Download Egyptian Water Clocks PDF

TitleEgyptian Water Clocks
TagsAncient Egypt Hour Clock Latitude History Of Science
File Size3.6 MB
Total Pages28
Table of Contents
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	p. 424
	p. 425
		Front Matter [pp. 319-322]
		A Hindu Decimal Ruler of the Third Millennium [pp. 323-326]
		The Dualistic Cosmogony of Huai-nan-tzǔ and Its Relations to the Background of Chinese and of European Alchemy [pp. 327-340]
		Duhem and Jordanus Nemorarius [pp. 341-362]
		Johann Virdung of Hassfurt Again [pp. 363-371]
		Joseph Black's Lectures on the Elements of Chemistry [pp. 372-390]
		Vasilij Vladimirovic Petrov and His Physico-Chemical Work [pp. 391-398]
		On a Curious Subdivision of the Egyptian Cubit [pp. 399-402]
		Egyptian Water Clocks [pp. 403-425]
		The Babylonian Tables of Reciprocals [pp. 426-432]
		Decimal Division of Scales before the Metric System [pp. 433-436]
		The Velocity of Light [pp. 437-448]
		Notes and Correspondence [pp. 449-460]
			Review: untitled [pp. 461-464]
			Review: untitled [pp. 464-465]
			Review: untitled [pp. 465-466]
			Review: untitled [pp. 466-470]
			Review: untitled [pp. 470-471]
			Review: untitled [pp. 471-473]
			Review: untitled [pp. 473-476]
			Review: untitled [pp. 476-478]
			Review: untitled [pp. 478-488]
			Review: untitled [pp. 488-489]
			Review: untitled [pp. 489-491]
			Review: untitled [pp. 491-493]
			Review: untitled [pp. 493-496]
			Review: untitled [pp. 496-504]
			Review: untitled [pp. 504-507]
			Review: untitled [pp. 507-508]
			Review: untitled [pp. 508-510]
			Review: untitled [pp. 511-513]
			Review: untitled [pp. 513-520]
			Review: untitled [pp. 520-521]
		Forty-Sixth Critical Bibliography of the History and Philosophy of Science and of the History of Civilization (To End of February 1936,--With Special Reference to China and Japan) [pp. 522-613]
		History of Science Society Reports for 1935 [pp. 614-619]
		Isis Report for 1935 [p. 620]
		Brief Table of Contents of Vol. XXV (1936) [pp. 621-623]
		Back Matter
                        
Document Text Contents
Page 1

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Page 2

Egyptian water clocks

ABSTRACT

Reconstruction of a prismatic prototype of cylindrical inflow clocks. Operating
with the simplest fractions, I/2 and '/3, and drawing straight lines only, we may
construct a prismatic diagram which accounts for the unusual features of the
cylindrical diagram of the Edfu inflow clock. The new diagram points to an
Egyptian-not Greek- origin of several passages of classical literature dealing
with the rate of increase of the length of the day.

Reproduction and discussion of hitherto unpublished items connected with
water clocks, such as the prismatic model in the Metropolitan Museum (Acc.
No. 86.1.93) and the Medinet Habu astronomical ceiling. It is shown that
the decanologue of the Karnak outflow clock is closer related to the Senmut
decanologue than to those of the Ramesseum and of Medinet Habu.

i. Introduction.

A detailed treatment of Egyptian methods for measuring
time-by the flow of water or the apparent motions of the sun
and of the stars-will be found in L. BORCHARDT'S (I) monumental

Altagyptische Zeitmessung; a good survey of the more important
problems is given in R. W. SLOLEY'S (z) papers on the same
subject. The present paper will be devoted to some of the
neglected aspects of the problems presented by Egyptian water
clocks.

z. Kircher.

" The theories of KIRCHER as to the content of the hieroglyphic
inscriptions exceed all bounds in their imaginative folly " (3);

(i) Die Geschichte der Zeitmessung und der Uhren, hrsg. von E. v. BASSERMANN-
JORDAN. Bd. I, Lieferung B; LUDWIG BORCHARDT, Die Altagyptische
Zeitmessung. Berlin, 1920.

(2) Ancient clepsydrae. Ancient Egypt, 43-50. London, 1924. Primitive
methods of measuring time, with special reference to Egypt. The J'ournal of
Egyptian Archaeology, 17, I66-78. London, I93I.

(3) ALAN H. GARDINER, Egyptian Grammar, p. x I. Oxford, 1927.

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Page 14

EGYPTIAN WATER CLOCKS 415

in the preceding paragraph,-the ratio of the width to the height
was dictated by practical and aesthetical rather than by theoretical
considerations: it was a compromise between the tendency to
lengthen the scales by reducing the cross section, and the necessity
of reducing the depth, in order to simplify the engraving and
reading of the scales. We shall see that the simple ratios of
I:1, I:2, and I:3, between the width and the height, must have
been in use. The longest scale of the prism being, traditionally,
14 fingerbreadths, the side of the rim had to be, in the case of the
1:2 ratio, 7 fingerbreadths; the cylinder of Edfu is x4 fingerbreadths
deep, and the developed horizontal length of its diagram is z8
fingerbreadths.

The emptying of an inflow clock offered architectural and
sculptural opportunities which could not have escaped the Egyp-
tians. In the case of an outflow clock, its very operation, during
the night, left but a small amount of water, in the lower third
of the " flower pot," at sunrise; since the clock had to be filled
to the upper level, in the evening, this " residual" water was,
probably, drained off but occasionally. In the case of an inflow
clock, the result of a night's running was a prism full of water
which had to be drained, before the next evening, to the bottom
of the scale corresponding to the current month; the evacuation
of the water, through the cynocephalos squatting at the base
of the prism, could be easily adjusted in such a manner that
it lasted until evening; the decreasing volume of the outflow
was irrelevant, since no measurement of time was involved. A
little rectangular basin at the foot of the prism, in front of the
cynocephalos, could, therefore, become a decorative as well as
a useful part of the draining arrangement; it was but natural
to incorporate, into the design of the rectangular basin, a sun
clock of the " flight-of-stairs " type, if the prismatic inflow clock
happened to be located in a court.

Almost a century ago, C. LEEMANS (zi) gave the following
description of the Leiden model of an inflow clock:

" Terre bnaillie. CYNOCEPHALE, accroupi entre deux reservoirs, dont

(21) Monumens egyptiens du Mus6e d'antiquit6s des Pays-Bas a Leide, p. I6,
Pi. XIX, no. 47. Leiden, I842. Dutch edition, p. 17.-P1. XIX, no. 23
represents a squatting cynocephalos, on a slab, with an opening below the
cynocephalos; apparently, a fragment of a water clock or of a model of a clock.

7

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Page 15

4I6 A. POGO

le plus grand se trouve derriere l'animal, l'autre, plus petit, devant ses pieds;
un trou est perc6 de l'un dans l'autre de ces r6servoirs et un escalier de six gradins.
conduit sur le bord du demier. Ce petit monument nous offre peut-etre le modele
d'une clepsydre Egyptienne, analogue a celles que d6crit HORAPOLLON, Hierogl
I. i6."

The Leiden model, shown in Figure 4, is made of green faience;
it is 44 mm. high; the water clock is formed by a low, rectangular
prism; there is no graduation, of course; the rectangular shape
indicates that the model represents an inflow clock which must
have been different from the sqaure prototype of the Edfu clock.
The outside walls of the Leiden model show some tapering.

The GRE'AU-MORGAN model of a rectangular inflow clock is
reproduced on Plate 4, top, left; see also the excellent reproduction

FIG. 4. -- Leiden model of a prismatic inflows clock. Height, 44 mm.
After: C. LEEMANS, Monumens 6gyptiens, P. XIX, no. 47. Leiden, I842.

in the catalogue of the GRE'AU-MORGAN collection, P1. 294.6;
green faience; the height of this (late dynastic?) model is 55 mm.
According to FROEHNER'S (22) description, it is a " gaine carre,e
portant sur le devant un cynocephale accroupi "; the Metropolitan
Museum (23) lists it as a " Nilometer. In the form of a tank,
with 6 steps and with figure of ape sitting on the front." The

(22) Collection JULIEN GREAU. Verrerie antique. emaillerie et poterie apparte-
nant a M. JOHN PIERPONT MORGAN. Texte redige par W. FROEHNER. Page 234
and P1. 294.6. Paris, 1903.

(23) Acc. No. 17.194.234I.

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Page 27

424 A. POGO

TABLE III

Decanologues of the XVIIIth, XIXth, and XXth dynasties

17 16 1i 14 13 12 11 10 9 8 7 6 5 4 3 2 1

12 11 10 9 8 7 6 6 5 5 4 4 3 3 2 2 1 S c

(12)(11) 10 9 8 7 6 6 5 5 4 4 3 3 2 2 1 1

12 11 10 9 8 7 6 6 5 5 4 4 3 3 2 2 1 R

t12) 11 10 9 8 7 6 .6 5 5 4 4 3 3 2 2 1 Y )

37 36b .54 32b 32a 31 30 29 28 27 24 23b 23a 22 21 20 19 18

**
29 26 24 28 - 23 27 22 22 21 20 19 18 17 16 15 14 13 8 25

29 26 (24 28 - 23 27 22 22 21 20 19 18 17 16 15 1 13 IC

28 25 24 27 26 - 23 22 22 (21) 20 19 18 17 16 15 14 (13) R

24? 23 22 22 18 16 15 14 13 IV

S - SENMUT ceiling XVIIIth dyn., about I5oo B.C.
K - Karnak clepsydra XVIIIth dyn., about 1400 B.C.
R - Ramesseum ceiling XIXth dyn., about 1250 B.C.
M - Medinet Habu ceiling XXth dyn., about II75 B.C.

Although the state of preservation of the Medinet Habu ceiling
leaves gaps in the western half of the table, it is obvious that
the Medinet Habu and the Ramesseum decanologues differed,
in the Orion region, from the SENMUT and the Karnak lists.

i i. Acknowledgments.

I hereby express my thanks to the following men and museums:
To Dr. W. D. VAN WIJNGAARDEN, for written information

concerning the Leiden model reproduced in Figure 4.
To the Metropolitan Museum of Art, for the photographs

reproduced on Plate 4. The MASPERO model is a hitherto

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Page 28

EGYPTIAN WATER CLOCKS 425

unpublished item. I believe that no photograph of the votive
offering from Sakkara has been published before.

To Dr. H. H. NELSON, for the hitherto unpublished
photographs of the Medinet Habu ceiling reproduced on Plates 5
and 6.

To Dr. SIEGFRIED SCHOTT, for the original positives on which
Plate 7 is based. To Mr. A. C. BOECKER, of the Fogg Museum
staff, for his excellent enlargements and reductions which led
to the final composite positive. It was, unfortunately, impossible
to preserve the beauty and legibility of this Ramesseum photograph
in the reduced half-tone reproduction.

Carnegie Institution A. POGO.
of Washington.

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