I wish to thank the Royal Society Library, BM and Bodleian; the Librarian of All Souls, Dr M. A. Hoskin and the Cambridge History & Philosophy of Science Seminar for their kind assistance.

1 M. Whinney, Wren (1971).

2 K. Downes, Christopher Wren (1971).

3 Parentalia: or, Memoirs of the Family of the Wrens… (1750), pp.351–360 Google Scholar. The evidence suggests that the commentaries on ancient buildings (pp. 360–368) do not belong to Tract IV.

4 The MS, in Christopher Jr’s hand, is bound up in the Heirloom Copy of Parentalia at the RIBA and is headed ‘Discourse on Architecture By Sr C:W:’. It was marked ‘Tract V by the Wren Society editors (xix, p. 140) and this will WREN ON be followed for convenience.

5 Royal Society MS 249.

6 All Souls MS313.

7 British Museum MS Add. 25,071.

8 The more familiar MS in the Lansdowne Collection (British Museum MS Lansdowne 698 No. 4) headed ‘Chronologica Series Vitas et Actorum Dⁿⁱ Christophori Wren Eq: Aur: Ec, Ec, Ec.’, which was endorsed by Wren in 1720, includes: ‘De Architecturâ’, ‘De Templo Paris’ and ‘De Templo Martis Ultoris’. Cf. also the MS headed ‘Chronologica Series…’ in the Heirloom Parentalia, reproduced in the Gregg Press reprint of 1965.

9 Quotation clearly acknowledged in the printed tract. See Parentalia, p. 354 Google ScholarPubMed.

10 This was pointed out by the Wren Society editors, vol. 19, p. 121.

11 The book concerned is Francesco Scipione Maffei, A compleat history of the ancient amphitheatres… Made English from the Italian by A. Gordon (1730). Christopher Jr had a copy. See A Catalogue of the Curious and Entire Libraries of that ingenious architect Sir Christopher Wren, Knt. and Christopher Wren, Esq; his Son… [1748], lot 170.

12 The biographer of the Gresham Professors. Christopher Jr was anxious to assist in compiling his father’s biography. It is interesting to see Ward annotating his own copy of the Lives of the Professors of Gresham College (1740) (British Museum, 611 m 16) with information from Christopher Jr.

13 James Hodgson, a master in the Mathematical School at Christ’s Hospital, had first told Christopher Jr of Ward’s work. Ward describes him as Wren’s kinsman ( ibid., p. 105Google ScholarPubMed) and Christopher Jr addresses him as ‘Cosin Hodgson’ (British Museum MS Add. 6209, f.205). He had previously worked under Flamsteed, to whom he was also related, through marriage, at the Royal Observatory, where, in his own words, ‘I had the Happiness to have my Education’ (The Theory of Navigation Demonstrated … (1706), Preface). Flamsteed’s records (see for example Baily, F., An Account of the Rev. fohn Flamsteed (1966), p. 238 Google Scholar) show that Hodgson was on good terms with Wren.

14 British Museum MS Add. 6209, ff. 203–221.

15 ibid., f.207.

16 ibid., f.215.

17 For example, passages from Wren’s letter to Brouncker, , Parentalia, pp. 224–227 Google Scholar, also occur on pp.217, 208, 213, 209,216. Cf. also passages from pp.213 & 221.

18 For example, compare Wren-Brouncker, , Parentalia, pp.224–227 Google Scholar, with a copy by Henry Oldenburg, Royal Society MS EL. W.3 No. 3. Also the originals of Flamsteed’s letters to Wren, Parentalia, pp. 248–252 Google ScholarPubMed, 252–253 & 253–254, are in Royal Society MS 249. Compare also Wren’s report on Old St Paul’s in Parentalia, pp. 274–277, and Wren Society xiii, pp. 15–17 Google Scholar, and his report on Salisbury cathedral in Parentalia, pp.304–306, and in Wren Society xi, pp.21–26.Google Scholar There are also many possible comparisons with printed sources.

19 For example, cf. Parentalia, pp.221 Google ScholarPubMed & 213, 225 & 217, 225 & 208, 226 & 213, 226 & 209.

20 For example, Wren Society xix, pp. 122–123 Google Scholar.

21 Colvin, H., ‘Roger North and Sir Christopher Wren’, Architectural Review cxi (1951), p.259 Google Scholar.

22 The possibility of rearrangement is suggested, but not proved, by the fact that several passages are common to Tracts IV & V. However, since both are extant only in Christopher Jr’s hand, there seems to be no reason for following the Wren Society editors in accepting Tract V as the authentic version (see Wren Society xix, p. 121 Google Scholar). Comparisons also show that Christopher Jr is capable of ‘explanatory insertions’, but it is possible to learn to suspect where these exist.

23 Pevsner, N., An Outline of European Architecture (1968), p.326 Google Scholar.

24 Summerson, J., ‘The Mind of Wren’, Heavenly Mansions and other Essays on Architecture (1949), pp. 79 & 85Google Scholar.

25 ibid., p.84 Google ScholarPubMed.

26 Sekler, E. F., Wren and his Place in European Architecture (1956), p.94 Google Scholar.

27 Whinney, , op. cit., p. 202 Google Scholar.

28 Sekler, , op. cit., p. 187 Google Scholar.

29 Parentalia, p. 351 Google ScholarPubMed.

30 ibid., p.351 Google ScholarPubMed.

31 Downes, , op. cit., p.48 Google Scholar.

32 Summerson, J., Sir Christopher Wren (1953), p. 134 Google Scholar.

33 Fuerst, V., The Architecture of Sir Christopher Wren (1956), p. 173 Google Scholar.

34 ibid., p. 178 Google ScholarPubMed.

35 ibid., p. 175 Google ScholarPubMed.

36 See Parentalia, p. 183 Google ScholarPubMed.

37 Turnbull, G. H., ‘Samuel Hartlib’s Influence on the Early History of the Royal Society’, Notes & Records Roy. Soc. Lond. x (1952–53), pp. 109–110 Google Scholar.

38 The Diary of John Evelyn, ed. de Beer, E. S. (Oxford 1955), iii, pp. 110–111 Google Scholar.

39 An English draft for the speech is in Parentalia, pp. 200–206.

40 The Correspondence of Isaac Newton, ed. Turnbull, H. W. & Scott, J. F. (Cambridge 1959- ), iv, pp. 266–267 Google Scholar.

41 Parentalia, p. 351 Google ScholarPubMed. It is clear from the following paragraph in Tract I that Wren is using the term ‘orders’ here in a very general sense.

42 Kerry Downes has pointed out that John Evelyn, in his Account of Architects and Architecture, expressed the wish that ‘some Ingenious Person’ would consider the theory of architecture ‘and Advance upon the Principles already establish’d, not so Acquiesce in them as if there were a Non Ultra Engraven upon our Columns…’ See ‘John Evelyn and Architecture’, Concerning Architecture …, ed. Summerson, J. (1968), p. 39 Google Scholar.

43 In his proposed ‘Preamble of a Charter to incorporate the Royal Society’, Parentalia, p. 197 Google ScholarPubMed.

44 Parentalia, p. 351 Google ScholarPubMed.

45 ‘A Catalogue of New Theories, Inventions, Experiments, and Mechanick Improvements, exhibited by Mr. Wren, at the first Assemblies at Wadham-College in Oxford…’ includes ‘New Designs tending to Strength, Convenience, and Beauty in Building’. Parentalia, p. 198 Google ScholarPubMed.

46 English draft for the Gresham address, Parentalia, p. 200 Google ScholarPubMed.

47 ibid., pp. 200–201 Google Scholar.

48 For example, see Summerson, J., ‘Sir Christopher Wren, P.R.S. (1632–1723)’, Notes & Records Roy. Soc. Lond. xv (1960), p. 102 Google Scholar.

49 Parentalia, p. 202 Google ScholarPubMed.

50 ibid., p.353 Google ScholarPubMed.

51 ibid., p.351 Google ScholarPubMed.

52 ibid., p.204 Google ScholarPubMed.

53 ibid., p.204 Google ScholarPubMed.

54 William Gilbert, De Magnete, magneticisque corporibus, et de magna magnete tellure; etc. (1600).

55 See the sale catalogue of Wren’s library (n.11), lots 118, 17 & 523.

56 Parentalia, p. 221 Google ScholarPubMed.

57 In ‘The rising of the Sap in Trees’, MS in Heirloom Parentalia, 1965 reprint.

58 Parentalia, p. 222 Google ScholarPubMed.

59 Bacon, Francis, Sylva Sylvarum: or a Natural Historie in Ten Centuries… (1628), p. 100 Google Scholar (see also pp. 164, 184, 197, 204). See also Hooke in Knowles Middleton, W. E., ‘A Footnote to the History of the Barometer’, Notes & Records Roy. Soc. London, xx (1965), p. 145 CrossRefGoogle Scholar. Here Wren may well have been influenced by Sir Thomas Browne’s Pseudoxia Epidemica: or, enquiries into very many recieved tenents, and commonly presumed truths (1646) (see sale catalogue, lot 523, and O 2. 26 Art Seld in the Bodleian Library, annotated by Dean Wren), pp. 213–231, especially considering the context of ‘critical days’.

60 Yost, R. M., ‘Sydenham’s Philosophy of Science’, Osiris ix (1950), p. 97 Google Scholar.

61 It seems possible that the annotations in a volume of Galileo’s Works, which belonged to Wren and is now in the Bodleian Library (Savile A. 19), give some evidence of the influence of Seth Ward in this context.

62 Hesse, M. B., ‘Hooke’s Philosophical Algebra’, Isis lvii (1966), pp. 67–83 CrossRefGoogle Scholar.

63 Parentalia, p.201 Google ScholarPubMed.

64 This claim occurs in a letter to his cousin, Matthew Wren, transcribed in the BM MS volume (MS Add. 25,071). It is not included in the printed Parentalia.

65 The frequent references in the secondary literature to Wren’s two kinds of beauty, reach their extreme expression in Reyner Banham’s article ‘Revenge of the Picturesque …’, where he actually quotes what he calls ‘Wren’s well-known dictum’, as ‘There are two kinds of beauty - natural and customary’. See Concerning Architecture…, ed. Summerson, J. (1968), p. 269 Google Scholar.

66 Parentalia, p. 351 Google ScholarPubMed.

67 Wren Society xix, p. 140 Google Scholar.

68 Parentalia, p. 352 Google Scholar.

69 ibid., p.261.Google ScholarPubMed

70 Tract, V, Wren Society xix, p. 140 Google Scholar.

71 Van Helden, A., ‘Christopher Wren’s De Corpore Saturni’, Notes & Records Roy. Soc. Land, xxiii (1968), pp.220, 222Google Scholar.

72 Wren-Sir Paul Neile, 1 October 1661. Royal Society MS EL. W.3 No. 2.

73 The original is Royal Society MS CP. 111 (1).43. It was printed in Philosophical Transactions, No. 43 (11 January 1668/9), pp. 867–868. For a translation and comment see Hall, A. R., ‘Mechanics and the Royal Society, 1668–70’, Brit. J. Hist. Sci. iii (1966–67), 24–38 CrossRefGoogle Scholar.

74 For Wren’s comments on a possible ‘demonstration’ see The Correspondence of Henry Oldenburg, ed. A. R., & Hall, M. B. (Madison, 1965- ) v, pp.347 & 375Google Scholar.

75 Neile-Oldenburg, 18 December 1668, ibid., p. 263.

76 Royal Society MS EL. W.3 No.3. See also Parentalia, p. 225 Google ScholarPubMed.

77 Parentalia, p. 351 Google ScholarPubMed.

78 Fuerst, , op. cit., p. 173 Google Scholar.

79 Colvin, H., op. cit., p.259 Google Scholar.

80 Wren-Sancroft, 7 May 1666, Wren Society xiii, p.44 Google Scholar.

81 Perrault, Claude, Ordonnance des cinq espèces de colonnes selon la méthode des anciens (Paris 1683)Google Scholar. (It is interesting that the Royal Society was given notice of this publication. See Birch, T., History of the Royal Society (1756–57) iv, p. 205 Google Scholar.) translation by John James, A Treatise of the five orders of columns in Architecture … (1708).

82 Wren’s natural beauty was relevant to determining proportions; the unprejudiced viewer would naturally prefer certain general proportions, as he would prefer regular shapes. In his report on Salisbury cathedral, Wren speaks of ‘ye natural beauty which arises from Proportion of ye first dimensions’ ( Wren Society xi, p.21 Google Scholar). Also, he told Roger North that there was a distinction between graceful and ugly in ‘the stated demensions of Columnes’ ( Colvin, H., op. cit., p.259 Google Scholar). However, Wren makes it clear that such proportions were not determined a priori and were certainly not ‘Rules, too strict and pedantick, and so as not to be transgressed, without the Crime of Barbarity’ ( Parentalia, p. 353 Google ScholarPubMed). He assures us that the ancients themselves were not very strict about the orders. ‘Correct’ proportions are determined by the judgement, they have their origin in apprehension and can be modified according as the view is modified. Thus Wren says in Tract I: ‘In Buildings where the View is side ways … there seems no Proportion of Length to the Heighth … on the contrary, Fronts require a Proportion of the Breadth to the Heigth; higher than three times the Breadth is indecent, and as ill to be above three times as broad as high…. I except… long Porticoes, though seen direct, where the Eye wandering over the same Members infinitely repeated, and not easily finding the Bounds, makes no Comparison of them with the Heighth’ ( Parentalia, p.353 Google ScholarPubMed).

83 See the sale catalogue of Wren’s library, lot 561.

84 British Museum MS Lansdowne 698 No. 4 (see n.8) dates ‘De Architecturâ to 1700, but this can, at best, be taken only as a very rough guide, since other dates in the catalogue are known to be inaccurate.

85 Wren Society xi, p. 21 Google Scholar.

86 Fréart, Roland, Parallèle de l’Architecture Antique et de la moderne,… (Paris 1650)Google Scholar. Translation by John Evelyn, A Parallel of the Ancient Architecture … (1664).

87 ibid., Preface, p.3.

88 ibid., p.2.

89 ibid., p.4.

90 See Evelyn-Wren, 4 April 1665, in Elmes, J., Memoirs of the Life and Works of Sir Christopher Wren (1823), p. 161 Google Scholar.

91 See Keynes, G. L., John Evelyn; a Study in Bibliophily, with a Bibliography of his Writings (Oxford 1968), p. 166.Google Scholar Another copy of the Parallel was given by Wren to the Savilian Library at Oxford in 1673 and is now in the Bodleian Library, Savile E.7.

92 See the sale catalogue of Wren’s library, lot 567.

93 See n.59. We remember that Wren’s copy had been annotated, although we cannot be certain that the notes were Wren’s.

94 Bacon, , op. cit., p.37 Google Scholar.

95 Parentalia, p.352 Google ScholarPubMed. The other references have already been given.

96 Fuerst, , op. cit., n. 1023 Google Scholar.

97 Downes, K., Christopher Wren, p. 49 Google Scholar.

98 Neile-Oldenburg, January 1668/9. Oldenburg Correspondence v, p. 363 Google Scholar.