Today | News | Books | Recipes Adventure | Science Fiction | Ghost stories | Poetry | Children | History Bookastrolabe had been procured ready-made. The second part of the treatise, or 'Operatio Astrolabii,' begins with the words 'Nomina instrumentorum sunt hec.' This is evidently one of the sources from which Chaucer drew largely[55]. Chaucer's Part i. is almost wholly taken from this, but he has expanded it in several places, with the evident intention of making it more easy to understand. In Part ii. he has taken from it, with more or less exactness, sections 1-3, 5-8, 10, 11, 13-18, 20, 21, 24, 25, 27-31, 33-37, 41 and 42; whilst sections 4, 9, 12, 19, 22, 23, 26, 32, 38-40 and 43 do not appear in it. In other words, Messahala's treatise accounts for thirty-one conclusions out of forty-three, or about _two-thirds_ of the whole. In some places, Chaucer has translated almost word for word, so as to leave no doubt as to his authority. Besides which, I have already remarked that Chaucer's version is _directly_ connected with Messahala by the quotations from the latter which appear in MS. E.; see description of this MS. at p. lix. If it be inquired, whence did Chaucer derive the remaining third of his Second Part, I think it very likely that some of it may be found amongst the varied and voluminous contents of such a MS. as Ii 3. 3, which is a sort of general compendium of astronomical and astrological knowledge. The complete solution of this question I leave to some one with more leisure than myself, being satisfied that to have found the original of Part i. and two-thirds of Part ii. is to have made a good start. It must not be omitted, that the MSS. of Messahala are not all alike; that some copies have propositions which are not in others; and that the order of the Conclusions is not invariable. The chief noteworthy difference between Chaucer's version and the Latin original is in the order of the Conclusions; it is clear that Chaucer not only took what he liked, but rearranged his materials after his own fashion. § 26. VARIOUS EDITIONS. About the early printed editions of the Astrolabe, I have not much to say. The Editio Princeps of 1532 was clearly derived from some MS. of the second class, and, what between the errors of the scribes and printers, absurdities abound. After a careful examination of the old editions, I came to the conclusion that the less I consulted them the better, and have therefore rather avoided them than sought their assistance. All the editions not only give the conclusions in a wrong order, but (like the MSS. of the second class) absurdly repeat Conclusion I. of Part ii., and reckon the repetition of it as Conclusion III. MSS. of the first class are free from this defect, and may thus be easily known. The only edition worth consulting is that by Mr. A. E. Brae, published quite recently, in 1870. Mr. Brae made much use of MS. I., besides which he consulted the Printed Editions, and MSS. H. and L. See the descriptions of these MSS. above. From this edition I have taken many hints, and I wish to express, very thankfully, my obligations to it. Mr. Brae has brought to bear upon his work much skill and knowledge, and has investigated many points with much patience, minuteness, and critical ability. But I cannot but perceive that he has often expended his labour upon very inferior materials, and has been sometimes misled by the badness of those MSS. to which alone he had access[56]. Besides his print of Chaucer's Astrolabe, Mr. Brae has reprinted some curious and interesting critical notes of his own, and has added some essays on Chaucer's 'prime,' on 'the Carrenare,' and 'shippes opposteres.' To all that he has done I am much indebted. § 27. WORKS ON THE SUBJECT. The works upon, and descriptions of, the astrolabe, are numerous. I have had neither time nor inclination to make researches into the subject; for which reason I here note the names of a few books which may be examined by the curious reader. In his Universal Lexicon, Zedler explains that astrolabes are of two kinds, 'universal' and 'particular.' He speaks of the astrolabes (1) of Gemma Frisius; see Petri Apiani Cosmographia, per Gemmam Phrysium restituta; (2) of Johan de Rojas, a Spaniard, A.D. 1550; (3) of De la Hire the elder, professor of mathematics at Paris, A.D. 1702; (4) of Johannes Stoflerinus (or Stöffler), A.D. 1510. The last of these varied from the others in adopting a different and more convenient system of projection, viz. that upon the plane of the equator, or one parallel to it, the eye being in the antarctic pole, and the arctic pole being made the centre of the instrument. This projection is the same as that which was used by Ptolemy, and it is adopted in the diagrams which accompany Chaucer's treatise in some of the MSS. It should be observed here that the term 'astrolabe' alone is vague; it was originally a general name for any circular instrument used for observation of the stars; but in the sixteenth and seventeenth centuries it was restricted to the particular kind called the 'Astrolabe Planisphere,' or astrolabe _on a flat surface_, in which sense alone the word is used throughout this volume. See the English Cyclopaedia, Arts and Sciences, s.v. _Astrolabe_. The simplest work is that by Stöffler or Stoflerinus, as he calls himself; see also Gemma Frisius, Metius, Clavius Bambergensis, the Cursus Mathematicus of Dechales, vol. iv. p. 161, Delambre's History of Astronomy, and other works. The plates in Metius are most exquisitely engraved, and on a large scale, and give a better representation of the instrument than any others that I have seen. One of the MSS., viz. MS. E., refers to an astrolabe belonging to Merton College, Oxford[57]. There is a very nice one, made of brass, and by a Dutch engraver, in the library of King's College, Cambridge. It has several discs or plates, or, as Chaucer calls them, 'tables[58].' Of this instrument the same library contains a written description, with some account of the problems it will solve, and an investigation of its probable date, by H. Godfray, Esq., of St. John's College. There is a book entitled 'A verie briefe and most plaine description of Mr. Blagrave his Astrolabe,' &c., by Mr. Blundevill; London, printed by William Stansby. But it turns out to be of little practical assistance, because Blagrave's astrolabe was on a different principle. § 28. DESCRIPTION OF THE ASTROLABE PLANISPHERE. There is not, however, much need of reference to books to understand what the astrolabe used by Chaucer was like. The instrument may be readily understood from a brief description, and from the Plates in this volume. The most important part of the 'astrolabe planisphere' consisted of a somewhat heavy circular plate of metal from four to seven inches in diameter, which could be suspended from the thumb by a ring (i. 1), working with such freedom as would allow the instrument to assume a perfectly perpendicular position (i. 2). One side of the plate was perfectly flat, and was called the _back_. This is represented in Fig. 1. On it |