A T-square is likely, in careless hands, to have its working edge chipped or notched. It is then necessary to take the blade and cross-piece apart and have the edge reshot; but it is much better for this necessity not to arise. An ebony edge will not get damaged in this way very readily unless it be actually cut, by using it as a guide for a penknife when cutting paper. This should never be done - nor should paper be cut on the face of a drawing board, which in this way is soon scarred and rendered uneven. It is best to draw pencil lines where paper is to be cut, and then to remove it from the board and cut it on the top of the drawing table, using the back of a T-square, and not its working edge, as a guide.

Drawing boards and T-squares are made to standard sizes to suit the recognised sizes of drawing paper, the comparison being as follows: -

Name of Paper.

Size of

Paper in Inches.

Size of

Board in Inches.

Length of T-square from Cross-piece to end of Blade in Inches.

Half Imperial ....

20

x

15

23

x

16

24

Imperial........

30

x

22

31

x

23

31

Double Elephant..

40

x

27

42

x

29

42

Antiquarian .....

53

x

31

54

x

33

54

An even larger paper, 72 by 48 inches, known as "Emperor," is also made by Joynson, but neither this nor "Antiquarian" is much used, continuous paper, obtainable in rolls 50 yards in length and either 30, 40, 54, or 60 inches wide, being preferably employed in offices where large drawings are likely to be required.

Drawing Paper. It is well recognised to be false economy to employ any other than thoroughly good paper for contract and show drawings, and the papers almost invariably used are either: -

For fine pen-and-ink work, Whatman's "Hot pressed" or Joynson's "Smooth."

For general contract drawings with colour, Whatman's "Not" orJoynson's "Cold pressed."

For artistic colour work only, Whatman's " Rough " or Joynson's "Artist's Rough." These can all be obtained in any of the above sizes, and of several different thicknesses, known by weight.

Only "insides" sheets should be used for good work, as "outsides" are liable to defects, such as soft absorbent patches which take colour badly, which cannot be detected till colour is applied.

The right side to use is that which shows the water mark, usually the maker's name, correctly when held up to the light.

For ordinary office use, such as the preparation of sketches or of details, there are many papers to select from, the slightly absorbent, buff-toned "cartridge" being perhaps the most popular, though many prefer the harder "web" or the thinner "detail" papers. When selecting, the best thing to do is to obtain samples, which any dealer will supply, and to test them with pencil and rubber, to ascertain whether pencil marks are removable from them; and with a colour wash to discover if they are free from blotches.

Tracing Paper is obtainable either in sheets of the same standard sizes as drawing paper, or in rolls, the latter form being much the more convenient for office use. Many different widths are made, varying between 28 and 60 inches, while the lengths most usually found in each roll are 20, 21, 22, and 50 yards. It is necessary to consider both width and length when comparing the prices of various papers per roll, and it is also advisable to select such a width as will not cut greatly to waste. Thus in an office in which almost all drawings are made on Double Elephant or Imperial paper there is little waste on tracing paper 30 inches wide, and much on that which is 40 inches wide - which shows a wide margin to Imperial paper whichever way it is cut; the tendency of most young draughtsmen being to throw away the surplus rather than to use it for odd purposes.

In selecting tracing paper it is necessary to keep in mind the purpose for which it is required. If it be for pencil sketching and the elaboration of plans in pencil, a tough paper is needed which will permit the rubber to be used with freedom, while it should be as transparent as this condition will permit. If fine ink line drawings are to be made for subsequent copying by sun process, a very smooth and transparent paper is needed. On the other hand, toughness is the principal requirement in a paper to be subjected to rough handling by workmen on a building, and whiteness of colour if the drawings made on it are to be reproduced by photography for purposes of illustration. All tracing paper turns yellow and becomes more or less opaque with age.

Tracing Cloth, which is made of linen rendered transparent by coating it with some mucilaginous substance, is made either 18, 27, 30, 36, 40, 43, or 54 inches wide, in rolls which almost invariably contain 24 yards. Some is glazed on both sides, but most of it is glazed on the face and dull backed. It is largely used for tracings which have to stand the test of hard wear, but unfortunately is not reliable in the matter of scale, as it shrinks considerably when drying after being coloured.

In most offices, though not invariably, ink lines are drawn on the glazed face, into which powdered chalk has first been well rubbed with a piece of blotting paper and then dusted off; while colour is, as with tracing paper, applied on the back, which is best also chalked first in a similar manner. Indian ink can be removed from either surface by ink-eraser, carefully used.

Tracing cloth turns an opaque white if water is applied to it; and if boiled and washed can be converted to the original linen from which it was made, no sign of any drawing which may have been made upon it remaining after the process.

Rubber should be very carefully selected. The pure bottle indiarubber is now very seldom seen, as it is too soft and slimy to remove pencil marks perfectly, and it leaves smears on the paper also. Much that is sold is similarly too soft except for removing the marks of very soft pencils very softly applied, crumbling up in use; while other is so hard and gritty as to remove and roughen the surface of the paper to which it is applied, and therefore is only useful for the removal of ink lines or colour. For general office use it would possibly be difficult to improve on Wolf's or Halden's, square and flat cakes being best.