PREFACE.

Greater Work (Brewer, pp. 38, 99, 117, 227). It is a treatise on the propagation of radiant forces, usually spoken of as the Multiplication of Species Latin: "Multiplicatio Specierum." Bacon used the term "species" to describe the force or likeness that an object projects into the medium around it, such as light or heat., but in one passage entitled Treatise on Rays, which I sent to you separately from the Greater Work Latin: "Tractatus de Radiis, quem vobis misi separatim ab Opere Majori.". In the present edition this treatise will be found in its proper place as an appendix to the Opus Majus Latin: "Greater Work.".

It must be added that the text, as edited, is in certain parts of the work far from perfect. This remark applies especially to the third and sixth sections. In the third section several missing pages have been supplied from a Cottonian manuscript Referring to the collection of Sir Robert Cotton, now held in the British Library. "Julius D.v." is the specific shelfmark for this volume., containing amongst other things a Greek and a Hebrew alphabet. It is the more remarkable that Jebb should have omitted these passages, since it is clear that he had consulted this manuscript and had made frequent corrections from it. The sixth section, on Experimental Science, has been so carelessly edited that it seems probable that the editor must have entrusted the work to a less competent assistant. Contractions of the most ordinary kind are misinterpreted (as for example "on the contrary" Latin: "e converso." is rendered "therefore" Latin: "ergo.", "conclusion" Latin: "conclusio." is written "question" Latin: "quaestio.", etc.), and in some passages sentences have been omitted. While indicating these shortcomings, it ought at the same time to be added that other parts of the work give proof of great labour and care in the collation The process of comparing different versions of a text to identify variations and determine the most accurate reading. of the manuscripts consulted. This is especially the case with the fourth and fifth parts, which form a very large proportion of the whole work. Having spent much time over the manuscripts used by Jebb, in addition to others, I can bear testimony to the accuracy with which variations have here been noted. All of them which are of more than verbal importance have been noted in the present edition.