[marzsit]

the way i understand it, if you find an official us geological survey marker on a peak (like pugh, for example.) then the stated altitude is that which is on the official marker. on peaks that don't have official markers, their altitude is determined from optical sights from peaks that do have markers. from a long distance the sighting isn't very accurate, so the true altitude really isn't known. that's why there are always errors on maps from different manufacturers

[mb]

I don't know the measurement technique (though I assume they'd just use GPS now days), but your story reminds me of Mt. Kahahdin (northern end of the Appalachin Trail and highest point in Maine). It's 5260 (or 5267) feet high, so there's a big cairn to make it a mile. Apparently the geological survey monument is under the cairn somewhere... http://home.maine.rr.com/trudge/at/p67knife.html

[Sore Feet]

If Katahdin is 5260, then there'd have to be a 20 foot cairn on there for it to make a mile...

[kleet]

Most elevations computed pre-GPS were referenced to the geoid (sea level). Problem with that is sea level varies by hundreds of feet across the earth depending on the strength of gravity. GPS elevations are derived by a model created from gravity measurements taken in millions of places around the earth. It calculates sea level much more accurately. Below is some historical measurements of Mt. Rainier showing how accepted height measurements change over time: 1842 - Triangulation from a baseline - 12,330' 1856 - Triangulation - 14,444' 1888 - Barometer - 14,524' 1889 - Triangulation - 14,519' 1897 - Barometer - 14,528' 1914 - Triangulation - 14,408' 1956 - Triangulation with reciprocal angles - 14,410' 1988 - GPS - 14,411.1' 1999 - GPS - 14,411.05' So were all the measurements to the same exact spot? moooooHAHAHA!

[Stefan]

I have been atop many peaks. Many of these peaks have gauge wires with little pieces of wood. The peaks also have a number on top of them on the USGS maps. I am positive the surveyors used the wire and wood for triangulation purposes to get the exact elevation. So my question is this: How did the surveyors use the wire and wood combination to measure the elevation of the peak they were on?

[Dean]

Alan stated:

[MikeCollins]

Stefan...I had always thought the wire and wood held up cloth which could then be quite visable from a distant peak. Then the peak could positively be identified amoung all the others surrounding it. Overcoat Peak supposedly got its name from the surveyor draping his coat over the capstone for this reason. I was recently on Castle Rock near Stehekin and it had the wires on it also.

[MikeCollins]

Some wires though, like on Mt. Pugh, were for communication and one can follow those far down the mountain.

[Newt]

Here's another way it could have been done. Tho Chinese, it would still apply. Thru the use of established benchmarks and monuments, it wouldn't be that hard. Just a lot of work and packing equipment. Survey This link has a use for cairns. Cairns NN

[Mike Collins]

The link for "cairns" describes what I was mentioning above. A tripod frame was covered with cotton cloth to facilitate the surveys.

[kleet]

There's another method based on a 45-degree triangle (length = height) which was used in India to determine tree heights. I suppose it could be used in an emergency to roughly measure mountains as well. Here’s what you do: Bend over and look at the mountain between your legs. Note: ignore those people staring at you. Move towards or away from the mountain until you can just see the top of the mountain. At this point your distance from the mountain is approximately equal to the height of the mountain. Pace the distance to the mountain and convert the paced distance as meters. This is the approximate height of the mountain.

[Mentalfloss]

Wouldn't the snowpack on Rainier make a difference?