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A Key to Civil Architecture : Or,

Within the power and circumscription of the Ba-lance, many ingenious enquiries may be made ; suchas measuring the weight and force of blows, thestrength of Brings, or other oblong substances, thedistinct proportion of several metals mixed together,and the different gravities of divers bodies in thewater, from what they have in the open air. But,as these things are foreign to the present design, Ishall conclude, without farther essay on the Ba-lance, with this observation, that whatever geo-metrical definitions may be in any wife serviceable,relative to the Balance, I shall speak of them in thedifferent parts of practice, as they occur; especi-ally of geometry stairs.

LECTURE III.

Of the Lever.

T H E second mechanical faculty is the Lever,the first invention of which is generally givento Neptune, the God of the Sea, and represented byhis trident.

The properties and principles of this powerfuland uleful instrument bear almost the fame propor-tions with the Balance, only with this difference—mark the following

EXAMPLE.

As the weight is to an equivalent power, so isthe distance betwixt the weight and the center untothe distance and the ppwer ; and so reciprocally.Or thus—The power that doth equiponderate withany weight, must have the fame proportion unto it,as there is betwixt their several distances from thecenter or fulciment.

The