I believe The answer is: <span>Hunting and fishing
One of his most popular books , old man at the see, depict a lot of scenes that wouldn't be possible to write without any prior knowledge on fishing.
Beside that, his book under Kilimanjaro also depict a lot of scenes that require prior knowledge in hunting.</span>
The kepi was formerly the most common headgear in the French Army<span>. Its predecessor originally appeared during the 1830s, in the course of the initial stages of the occupation of Algeria, as a series of various lightweight cane-framed cloth undress caps called </span>casquette d'Afrique<span>. These were intended as alternatives to the heavier, cloth-covered leather French Army </span>shako.[1]<span> As a light and comfortable headdress, it was adopted by the metropolitan (French mainland) infantry regiments for service and daily wear, with the less practical shako being relegated to parade use. In 1852, a new soft cloth cap was introduced for campaign and off-duty. Called </span>bonnet de police à visière<span>, this was the first proper model of the kepi. The visor was generally squarish in shape and oversized and was referred to as </span>bec de canard<span> (duck bill). This kepi had no chinstrap (</span>jugulaire<span>). Subsequent designs reduced the size of the cap and introduced chinstraps and buttons. The kepi became well known outside France during the </span>Crimean War<span> and was subsequently adopted in various forms by a number of other armies (including the U.S. and Russian) during the 1860s and 1870s.</span>
