By Alhazen (lbn al-Haytham), 965-1039 ; A. Mark Smith (editor, translation, commentary)

**Read Online or Download Alhacen on the principles of reflection. A Critical Edition, with English Translation and Commentary, of Books 4 and 5 of Alhacen’s De aspectibus. Volume One - Introduction and Latin Text ; Volume two - English Translation PDF**

**Best books books**

**Bibliography and the Sociology of Texts**

D. F. McKenzie indicates how the fabric type of texts crucially confirm their meanings. He demonstrates that as works are reproduced and reread, they tackle assorted types and meanings. this can be actual of all kinds of recorded info, McKenzie claims, together with sound, snap shots, motion pictures, panorama and new digital media.

**Iberian Books - Libros ibéricos (IB)**

Alexander S. Wilkinson, M. Litt. , PhD (2002) in background, college of St. Andrews, is Director of the Centre for the historical past of the Media at college collage Dublin. he's the writer of a few reports of the booklet global of early-modern Europe.

**Eat Well, Waste Less: An A-Z Guide to Using Up Leftovers**

Must you throw away that unmarried carrot? how will you make that chilly bird tasty? are you able to use that yoghurt behind the refrigerator? all of us have leftovers, which frequently get thrown away - the typical family places over GBP500-worth of fit to be eaten foodstuff within the bin each year! This e-book: * is filled with rules for utilizing up your leftovers * supplies recommendation on making plans, purchasing and storing nutrition * might help you decrease your foodstuff money owed * may help lessen your environmental influence

**Extra resources for Alhacen on the principles of reflection. A Critical Edition, with English Translation and Commentary, of Books 4 and 5 of Alhacen’s De aspectibus. Volume One - Introduction and Latin Text ; Volume two - English Translation**

**Sample text**

But we have already established that angle XDQ (which = angle XDP + angle PDQ) = one-half angle BGA. , angle XDP + angle PDQ) = angle BGA. It follows, then, that angle XDB + angle PDQ = one half angle BGA, so angle XDB = angle XDP. The next step is to demonstrate that, if PD is extended toward point A, it will intersect GA at that very point. That it does rests on showing that the resulting triangle PAG will be similar to triangle PDS, which follows from the fact that angle PDS = angle BGA by construction, while angle APG is common to both triangles.

420-422—see esp. 169, p. 421). Proposition 20, lemma 2, pp. 419-420, shows how to drop a line from some point on the circumference of a circle through the diameter such that the segment of this line from where it intersects the diameter to where it intersects the opposite arc on the circle is equal to some randomly chosen line. Thus, as illustrated in figure 5, p. 525, the objective is to drop line AD from randomly chosen point A through diameter GB of the circle so that ED equals randomly chosen line HZ.

415-419, however, there follows a set of six lemmas that are instrumental in one way or another to the subsequent determination of reflection-points in convex and concave mirrors. , lemmas 3-6—are directly implicated in those determinations; the other two play ancillary yet critical roles in laying the requisite groundwork for them. In the first lemma, which is dealt with in proposition 19, Alhacen shows how to generate a line extending from some randomly chosen point on a circle to the extension of its diameter such that the segment of this line between where it intersects the circle and where it intersects the diameter is equal to some randomly chosen line.