127 



TORRICELLI, EVANGELTSTA. 



TORRIGIANO, PIETRO. 



123 



various embassies and political negociations. In 1595 he wasappointed 

 Archbishop of Mechlin, but before the documents arrived from Rome 

 which were necessary to enable him to enter upon his now dignity, he 

 died at Brussels in tho seventieth year of his age. He was buried in 

 the cathedral-church of Antwerp. He left his library and collection 

 of antiquities to the college of Jesuits at Louvain. 



Torrentius was an accurate scholar, and well acquainted with 

 Roman antiquities, but he did not write much. The only work of 

 his which was published in his lifetime is a Commentary on Suetonius, 

 which originally appeared at Antwerp in 1578, and was reprinted in 

 1592 : it is also contained in Grcevius's edition, published in 1672. 

 This Commentary is also interesting from the many wood-cuts it con- 

 tains, representing coins of the Roman emperors and their families. 

 Torrentius's Commentary on Horace was not published till after his 

 death: it appeared at Antwerp in 1608, 4to, together with a small 

 treatise of his entitled ' Commentariolus ad Legem Juliam et Papiam 

 de Matrimoniis Ordinaudis.' Besides these Commentaries, Torrentius 

 also published in his lifetime several Latin poems, of which a collec- 

 tion appeared at Antwerp in 1576, 8vo, under the title of Poemata 

 Sacra.' Torrentius was called by his contemporaries the Christian 

 Horace ; and his poems are distinguished by great ease of versifica- 

 tion. He also edited the posthumous works of J. Goropius Becanus, 

 Antwerp, 1580, with an apology for Becanus, who had been attacked 

 by Scaliger. (Foppens, Bibliotheca Belgica; Saxii, Onomasticon.) 



TORUICELLI, EVANGELISTA, a learned Italian mathematician 

 and philosopher, was born October 15, 1608, at Piancaldoli in 

 Romagna, and being, probably at an early age, an orphan, he was 

 supported by an uncle who resided at Faeuza. At this place, and in a 

 school of the Jesuits, the youth received a mathematical education, 

 and he speedily distinguished himself by the progress which he made 

 in acquiring a knowledge of the sciences. 



At twenty years of age his uncle sent him to Rome where he 

 became intimately acquainted with Benedict Castelli, who was then 

 professor of mathematics in that city, and by whom his studies were 

 directed. The Dialogues of Galileo appear to have particularly 

 engaged Torricelli's attention, and he composed two tracts, one on the 

 subject of mechanics, and the other on the motion of fluids, which 

 were published with the rest of his mathematical works in 1643. 

 Torricelli seems to have been the first who established the principle, 

 that when two weights are so connected together, that being placed in 

 any position their common centre of gravity neither ascends nor 

 descends, those weights are in equilibrio ; and on this principle he 

 investigated the ratio between two weights when they are in equilibrio 

 on a double inclined plane. He also investigated the motions of 

 falling bodies and projectiles ; and among the results of his researches 

 13 the remarkable fact, that the paths of any number of projectiles 

 (in a non-resisting medium) when discharged from the same point 

 with equal velocities, but at different angles of elevation, are parabolas 

 situated within one curve which is a tangent to all of them, and is 

 itself a parabola. In the tract on the motion of fluids he assumes 

 that water will flow through an orifice at the bottom of a vessel with 

 a velocity equal to that which would be acquired by a body falling 

 through the height of the fluid in the vessel, and he endeavours to 

 establish the principle by the supposed fact that water so flowing 

 ascends in a vertical tube connected with the vessel at the orifice (the 

 resistance of the air being abstracted) to the level of the upper 

 surface of that which is in the vessel : he hence concludes that the 

 velocities of effluent water must vary with the square-roots of the 

 pressures. 



Galileo, having received copies of the tracts above mentioned, was 

 desirous of becoming acquainted with the author, and he pressed the 

 latter to join him at Florence. Torricelli, having formed connections 

 at Rome, at first hesitated, but at length decided to accept the invita- 

 tion : he was kindly received by Galileo, and it is said that his society 

 and conversation contributed to soothe the last days of the venerable 

 philosopher, who was then infirm and blind, and who died at the end 

 of three months from his arrival. Having been honoured by the 

 grand-duke with the appointment of professor of mathematics in the 

 Accademia, Torricelli became the successor of Galileo in the institution, 

 and he resided at Florence till his death, which happened in 1647, 

 when he was thirty-nine years of age. 



About the year 1637 Roberval, in France, discovered a method of 

 determining the area of a cycloid, and seven years later Torricelli 

 published a solution of the problem in an appendix to the collection 

 of his works. As the Italian mathematician appeared to consider 

 himself to be the discoverer of the rule, Roberval's jealousy was 

 excited, and he accused Torricelli of plagiarism ; asserting that the 

 latter had taken the solution from some papers which had been sent 

 to Galileo, and which had fallen into his hands on the death of that 

 philosopher : Torricelli however, in a letter to Roberval, denies that 

 assertion, and there seems no reason to doubt that he made the 

 discovery without any knowledge of what had already been done in 

 France. He subsequently gave rules for finding the volumes of the 

 solids formed by the revolution of a cycloid about its base and about 

 its axis ; that which is applicable to the first case is correct, but the 

 other is only approximate, so that it may be doubted whether or not 

 Torricelli was in possession of an accurate solution of the problem. 



But the discovery which has immortalised the name of Torricelli is 



that of the barometer. Galileo had occasion, some time previously, to 

 observe that a column of water exceeding 18 cubits (about 33 feet, 

 English) in height could not be raised in a pump ; and, though he had 

 already made the discovery of the pressure of the atmosphere, the 

 reason why that limit could not be exceeded remained unknown to 

 him. Torricelli, in 1643, wishing to find, in a more convenient 

 manner, the weight of the quantity of fluid which could be supported 

 above its general level, performed an experiment similar to that which 

 is exhibited when a pump is in action; and, instead of water, he used 

 mercury, which is about fourteen times as heavy. He filled with 

 mercury a glass tube which at one end was hermetically closed, and 

 having inverted it, he brought its open extremity under the surface of 

 mercury iu a vessel ; when he observed that the top of the column 

 descended till it stood at a height equal to between 29 and 30 inches 

 (English) above the level of the mercury in the vessel, leaving what is 

 considered as a perfect vacuum between the upper extremity of the 

 column and that of the tube. The specific gravity of mercury being 

 known, the weight of the supported column could, of course, be found. 



By this experiment the opinion that a vacuum was contrary to a 

 law of nature was immediately proved to be unfounded, but it is 

 uncertain whether or not Torricelli was aware of the true cause of the 

 column of mercury being so supported, and the honour of having been 

 the first to prove decisively that it was the pressure of the atmosphere 

 on the surface of the mercury in the vessel, is ascribed to Pascal, who, 

 in 1648, on conveying a tube so filled to stations at different heights 

 above the level of the plains, found that the column of mercury dimi- 

 nished in length as the station was more elevated ; that is, as the 

 weight of the column of atmosphere above the vessel diminished. 



It may be easily conceived that Torricelli would communicate his 

 ideas to his friends before he actually made the experiment above meu- 

 tioued ; and such a circumstance may account for the pretensions of 

 Valerianus Magnus, Honoratus Fabri, and others, to priority in the dis- 

 covery of what is called the Torricellian vacuum. It ought to be 

 observed however that in one of the letters of Descartes, dated 1631, 

 that is, twelve years before the experiment of Torricelli was made, 

 this philosopher mentions the support of a column of mercury in a 

 tube, and expressly ascribes the cause to the weight of a column of 

 air extending upwards beyond the clouds. 



Torricelli published at Florence, in 1644, a volume in 4to, entitled 

 ' Opera Geometrical A paper which he wrote on the course of the 

 Chiana is in the collection of writings on the movement of fluids 

 (Florence, 1768). His discovery of the barometer is given in his own 

 work on mathematical and physical subjects, entitled ' Ldzione Acca- 

 demiche' (Florence, 1715). And his letter to Roberval on the cycloid 

 is in the third volume of the ' M cmoires ' of the Academy of Sciences at 

 Paris. He is said to have been the inventor of the small simple micro- 

 scopes of short focus, which consist of a globule of glass melted in the 

 flame of a lamp. His manuscripts are preserved in the Medicean 

 Palace, and in the same edifice there are some object-glasses for 

 telescopes, of considerable dimensions, which bear his name. 



TORRIGIA'NO, PIE'TRO, an Italian sculptor, whose name is con- 

 nected with the history of art in this country, he being one of the 

 foreign artists employed by Henry VIII., was hardly less remarkable 

 for the ferociousness of his temper, the singularity of his conduct, and 

 the strangeness of his fate, than for bis ability in his profession. He was 

 a native of Florence, and though the time of his birth is not mentioned, 

 it was probably about the same as that of Michel Angelo (1474), as they 

 studied together from the antiquities in the gardens of Lorenzo do' 

 Medici, il Magnifico ; a circumstance which Michel had good cause to 

 remember, for such was Torrigiano's jealousy of and spite towards him, 

 that he one day assaulted him, and inflicted so severe a blow upon his 

 nose as to crush and disfigure it for ever. Being obliged to leave 

 Florence in consequence of this affair, Torrigiano went to Rome, where 

 he was employed by Pope Alexander VI., and afterwards enlisted and 

 served as a soldier, first under the Duke Valentino in Romagna, next 

 under Vitelli and Piero de' Medici. Strange as this change was, he was 

 well suited to his new profession, and that to him ; for, as described both 

 by Vasari and Cellini, he was a large, handsome, and powerful man ; 

 was gifted with great "audacity, and had more the air of a rough 

 soldier than of an artist." But though he distinguished himself by his 

 prowess, and obtained the rank of ensign, he saw no chance of speedily 

 advancing higher, and therefore returned to his former profession, 

 which he practised for awhile, but only, it would seem, iu small 

 bronze figures, executed for some Florentine merchants, whom he 

 afterwards accompanied to England. His talents, and perhaps his 

 personal qualities also, recommended him to the favour of Henry VIII., 

 for whom he executed a variety of things, but his chief work was the 

 tomb of Henry VII. in Westminster Abbey, which he completed iu 

 1519, and for which he received the sum. of 1000/. The tomb of 

 Margaret, countess of Richmond, in Henry VII.'s chapel, is also 

 supposed to have been by him. 



While engaged upon Henry's tomb he returned to Italy, in order to 

 carry back with him other assistants, and endeavoured to persuade 

 Benvenuto Cellini, then only eighteen, to accompany him ; but the 

 latter tells us he was so disgusted with Torrigiano, on learning from 

 him how brutally he had treated Michel Angelo, that so far from 

 associating with him in any way, he could not even endure tho sight 

 of him. 



