378
Transpositions needed for the 18mo
Scheme 41 the paper turns on the short cross. The two outer tiers of mated pages are at the In
ends of the sheet, where they back one another So do pages 17 and 18 in the offcut; properly. but pages 7-10 and 8-9 would be wrongly backed by this turn upon the short cross. When the sheet has been printed on the first side, page 7 must be transposed with page 9, and page 8 with page 10.
The transposition of pages in the form produces the same result as the turn on the long cross. In folding, the sheet is cut in three long strips, marked with dotted lines in the scheme. Pages 5-12 and 6-11 are in an offcut that is inset in the
as
The centre tier is then cut in three and pages 7-10 and 8-9 make another
larger folding.
equal parts, This leaves one third of the centre strip with As they have no mated leaf, it is 17-18. pages inset.
necessary to cut them through the centre and paste them down on page 16 at the end of the signature.
not an imposition to be recommended, for the sheet has to be cut in eight pieces and requires
It is
1 special care in folding. i The 18mo without transposition is laid down in some manuals page 7 lines with 8 and page 9 with 10 ; the centre tier of pages :
is
cut through the back margins,
making three single leaves that must be pasted down in the centre of the complete section. The inconvenience of transposition is not so great as that produced by the handling of three single
leaves and the insecurity of an unworkmanlike binding. It may be tolerated in the side-stitched pamphlet of one sheet only, but not as a section of a book for the library. Other schemes for the 18mo in one section are equally
troublesome, and they should be accepted only as a last resort when no other imposition can be used.