Possible source of error :

- [Lituus](http://www-history.mcs.st-and.ac.uk/Curves/Lituus.html) :

>The *lituus* curve originated with Cotes in 1722. Lituus means a *crook*, for example a bishop's crosier. Maclaurin used the term in his book *Harmonia Mensurarum* in 1722. The lituus is the locus of the point $P$ moving in such a manner that the area of a circular sector remains constant.

But MacTutor list of Maclaurin's [publications](http://www-history.mcs.st-and.ac.uk/Extras/Maclaurin_publications.html) does not list [Harmonia mensurarum](https://books.google.it/books?id=J6BGAAAAcAAJ&printsec=frontcover), while it is named as [Cotes](http://www-history.mcs.st-and.ac.uk/Biographies/Cotes.html)' posthumous work.

See [Scholium](https://books.google.it/books?id=J6BGAAAAcAAJ&pg=PA85), page 85 :

>quam *Litui* Figuram appello propter formae similitudinem.