74 CORN MILL *792 (:slj4zS Fig. 7»
By Jochem Cats, Amsterdam
Signed behind the hand-crank: MR GATS 1792
Base 720 x 310, overall height 580.
Constructed of mahogany, with some boxwood, this model shows theBnternal
mechanisms of a two-horse powered corn mill. There are two grinding machines
with their hoppers and collecting bins,, graders and storage chests. It is described in
the Inventory as: “ Een model van een Grutters Molen en volledige Grutterij door
Catz” (complete corn-chandlers). On 22 June, 1792, it was minuted that this model
be bought from Cats at a price off 350.
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75 WATER LIFT % 18th C. ’ ; M | 'Fig. 73
Possibly by Jochem Cats, Amsterdam
Base 295 x 210, height 710; wheel diameter 265.
A mahogany frame holds a brass reservoir at the bottom and another at the top, which
carries a chute directed to a return pipe. A crank wheel rotates a toothless bobbin, which
drives a chain over a pulley-wheel in the upper reservoir.
This model is intended to show that a chain can, by itself, carry up a certain
amount of water provided it moves with considerable speed. This is achieved by using
a large driving wheel, so that the water adhering to the chain is quickly carried to the
head of the lift where it is thrown off when the chain changes direction on passing
over the upper pulley. The principle is quite distinct from the more usual bucket lift,
where small buckets are attached to a chain in the manner of the dredger (Cat. 73).
A bucket pump is illustrated by Desaguliers.
George Adams describes and illustrates what he calls “Vera’s Pump, or an Engine
to raise Water by Means of Hair Ropes” . Such a machine operating at a well ninety-
five feet deep can raise nine gallons per minute when it is operated as fast as possible.
The model clearly represents this type of water lift, and a Teyler’s Museum inventory
of the 1840s lists, in case K item 17: “Een model van een wateropbrenging werktuig
met snel bewogen keten” . Van Marum’s Inventory records: “ Een Model van het
werktuig van Vera, waar in het water langs een opgaand touw op geheven wordt” .
It is possible that the chain was substituted for rope at a later date. No information
on the purchase of the model has been found, and there is no note of the maker;
Cats would be a possibility.
Desaguliers (1744) XXXIV; Adams (1794) iii, 494, III, fig. 8.
Inv. i6\6
76 LOCK-GATE 1793 (nil) Fig. 74
By S. Kros, Dordrecht
Size of outer frame-work 405 x 150, overall height 175.
A wooden model of a lock-gate to a dyke (schipdeur) in the form of the hull of a ship.
The structure is sunk by opening traps underwater so that it sinks into its sea-bed
housing. To open the lock, the water is pumped out, the hull floats and is moved
to one side of the channel. Such a lock was constructed, c. 1783, at Nieuwe Diep,
North Holland. The Inventory records “ Een model van de Sluis a an ’t Nieuwe Diep
aan den Helder, waarin de Rhynlandsche voet op 1/4 duim verkleind is, door Kros” .
Payment- of ƒ 400 was made on 30 April, 1793, to the “Molen Maker S. Kros van
Dordrecht” .
Note: Sluis translates into English as lock or sluice.
Forbes (L & W iii 1:971 a) chap. 12.,
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77 TRACK 4/,f 18th C. (51) Fig. 75, 76, 77
The various sections of the mahogany track are as follows : a turntable, 365 x 200 ; two
lengths of track, 500 x 200, depth 50; a load-carrying platform, 360 x 205, to be placed
on top of the track so that the ball bearing channels are adjacent. The balls, diameter
20, arc of bronze and run in brass channels. All the wooden sections have rings set in
the sides for hauling and steadying by cords.
This model track is intended to demonstrate the movement ofa massive piece of stone
(weighing 160 lbs, according to the Inventory) by the use of balls located by the
channels in the track. The inspiration for the model was the means by which the
million and a half kilogram block of granite was transported to St. Petersburg to
provide a base for an equestrian statue of Czar Peter the Great. To move this
granite block, the Greek engineer, Count Marin Carburi (d. 1782), lecturer at the Naval
Academy at St. Petersburg^proposed a form of metal track with metal balls, because
a stone of such weight would crush wooden rollers. The stone was moved during
the winter of 1769/177°) when the ground was well frozen. The monument stands
today in Leningrad on the south bank of the River Neva. A 1:10 scale model of
the prepared track was made for Carburi, and this is now in the Conservatoire des
Arts' et Métiers, Paris. Fig. 76 is a reproduction of a contemporary engraving by
G. Velten and I. van Schley in the Rijksmuseum, Amsterdam. Fig. 77 is from a
photograph taken by the author in September 1971.
Carburi (1777) ; Feldhaus (1924).
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