nebulous necessary object observed paratonnerres pass phenomena piston piston-rod placed plane position principle produced proportion pulley quantity raised received rendered represented in fig resistance revolving rope screw sensible heat Sir William Herschel slide space steam steam-engine stroke sufficient suppose surface telescope temperature thermometer tion tube upward vacuum valve vapor velocity vertical vessel weight wheel wire
Δημοφιλή αποσπάσματα
Σελίδα 246 - The modifications and corrections, thus suggested as necessary to be introduced into our former conclusions, are applied, and a second approximation, but still only an approximation, to truth is made. For, in investigating the laws which regulate the several effects just mentioned, we are compelled to proceed upon a new group of false suppositions. To determine the laws which regulate the friction of surfaces, it is necessary to assume that every part of the surfaces of contact is uniformly rough...
Σελίδα 77 - And God remembered Noah, and every living thing, and all the cattle that was with him in the ark: and God made a wind to pass over the earth, and the waters assuaged...
Σελίδα 370 - Allotted there; and other suns perhaps, With their attendant moons, thou wilt descry, Communicating male and female light, Which two great sexes animate the world, Stored in each orb perhaps with some that live.
Σελίδα 379 - Herschel, whose powerful telescopes have effected a complete analysis of this wonderful zone, and demonstrated the fact of its entirely consisting of stars. So crowded are they in some parts of it, that by counting the stars in a single field of his telescope, he was led to conclude that 50000 had passed under his review in a zone two degrees in breadth, during a single hour's observation.
Σελίδα 392 - I have seen double and treble nebulae variously arranged ; large ones with small, seeming attendants ; narrow but much extended lucid nebulae or bright dashes ; some of the shape of a fan, resembling an electric brush issuing from a lucid point...
Σελίδα 248 - Scissors, shears, nippers, pincers, and other similar instruments are composed of two levers of the first kind; the fulcrum being the joint or pivot, and the weight the resistance of the substance to be cut or seized ; the power being the fingers applied at the other end of the levers.
Σελίδα 288 - This is the case when pins, bolts or nails are used for binding the parts of structures together ; in which case, were it not for the friction, they would recoil from their places, and fail to produce the desired effect. Even when the wedge is used as a mechanical engine, the presence of friction is absolutely indispensable to its practical utility. The power, as has already been stated, generally acts by successive blows, and is therefore subject to constant intermission, and, but for the friction,...
Σελίδα 446 - A patent for certain new methods of applying the vibrating or reciprocating motions of steam or fire engines to produce a continued rotative or circular motion round an axis or centre, and thereby to give motion to the wheels of mills and other machines.
Σελίδα 436 - I mentioned to you a method of still doubling the effect of the steam, and that tolerably easy, by using the power of steam rushing into a vacuum, at present lost.
Σελίδα 388 - I know not how to describe it better than by comparing it with a curdling liquid, or a surface strewed over with flocks of wool, or to the breaking up of a mackerel sky, when the clouds of which it consists begin to assume a cirrhous appearance.