208 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[July, 



inch with tliis change only. This shows that the materials with which 

 an architect, engineer, or builder has to deal, are always varying lu 

 their bulk, and that no two sides of a building are at all times ot the 

 same height, except when there is an unusally uniform and still atmo- 

 sphere; and of course the external walls of the tower which support 

 the floor, from which this variation is measured, are also subject to 

 constant changes, bv alteration in the heat of the atmosphere. Thus 

 it is seen that a variation in size with every change of temperature, 

 roust take place in the external parts of all buildings, even a garden 

 wall cannot be of the same height on both sides, when there is more 

 sun, wind, or rain on the one side than on the other. 



The chimney is parallel, and the internal diameter in 5 feet ; its 

 height from the surface is 1U8 feet. The foundations were laid at a 

 depth suitable to the nature of the soil, being on a layer of gravel 11 

 feet from the level of the ground ; and in order to spread the weight 

 of the building over a large surface, a bed of concrete was formed 23 

 feet square, and 3 feet in thicknpss ; on this a mass of brickwork 21 

 feet square, 2 feet thick, was laid in cement, forming a solid block, 

 equal to being in one piece of stone, like a large solid landing, to 

 carry the upper work. In the centre of this foundation, and through 

 the whole of the before-mentioned brickwork, a well IS inches dia- 

 meter was left, and taken down below the water line deep enough to 

 insure the lower extremity of a lightning conductor being always un- 

 der water. The walls of the tower are 14 inches thick from the bot- 

 tom to the top, and inclose a space of 14 ft. 9 in. square in the clear 

 at base, and 1 foot less at the top: the tower being tapering, stairs 

 are built in the walls for the purpose of communicating with the belfry 

 and ciock room, and with a supply cistern for steam boilers; also for 

 easy access to the top of the chimney, to ascertain what is occurring 

 there, with respect to the temperature of the vapours emitted, and 

 that in case too much heat were given out or wasted at the top, where 

 it could no longer be of any service, such waste might not happen 

 without means of ascertaining the fact that it was occurring. 



The srrioke shaft in the centre is for 24 ft. 3 in. upward, from foot- 

 ings Ik bricks in thickness; but at the base, where the flues enier, it 

 is strengthened round the openingsby an additional brick in thickness. 

 So far the work is done with bricks of the usual form and size ; but 

 above this, they are segment-shaped, and were made purposely for 

 the shaft. In the second piece, 11 ft. Sin. in height, the work is 10 

 inches thick ; in the third piece, 40 ft. 3 in. in height, it is 9 inches in 

 thickness ; in the fourth piece, 17 ft. 9 in. in height ; it is 8 inches in 

 the fifth piece, 17 ft. 3 in. in height, it is 7 inches, aud in the remain- 

 ing height the work is inches in thickness. 



The iirst object aimed at in designing the tower, was to conceal the 

 chimney shaft ; the appearance of which was thought to be objection- 

 able to the neighbourhood. As it was intended that no black smoke 

 should be suffered to escape, it seemed that if the chimney were con- 

 cealed from view, its existence might remain unknown ; but it was 

 also considered that other direct advantages might be gamed to justify 

 the erection and compensate for the increased outlay. These, ex- 

 pected advantages have been realized. 



A considerable saving of fuel has been effected owing to the chim- 

 ney being protected from a cold atmosphere, from rain or snow beat- 

 ing against it, which would rob it of its heat, in proportion as the 

 evaporation from the outer surface was more or less rapid. There 

 seems however as much propriety in protecting a chimney from cool- 

 ing influences, as there is in clothing any other part of the flue, or 

 steam boiler itself; for in order to insure a sufficient supply of air to 

 support combustion, it is necessary that the ascending smoke and 

 vapours should have been heated, so as to become in the required de- 

 gree lighter, than the external air. In the degree that the strength 

 or force of the draught is required to be increased, so must the air 

 and vapours given off from the furnace be allowed to pass at a higher 

 temperature; consequently, the amount of the difference of heat lust 

 from a chimney exposed to the weather, and from one clothed, is by 

 so much a clear gain. 



The height of the tower affords sufficient pressure to make avail- 

 able, a capacious cistern fixed at its top for supplying the steam boilers 

 with water, thus giving great power to the pi-rson who has charge of 

 the engine, should occasion require Us being brought into action, 

 either through the failure of the force pump, or through evaporation 

 of water from the boilers, or neglect in filling them at the proper time, 

 thereby diminishing to a very great extent the risk of explosion from 

 such causes, or at least rendering the boiler less liable to be deranged. 

 It will be observed that the shaft is much thinner than it could have 

 been had it been erected without its casing. The quantity of brick- 

 work saved in the shaft, and the economy of fuel, will go very far 

 towards paying the additional cost of the tower, which may iherefore 

 he considered as a matter of very little, if any, additional cost, when 

 the advantages are all taken taken into account. 



ON THE ABUSE OF OIL AS NOW USED IN PAINTING, 



AND THE INVERSION OF PRACTICE NECESSARY TO 



SECURE PERMAMENCE IN PICTURES. 



No. III. 



The truth of the proverb " himanum est errare," obvious as it is in 

 all the acts and theories of man, never was more perfectly demon- 

 strated than in the present practice of painting. It appears to be an 

 ordination that the moment he makes a discovery and succeeds in 

 applying it well, his restless ambition to do teller becomes the track 

 of his retrogradation. Painting had no sooner left the high-road of 

 encaustic than wax rapidly sank in the painter's estimation ; resin, at 

 first the mere modifier, became the agent in chief; oil, doubtless from 

 its brilliant effects on colours and its powers of working, succeeded, 

 and, in Leonardo da Vinci's hands, became the grand panacea : now, 

 rould Leonardo rise from the grave, I have little doubt but he would 

 tell us " his pure oil was le grande ouvre." Alas, we have a living 

 instance of such blindness in man; and perhaps more unpardonable, 

 for the living man professes to teach in his public prelections that 

 which in his own private practice evaporates in smoke. I have my- 

 self asserted, in reply to M. Merimee's foolish crotchet," — so foolish 

 that any tyro can disprove it in five minutes, — that " there never was 

 and never will be a varnish made which gives half the brilliance of 

 pure oil alone ;" but this power has palpably its limits — brilliance is 

 not permanence; and Mr. B. R. Haydon, in the conclusion- of his 

 scraps of Reynolds's M.S. diary — which could only be valuable 

 to man as a whole — seizes on this reply to Merimee to give his 

 premonitory cautions to the rising artist against using avy but pure 

 and simple agency alo}ie (a-iea.n\r\g oil), with certain flourishes about 

 Titian, as if any man had ever yet libelled Haydon's colouring by an 

 ironical allegation of semblance. In the first place, Haydon cannot 

 prove that Titian used pure oil alone : nay, common sense inferences 

 are against the bare supposition, for Titian's pictures are notoriously 

 more perfect than those of Da Vinci, who did use it lavishly, as testi- 

 fied in his own handwriting. Haydon's private practice denies, in the 

 next place, his public doctrines. 



Oil gives inimitable splendour, but, obviously, no permanent picture 

 ever was or ever will be painted with it alone. Every boy knows oil 

 rises, and skins, and horns, in defiance of every ordinary shift of the 

 painter's art; and though a picture painted in Italy will carry safely 

 double the quantity of oil any English painting will allow, even there 

 it shows the cloven foot, — as evidenced in Leonardo's observance of 

 this rising, in Cennini's use of ultramaiine with white lead to cover 

 the yellow, and John Thompson's green skies of ultramarine glazed in 

 McGelp upon gluten without eil. But, as it may be alleged this is my 

 assertion only as to Haydon's practice, let us see his printed confes- 

 sion. In his concluding scrap from Sir Joshua's diary in the February 

 number of this Journal, he has registered the fact thus : — " Pr(ecip» — 

 on ran cloth sensa olio, Venice turp. et cera. (Seen by Sir George the 

 year before it /cas burnt at Belvoir, and said by him to be perfect. — 

 B. R. H.)" Again, iu the same — " 1781. Dido, oil. (In beautiful 

 condition. — B. R. H.) Manner — colours to be used, Indian red, light 

 ditto, blue and black^f/itsAei aith varnish without oil, poi ritoccato con 

 giallo." 



Now here, in troo special cases, we have his own assurance of beauty 

 and preservation, very rare with Reynolds and not due to oil; but 

 more of Sir Joshua anon ; and I deny in toto that he used "every gum, 

 every spirit, every oil, which earth produces :" he used many, it is true, 

 and abused more, for a mure wavering, empirical man in practice 

 never breathed ; and it is somewhat strange that the greatest practical 

 truth Sir Humphry Davy ever committed to print, viz. that " all oils 

 become varnishes in time," arose out of his profound practical igno- 

 rance :' he was perfectly innocent of the fact of many of the pictures 

 examined by him having been painted iu solutions of resin, in fact 

 almost all resin, and that to such they were indebted for their perma- 

 nence alone. 



There is, however, yet another and most material source of change 

 in all modern pictures, not at all suspected by the artist, and arising out 

 of the total neglect of climate, and the blind abuse of what, in the first 

 instance, was doubtless a great convenience if not a high improve- 



iing their drying power.' 



t That copal " brightens colours without i 



2 In the February Number, page 41. 



3 This is palpable ; and, I repeat, Davy was practical on nothing but salmon fishing; 

 his every attempt at " practical science" >vas a deal failure— save alone the decompi|sitiou 

 l,by better agency than Baron Borne possessed) of the alkalies; witness his Gfilvanic De- 

 tenders and the Explosion Lamp. Indeed he knew it and felt it ; hence arose his sug- 

 gestion of a College of " Practical" Chemistry, which, God knows, is much wanted. The 

 theoretic geulrv amply exposed themselves in a late trial, as well as in that of Bellany, 

 in which really toxicologists and jurists, without ever having saved a single life, dared to 

 peril that of anotrier, or gave scrap evidence, collected from bad books and out of date 

 authorities 



