An introduction to natural philosophy: designed as a text book, for the use of the students in Yale College ...


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Seite 315 - ... fluid, or with which it will descend, if it is heavier, is equal to the difference between its own weight and the weight of an equal quantity of the fluid.
Seite 155 - DB ; hence, (Art. 177,) the time of one vibration will be to the time of a body's falling freely down half the length of the pendulum, as the circumference of a circle to its diameter.
Seite 87 - MECHANICAL POWERS, are six in number ; viz. 1 . The Lever ; 2 The Wheel and Axle ; 3. The Pulley ; 4. The Inclined Plane ; 5 The Screw; 6. The Wedge.
Seite 91 - The pulley is a small wheel, movable about its axis by means of a cord, which passes over it. When the axis of a pulley is fixed, the pulley only changes the direction of the power ; if movable pulleys are used, an equilibrium is produced, when the power is to the weight, as one to the number of ropes applied to them.
Seite 250 - The' pressure thus excited is so intense, that the seeds in the bags are formed into a mass nearly as solid as wood. Instances have occurred in which the wedge has been, used to restore a tottering edifice to its perpendicular position. All cutting and piercing instruments, such as knives, razors, scissors, chisels, nails, pins, needles, awls, &c. are wedges. The angle of the wedge, in these cases, is more or less acute, according to the purpose to which it is applied.
Seite 250 - In determining this, two things are to be considered — the mechanical power, which is increased by diminishing the angle of the wedge ; and the strength of the tool. which is always diminished by the same cause. There is, therefore, a practical limit to the increase of the power. and that degree of sharpness only is to be given to the tool, which is consistent with the strength requisite for the purpose to which it is to be applied. In tools intended for cutting wood the angle is generally about...
Seite 156 - CIRCULAR arcs, is to the time down half the length of the pendulum, as the circumference of a circle to its diameter ; and therefore, within moderate limits, the time will be the tame, whether the arc of vibration be larger or smaller.
Seite 46 - If three forces acting at a point are in equilibrium they can be represented in magnitude and direction by the three sides of a triangle taken in order.
Seite 309 - From 4-1 it follows that the weight of the body must be equal to the weight of...
Seite 259 - The cutting tool, shaped according to the pattern to be executed, is attached to the end of a screw; and the metal being held in a proper position beneath it, the Fly is made to urge the tool downwards with such force as to stamp out pieces of the required figure. When the pattern is complicated, and it is necessary to preserve with exactness the relative situation of its different parts...

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