Neate W62; Perret 4458-A. Whymper travelled in the Andes in 1879-80, making several ascents. During the expedition, Whymper noticed certain irregularities in the readings of aneroid barometers at high altitude. Consideration of the instrument resulted in the publication of the present work, which led to important improvements in their construction. Based on observations he took in the Andes, it also advertises on its rear wrapper Whymper’s book of the expedition, Travels amongst the Great Andes of the Equator (1892), and the scientific supplement. For this reason, How to use the Aneroid Barometer has often been regarded as an addendum to the narrative work.