Inferior instruments will never wear satisfactorily, whereas those well made improve by use, and attain a peculiar working smoothness. The extra cost of purchasing the case and the nearly useless rules, would, in many instances, be equal to the difference between a good and an inferior set of instruments without the case. Instruments may be carefully preserved by merely rolling them up in a piece of wash leather, leaving space between them that they may not rub each other; or, what is better, having some loops sewn on the leather to slip each instrument separately under.
The qualities a good drawing board should possess are: an equal surface, which should be slightly roundel from the edges to the centre, in order that the drawing paper when stretched upon it may present a solid surface; and the edges perfectly straight, and at right angles to each other.
It should be held very nearly upright, between the thumb and first and second fingers, the knuckles being bent, to that it may be held at right angles with the length of the hand. The handle should incline only a very little - say ten degrees. No ink should be used except Indian iuk, rubbed up fresh every day upon a clean palette. Liquid ink and other similar preparations' are generally failures. The ink should be moderately thick, so that the pen when slightly shaken will retain it a fifth of an inch up the nibs. The pen is supplied by breathing between the nibs before immersion in the ink, or by means of a small camel-hair brush; the nibs will afterwards require to be wiped, to prevent the ink going upon the edge of the instrument to be drawn against. The edge used to direct the pen should in no instance be of less than a sixteenth of an inch in thickness; a fourteenth of an inch is perhaps the best. If the edge be very thin, it is almost impossible to prevent the ink escaping upon it, with the great risk of its getting on to the drawing.
Before putting the pen away, it should be carefully wiped between the nibs by drawing a piece of folded paper through them until they are dry and clean.
Lay the straightedge upon a stretched sheet of paper, placing weights upon it to hold it firmly; then draw a line against the edge with a needle in a holder, or a very fine hard pencil, held constantly vertical, or at one angle to the paper, being careful to use as slight pressure as possible. If the straight-edge be then turned over to the reverse side of the line, and a second line be produced in a similar manner to the first at about the twentieth of an inch distance from it, any inequalities in the edge will appear by the differences of the distances in various parts of the lines, which may be measured by spring dividers.
Another method will be found to answer well if three straight-edges are at hand; this method is used in making the straight-edge. Two straight-edges are laid together upon a flat surface, and the meeting edges are examined to see if they touch in all parts, reversing them in every possible way. If these two appear perfect, a third straightedge is applied to each of the edges already tested, and if they touch it in all parts the edges are all perfect. It may be observed that the first two examined, although they touch perfectly, may be regular curves; but if so, the third edge applied will detect the curvature.
. Using' the Plain Parallel Rulo. - One of the rules is pressed down firmly with the fingers, while the other is moved by the centre stud to the distances at which parallel lines arc required. Should the bars not extend a sufficient distance for a required parallel line, one rule is held firmly, and the other is shifted, alternately, until the distance is reached.
It is considered best to place the forefinger upon the head, and to move the legs with the second finger and thumb. In dividing distances into equal parts, it is best to hold the dividers as much as possible by the head joint, after they are set to the required dimensions; as by touching the legs they are liable to change, if the joint moves softly as it should. In dividing a line, it is better to move the dividers alternately above and below the line from each point of division, than to roll them over continually in one direction, as it saves the shifting' of the fingers on the head of the dividers. In taking off distances with dividers, it is always better, first to open them a little too wide, and afterwards close them to the point required, than to set them by opening.
If a drawing could be at once placed to the best advantage on the paper, and surely made without mistake and with all its lines correctly limited when, first drawn, it might be made in ink directly on the blank paper. To avoid the errors inevitable in the first copy of any production, even when made by those most practised, drawings are first pencilled and then inked. The whole theory of pencilling, then, is to lay out correct tracks on which the pen is to move, leaving the mind, during the inking, nee from all thought of accuracy of the construction, that it may be given to excellence in execution. Therefore, the whole of the pencil construct ion should be most accurately made in the finest faint lines with a hard pencil.
While "Finish a drawing without any error or defect,", should be the draughtsman's best motto, he should never be in haste to reject a damaged drawing, but should exercise his ingenuity to see how far injuries done to it may be remedied. "Never lose a drawing once begun," should be his second motto; and since prevention is easier and better than cure, let him always work calmly, inspect all instruments, hands, and sleeves, that may touch a drawing, before commencing an operation; let the paper, instruments, and person be kept clean, and when considerable time is to be spent upon a portion of the paper, let the remainder be covered with waste paper, pasted to one edge of the board.
For the final cleaning of the drawing, stale bread, or the old-fashioned black rubber, if not sticky, is good; but, aside from the carelessness of ever allowing a drawing to get very dirty, any fine drawing will be injured, more or less, by any means of removing a considerable quantity of dirt from it.
Another excellent means of preventing injuries, which should be adopted when the drawing is worked upon only at intervals, is to enclose the board, when not in use, in a bag of enamelled cloth or other fine material.