LIFE in Colonial MEXICO , Collection of letters from a woman living in Nueva Espana

Hola !
I am trying to locate the name of a book I used to read online. It was a collection of letters in ingles, from a woman in Collonial Nueva Espana Mejico.

The woman I belive was the wife of perhaps an Ambassador? and wrote to her friend either in the USA or England. The book gave a interesting view point of her travel by ship, by coach from the gulf to the interior, her contact with native peoples, and the nobles on the continent.

The book used to be availble to read online but if not i would just like to know the name.. thank you.