[Proj] A bit of help with French, por favor.

[Gerald I. Evenden]

I have run into three phrases labeling projection states:

cas de la sphere de courbure
cas de la sphere equatoriale
cas de la sphere bitangente

The equitorial case seems obvious, the translation web site can't come up with 
anything for bitangente and "curve" for courbure does not mean anything to 
me.

Any ideas would be helpful.

I apologize for being too lazy to do the accents.
-- 
The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939)  British psychologist