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Inventory no. 74463 - Former Display Label

Portuguese EQUINOCTIAL DIAL
c.1775

Brass. Signed, "Joze Gaspart Fait à Lisbonne"; undated.

This type of equinoctial dial is used in the same way as an equinoctial ring-dial; it was described and illustrated by Dom François Bedos de Celles in his work, La gnomonique pratique, ou l'art de tracer les cadrans solaires ... , 2nd ed., Paris, 1774, pp. 356-364 & pl. 38. He calls it a "Cadran Equinoxial universel sans Boussole", and says, "C'est un cadran nouvellement inventé ..." and that "Ce cadran est meilleur que tous ceux qui marquent l'heure par les hauteurs du Soleil; il est même préférable à l'Anneau astronomique, parce que celui-ci ne peut pas servir s'il fait du vent ... ". In this example, the hour-'ring' is not adjustable for use in different latitudes but fixed at an angle suitable for use in latitude c.50°. The hour-'ring' is pivoted on the base-plate, enabling the dial to be used in dialling for measuring declinations of walls, etc. The plummet is a modern replacement.

[M. 32]
Presented in 1928, to the Lewis Evans Collection, by Mrs. W. C. Johnson, in memory of Walter Claude Johnson, Esq., F.R.A.S.

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