IN Fig. 6, Q C is the extra link pivoted to the fixed point Q, the other pivot on it C, describing the circle OCR. The straight lines? ? and F M' are supposed to be perpendicular to M R Q M'. You have ...

The Modmin has been a go-to for quality videos and tutorials on architectural drawing and sketching. Their newest video tackles a drawing fundamental: the ability to draw a straight line. For many ...

III. BEFORE leaving the Peaucellier cell and its modifications, I must point out another important property they possess besides that of furnishing us with exact rectilinear motion. We have seen that ...