There he was given information by his half-brother Charles, which he would report to the French War Office on his return to Paris. Basically Appell and his brother Charles were acting as spies and informants for France against Germany. Charles was to pay a price for this when, in 1889, he was imprisoned for anti-German activities.
Doon siya ay ibinigay na impormasyon sa pamamagitan ng kanyang half-brother Charles, na kung saan siya ay ulat sa French War Office sa kanyang bumalik sa Paris. Basically Appell at ang kanyang mga kapatid na lalaki Charles ay kumikilos bilang spies at informants para sa Pransya laban sa Alemanya. Charles ay upang magbayad ng isang presyo para sa mga ito kapag, sa 1889, siya ay nabilanggo para sa anti-Aleman na gawain.