Sentence:  This reel need not be very large, nor yet very expensive, a plain, easy-running wooden one about three inches in diameter, and costing no more than  from two to three shillings, will be plenty good enough ; but one thing the tyro ought to observe, and that is, the reel should have a strong <WSD>crossback</WSD> to it ; the brasswork on the back should be fitted right across and in four opposite directions. 
Meaning of the word marked with <WSD> tags:  Two pieces on the back of an item (for attaching or bracing it) which form an "X".