Unlike most of the other 11 paintings from the book, Image 10 does not have any (known) numbers representing latitude or longitude.  Perhaps to balance out those missing map clues, the image includes more than the usual number of city-level clues to get us started in the right place.

  Our first clue is the combination of the millstone, the cane and the key being juggled.  They form a rebus telling us the city where we should be searching:

"mill" + "walk" + "key" = Milwaukee.

  The hands of the juggler seem to be representations of the hands of Solomon Juneau in the bronze relief on the Juneau Monument in Juneau Park.

  (Just as in the puzzles for New York and Houston, the artwork here includes images from various parks where the casque isn't hidden, partially as clues to the correct city and partially as red herrings to distract readers from the correct location.)

All of the clues up to this point combine to put us somewhere in the metropolitan area of Milwaukee, Wisconsin.

1) View the three stories of Mitchell

  Mitchell Hall is a three-story building located on the corner of E. Kenwood Blvd. and N. Downer Ave on the campus of the University of Wisconsin-Milwaukee.  It is the closest campus building to Lake Park.

2) As you walk the beating of the world

  Kenwood is a company that makes electric kitchen mixers (blenders) and they advertised their "Electric Chef" model as being a "Kitchen WORLD BEATER."

  This line is clearly confirming that we have the correct three-story Mitchell building and that we should start walking down East Kenwood Boulevard.

3) At a distance in time

4) From three who lived there

  The "three who lived here" is a reference to Downer, Hackett and Shepard avenues east of the UWM campus.  Those three avenues were named after some of Milwaukee's most prominent early citizens.

5) At a distance in space

6) From woman, with harpsichord

7) Silently playing

  "Woman with harpsichord" apparently means Marietta Robusti (1560? – 1590), whose self-portrait shows her by a harpsichord.  This is therefore a reference to Marietta Avenue, the next street one would cross moving eastwards along Kenwood Blvd.

8) Step on nature

  After crossing Downer, Hackett, Shepard, and Marietta, one reaches Lake Park, a large natural area on the edge of Lake Michigan.  This line is telling us to enter the park.

9) Cast in copper

  The most common object "cast in copper" is, of course, a penny, which features a profile of President Abraham Lincoln on the front and a picture of the Lincoln Memorial on the back.  This reference is telling us to continue from the end of Kenwood and go directly into Lincoln Memorial Drive, which runs along the east side of Lake Park.

The map above uses the line numbers from Verse 8 to illustrate the steps so far.

10) Ascend the 92 steps

  Following Lincoln Memorial Drive around the north and eastern edges of Lake Park brings us to the Grand Staircase. Searchers on the spot have carefully confirmed that the staircase does, indeed, have 92 steps.  This is a very precise confirmation that we are in the correct spot and should go up the stairs.

11) After climbing the grand 200

  "The grand 200" is thought to be a reference to the Grand Staircase because, when viewed from above, the outline of the staircase is a double C.  Two C's in Roman numerals equal 200.

12) Pass the compass ...

  Byron Preiss liked his wordplay, and he probably knew that most searchers would assume that "compass" meant the navigational tool that points northwards.  But, in this case, the "compass" we need is the tool used for drawing circles and arcs. 

  Lampposts in Lake Park display a Masonic symbol that features a prominent compass.  One such lamppost is located at the top of the Grand Staircase.  If we pass that compass and go around the north side of the Lake Park Pavilion, we are standing at Point 12 in the map below.  There is a footbridge to the northeast of us and a broad, flat lawn to the southwest.

  At this point, the two red balls held by the juggler very likely have a dual significance.  It's possible that the pair of spheres represent the two large, circular openings seen in the arches at each end of the Lake Park Footbridge.  That footbridge is directly beside where we are standing at Point 12.

Lawn bowling photo by lhourahane on Flickr, licensed under CC BY 2.0

  Given the way the balls are being held and tossed, however, it's even more likely that they represent the balls used in lawn bowling.  And, standing at Point 12 in the photo above, one would be directly beside the Lake Park lawn bowling greens.  (The greens are located 100 yards west of the Lake Park Pavilion and are just out of view on the left side of the aerial photo above.)  This is a powerful confirmation that we are in the correct place.

12) ... and reach

13) The foot of the culvert

14) Below the bridge

  There would be no "culvert" at the Lake Park Pavilion or the Lake Park Bowling Greens.  If we are to find a nearby culvert from Point 12 in the photo above, we will need to continue northwards and approach the footbridge and the nearby ravine.

  Crossing the Lake Park Footbridge brings us to a culvert at the northern end of the bridge.  The culvert drains water and also provides access to a hiking trail that leads down the slope, following the side of East Ravine Road as it runs southeast. 

15) Walk 100 paces

16) Southeast over rock and soil

  The Locust Street Ravine Trail runs southeast as it passes under the footbridge and descends to Lincoln Memorial Drive.  The trail has flat sections of soil interspersed with stone steps, as shown in the photos below.

17) To the first young birch

There are currently no living birch trees along that stretch of the trail, but if you look in the overgrown area between the trail and the road you can still see the stumps with the distinctive white bark and horizontal lenticels, as shown in the photos below.  There were clearly birch trees here at one time and we may still be able to find all the stumps and count them.

18) Pass three, staying west

19) You'll see a letter from the country

20) Of wonderstone's hearth

21) On a proud, tall fifth

  "Staying west" tells us that we should reach the correct tree without crossing Lincoln Memorial Drive. 

  It isn't clear what would represent a "letter from the country of wonderstone's hearth," but that reference point disappeared when the trees were cut down.  It could have been a sign or a marker posted on the tree, or it could have been a shape carved into the bark.  In any case, we should still be able to find the correct tree by counting the stumps and looking for the fifth one.  The description of a "proud, tall fifth" tells us we should only consider large, established trees.  We can ignore any stray saplings.

  Three of the folds in the man's cape resemble outstretched fingers, with wrinkles at the knuckles.  It's possible though that they actually represent spreading birch trees.

  Between the "fingers," however, there is a slightly different shape that is much straighter, with a consistent width and no wrinkles.  It resembles a pipe.  And it bends over at the top in a U-turn with the free end pointing down.

  As it happens, there is just such at pipe at the bottom of the Locust Street Ravine Trail, beside the concrete "millstone." It's very possible that this view of the folds is meant to be our "Aha moment" where the searcher would see the overflow pipe by looking through a cluster of birch trees.

22) At its southern foot

23) The treasure waits.

  The route down the hiking trail along East Ravine Road will take one toward the intersection with Lincoln Memorial Drive.  Near the final tree before the intersection, there is a large cement disk similar to the millstone shown in Image 10.  The disk is likely our final clue to confirm that we are in the right place. But the burial spot would be before the disk and the pipe, somewhere slightly up the hill where a "proud, tall fifth" birch once stood.

Final Location: 43°04'08.1"N, 87°52'06.1"W

(Latitude: 43.0689167°, Longitude: -87.8683611°)