Accession No

6653

Brief Description

compendium with tide computer and calendar disks, attributed to Charles Whitwell, English, late 16th century

Origin

England; London

Maker

Whitwell, Charles [attributed]

Class

dials; calculating

Earliest Date

1596

Latest Date

1600

Inscription Date

Material

metal (brass); ivory

Dimensions

58mm diameter

Special Collection

Provenance

Purchased from Tesseract, Box 151, Hastings on Hudson, New York, 10706, U.S.A. on 13/01/2018. Item no. 19, Catalogue 106, Winter 2017/2018.

Inscription

Description Notes

Compendium with tide computer and calendar disks, attributed to Charles Whitwell, English, late 16th century

A small compendium comprising a tide computer on one disk and a calendar disk, sandwiched together with a white revolving centre. Both sides have one rotating volvelle.

The tide computer has a 24-hour sale divided every half hour and numbered twice XII, followed by a 32-point compass rose labelled every other point starting with North aligned with 1/2, and within a volvelle with aspectarium, both volvelles bearing index pointers. To find the time of high tide for a given seaport, set the first volvelle to the establishment of that port (i.e. tot the time high tide would occur there if new or full moon, as listed in the rutter for that port), then set the inner volvelle to the age of the moon, and read the time of the local high tide on the outermost scale. The compass rose gives the sailor's traditional method of specifying the time as a direction.

The calendar disks can be used for the conversion of Zodiacal, solar and lunar systems. The outer scale on the fixed disk is divided every day of the year, labelled by months and each with the correct number of days. Inside this is the Zodiacal scale, divided by each day and labelled with months in correct relation to the outer scale. The first point of Aries, is given as about 10.3 March, consistent with the Julian calendar. Within this volvelle with index and within that a volvelle (Tesseract notes that it is missing an index tab), engraved with aspectarium and pierced with a window showing the Moon's phase (unclear if this is damaged - underneath the plate is a white paint but this seems to be faded/rubbed away

References

Events