A system of natural philosophy, designed for the use of schools and academies (1845)
Moffat, J[ohn] M. [from old catalog] · Philadelphia, E. C. Biddle · leaf 348
annexed diagram, let S re-present the sun, or any other sourceof light, and A B any opaque body,the true or proper shadow of which,on the plane M N, will be termi-nated by the tangential line C A F,and the space B A F will be entirelyshaded; but the penumbra will ex-tend from F to I, including the… … * From the Latin pe7ie, almost, and umbra, a shadow 346 OPTICS. F A I, which will be partially enlightened, the shade gradually di-minishing as it recedes from F towards I, where it will be terminat-ed by the second tangent E A I. 41. An eclipse of the sun being occasioned by the interpositionof…
Physics
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