The satisfactory cutting of this groove is not a very easy matter, but if its position is first carefully marked, a long rat-tail file may be made to plough it out neatly and regularly. As an alternative the following plan is good. First cover the wood with a layer of cork about a _quarter_ of an inch thick, and then glue on the top of this _two_ narrower strips, about as thick as the bodies of the insects for which the board is intended, leaving a space of the required size between them, as shown in fig. 60. In this way you get a groove of square section, that is in some respects preferable to the round one cut out by means of the rat-tail file. [Illustration: FIG. 61.--SECTIONS OF SETTING BOARDS.] Now comes a question about which there is a difference in the tastes or fancies of entomologists. Shall the boards be perfectly flat on the top, or shall the sides slope from the groove, or shall the surface be rounded? A glance at the three sections of setting boards will show clearly what is meant. The rounded board is most commonly used, and the graceful curve thus given to a butterfly or moth set on such is certainly attractive; but it is not natural. The wings of these insects are rigid, and are never seen bent into such curves in a living specimen. For this reason I much prefer a perfectly plane surface on each side of the groove. Then, as to whether there shall be a slope or not, this is a matter of less importance. A very decided sloping of the wings is certainly not so convenient for future examination; nor does it, to my mind, look nearly so well as both sides in the same plane, or at a very gentle inclination. But perhaps this subject had better be left to the taste of the reader, remembering, however, that, whatever plan be adopted, all the boards should be alike in this respect, so that there may be a degree of uniformity in the cabinet. The surface of the cork must, in all cases, be nicely smoothed down with glass paper, and then covered with thin white paper, fixed to its surface with ordinary paste. When insects are on the boards, they should be placed in an airy spot, as free as possible from dust, while they are drying. Hence the advisability of some form of 'drying house.' This is simply a box, standing on end, and provided with a hinged door consisting of a sheet of perforated zinc in a wooden frame. The boards may slide in this on little slips of wood nailed or glued on to the sides, or the wooden bases of the boards may project beyond the cork at the ends, and slide into grooves in the side of the house. [Illustration: FIG. 62.--A BUTTERFLY ON THE SETTING BOARD.]