cost Dfl. 850. Both are listed in Ven (1882a), nos 739, 740. This cathe-
tometer is mentioned in some of Van der Ven s papers, e.g. Ven
(1882c), 177. Perreaux had a very high reputation for his dividing
engines and cathetometers.
362 PENDULUM, REVERSIBLE (76) 1878
Signed: A. Repsold & Söhne Hamburg 1878
Overall height 1,430; base 740 maximum width; length of
pendulum between knife edges 1,000
362
A reversible pendulum is used for measuring the gravitational constant,
G. There is a tripod base,(blackened, with levelling screws and a bubble
level, and three long brass struts to support the attachment for the pendulum.
This is swung on an agate knife edge let into a V notch. A swivelling
central pillar with a micrometer and telescope at each end is for
making measurements on the pendulum ends.
Accessories have me museum inventory numbers 76A,||6B.
They comprise a bar (overall length 730) with three supports; a card
box with two adjustable plates (40 x 24) on iron supports with brass
bases (2lfi Purchased in advance in February 18HK>r Dfl. 1,438.43.
Repsold (1914), 26, 38; Turner (1985), 235-8.
363 APPARATUS FOR TESTING
BUBBLE LEVELS ,'3 © ® 1882-1898
Signed: Gebr. Caminada, Rotterdam.
Overall length 335; height 99; width 70
The apparatus consists of two frames made in brass, blackened, the
lower with two fixed feet at one end and an adjustable foot at the other.
Above is another frame fixed at one end and adjustable at the other by
a wide, knurled wheel. This is divided 0-180 by ones. On the upper
bar are sliding brackets with marble Vs to carry a bubble or water level.
The maker's inscription is on the upper bar. The glass bubble level is
broken. Not in Ven (1882a).
Johannes Antonius Caminada (1831-1887)i and his brother
Carel Antonius (born 1829) started the firm Gebr. Caminada in 1856
at Rotterdam. At the national exhibition of 1861 at Haarlem, prizes
were won for water levels and mathematical instruments. The firm was
taken into the twentieth century by the sons of the founders; see Mooifl
(1988), 130-132. Frick (1905), pt 2, 815-8167
364 STANDARD KILOGRAM (8® 1856
Made by Eduard Wenckebach, Amsterdam
Diameter of weight 5 2 « overall height 7?, 2
Diameter of case 74; overall height 100
364
A boxwood circular case;, lined with green velvet, holds the gilded copper
standard kilogram weight; both lip of case and weight marked 1 .
The domed kn<t§5 unscrews for the insertion of a small coil of gold wire
to achieve the critical weight. It was sold by the Koninklijke Akademie
van Wetenschappen, in June 1869, along with the glass metre (360) for
DflBpO.
1 Accompanying the weight is a brown envelope ||ntaining documents
of verification. There is a typed memorandum signed byljH^ffi
Siertsema, and dated Delft, 28 June 1927, and a hand-written letter
signed L.H. Siertsema, Wassenaar, 4 July 1927. One Certificate has written
in manuscript: "Verificatie van het verguld koperen Kilogram No. 1
van Teyler Physisch; Kabinet, J.A.C. Oudemans, Utrecht 19 April
1886". Certificates have printed columns and manuscript calculations;
there is another form with calculations of temperature and ^pressure;
also a copy, written in a different hand. Also a number of blank verifi-
" cation forms. Stamkart (1857), "Kopijen van den standaard-meter en
her standaard- kilogram"; Oudemans (1887); Siertsema (1889)l"Over
de veranderlijkheid van oude standaard-kilogrammen"; Turner (1983),
55-6; De Clercq (1985a), 211-15; Mooij (1988), 98.