1847.] 



THE CIVIL ENGINEER AND ARCHITECPS JOURNAL. 



15 



which the schools are worked is calculated to direct uot only llie hand and 

 eve of the pupils, but also their taste. For this result, the study of the 

 fiVure is found by practical experience to be the most instructive. Geome- 

 trical forms alone, tliou^h useful to exercise the lingers, are msufiicient to 

 Eive a perception of beauty, and harmony of outline— a fact tully proved 

 by the practice of the School at Toulouse, wliere the latter mode of study 

 has been substituted for the former. Cold and Huineaniug lines convey no 

 intelligence to the pupils, and excite no interest. Hence the pupils who at 

 Toulouse pass from the elementary to the higher classes, are found to be 

 strikinuly inferior to those of the same standing at Pans aud Lyons. When 

 they come to draw other objects from the round, they are altogether deli-^ 

 cient in the knowledse of light and shade, aud relief, and even facility of 

 hand The error which has been experienced at Somerset House seems to 

 have been committed at Toulouse, of confining the study of the figure to a 

 small aud select class, the master of which has another class to attend to; 

 so that to use M. Texier's words, 'the figure has only /irt// a Professor 

 knotted to it.' It is theref.^re proposed, as an improvemeut of the utmost 

 necessity that the School of Toulouse should be assimilated, in this respect, 

 to those of Paris and Lyons. A pupil who has followed the elementary 

 study'of the fiiure, with the management of the chalk and slump, is founil 

 to possess a knowledge of shadows aud reflections, which open to him a 

 thorou-h uuilerslandingof every work in relief before which he may be 

 placed" The School is also deficient in other particulars : the classes sit 

 for two hours onlv even for the study of the figure— a space of time totally 

 insuflicieut There is no class for plants, and the class for demonstrating 

 the composition of ornaments of all dates and styles, described under the 

 Paris School, is much to be desired, not only at Toulouse but at Lyons. 

 There seems to be some dilliculty in finding a competent Professor. The 

 Council of Toulouse wish for tiie establishment of a course of chemistry 

 applicable to manufactures. rn • 



'' I could have wished to take such a view of the manufactures of Pans 

 asmi-'ht have enabled me to draw some comparison with those of our own 

 country; but as the time at my disposal did not admit of any general in- 

 quiry, I confined mvself to the subject of stained glass, of which a great 

 quantity has lately been executed iu France. The church of .5t. Deuis has 

 been completely fitted up with modern coloured glass, in a style which it is 

 impossible to commend. Part of this glass is designed on the imbecile 

 principle unhappily too prevalent in England, of imitating the wretched 

 drawin- and composition of the middle ages, under the notion that this per- 

 version"of art is essential to the character of the work. But the glass of 

 this order at St. Denis is destitute of the archajological knowledge and 

 taste in the arrangement of colour, which are the redeeming quality of 

 many Ent-lish performances of this class. Other portions of the glass at 

 St. Denis'^are designed on the still more mistaken system of assimilating 

 glass painting to painting on canvas. ,. v . i 



" \t the royal manufactory of Sevres, great pains have been bestowed 

 on tlie improvement of stained glass. Being, hon ever, doubtful of the im- 

 pression to be produced by the view of mere specimens, I did not visit 

 Sevres but performed a journey to Dreux, about sixty miles from Pans, 

 where a magnificent chapel, designed by the present king as a mausoleum 

 for his family, has been completely fitted up with Sevres glass. Ihere is 

 much ^ood art in this glass. There are figures and groups, of which the 

 drawing, composition, and expression are extremely fine, but the colouring 

 is in some portions crude, and iu oihers vapid. There is an insuflicieucy 

 of the detail essential to the proper efl'ect ot stained glass. The drapenes 

 are too plain. There is an attempt at diaper-work upon some of the back- 

 eronnds but it is feeble aud inefficient, and the general eiiect of the whole 

 is poor The artists, with all their merit, and it is great, have evidently 

 been hampered by the principles and practice of painting on canvas, and 

 the mechanical process of joining the glass has been so ill understood that 

 all the subjects are cut up into squares by the ironwork. The same ob- 

 servations will apply to the glass in the chapel erected at Pans to the me- 

 morv of the late Duke of Orleans, also from the Sevres manufactory. 



"The modern glass displayed in the new church of St. Vincent de Paul 

 is of extraordinary qualiiy. In this the artist has solved the problem of 

 uniting high art with the conditions required for the due ertect of painting 

 on 'lass. Fine design, drawing, and expression, combined with a perfect 

 conception of the distribution aud collocation of colour, and a profusion of 

 detail in the draperies, background, aud borders, render it an example of 

 rare perfection in stained glass, not inferior to the ancient in brilliancy and 

 harmony, and immeasureably beyond it as a work of art. Each window 

 contains a figure, or two, on a blue background, richly diapered, within a 

 border of small figures iu compartments, formed by green arabesque. This 

 glass is the work of RI, Marechal, of Metz, an artist also greatly distin- 

 guished as a crayon painter. I should consider a fine specimen of his 

 work an important acquisition to our School, if it could be obtained at any 



" It is probable that some of the facts and observations which I have 

 now had the honour to submit to the Council, may bear upon circumstances 

 connected with our own establishments, and it is not impossible that coin- 

 parisous may ofler themselves during my approaching visit to the Provin- 

 cial Schools. I have therefore hastened to submit these remarks to the 

 Council whilst they were fresh iu my mind, aud unbiassed by anything 

 arising in the course of my tour of inspection. 



7th Oct. 18-15. " Ambrose Poynter. 



REVIH-WS. 



Turniiig and Blaiiipulation. By Chari.es Holtz\pffel, Vol. 11. Illus- 

 trated by upwards of 701) woodcuts. HollzaplVel. London : 1S46. Svo. 



[SCCOND NOTICE,] 



In the former notice of this interesting work we gave a brief outline of its 

 contents. The volume concludes with an appendix containing papers by 

 several contributors, aud additional notices of new processes and inventions 

 which have come to the author's knowledge while the work was pass- 

 ing through the press. The author has directed our attention to the fol- 

 lowing remarks, which we accidentally overlooked when alluding to the 

 contributions by Prof. Willis. 



" The formation of the tools used for turning and planing the metals is a 

 subject of very great importance to the practical engineei', as it is indeed 

 only when the mathematical principles upon which such tools act, are 

 closely followed by the workman, that they produce their best eti'ects. 

 With a full conviction of the advantages which result when theory and 

 practice are thus associated, the author has to congratulate himself on being 

 alile to present to his readers, two original papers, respectively writlen on 

 the subject of the principles of tools for turning and planing metals, by 

 Charles Babbage, Esq., K.R.S., &c., and Professor Willis, A.M., F,K,S., 

 &c , both distinguished by their high mathematical aitaimneuls, aud their 

 intimate practical experience iu the use of tools." 



The first paper by Mr. Babbage treats of the nature of the resistance to 

 be overcome in the cutting a revolving substance by means of a fixed tool, 

 and is an admirable instance of the importance of applying general in- 

 ferences from the theory to the practice of mechanics. Of course it would 

 be impossible to calculate with perfect accuracy the amount of resistance 

 to the progress of the tool, as the material will never be perfectly homo- 

 geneous, nor the thickness of the shaving separated from it perfectly uni- 

 form. Still in this, as in other instances of the application of theory tj 

 practical cases, though the numerical results may nut be depended upon, 

 the general conclusions are of the utmost value. The principles here laid 

 down', by Mr. Babbage, would tend to a considerable modification to the 

 forms of tools, and would probably have this advantage — that the construc- 

 tion of cutting instruments would be made to depend not upon uncertain 

 arbitrary rules, but upon fixed and reasonable laws. 



" Steel of various degrees of temper and under various forms, is almost 

 universally employed for cutting metals. Before deciding on the forms of 

 the difi'erent tools it is desirable to inquire into the principles on which 

 their cutting edges act, and to assign special names to ceitain angles on 

 the relations of which to each other, and to the metals upon which they 

 are used, their perfection mainly depends. 



In the engraving c is a cylinder of steel or other metal, and T is a plan- 

 ing or turning tool acting upon it at the point a. A c is a horizontal line 

 through the center c, and the cutting point a. B a, is a line passing through 

 the cutting point a aud along the upper plane b a, of the cutting tool T. C 

 o, is a line passing through the cutting point a and along the front plane e it, 

 of the cutting tool. D a, is a line from the cutting point a, at right angles 

 to the radius c a. The angle D « C, may be called the angle of relief, be- 

 cause by increasing it, the friction of that face of the tool upon the work is 

 diminished. The angle C « b, may be called the angle of the tool. The 

 angle B a A, may be called the angle of escape, because the matter cut 

 away by the tool escapes along it. 



The forces to be overcome in cutting a thin shaving of metal from a 

 cylinder or from a flat surface are of two kinds, 



1st. It is necessary to tear along the whole line of section each atom 

 from the opposite one to which it was attached. The force required for 

 this purpose will obviously be proportioned to the length of the cutting 

 edge of the tool, and dependent on the nature of the metal acted upon. 

 But it will be quite independent of the thickness of the part removed. 



2nd. The shaving cut ofl' by the tool must, iu order to get out of its 

 way, be bent or even curled round into a spiral. This second force is 



