Many of my favorite Victorian explorer-scientists were featured in this excellent book, with a few thrown in that I wasn't familiar with for good measure. The main draw for me was Alfred Russel Wallace (who rates an entire chapter), but then there's also Mary Kingsley, Richard Burton, Joseph Hooker, Henry Walter Bates, and a host of others.
Raby does a fine job of describing the boundless energy and insatiable curiosity of these peripatetic Victorians. I confess to being almost hopelessly nostalgic for an age when there was so very much of the globe to be discovered -- when explorers were really venturing into terra incognita. Of course, many of them were more than a bit eccentric and even downright obsessive, but apparently it's what kept some of them going down that river or over the next mountain range. The best of them, such as Kingsley and Wallace, were clear-eyed enough to predict the destructive nature of the inevitable "civilizing" forces that were to follow them.