F Ole Rømer’s Room

The astronomer Ole Rømer (1644-1710) studied at the University of Copenhagen, but from 1672 to 1681 he lived and worked at the Paris Observatory.

He won international fame when, during the course of his observations of Jupiter’s satellites, he discovered the “procrastination of light”, that is, the speed of light. In 1680, he demonstrated a machine showing the orbits of the planets (a planetarium) and a machine for calculating the Moon’s eclipses (an eclipsarium) to the Académie des Sciences in Paris and to King Louis XIV. Both machines are still preserved in Paris. Christian V acquired a set in 1682, and in 1685 similar sets were presented to the King of Siam and the Emperor of China.

On his return to Denmark in 1681, Ole Rømer became the King’s trusted adviser in all technical matters. He rationalised a number of existing systems and introduced a uniform system of weights and measures. The original “national standard prototypes”, presented to the King in 1683-84, are displayed in this room.

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Objects in this room
3700. Planetarium. Constructed by Ole Rømer to demonstrate the orbit of the planets round the Sun. Made in Paris 1678-79 by Isaac Thuret, royal clockmaker.
3702. Eclipsarium. Constructed by Ole Rømer to calculate the Moon’s orbit and eclipses. Made in Paris 1678-79 by Isaac Thuret, royal clockmaker.
3704. Cubic foot of bronze and iron. 1683. Inside measurement of each section 31.5 cm (= 1 Rhenish foot).
3706. A quart (approx.) measure of bronze. 1683. Holds 979 gr. water.
3708. A quart (approx.) measure of pewter.
3710. A pint (approx.) of pewter. 1683.
3712. A “yardstick” (63 cm = approx. 2 ft.) of ebony and silver. 1683.
3714. Weights of bronze. Dated 1684. 1 lispund equals 16 lbs. After 1686/87, 1 lb equalled 499.7 gr. The biggest weight weighs 10 lispund, equal to 80 kg.
3716. Weights of bronze in boxes of inlaid wood. 1683. The small weights have been missing for many years.
3718. Scales of brass and iron. 1683.