1846.] 



THE CIVIL ENGINEER AND ARCHITECPS JOURNAL. 



337 



uncertainty and difficiilly I have mentioned as besetting the use of the 

 common dial and that of the circumferentor. 



Briefly to illustrate its use, permit me to refer you to the sketch, sup. 

 posing it requisite to take the angle formed by the two lines joining re- 

 gpeclively A B, BC, the instrument is placed at the angle, and the limb x 

 y z, which is flat, circular, and divided on the outer edge into 720 or half 

 degrees, each indicating in an observation a whole degree — this limb is 

 then turned on a joint below, admitting horizontal motion, until the candle 

 A is reflected from the mirror B, to the eye of the observer placed any- 

 where opposite the vertical line D E — this mirror B is fixed vertically on 

 the lower limb, with the silvered surface exactly in the centre. Then the 

 upper limb is so adjusted (hat the candle C is also reflected from the mirror 

 G (which is fixed vertically to this limb, and whose centre of motion is in 

 the plane of the mirror B,) to the eye of the observer on the line d c, of the 

 sight D E, during this adjustment if any movement occurs in the instru- 

 ment, it is instantly detected and adjusted by the observer without change 

 of place, witJKjut difficulty, and in the leaU imaginable time. The angle 

 required is then indicaied by the vernier at either end of the limb 7, ?•, s, /, 

 at 1/ or t. To test the efficiency of the instrument, I made the subjoined 

 survey wiih it, of a small but very hilly sloping piece of ground, of which 

 I subjoin the plotting showing the error, which considering the iuiperfec- 

 tion of the model, will be considered, I think, very small. 



irror 3. 



The model is constructed, the lower limb of wood and divided by the 

 hand, and the upper one of brass, and with the whole filling constructed 

 by a workman unaccustomed to instrument making. I propose in the per- 

 fect insUument to place tno levels at right angles on the lower limb, to fix 

 it upon a ball and socket joint or parallel plates to facilitate the levelling 

 thereof, and to apply rack -work capable of being easily thrown in and out 

 of geer to the upper limb, and similar racks and a champ screw to the sight 

 D E, which is moveable round the lower limb, and which in the model is 

 a Blip of glass— for this I propose to substitute an ordinary sight with a 

 vertical thin wire in lieu of the line on the glass. I should mention that 

 the mirrors are marked by vertical lines on the silvered surfaces, and that 

 these lines are in the axis of motion of the upper mirror. I should men- 

 tion that in the graduation of the lower limb, there are two opposite points 

 marked zero, situated in the line of the silvered surface of mirror B, and 

 marked in the sketch K L respectively. 



I remain. Sir, your most obedient servant, 



William Peace. 



Haigh Culliery, \Vi«;an, October 9, 1846. 



ENCAUSTIC-PAINTING, WITH WAX, UESIN, AND OIL. 



By Mr, Linton. 



(Communicated to the Commissioners 0/ Fine Arts.) 



Wax was the most important ingredient in the vehicles for painting em- 

 ployed by the ancients. Its use is tracealile from the early ages of Egypt,' 

 and throughout those of Greek and Roman art. It was extensively and al- 

 most exclusively used hy the early Chrisiian painters, and continued to be 

 commonly employed ti'l a late (leriod in the middle ages. There is also 

 abundant evidence of the use of resins hy the ancients, and the employment 

 of such suhslances among the ingredients for painting, as well as for var- 

 nishes, was continued after the invention and improvement of oil-paintinj. 

 The process which has been fnund most s:itisfactory is that vxhich excludes 

 the fixed oils as much as possible, suhslituting for them wax, re^in, and an 

 essential oil- As a first condition aflecting the durability and brilliancy of 

 the work, a ground of pure wliite is recommended- In this, the practice of 

 remote antiquity has been confirmed by the best modern authorities. The 

 Egyptians, in the preparation of the surface for painting on walls and on 

 mummy cases, have left proofs of the estimation in which white grounds 

 were held in the earliest times. The practice of the Greeks and Romans is 

 exemplified by the prepared white tablet which was found among the ruins 

 of Herculaneum- Aristotle among the ancients, and Leonardo da Vinci and 

 Armeuini among modern writers, speak of white grounds as essential to the 

 brightness and durability of pictures- Caravaggio and others of the " Tene- 

 hrosi," on the contrary, who were instrumental to the decline of ait by em- 

 ploying dark grounds, have proved that the effects of time are accelerated 

 by that piactice. Many of the works of Tintoret have suffered from the 

 same cause. 



In the method about to be described, wax with resin may be considered, 

 as a substitute for a portion of the oil usually employed ; " the object being," 

 as a French chemist observes, '-to replace an alterable recipient for the 

 colours, such as oil is, by one whose nature it is to resist the action of time 

 and the agents of destruction."- 



The Process. — Secure a stout and well. pumiced canvas, free from size 

 and gummy matter. Fasten it slightly on the stretcher, with the smooth 

 surface undermost. Dissolve any quantity of bleached wax in double its 

 weight of oil of turpentine, and saturate tlie canvas with the solution while 

 hot, and near the fire. Then take the canvas oft" the frame and strelch and 

 fix it properly, the smooth side being now in front for the reception of the 

 ground. 



The Vehicle. — Prepare the vehicle, which is to be exclusively employed 

 throughout both ground and picture, in the following proportions : — 



3 ounces of essential oil (of turpentine, lavender, or rosemary, &c.) 

 2 „ resin (mastic. Copal, or Damara, &e.) 



1 „ bleached hees' wax. 



Place them in a glazed put near the fire, occasionally stirring them with a 

 stick, until the solution is completed. When cool it will be a magylp ready 

 for use. 



Procure a quantity of white-lead ground in oil ; that of the shops may 

 answer the purpose lor the two first coats, but flake white is preferable, and 

 is indispensable in the two last layers. Mix a pnrtion of tlie vehicle with 

 the lead, and reduce to a creamy consistence by the addition of turpentine 

 essence. 



Ground. — Spread, with a large flat knife or trowel, four coats of this white- 

 lead cream over the canvas as smoothly as possible, allowing several hours to 

 intervene between the layers. 



Picture. — In proceeding with the picture, the usual tube' or bladder- 

 colours of colourmen, ground in oil, may lie employed (unless the painter 

 have this labour performed at home), while the vehicle may be placed on the 

 palette near the colours, in the usual way, to he ready as a diluent. If a 

 rapidly obtained impaslo be desired, a portion of the ve lii'Me must be mixed 

 with the colour, which in a very short time "ill be found to have obtained a 

 consistence almost fit for modelling.* The vehicle can also be thinned at 

 pleasure by additional oil of turpentine, which will enable it to work more 

 freely ; or it may he softened and retarded in drying by a slight addition of 

 plain oil; or stiffened by replacing it near the fire to diminish the essence. 

 The most careless or lavish use of it cannot he followed by any injurious re- 

 sults, since, after the essential oil has evaporated, the ingredients subside 

 into a firm and unchangeable mass among the colours, witliout eitlier shrink- 

 ing or losing the foinis into which they have been wrought by the hand of 

 the painter. The essential oil has free egress, by the agency ot the wax, 

 through the back of the canvas, as well as through the front of the pictur'. 



1 See, among otller examples. No. ;jt in the J3ritisll Museum — a small funereal group 

 of painted srulpture. 



2 Diirosiez, ib. p. 12. — I took a quantity of the best flake white ground in oil, and 

 thiuniUR it with nut oil, I put several layers on a piepared millboard. From the (■iime 

 parcel of oil white lead I took anutlier portion, and diluting it to a working consistence 

 with wax creatu ;wax and oil of turpenline) I put tlie sunic number of layers on another 

 part of the millboard. In a few weeks the portion ubicli was diluted with additional oil» 

 had become of a decidedly yellow tint, while that which was mixed with the wax cream 

 remained as purely white as at hrst. 



a Bladder-culours beco[ne fat and rancid from the access of air in the course of time, 

 and many of the colours in tubes oxidize or blacken in a few months; among the latter 

 1 have found while lead, Naples yellow, yellow ochre, raw bieuua, &e.. so elfected. 



•* It may be as well to reinaik that an excessive application of essential oii in painttiig 

 has a tendency to ininre ttie teuncity ot the paint, as may be seen in uhut honse-painters 

 term bad " fljtting." The rapid evaporation of the essence from the more suLstautial 

 maleriois witli which it is combined breaks up, in some Ue^rck-, their cotiesiveaeas. 



