4.26 



MECHANICAL. 



It is of great importance that knotting of 

 good quality be used; it may be pur- 

 chased at half the cost of the well known 

 patent knotting, but will answer no pur- 

 pose. The best driers are prepared from 

 sugar of lead; the lighter the driers the 

 better their quality. The quantity of 

 . driers required depends upon the time ot 

 the year the paint is used, and the charac- 

 ter of the oil. There is a great deal of 

 bad oil in use now, distilled, or by other 

 means prepared from resin ; this will not 

 dry properly, do what you will with it, 

 and it should be condemned for paint- 

 work at once. It does not cost half so 

 much as linseed oil, and there is, there- 

 fore, at all times danger of it getting into 

 our work. When fresh, and sometimes 

 when of long standing, it may be killed 

 by an application of petroleum spirit, or 

 potash; but generally, when this oil 

 proves to be in the paint, the best course 

 is to scrape the whole off with salaman- 

 cas, or hot irons, in the usual way. No 

 oil will answer so well as linseed oil, well 

 boiled or raw, when there is not the 

 necessity for so much driers; raw oil may 

 be used in summer weather, and should 

 always be used for white paints, as the 

 boiled oil discolors them; driers in this 

 latter case must be added. Often when 

 we specify the best copal varnish, we get 

 nothing but common oak, though the 

 difference in cost may be from seven 

 shillings to twenty-one per gallon. The 

 best proceeding for the architect is to 

 price the varnish, and take special means 

 for obtaining it. For ordinary purposes, 

 where we usually specify common oak var- 

 nish, copal varnish diluted with oil answers 

 better, and in practice is often adopted. 



PAINT, Mixing Oil Colors. — In mixing 

 different colored paints to produce any 

 desired tint, it is best to have the princi- 

 pal ingredient thick, and add to it the 

 other paints thinner. In the following 

 list of the combinations of colors required 

 to produce a required tint, the first named 

 color is the principal ingredient, and the 

 others follow in the order of their im- 

 portance. Thus, in mixing a limestone 

 tint, white is the principal ingredient, and 

 red the color of which least is needed, 

 etc. The exact proportions of each de- 

 pending on the shade of color required. 



List of compound colors, showing the 

 simple colors which produce them. 



Buff, white, yellow ochre, red. 



Chestnut, red, black, yellow. 



Chocolate, raw umber, red, black. 



Claret, red, umber, black. 



Copper, red, yellow, black. 



Dove, white, vermillion, blue, yellow. 



Drab, white, yellow ochre, red, black. 



Fawn, white, yellow, red. 



Flesh, white, yellow ochre, vermillion. 



Freestone, red, black, yellow ochre, 

 white. 



French Gray, white, Prussian blue, lake. 



Gray, white lead, black. 



Gold, white, stone ochre, red. 



Green Bronze, chrome, green, black, 

 yellow. 



Green Pea, white, chrome green. 



Lemon, white, chrome yellow. 



Limestone, white, yellow ochre, black, 

 red. 



Olive, yellow, blue, black, white. 



Orange, yellow, red. 



Peach, white, vermillion. 



Pearl, white, black, blue. 



Pink, white, vermillion, lake. 



Purple, violet, with more red and white. 



Rose, white, madder lake. 



Sandstone, white, yellow ochre, black, 

 red. 



Snuff, yellow, Vandyke brown. 



Violet, red, blue, white. 



LAND, Measuring. — Land measuring 

 is the art by which we ascertain the su- 

 perficial contents of any tract of ground. 



There are various methods of obtain- 

 ing the measurement — some of them re- 

 quiring familiar acquaintance with mathe- 

 matical treatises more intricate and com- 

 prehensive than the present work ; whilst 

 others need nothing beyond a knowledge 

 of the simplest principles of mensuration. 



As the present work addresses itself 

 entirely to practical men, we shall confine 

 our remarks to the popular method ordi- 

 narily employed. 



Land is commonly measured with 

 what is called Gunter's chain. This chain 

 is divided into ioo links, having at the 

 end of every ten links a piece of brass 

 fixed with notches denoting the number 

 of tens, so that the number of links may 

 be readily ascertained. The English 

 chain is 22 yards or 66 feet in length, and 

 each link 6.92 inches, 



In taking measurements in the field,, 

 the various distances are set down in 



