translation.en: It was of common quality, grayish in colour. The address, "Sir Henry Baskerville, Northumberland Hotel," was printed in rough characters; the postmark "Charing Cross," and the date of posting the preceding evening.
translation.pl: Była to zwykła, szara koperta; adres: _Sir Henryk Baskerville_, _Northumberland Hotel_ -- wypisany był drukiem, stempel Charing Cross i data na kopercie z poprzedniego wieczora.