151 



''SPANNERS" OR SETTING BRISTLES. 

 By H. Guard Knaggs, M.D., F.L.S. 



'' Spanners " are invaluable to the collector for the purpose 

 of setting out Lepidoptera, an operation which they greatly 

 facilitate. Their use is, firstly, to assist in getting the wings into 

 position ; and secondly, to hold them in their place until suitable 

 braces have been applied. The instrument under the finger at 

 A in the figure will give an idea of what a spanner is, and how it 

 is put together, thus : a stout pin is passed through one side of 

 a quarter-inch cube of silver cork, or cork carpet, so as to come 

 out on the opposite side, and is then withdrawn in order to allow 

 of the insertion of a bristle, represented in the figure by a cat's 

 whisker, the last quarter inch of the thick end of which has been 

 twice dipped in varnish in order that it may be firmly fixed in 

 the cube; a pin (a bead-headed steel toilet-pin being neatest and 

 most convenient) is then driven through two other opposite sides 

 of the cube, crosswise to, and at an angle slightly obtuse to, the 

 bristle, care having been taken that the concave curve of the 

 latter faces downwards. 



Nothing, so far as I know, has yet been introduced as a 

 spanner to beat the well-formed whisker of an old torn cat. It 

 was, I believe, the invention of my old friend Bond; it superseded 

 bristles and fibres from brooms and brushes, and cut quills (ex- 

 cepting for the larger insects), and has been adopted by most of 

 our best collectors during the past half-century. About forty 

 years ago my old friend Fereday tried to persuade us to use a 

 fine " beading-needle," as fine as a hair, but its action was com- 

 paratively harsh, and the material was not sufficiently flexible 

 and springy, so that it did not catch on. 



The qualities desirable in a spanner are roundness, smooth- 

 ness, and flexibility with stiff springiness ; the cat's whisker not 

 only possesses these in high degree, but is so graduated, in 

 thickness and strength, that, within certain limits, any required 

 pressure can be applied at will, from the gentlest touch of the 

 point to the most delicate micro, to the firm grip, by the stouter 

 portion, on the wings of a good-sized insect. Its manipulation, 

 of course, like everything else, wants a little judgment and 



