Sentence:  I take account of conical and biplanar nodes, or, as I call them, cnicnodes, and binodes; of pinch-points on the nodal curve; and of close-points and off-points on the cuspidal curve: viz. I assume that there are / C, cnicnodes, / B, binodes, / j, pinch-points, / \chi, close points, / \theta, off-points, / deferring for the present the explanation of these singularities. The same letters, accented, refer to the reciprocal singularities. Or using "<WSD>trope</WSD>" as the reciprocal term to node, these will be / C', cnictropes, / B', bitropes, / j', pinch-planes, / \chi', close-planes, / \theta', off-planes; / but these present themselves, not in the equations above referred to, but in the reciprocal equations. 
Meaning of the word marked with <WSD> tags:  The reciprocal of a node on a surface.