April 29, 2017

How to Measure the Height a Building… with a Barometer!

(Editor’s Note: This week’s big expose post is totally tongue and cheek, but does serve as a good creative mental exercise in scientific thinking. Back in our High School pre-Internet days, an interesting science dilemma came our way (we used to read BOOKS and NEWSPAPERS in those benighted days). This idea, like so many others, has morphed over decades (via the Internet) to monstrous (re: silly) proportions. It appears to have had its hoary roots way back in a Saturday Review article dated December 21, 1968 and, well, things just get crazier from there…More images are forthcoming!)

The challenge was simple, yet succinct. It came to our attention whist in repose, sipping an Armagnac brandy (shaken not stirred) at the then stately Very Small Optical Observatory (VSOO)  in Vail, Arizona. It was in these halcyon days that my trusty assistant, Marianne (names changed to protect the guilty) brought forth a rather impenetrable dilemma; how to measure a building with a barometer.

We were flummoxed. The hounds paced with canine anticipation as we pondered the challenge before us. I thought to myself of how those astronomers of yore had first measured the mountains of our Moon, using the sun angle and noting the lengths of the shadows cast. To this end, a simulation was built wherein creating this shadow casting barometer event might just be possible:

But alas, the issues posed by the shadow casting barometer paradox proved to be many; the shadow of the barometer proved to be diffuse at long baseline lengths, and the sun fickle. Marianne resisted the urge to ‘clock’ me (her words) with said barometer and instead suggested a more holistic approach, using the barometer as a rather hefty paper weight to assist with the reading of the building blue-prints;

But again, all was for naught. “Such a silly lass” I stated, as the blueprints were suitably vague and thus easily corruptible. However, the attraction of the barometer by the Earth’s gravitational field as it rested upon the table gave me an idea. We made haste to reconvene the experiment on the roof top of the stately VSOO headquarters. In the true spirit of Galileo, several trials were made and timed by myself and my trusty assistant Marianne to ascertain the transit time of the barometer from the roof top to the surface of the Earth:

Its raining barometers…

Of course, the chief stipulation raised mostly by myself was that the barometer to be used for said experiment would be a cheap mass produced aneroid, and not one of my prized mercury Fitzroy’s. While effectively demonstrating the non-discriminatory nature of gravity, it was felt that the reflex time of the release and the timing to have been too imprecise, perhaps due to the wealth of the Armagnac. To compound issues, dropping the barometers did on occasion prove a might bit hazardous for unsuspecting passersby:

My trusty assistant Marianne devised an alternate roof top-centric plan. “What if we simply tied a rope to the barometer lowered it to the ground and measured the length of rope?”

“Brilliant,” I exclaimed, although I was somewhat concerned for the perhaps rather mundane application of such a fine barometer as a plum bob. I also pointed out to Marianne that one should remember to add the diameter of the barometer to the length measured.

“There,” she decreed, “Crisis solved!”

“But did you take into account the relativistic effects of Lorentz contraction in a gravitational field?” I replied, “It’s slightly different from the ground level to the top of the building, you know…”

Marianne replied that such a factor was hardly discernable, but knew in her heart that all science released from the VSOO must be of the most precise nature. Despair ensued. Perhaps, we began to think, man was simply not destined to know such things as the height of buildings, least of all with such frivolous device as the humble barometer…

“Eureka,” cried Marianne, “I have it!” Excitedly, she swept up the barometer and presented it to Joe, our prescient and all-knowing janitor who is sometimes given to quote Chaucer on his appointed rounds.

“Joe,” She exclaimed, “I have this wondrous and freshly polished barometer I would like to present to you, if only you would reveal to me the height of the building…”

And thus, the mystery was solved. The Armagnac flowed, (root beer for Marianne) and Joe now knows the precise air pressure and the rise of an impending storm. Perhaps, Joe was also silently thankful that errant barometers no longer rained with impunity from the sky. All is right with the universe, as the VSOO stands triumphant as a stalward bastation of truth and learning and free to once again ponder the mysteries of the cosmos. I’ve heard it said in dispatches from distant lands that they’ve mastered dozens of other methods by which to measure a building with a barometer, but I’d like to think that Marianne and I were early pioneers of the technique. I’ve even heard some redolent detractors exclaim that we should simply measure the incumbent air pressure at both the bottom and top of the building and compare the two, but we believe such a brute force approach ignores the richness and creative element of all that is science. Now that this era of bloggery is neigh upon us, allowing anyone who receives an AOL disk by postal dispatch to leave a wry or witty aside, we invite you to dust off those noble barometers and perhaps tell of your own innovative approach!

(Editor’s Note: No janitors, brandy snifters, or barometers were harmed during this experiment!)



  1. Maruza says:

    There is a simple way to check height, only by using cardboard, yarn, pin, nut, pencil and ruler. No need protractor..
    No need to get close to object, no need to climb object, you can measure from a distance. Only need a certain length of path to get ratio for scale.
    The method is using 2 similar triangle, both have same angles, but one smaller (drawing on paper) and the other bigger (imaginery in landscape). Ratio of each sides will become scale. If you now only one distance, then you can calculate the rest, including the height.

    Please check to:



  1. [...] This post was mentioned on Twitter by David Dickinson, Ben Reed. Ben Reed said: RT @astroguyz: A sneak peak at tomorrow's post… How to Measure the Height of a Building with a Barometer: http://bit.ly/fcE1KJ #science [...]

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