NavList:

>>However, you would still need to know where the horizontal or vertical was or to level the inclinometer.  I’m told that this is possible electronically with MEMS technology and is used in smart phones.  <<

Maybe some smart phones, but not my Moto G by Motorola nor my older Samsung.  I worked with the programmer of the Android app called "AR Bearing + Baseplate Compass" to tweak his app so it could be used for celestial navigation.  He was very cooperative...setting up the augmented reality (which is the AR in the app name) display to display time to the nearest second, and fine tuning the size of the target crosshairs so they could take a sight on a planet.  But little variations from my phone's inclinometer in the altitude displayed meant my fix could be as close as 2 or 3 miles away from my actual position, or as many as 50 miles off...and there was no predicting which it would be.

It may be that the day will come when having a suitable augmented reality display on your smartphone screen, and the ability to snap pictures which include that AR data, will make a cellphone's inclinometer a poor-man's sextant...but that day is not yet here.

Bob