《National Geographic Magazine Vol. 02 No. 1-2》 - 免费有声读物

National Geographic Magazine Volume 2 Number 1 April 1890.:
* On the Telegraphic Determinations of Longitude by the Bureau of Navigation
* Report: Geography of the Land
* Report: Geography of the Air

National Geographic Magazine Volume 2 Number 2 May 1890.:
* The Rivers of Northern New Jersey, with notes on the classification of rivers in general.
* A Critical Review of Bering's First Expedition, 1725-30, together with a translation of his original Report upon it.
* Supplementary note on the alleged observation of a Lunar Eclipse by Bering in 1728-9.