More words...

1. yew hedge -some wall from living plants

"There are two lines of old yew hedge,... "

2. impenitrable - smth what we are not available (syn: impassable, ant: accessible, permeable)

 "...twelve feet high and impenetrable."

3. exceedingly - very strong, extremely (syn: extraordinarly)

"You interest me exceedingly."

4. padlock - lock to lock smth 

"Closed and padlocked."

5. wicket-gate - a little door in the garden, for example (syn: pass)

"And what marks did you see by the wicket-gate?"

6. gravel - small stones, pebbles

" He had left his own marks all over that small patch of gravel."

7. immense - smth very large, great (syn:massive, huge, enormous)

"...,and one which presented immense opportunities to the scientific expert."

8. hesitate - doubt smth (syn: falter, flounder, waver; ant: ascertain, choose, continue, decide)

"Why do you hesitate?"

9. acute - sharp or pointed (for example: acute eyesight)

"There is a realm in which the most acute and most experienced of detectives is helpless."

10. reconcile - make friends (syn: adjust, settle)

"Since the tragedy, Mr Holmes, there have come to my ears several incidents which are hard to reconcile with the settled order of Nature."

11. hitherto - before it, before the present time

"I have hitherto confined my investigations to this world."

12. diabolical - wicked, cruel, devilish (syn. damnable)

"..., and yet he was diabolical as well."

13. tug - drag or pull with a force

 " The original hound was material enough to tug a man's throat out."

14. trustee -  person who controls the property on trust

"I speak now not as a medical man but as a trustee and executor of Sir Charles's will"