Tubing 3/16 or 1/8 inch in external diameter is suitable.  Break it up (by nicking with a file) into 9-inch lengths.  Take a piece and hold its centre in the flame of a small spirit lamp, and revolve it till it softens.  Then draw the glass out in as straight a line as possible, so that the points may be central.  If the drawing is done too fast, the points will be much too long to be of any use:  half an inch of taper is quite enough.

Assuming that a point of satisfactory shape has been attained—­and one must expect some failures before this happens—­the pen may be placed in the pen lever and ground down on a perfectly clean wet hone laid on the card platform, which should be given a circular movement.  Weight the lever so as to put a fair pressure on the point.

The point should be examined from time to time under a strong magnifying-glass, and tested by blowing through it into a glass of water.  For very liquid ink the hole should be as small as you can possibly get it; thick inks, such as Indian, require coarser pens.

The sharp edge is taken off and the width of the point reduced by drawing the pen at an angle along the stone, revolving it all the time.  The nearer to the hole you can wear the glass away the finer will be the line made by the pen.

Another method is as follows:—­Seal the point by holding it a moment in the flame.  A tiny bulb forms on the end, and this has to be ground away till the central hole is reached.  This is ascertained by the water test, or by holding the pen point upwards, so that light is reflected from the tip, and examining it under the magnifier.  Then grind the edge off, as in the first case.

Care of Pens.—­The ink should be well strained, to remove the smallest particles of “suspended matter,” and be kept corked.  Fill the pen by suction.  On no account allow the ink to dry in the pen.  Squirt any ink out of it when it is done with, and place it point downwards in a vessel of water, which should have a soft rubber pad at the bottom, and be kept covered to exclude dust.  Or the pen may be cleaned out with water and slipped into a holder made by rolling up a piece of corrugated packing-paper.  If the point gets stopped up, stand the pen in nitric or sulphuric acid, which will probably dissolve the obstruction; and afterwards wash it out.

Inks.—­I have found Stephens’s coloured inks very satisfactory, and can recommend them.

Paper and Cards.—­The paper or cards used to draw the figures on should not have a coated surface, as the coating tends to clog the pen.  The cheapest suitable material is hot pressed paper, a few penny-worths of which will suffice for many designs.  Plain white cards with a good surface can be bought for from 8s. to 10s. per thousand.

Lantern Slides.—­Moisten one side of a clean lantern slide plate with paraffin and hold it over a candle flame till it is a dead black all over.  Very fine tracings can be obtained on the smoked surface if a fine steel point is substituted for the glass pen.  The design should be protected by a cover-glass attached to it by a binding strip round the edges.