Here some facts about the book you mentioned.
Small Rain was first published by the Religious tract Society in London
and at the same time also by the American Tract Society of New York. At
least 40 editions appeared; the first one about 1830.
Mostly the are no dated but as your copy is printed by Whittingham and
Wilkins it must be a later edition, after 1840 (the 19th ed was still
printed by Whittingham only). I have seen several editions both in morocco
and in paper. According to Spielman the were published until 1870 bu Bondy
mentioned a special edition of 1890. These kind of book were very popular
in ther time.
See also Mikrobiblio 21st edition, # 209.
It must be a fine acquisition for your collection.