(painting of Don Josef de Mendoza y Rios found on the net. I don't know its origin).

The following article appeared in the Transactions of the Royal Society (London) in 1797. It is a compilaton of Mendoza Rios's analyses of two important problems in nautical astronomy: latitude by double altitudes and longitude by lunars. Most of this material was previously published by Mendoza Rios. The article discusses minor corrections (e.g. other quadratic terms in lunars) which are completely un-necessary in practice and only of interest theoretically. Mendoza Rios is aware of this as can be seen in his worked examples at the end of the article.

The article is in French:
Recherches sur les Principaux Problemes de l'Astronomie Nautique