"On the Origin and Investigation of Porisms : from the Transact: of the R. Soc: of Edinb" . "On the origin and investigation of porisms By Mr. John Playfair, F.R.S. Edin. And Professor of Mathematics in the University of Edinburgh. From the third volume of the transactions of the Royal Society of Edinburgh" . . "On the origin and investigation of porisms. By Mr. John Playfair ... From the third volume of the transactions of the Royal Society of Edinburgh"@en . . "On the origin and investigation of porisms By Mr. John Playfair, ... From the third volume of the transactions of the Royal Society of Edinburgh" . . "Electronic books"@en . . . . . . "On the origin and investigation of porisms. By Mr. John Playfair, F.R.S. Edin. And Professor of Mathematics in the University of Edinburgh. From the third volume of the transactions of the Royal Society of Edinburgh"@en . . "On the origin and investigation of porisms By Mr. John Playfair, ... From the third volume of the transactions of the Royal Society of Edinburgh : By Mr. John Playfair, ... From the third volume of the transactions of the Royal Society of Edinburgh" . . . . "On the origin and investigation of porisms"@en . . . "Early works"@en . "Early works" . . . .