NavList:

Frank,

I am no expert but I have studided navigation, surveying, history, astronomy, etc. for a long time.   First rember that inland explorers and navigators did not have the same problems to overcome as mariners.  Finding vertical was a simple as a string and plumb bob.  Finding horozontal was as easy as filling a ditch with water.  If the explorers camped for only a few days then due south (or in your case due north ) was also easy.  A stick or pole that would cast a shadow could be erected and then just mark where the shadow fell.  The highest ( longest ) mark was when sun due south or north.  Measure the height of the stick and length of shadow would give you the angle. ( a table or logarithums to figure the cosigne ).  Alamancs had been published since Ptolmey.

Rember that an artifical horizon is only used when utilzing a sextant.  On land you would use a transit  ( theodilate ), or a gravity device like a astrolabe.  Real acruate degree markings came about with the sextant ( Jesse Ramsden ) Inland explorers and surveyers used tools and instruments more akin to astromentors.  Rember that the famous line Mason-Dixon -- Mason and Dixon were astronometers.

Longitude was also not a big problem on land.  Using a telescope to see the moons of Jupeter eclipts would give you the time.  Tables were published hundredes of years ago for that pourpose.  Also used was lunar eclipses. The explorers would set their clocks or sand hour glass to noon ( when the shadow was longest ).  A good pendulem clock keeps very accruate time - on land. 

Navigators are so used to thinking of overcoming the problems on the sea or in my case in the air but inland explorers did things different, more like surveying.

Hope my ramblings help.

John H.