“And who could it be who was her confederate (но кто же мог быть ее сообщником)? A lover evidently, for who else could outweigh the love and gratitude (очевидно, возлюбленный, потому что кто еще мог пересилить любовь и благодарность) which she must feel to you (которые она должна была питать к вам = должно быть, питала к вам)? I knew that you went out little (я знал, что вы мало бываете в обществе), and that your circle of friends was a very limited one (и что круг ваших друзей очень ограничен). But among them was Sir George Burnwell (но среди них был сэр Джордж Бэрнвелл). I had heard of him before as being a man of evil reputation among women (я и раньше слышал о нем как о человеке дурной репутации среди женщин = что он нехорошо поступает по отношению к женщинам). It must have been he who wore those boots and retained the missing gems (должно быть, это он носил те ботинки и держал у себя пропавшие бериллы = это он человек в ботинках, и у него находятся пропавшие бериллы; to wear — носить /обувь, одежду/; to retain — держать /у себя/; удерживать). Even though he knew that Arthur had discovered him (даже если он и понимал, что Артур узнал его), he might still flatter himself that he was safe (он все равно мог тешить себя мыслью, что находится в безопасности; safe — защищенный от опасности; в безопасности), for the lad could not say a word without compromising his own family (так как ваш сын не мог бы сказать ни слова, не скомпрометировав /при этом/ свою собственную семью).

“Well, your own good sense will suggest what measures I took next (ваш здравый смысл предположит = логика подскажет вам, какие меры я предпринял затем). I went in the shape of a loafer to Sir George’s house (переодевшись бродягой: «в виде бродяги» я отправился к дому сэра Джорджа), managed to pick up an acquaintance with his valet (сумел познакомиться с его лакеем), learned that his master had cut his head the night before (узнать он него, что его хозяин расшиб голову накануне вечером), and, finally, at the expense of six shillings (и наконец за шесть шиллингов: «ценой шести шиллингов»), made all sure by buying a pair of his cast-off shoes (удостовериться во всем, купив пару старых ботинок сэра Джорджа; cast-off — выброшенная, ненужная вещь). With these I journeyed down to Streatham (с ними я отправился в Стритем) and saw that they exactly fitted the tracks (и убедился, что они в точности соответствуют следам /на снегу/).”

outweigh [aut'we], among ['m], compromising ['kmprmaz], measure ['me]

“And who could it be who was her confederate? A lover evidently, for who else could outweigh the love and gratitude which she must feel to you? I knew that you went out little, and that your circle of friends was a very limited one. But among them was Sir George Burnwell. I had heard of him before as being a man of evil reputation among women. It must have been he who wore those boots and retained the missing gems. Even though he knew that Arthur had discovered him, he might still flatter himself that he was safe, for the lad could not say a word without compromising his own family.

“Well, your own good sense will suggest what measures I took next. I went in the shape of a loafer to Sir George’s house, managed to pick up an acquaintance with his valet, learned that his master had cut his head the night before, and, finally, at the expense of six shillings, made all sure by buying a pair of his cast-off shoes. With these I journeyed down to Streatham and saw that they exactly fitted the tracks.”