[HN Gopher] Mechanical Integrators (1886)
___________________________________________________________________
Mechanical Integrators (1886)
Author : catlifeonmars
Score : 37 points
Date : 2022-02-26 07:56 UTC (15 hours ago)
(HTM) web link (books.google.com)
(TXT) w3m dump (books.google.com)
| kragen wrote:
| This link is demanding that I sign up for a Google account to
| read the "free" book.
|
| I suggest replacing the link to the malicious page with a link to
| the Archive's scan, which is higher quality anyway:
| https://archive.org/details/mechanicalintegr00shaw
| credit_guy wrote:
| > Major-General H. P. Babbage remarked that what most interested
| him was the contrast between arithmetical calculating- machines
| and these integrators. In the first there was absolute accuracy
| of result, and the same with all operators ; and there were
| mechanical means for correcting, to a certain extent, slackness
| of the machinery. Friction too had to be avoided. In the other
| instruments nearly all this was reversed, and it would seem that
| with the multiplication of reliable calculating machines, all
| except the simplest planimeters would become obsolete. [...] The
| author was obliged to express his disagreement with the opinion
| of General Babbage, that all integrators except the simplest
| planimeters would become obsolete and give place to arithmetical
| calculating machines. Continuous and discontinuous calculating
| machines, as they had respectively been called, had entirely
| different kinds of operations to perform, and there was a wide
| field for the employment of both. [...] No doubt the mechanical
| difficulties were great, but that they av ere not insuperable was
| proved by the daily use of the disk, globe, and cylinder of
| Professor James Thomson in connection with tidal calculations and
| meteorological work, and, indeed, this of itself was sufficient
| refutation of General Babbage's view.
|
| General Babbage is none other than Charles Babbage's son [1].
| He's obviously not an unbiased observer. Still, history proved
| him right, digital computers took over the world, while analog
| ones like these mechanical integrators have become historical
| curiosities.
|
| [1] https://www.computerhistory.org/babbage/henrybabbage/
| HPsquared wrote:
| The instrument is called a planimeter:
|
| https://en.m.wikipedia.org/wiki/Planimeter
|
| Would have been very useful before computers.
| jaclaz wrote:
| They were.
|
| https://news.ycombinator.com/item?id=16035057
|
| Calculating a road cross section area with a planimeter would
| take 5 minutes top, while doing the final analytical
| calculation manually (but already with a programmable
| calculator) took - including writing down the set of operations
| and partial results - more like 15-20 minutes (or even more,
| depending on the number of points in the section).
| fuzzfactor wrote:
| With scientific instruments doing dynamic measurement that
| have always been data-heavy, something like EKG recorders,
| before digital data storage typically it was a paper chart
| recorder where there was a roll of graph paper passing under
| a pen.
|
| When the signal was stable you get a straight line until some
| deviation then the pen moves positive or negative and draws
| the graph/curve in real-time.
|
| For applications where the areas of curves above a baseline
| are to be considered rather than just the comparative
| heights, the optional mechanical integrator was available on
| the premium chart recorders.
|
| There would be a second pen, connected to the integrator
| which followed the first pen's deviation, limited to its own
| small integration band of the roll paper where it would also
| draw a straight line in parallel to the raw baseline signal
| until some actual signal of interest appeared.
|
| Then following the deviation of the first pen, the second pen
| produced a blip for each unit area of deviation the main pen
| made from its established baseline, in real time.
|
| For a full-scale signal excursion on the main pen, in the
| integrator band it would draw maximum blips-per-second during
| the peak apex, with greater blip spacing upon the rise & fall
| slopes.
|
| When a different curve having the same area was detected
| which had far less than full-scale readings, it would
| naturally be over a longer period of time, and the more
| slowly drawn integrator blips over that longer period would
| add up to the same number as the taller but equal peak had
| produced.
|
| It sure beat counting the little squares on the graph paper
| while accomodating all the squares at the edges of the curve
| not fully included.
|
| Or cutting out the curves with a pair of scissors afterward
| and weighing them on the analytical balance, even when using
| the special uniform & humidity-resistant paper intended for
| this purpose. However depending on the various instruments'
| adjustments and how the total system was operating this could
| give you the greater number of significant figures when it
| comes to data precision.
|
| It sure was a lot quicker to just count the blips and do the
| math from there.
|
| No computer necessary and you could handle far more analog
| data in greater detail than any accessible computer at the
| time.
|
| But it was still data so you still needed fully appropriate
| storage and a proper file system.
___________________________________________________________________
(page generated 2022-02-26 23:02 UTC)