Perché haveressemo caro havere li ochiali, li quali te mandiamo notati in la lista qui inclusa, volemo che havuta questa debii vedere de recattarli che siano in perfectione per le etate como dice dicta lista; et mandarneli facendoli mettere in qualche scatola ben asettati et separati l'una sorte da l'altra cum li scripti attacati, in modo che quando li habiamo sapiamo discernere l'una sorte da l'altra; avisandone de quello costarano perché te faremo provisione al pagamento. Mediolani XIII iunii 1466.

Some models include a protruding clitoral stimulator, designed to tickle the vulva or anus during sex (and during masturbation while the ring is used on a dildo). Others, such as the vibrating ring, vibrate, either vibrating the ring itself, or using two removable bullet vibrators to provide stimulation to the testicles and clitoris. Some cock rings have vibrators attached that can be worn to stimulate the scrotum or perineum of a partner during sexual intercourse. Many women find that rings with vibrator attachments provide clitoral stimulation that is needed for achieving orgasm.

A cock ring[a] is a ring worn around the penis, usually at the base. The primary purpose of wearing a cock ring is to restrict the flow of blood from the erect penis to produce a stronger erection or to maintain an erection for a longer period of time. They are sometimes used as medical devices, on their own or in conjunction with a penis pump to assist in the management of erectile dysfunction. Genital adornment is another purpose, as is repositioning the genitals to provide an enhanced appearance.

Concavemirror

24 On this question, see Rosen, ‘The Invention of Eyeglasses,’ pp. 211-217. For Venetian guild regulations, see also Gasparetto, A., Il vetro di Murano dalle origini adoggi (Venice, 1958), pp. 52–63 Google Scholar, who, unaware of Rosen's article, tentatively accepted the Venetian origin of spectacles (p. 60, n. 59).

19 Ronchi (Scritti di ottka, p. xxi, and ‘A Fascinating Outline,’ p. 529) has already noted this advance in Renaissance optics, but he does not give the date of this discovery and cites no documents.

Cock rings worn just behind the corona of the glans of the penis are known as glans rings, head rings or cock crowns. A ring that is worn around the penis and scrotum is also usually called a cock ring, but is sometimes referred to as a cock and ball ring. Rings that are worn just around the scrotum, in order to hold the testicles, are called testicle cuffs or ball stretchers.

4 ‘The Sense of Vision and the Origins of Modern Science,’ in Debus, A. G., ed., Science, Medicine and Society in the Renaissance. Essays to Honor Walter Pagel, 1 (New York, 1972), 29.Google Scholar

27 ‘A Giovanni Bonsi [Alessandra's son-in-law, also residing in Florence] farò comperare gli occhiali e de’ più fini, come tu di', e per primo si manderanno. Questo di si comperorno gli occhiali, e ti si mandano sotto lettere di Niccolo Strozzi a Roma pel fante: sì che fa’ d'avergli… .’ Alessandra Macinghi negli Strozzi, Lettere di una gentildonna fiorentina del secolo XV ai figliuoli esuli, ed. C. Guasti (Florence, 1877), p. 277. Both sentences were written on the same day (March 23), but earlier portions of the letter were written on the preceding day, which means that the spectacles were purchased in a day or less. For reference to this and the following letter by Alessandra Strozzi, I am indebted to Ellen Potash, an undergraduate at Brown University, who in her research on the family in the fifteenth century kept her eyes open and found the two passages here cited.

A ring made of stretchy material is stretched over the penis (and optionally also the scrotum, except when used with a pump for impotence) and situated against the body. Rigid rings are used differently: first each testicle is fed through the ring and the entire scrotum is pulled through, then the flaccid penis is pushed through the ring and the ring is situated against the body.[1]

48 I have not found any Lombard works of art depicting eyeglasses up to the end of the fifteenth century after consulting the following publications: Toesca, P., La pittura e la miniatura nella Lombardia. Dai più antichi monumenti alla metà del Quattrocento (Milan, 1912; rpt. Turin, 1966)Google Scholar; Gengaro, M. L. and Arano, L. Cogliati, Miniature lombarde. Codici miniati dall'VIII al XIV secolo (Milan, 1970)Google Scholar; Meiss, M. and Kirsch, E. W., The Visconti Hours (New York, 1972)Google Scholar; Berenson, B., Italian Pictures of the Renaissance. Central Italian and North Italian Schools, rev. ed., 3 vols. (London, 1968)Google Scholar; D'Ancona, P. and Aeschlimann, E., The Art of Illumination. An Anthology of Manuscripts from the Sixth to the Sixteenth Century, tr. Brown, A. M. (London and New York, 1969)Google Scholar; and all the art sections in the Treccani Storia de Milano, Vols, v-viii (1310-1535) (Milan, 1955-57). Admittedly this represents a very small sampling of published works and a minute fraction of the total production, but the fact that spectacles have been found more readily in art outside Lombardy is significant in itself.

Unless otherwise noted, all documents here cited form part of my extensive microfilm collection of Renaissance diplomatic documents.

8 Some oculists as late as the nineteenth century believed that the use of spectacles with concave lenses might deform the eye. See Sorsby, A., A Short History of Ophthalmology, 2nd ed. (London and New York, 1948), p. 73.Google Scholar

Commercially available cock rings are made from many different materials, including: leather, rubber, silicone, neoprene, nylon, metals (including: aluminium, steel, titanium, silver, gold and platinum), wood, plastic, bone, horn, ceramic, glass, and semi precious stone. They also come in a wide variety of sizes, with an inner diameter ranging from 35–63 mm (1.4–2.5 in).

50 I have read the dispatches of Delia Scalona in 1462 and those of Andreasi from June through July 1466, Mantua, Archivio di Stato, Archivio Gonzaga, Carteggio-Milano, buste 1622 and 1623 respectively.

When used in cases of erectile dysfunction (ED), they are known by various other names, such as erection rings and tension rings.

Please list any fees and grants from, employment by, consultancy for, shared ownership in or any close relationship with, at any time over the preceding 36 months, any organisation whose interests may be affected by the publication of the response. Please also list any non-financial associations or interests (personal, professional, political, institutional, religious or other) that a reasonable reader would want to know about in relation to the submitted work. This pertains to all the authors of the piece, their spouses or partners.

Rings for ED must be able to be placed in position while a pump is connected; the erection is lost as soon as vacuum is removed unless the ring is already in place. This rules out most types other than simple elastic rings.

Do you have any conflicting interests? * Conflicting interests help Close Conflicting interests help Please list any fees and grants from, employment by, consultancy for, shared ownership in or any close relationship with, at any time over the preceding 36 months, any organisation whose interests may be affected by the publication of the response. Please also list any non-financial associations or interests (personal, professional, political, institutional, religious or other) that a reasonable reader would want to know about in relation to the submitted work. This pertains to all the authors of the piece, their spouses or partners.

An erection ring may be worn to treat erectile dysfunction (ED). When used for ED, a purpose-designed vacuum pump is used to produce an erection by simple mechanical and hydrodynamical action in spite of vascular or nerve damage, and the ring is slid off the pump's cylinder onto the base of the penis to maintain the erection before it is lost. The testicles are not ringed in this case. When used with a pump, a lubricating gel is always used to help the pump maintain a vacuum, in the same way vacuum grease is used with a vacuum pump in scientific applications. The gel also makes it easier for the ring to slide off the pump, and later, to remove it from the penis.

- No HTML tags allowed- Web page URLs will display as text only- Lines and paragraphs break automatically- Attachments, images or tables are not permitted

The writing in this letter and in the preceding two is faded in places. I am indebted to my collaborator, Dr. Mario Fara, who has transcribed these passages from the originals.

Concave lensesexamples

42 French Painting in the Time of Jean de Berry. The Late Fourteenth Century and the Patronage of the Duke, 2 vols. (London and New York, 1967), 1, 5, reproductions in II, Nos. 296-297, 826.

Concave lensesglasses

12 Ronchi errs in stating that no writing of any kind about eyeglasses is known for the fifteenth century and the first half of the sixteenth: ‘Nulla si conosce del secolo XV e della prima metá del XVI,’ (Scritti di ottica, p.xxii).For already known references to spectacles in fifteenth-century texts, see Heymann, Madame Alfred, Lunettes et lorgnettes de jadis (Paris, 1911), pp. 2ff.Google Scholar

20 See Jackson, E., ‘Historic Evolution and Use of Spectacles,’ American Journal of Ophthalmology, to (1927), 607–608 Google Scholar, and Gordon, ‘A Short History of Spectacles,’ p. 7.

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22 Ronchi (Scritti di ottica, p. 27) cited this passage from Codex F, fol. 25: ‘Questo ochiale di cristallo debbe essere netto di machie e molto chiaro e da lati debbe essere grosso un'oncia d'un'oncia cioè 1/144 di braccio e sia sottile in mezo secondo la vista che lui l'à adoprare, cioè secondo la proportione di quelli occhiali che a lui stanno bene.’ Ronchi claims that Leonardo simply wanted to indicate the degree of curvature of a convex lens, and adds that ‘per quanto non si abbiano notizie di sorta circa il periodo in cui si cominciarono a fare lenti divergenti, non sembra che al tempo di Leonardo tali lenti fossero ancora state introdotte nell'uso’ (pp. 27-28, n. 2).

Designs range from the simple to the complex. Simple rings may lie flat on a surface, while others are ergonomically curved to fit more comfortably on the wearer. Some designs are horseshoe shaped with a closure. In cross section, the rings may vary from round to flattened oval, the latter offering more friction on the penis and are therefore less likely to slip. Many of the newer rings also have different accessories and projections.

33 On the preeminence and influence of the Venetian glass industry in Europe through the seventeenth century, see Gasparetto, , Il vetro di Murano, pp. 66–70, 100-112Google Scholar; Mariacher, G., Il vetro europeo dal XV al XX secolo (Novara, 1964), pp. 77–92 Google Scholar; and Davis, F., Continental Glass from Roman to Modem Times (London, 1972), passim. Google Scholar

The purpose of a cock ring is to trap blood inside the penis in order to maintain an erection, or encourage a stronger erection. In order to do this, it must be placed at the base of the penis.

Cock rings that are too tight, or worn for too long can be dangerous: this may cause priapism, a medical emergency that, if not treated promptly, can result in severe and permanent damage, including penile gangrene that can result in the destruction and possible amputation of the penis. Rings for erectile dysfunction are invariably supplied with the instruction that they should not be left on for more than thirty minutes. Falling asleep with a ring on is a particular danger. This may lead to temporary or permanent nerve damage. Numbness in the glans penis, penis becoming cold or penis becoming white may be signs that a cock ring has been worn for too long and medical advice should be sought.

Concave lensesuses

14 Nicodemo Tranchedini to Giovanni Simonetta, Florence, November 4, 1462, Milan, Archivio di Stato, Potenze Estere-Firenze, cart. 270. The relevant portions of this letter follow: ‘Illustri [?] Domino Iohannes. El nostro Illustrissimo Signore, per soa littera sottoscripta de vostra mane, me scrive gli mandi tre dozine d'ochiali et che gli drizi ad voy et avisi de quel costano, che me manderà li denari. Mandovi dicti ochiali alligati ad questi, quali costano tre ducati perché gli ho voluti in totale perfectione. Non voglio ad verun modo dichiate el costo ad Sua Celsitudine, perchè el facto mio non sta cum Soa Excellentia in questi minuzoli. Et quando oltra ala mia provisione ho voluto da luy denari, cavali et altre cose, non é stato scarso meco, ma factomi più che non ho meritato. Quello che voglio da voy e che me recomandiate strectamente ad Soa Sublimità, et quella avisiati che per essere stato circa doy anni senza havere havuto cosa veruna de la provisione me da, mi trovo oltra al stentare como cane, in debito de parechie centenara de ducati… . Et pur in quest'anno ho havuto mandare a Madona doe some de bianco et vermiglio, che me costò circa 19 ducati cum le victure et gabelle. Questo inverno anche gli manday al Signore 18 para d'ochiali fine, mandare de li mei cum soe littere etc. A tucto va denari, et non ne havendo da Soa Sublimità, non ne posso havere da altri. Siché pregate Soa Sublimità m'aiuti fin a la morte, et ad quella enixe me recomando… . Lecta questa strazatella.’ Written on the verso of the letter: ‘Questi ochiali sono de quatro maniere. Veda el Signore de quali vole et avisatemene, che gli manderò quanti piacera ad Soa Celsitudine.’

Perché sonno molti che ne domandano delli ochiali che se fanno li ad Fiorenza, attento che la fama é che se fanno in più perfectione che in veruno altro loco de Italia, volemo te te [sic] commettiamo che ne deby mandare tre docene de dicti occhiali, acconzati in schatole che non se possano rumpere; zoé una docena de quelli sonno apti et convenienti ad la vista longa, zoé da zovene; et un'altra che siano convenienti ad la vista curta, zoé de vechy; et la terza da vista comune. Li quali te aviso non volemo per nostro uso, perché per la grazia de Dio nuy non ne havemo bisogno, ma li volemo per compiaceme ad questo et quello che ne li domandano. Mandandoli per le poste de nostri cavallari, li quali drizaray in mano de Zohanne Symonetta, nostro secretario, et avisandone de quello costarano perché te mandaremo li denari. Datum Mediolani XXI October 1462.

47 There is no mention of eyeglasses in connection with fifteenth-century portraits either in Pope-Hennessy, J., The Portrait in the Renaissance (New York, 1966)Google Scholar or in Alazard, J., The Florentine Portrait, tr. Whelpton, B. (New York, 1968, first published in 1948).Google Scholar

Cock rings must not be used without medical advice by those who have cardiovascular problems or who take blood-thinning medication.[citation needed]

36 See von Schlosser, J., ed., Lorenzo Ghibertis Denkwürdigkeiten (I Commentarii) (Berlin, 1912), Book III, esp. pp. 56, 121, 169-172, 184, 190-217, 220.Google Scholar Ghiberti's treatise, however, is composed largely of passages taken from ancient and medieval writers on optics. For Alberti's treatises, De pictura and Elementi di Pittura, see Alberti, L. B., Opere volgari, ed Grayson, C., III (Bari, 1973), 7–129.Google Scholar Professor Edgerton has informed me that he has not noticed any references to eyeglasses in works on perspective of the age, although he has not specifically looked for them.

7 Ibid., pp. 553-554. The same views are also expressed in Ronchi's earlier publications listed in n. 5. For the development of the microscope, see also Disney, A. N., Origin and Development of the Microscope (London, 1928).Google Scholar

Today, cock rings can be bought with accessories that stimulate the clitoris or anal area during intercourse. Other cock rings go around the scrotum and can significantly enhance erection and intensity of orgasms.[3]

16 Tranchedini to G. Simonetta, Florence, November 20, 1462, Milan, Archivio di Stato, Potenze Estere-Firenze, cart. 270: ‘Ad me é stato gratissimo el piacere scrivete hano havuto quelli nostri Illustrissimi Signori et Madona […] ochiali gli manday, ma molto maiore consolatione ho havuta che non vedano [cum] quelli da vechii et cum quelli da zoveni si, perhoché’ questo é il bixogno nostro. Ma non me piace Soa Celsitudine me mandi li denari che costorono et cossì il vino et l'altri, como scrivete. Desiderarey, et cossì ve ne prego gli faciate intendere, che como suo fameglio non posso stare qui col poco et quel poco anche non havere. Et pregassivo Soa Celsitudine [se] degnissi havermi compassione, ex consequenti aiutarmi, o saltern me consiglii che modo ho ad tenere a vivere, che non m'aiuti Nostro Signore Dio, se per mille ducati ussissi de li debiti me retrovo adosso, il che me fa stare in extrema desperatione….’ The top left portion of this dispatch, marked by bracketed ellipsis, is torn off.

11 Ibid., pp. 529 and 552, where Ronchi estimates ‘one page’ and ‘half page,’ respectively. In his Scritti di ottica, p. xxii, he estimates two pages considering the writings of philosophers and laymen combined.

Specialized underwear is available which comes with pre-fitted cock rings. The underwear has a pouch with an internal fabric/elastic cock ring which either slides along the penis and encircles the scrotum or, alternatively, simply snaps around the base of the scrotum to snugly—but not in a constricting way—attach the pouch to the genitals. While this type of pouch permits the wearer to "go backless", C ring pouches can be attached to either a thong or traditional jockstrap.

43 Most of these works, as well as others not mentioned here, are reproduced in Heymann, Lunettes, passim, and in E. C. Watson, ‘The Invention of Spectacles,’ American Journal of Physics, 21 (1953), 56-57. The former is the most extensive survey to date of early representations of eyeglasses in art. Three such portraits of St. Bernardino were painted by Pietro di Giovanni Ambrosi (1448), Bartolomeo Caporali (1488), and by Francesco di Gentile da Fabriano (undated) but presumed to be of the late fifteenth century, all reproduced in Berenson, B., Italian Pictures of the Renaissance. Central Italian and North Italian Schools, new ed., II (London, 1968), Nos. 572, 680, and 978 respectively.Google Scholar

21 Florence, Archivio di Stato, Archivio Mediceo avanti il Principato, filza xiv, N. 29. The first seven lines of this letter follow: ‘Io sì ò recevuto vostra letra e quatro para d'ochiali per le mano di Pessolo, vostro fattore, de chuale ve rengrazio grandemente. Vero é che ve n'era uno paro ch'era roto li vetri, per la chuale ve prego che me mandiate chualche vetri che siano bone. Io li voree che fusono vetri che se vedese da presso in peroché’ chueli m'avete mandati sono ochiali da la di longa, salvo uno paro che sono da presso. Fate che Chola d'Arezo, oraffo, ve mostre chuele m[…] che a me n'à dato per altre volte; li fae bone, e perché non s'abiono materia di rompere chueste vetre, io ve mando uno chasetino dove abiono a stare e dite al maestro che le fae, me le manda grosso de vetro sono migliore. Mandatimone insino a otto o desse de chueli vetri. Avisatime del chosto e daroe a Pessolo… . ’ Ardouino's letter, which came to my attention after the first draft of this article had been completed, was discovered by Professor Charles M. Rosenberg of the State University of New York at Brockport. Professor Rosenberg generously sent me a Xerox copy of the letter along with his transcription of the beginning seven lines dealing with eyeglasses, which are here published with his permission and with my emendations. The Xerox copy, in fact, is not clear in places, but the questionable readings do not alter the substance of the message. I am also grateful to Professor Creighton Gilbert who alerted me to this discovery.

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Concave lensesvs convex lens

However, there is one disadvantage: the more accessories that are added on, the greater the chance of developing discomfort or cold sensations from the device.

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5 Ronchi's views have been published in a number of works: Galileo e il cannocchiate (Udine, 1942; Turin, 1964), passim; Optics. The Science of Vision, tr. and revised by E. Rosen (New York, 1957), pp. 32-33, 37-39, 46; Scritti di ottica, pp. xx-xxvii; The Nature of Light. An Historical Survey, tr. V. Barocas (Cambridge, Mass., 1970), pp. 69-76, 78- 109; New Optics (Florence, 1971), pp. 26-27, 36, 47-53; ‘A Fascinating Outline,’ pp. 527-532, 552-554.

35 The influence of the rediscovery of linear perspective on the development of cartography in early fifteenth-century Florence has been admirably treated by Edgerton, S. Y. Jr., The Renaissance Rediscovery of Linear Perspective (New York, 1975), chaps, vii-viii.Google Scholar

3 For unsupported statements about the existence of concave lenses in the early sixteenth century, see King, H. C., The History of the Telescope (Cambridge, Mass., 1955), p. 28 Google Scholar, and Gordon, B. L., ‘A Short History of Spectacles,’ Journal of the Medical Society of New Jersey, 48, no. 1 (1951), 6, n. 12.Google Scholar In the chapter ‘Glass,’ in the Oxford History of Technology, ed. C. Singer et al., III (New York and London, 1957), 231, L. M. Angus-Butterworth wrote: ‘No reference to concave lenses for the correction of myopia appears to precede that of Nicholas of Cusa (1401-1464) in the mid-fifteenth century.’ The author supplied no exact reference to Nicholas’ writings, but he probably had in mind the treatise De beryllo, written in 1450, where Nicholas described beryl as a ‘bright, clear and transparent stone, to which a concave as well as a convex form is given; by looking through it you reach what was previously invisible’ (quoted by Rosen, ‘The Invention of Eyeglasses,’ p. 206, n. 290, who rightly pointed out the difference between a piece of beryl used as a magnifying glass and spectacles). It is possible, however, that Nicholas knew of the existence of concave lenses since they were in use at Florence and Milan during his time, as will be shown below.

23 This passage, which is not cited by Ronchi, was transcribed and translated by Richter, J. P., The Literary Works of Leonardo da Vinci, Compiled and Edited from the Original Manuscripts, 2nd ed., II (London, 1883; rpt. New York: Dover, 1970), N. 909, 168.Google Scholar Richter (p. 136) believes that Leonardo was using magnifying glasses and not a telescope to observe the moon since ‘telescopes were first made about 1600.’

38 For earliest references to eyeglasses, see Rosen, ‘The Invention of Eyeglasses,’ pp. 201-204; Heymann, Lunettes, passim, and Greeff, R., Die Erfindung der Augengläser (Berlin, 1921), pp. 101–103.Google Scholar

25 I have checked the correspondence with the ambassadors Antonio Guidobono, from September through November 1462, and with Gerardo de’ Colli from May through July 1466, Milan, Archivio di Stato, Potenze Estere-Venezia, cart. 349 and 353 respectively.

29 ‘Questa mia é scritta cogli occhiali: rileggete e rivolgete più d'una volta, tanto che la intendiate bene.’ Alessandra Macinghi negli Strozzi, Lettere, p. 347.

A cock ring may be used during sex or masturbation to prolong or enhance erections, delay orgasm, or for the sensation of tightness and engorgement that wearing one produces; vibrating models apply vibration to the base of the user's penis and to their partner. They can be worn as sex toys or for aesthetic reasons.

37 Historians of Milanese society and costume, however, make no mention of spectacles. See Pisetzky, R. Levi, ‘L'apogeo dell'eleganza milanese durante il Ducato,’ Treccani Storia di Milano, Vol. VIII (Milan, 1957)Google Scholar; Verga, E., Storia della vita milanese, 2nd ed. (Milan, 1931)Google Scholar; and Valeri, F. Malaguzzi, La corte di Lodovico il Moro, 2nd ed., 4 vols. (Milan, 1915-29).Google Scholar

Concave lensesfor sale

18 Milan, Archivio di Stato, Registri delle Missive, Reg. 77, fol. 89v. The complete Italian text, including the list, follows:

Vendors of cock rings and medical sources indicate that cock rings are not to be worn for more than about 30 minutes. Falling asleep or using illicit drugs at the same time is very dangerous. The first sign of pending problems is when the penis starts to become numb, painful, or cold. As soon as this happens, the cock ring must be removed.[2]

26 For the history, administration, and resources of the duchy of Milan in the fifteenth century, see Catalano, F. et al., Treccani Storia di Milano, Vol. vii, L'età sforzesca dal 1450 al 1500 (Milan, 1956)Google Scholar; Cipolla, C., “I precedenti economici,” ibid.,Vol. viii (Milan, 1957)Google Scholar; and Barbieri, G., Economia e politica nel Ducato di Milano (1386-1535) (Milan, 1938).Google Scholar For the development of Milanese diplomatic institutions under the Sforza and the huge volume of extant documentation, see Ilardi, V., ‘Fifteenth-Century Diplomatic Documents in Western European Archives and Libraries (1450-1494),’ Studies in the Renaissance, 9 (1962), 67–73 CrossRefGoogle Scholar, and Cerioni, L., La diplomazia sforzesca nella seconda metà del Quattrocento e i suoi cifrari segreti, 2 vols. (Rome, 1970).Google Scholar

34 Taddei, , L'arte del vetro in Firenze, pp. 64–72 Google Scholar; Ronchi, , Scritti di ottica, pp. 267–288, 441-451.Google Scholar

2 Ronchi's latest statement on this question was published in his article ‘A Fascinating Outline of the History of Science. Two Thousand Years of Conflict Between “Reason”hundred and “Sense,” ‘ Atti della Fondazione Giorgio Ronchi, 30 (1975), 530, where, in discussing the late discovery of concave lenses, he wrote: ‘Naturally I tried to find out when, who, where and by whom had concave glass disks been used to correct myopia. So far it has not been possible to give an answer to these questions. Furthermore: I have no evidence that any other historian of optics has ever asked these questions. Certainly this great step forward was accomplished in a rather late period: in all the literature and in all the historical documents (and I can add that they are many) known to me, the first mention of the existence of diverging lenses I found in a book with the title “La pratica della prospettiva” by the Venetian architect, Daniele Barbaro (1513-1570), published in Venice in 1568.’ In an earlier book, consisting of excerpts from early writings on optics, Scritti di ottica(Milan, 1968), p. 125, n. 3, Ronchi wrote of Maurolico's contribution in these terms: ‘É la prima volta che l'effetto convergente e divergente delle lenti é interpretato giustamente, per spiegare perché le lenti convergenti correggono la presbiopia e quelle divergenti la miopia. Il ragionamento é qualitative é intuitivo; ma é ammirevole la sua logica.’

A triple cock ring or triple crown is a cock ring that has additional rings for restraining the testicles. In orgasm, the testicles usually retract towards the body before ejaculation. A triple crown changes and intensifies the sensation of orgasm by forcing the testicles to stay away from the body.

17 See, for example, Queller, D. E., The Office of the Ambassador in the Middle Ages (Princeton, 1967), pp. 158ff.Google Scholar

Five recently discovered documents reveal for the first time that eyeglasses with concave lenses for myopes were manufactured in Florence from at least the middle of the fifteenth century, about one hundred years before they were thought to be in use. This new evidence throws additional light on the development and early use of spectacles and on the early history of optical instruments and glass technology in general. These documents also reveal for the first time that Florence was the leading manufacturing center of high-quality eyeglasses and that spectacles had already become a prestigious item of personal adornment at least at the court of the dukes of Milan. This information should be of interest to historians of art and costume as well.

Concave lensesformula

Another variation is an inflatable or stackable ring design, which can limit the depth of penetration to protect the receiving partner from pain or discomfort.

Concavelens ray diagram

28 Filze cxxxi and cxxxiii of the third series of the Carte Strozziane in the Florentine State Archives contain many letters by the Strozzi, including those by Alessandra published by Guasti, and they may contain Filippo's letters in question.

15 My own study of the diplomatic correspondence between Milan and Florence at this time has established that dispatches normally reached their destination in about two days.

39 These references by Petrarch and Sacchetti are well known, but they bear repeating because they are particularly significant in this context. Petrarch reveals in his Letter to Posterity (dated before, 1367 with additions in 1370-71) that at the age of sixty he felt the need to use eyeglasses: ‘I was possessed of a clear complexion, between light and dark, lively eyes, and for long years a keen vision, which however deserted me, contrary to my hopes, after I reached my sixtieth birthday, and forced me, to my great annoyance, to resort to glasses’ (Petrarch. A Humanist Among Princes. An Anthology of Petrarch's Letters and Selections from His Other Works, ed. D. Thompson [New York, 1971], p. 2). In his De remediis utriusque fortunae, Book 11, chap. 93 (written between 1354 and 1366), the poet extols man's dignity and ingenuity, in contrast to the helpless condition of animals, as shown by his capacity to invent remedies to correct imperfections in his body: ‘Finally he [man] aids and lifts himself in all ways; even when losing limbs he learns to make wooden feet, iron hands, wax noses, and to resist the accidents of chance; he erects failing health by medicines; he excites weakened taste by flavours, and failing sight he restores by eye-glasses’ (quoted by Trinkaus, C., In Our Image and Likeness. Humanity and Divinity in Italian Humanist Thought, 1 [Chicago, 1970], 194 Google Scholar; original Latin text, 399-400, n. 34).

1 This is the conclusion reached by E. Rosen in his definitive article, ‘The Invention of Eyeglasses,’ Journal of the History of Medicine and Allied Sciences, 11 (1956), 13-46,183-218. The inventor is unknown, but he probably came from Pisa. This article contains all the essential bibliography on the invention and early development of spectacles.

For suggestions and bibliographical references I am indebted to Professors Frederic C. Lane, Richard A. Goldthwaite, Edith W. Kirsch, and Samuel Y. Edgerton, Jr. Professor Edward Rosen has kindly shared with me his extensive knowledge of the history of eyeglasses and has encouraged me to publish the following documents. I am also grateful to William C. Cooley, Doctor of Ophthalmology, and Donald S. Call, Optician, for scientific and technological advice.

30 On the wealth of Filippo Strozzi, who by the end of the fifteenth century became almost as rich as the Medici, see Goldthwaite, R., Private Wealth in Renaissance Florence. A Study of Four Families (Princeton, 1968), pp. 52–73.Google Scholar

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40 Sacchetti narrates a story about a certain Tommaso Baronci, a Florentine Prior around 1358, on whom his colleagues had played a friendly trick by reversing his shoes. Baronci had to put on his spectacles to ascertain whether the shoes were his: ‘Elle [the shoes] non paiono le mia, benche io non le veggo bene, se io non ho gli occhiali. E cavossi gli occhiali da lato, e misseseli, e con essi si chinava quanto potea, facendosi verso la finestra’ ( Sacchetti, F., Il trecentonovelle, ed. Faccioli, E. [Turin, 1970], p. 214 Google Scholar).