Delvalle Lowry (22 September 1800 – 23 December 1859, married name Varley) was a British geologist and mineralogist and author.
Lowry appears to have been mostly concerned with conveying her information clearly to those with a bare knowledge of mineralogy and her prose has been criticized for its stilted dialogue and lack of character development.
Varley was spendthrift by nature and had very little business sense; he died of a kidney infection hiding from his creditors in 1842.
The Engineer's Manual was intended for professionals in the field and Rudimentary Geology was published by John Weale in his 'Rudimentary Series' of scientific books.
It went through at least four editions, the last two of which were entitled Rudimentary Treatise on Mineralogy and included a section by the American geologist James Dana.