There are several ways to solve most of these puzzles.  The walkthrough includes the quickest and not necessarily most satisfactory solutions.  Moreover, if you follow the walkthrough precisely, you'll miss most of the side detail of the game.  But here it is, nonetheless.


CROSSING THE LAKE

N. OUT. THROW ROCK AT BELL. LOOK AT MIRROR. LOOK IN MIRROR. TAKE ROCK. GET IN GONDOLA. GONDOLIER, N. 


GETTING THROUGH THE SILVER DOOR

N. TAKE LENS. E. LOOK AT TREES. TAKE APPLE. SHAKE APPLE. PUT APPLE IN FURNACE. PRESS BUTTON. TAKE APPLE. THROW IT. TAKE KEY. PUT KEY IN FURNACE. SET DIAL TO 4. PRESS BUTTON. TAKE IT. W. W. PUT KEY IN CONTRAPTION. E. UNLOCK DOOR. N. 


DEALING WITH THE WOODEN TUBE

TAKE TUBE. BLOW TUBE. TAKE SCROLL. READ SCROLL WITH LENS.


LOWERING THE PULLEY

S. W. PUT RING IN CONTRAPTION. G. G. E. N. W. D. PUT RING ON PULLEY. TAKE IT.


RAISING THE STONE

U. E. S. W. TAKE NEEDLE. PUT NEEDLE IN CONTRAPTION. G. G. E. N. E. LEVER STONE WITH NEEDLE. D. TOUCH FLOOR. U.


GETTING THE OCTAHEDRON

W. U. E. HIT FROGS WITH ROCK.  <Anything else will work too, provided it's hard.>  WIPE PEDESTAL WITH DRESS. CLIMB ON PEDESTAL. TAKE OCTAHEDRON. D.


DEALING WITH THE STAIRCASE

W. D. S. W. TURN CONTRAPTION. TAKE ALL FROM BOX. PUT BOX IN CONTRAPTION. WEAR BOX. E. N. U. W. PUT LENS IN SLOT. PUT TUBE IN OVEN. PRESS BUTTON. U. TAKE IT. D. 


GETTING UPSTAIRS FROM THE MID-TOWER

E. X STATUE. TAKE KEY. X PLACARDS. PULL COPPERY. UNLOCK GRATING. D. S. W. PUT STURDY KEY IN CONTRAPTION. TURN CONTRAPTION. PUT BALL IN CONTRAPTION. G. E. E. PUT BALL IN FURNACE. SET DIAL TO 2. PRESS BUTTON. TAKE BALL. W. N. U. UNLOCK GRATING. PUT BALL IN HOLE. U. TAKE IT. D.


GOING HOME

D. S. S. SHAKE BELLS. Z. Z. Z. GET IN GONDOLA. GONDOLIER, S. ENTER MIRROR.


(Yes, there are other endings.  Find them yourself.)