2006-10-23 03:48:45 · 16 answers · asked by alan n 1 in Science & Mathematics ➔ Earth Sciences & Geology
They drill a vertical hole right down the centre of the mountain. They stop when they hit water, because that's sea level. Then they drop a lead weight tied to a long piece of string down the hole, and when it hits the bottom they tie a knot in the string. Then they pull the string out of the hole, lie it flat and measure it with a very, very long tape measure.
2006-10-23 03:58:11 · answer #1 · answered by CAROL DOMINO 2 · 1⤊ 2⤋
These days by satellite, with laser distancing. At one time, by triangulation with a theodolite. You survey in a number of stations around the mountain, then measure the direction and angle up to the summit. The interstion of the various lines defines the summit elevation.
Back when they first surveyed Everest, they took several different triangulations and averaged out the results. It came to exactly 29,000 feet, which the surveyors reckoned sounded too contrived, so they added an extra 2 feet onto the "offical height", quoted as 29,002' for many years!
Recent satellite measurements have in fact lopped 2 metres off the figure of 8848m seen in most atlases. So 8846 is the figure. That's above the "geoid", the surfac where water would rise to if you could connect a hole down the mountain with the sea.
2006-10-23 16:48:38 · answer #2 · answered by Paul FB 3 · 3⤊ 0⤋
I think it has to do with parallax. They observe the summit from two vantage points and measure the distance between each vantage point. The distance of the third unknown point is done by triangulation. Stars are measured the same way. The background shifts. This shift in background observed from two vantage points (the postion of the earth in summer and the position of earth in the winter and knowing that distance in the case of stars) and the laws of geometry do the rest. That would tell them how far away the summit is and that could be consistent with its height if they're at the base of the mountain.
2006-10-23 12:06:31 · answer #3 · answered by Professor Armitage 7 · 0⤊ 1⤋
Very complicated process but it is done on the civil engineering elevation which has "0" as sea level. They use satelite topography imagining and other aspects to determine the elevation scale. When surveyors survey land on the side of a mountain it is done on a straight flat plane through the mountain and not up the side of the mountain!
2006-10-23 10:57:54 · answer #4 · answered by Anonymous · 0⤊ 0⤋
If you don't know this you should watch the movie "the englishman who went up a hill and came down a mountain", with Grant Hugh.
Great movie, very much fun.
2006-10-23 10:56:24 · answer #5 · answered by Vage Centurian 3 · 1⤊ 0⤋
Stand at the top and through down a ball of string, then measure the string at the bottom!!
2006-10-23 10:51:11 · answer #6 · answered by scragette2000 5 · 0⤊ 1⤋
trigonometry. Although, probably by satellite lasers now. If you want it down to mm. But trig is also effective (assuming you know the elevation from sea level of where you take readings)
2006-10-23 10:51:52 · answer #7 · answered by Paul E 2 · 2⤊ 0⤋
if you stand a certain at a certain point, and raise a 45 degree angle to the top,
then the distance you are away is the same distance as the height
of course an altimeter is easier....
2006-10-23 10:57:48 · answer #8 · answered by papeche 5 · 0⤊ 0⤋
Triangulation from a base line using trigonometry.
2006-10-24 17:08:09 · answer #9 · answered by bo nidle 4 · 0⤊ 0⤋
climb to top of the mountain then drop the pice of stone and wait to hear when the stone hit the ground ?!?! maybe who knows..lol
2006-10-23 12:44:50 · answer #10 · answered by saz_kh 1 · 0⤊ 0⤋