An important astrolabe by a leading instrument maker of 17th-century Lahore

in good overall condition, 5 plates, areas of patination and minor pitting, the reverse of the rete with traces of soldering, horse and pin later, as viewed
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This piece, though undated and unsigned, can be safely attributed to the late-17th-century school of instrument-makers in Lahore. It well reflects their initiative and technical competence.

The throne is elegant and pierced. The rete is distinctive and the star-pointers are connected by rather haphazardly arranged but carefully situated fronds. The horizontal bar and the ecliptic are counter-changed at the equinoxes, a feature not known from any other astrolabe. The star-pointers are sometimes difficult to identify, and some names are abbreviated. A first reading yields at least 25 named stars, roughly arranged counter-clockwise from the vernal equinox as follows:

dhanab al-qaytus / sadr al-qaytus / ghûl / ('ayyû)q / tâlî-yi masâfat al-nahr / rijl al-yusrâ / rijl-i yumnâ / yamânî / shâmî / muqaddam / fard / qalb-i asad / qâ'idat al-bâtiya / 'anâq / sarfa / fakka / a'zal / hayya / jâthî / (wâ)qi' / minqâr-i dajjâja / tâ'ir / sâq-i sâkib al-mâ' j(anûbî) / mankib / khadîb

The mater bears a gazetteer with 68 place-names and the associated longitudes and latitudes. As on most Lahore instruments, the associated qibla are not given.

The five plates with their ten sets of markings all have altitude circles for each 6°, and the prime vertical accentuated, but different additional markings. In all there are three categories. The first and second have azimuth circles for each 10° below the horizon; the third has them above the horizon.

Category 1: Two sets have additional dotted curves for the hours since sunset until midnight and for the hours before sunrise thereafter. These are for latitudes 28° and 29° with their longest daylight given as 13h52m and 13h55m. (Here and elsewhere the lengths of daylight are of the right magnitude if not accurate.)

Category 2: Five sets have additional dotted curves for each hour since sunset up till sunrise. These are for latitudes 32° (14h8m), 33° (14h12m), 35° (14h29m), 37° (14h36m) and 39° (14h47m).

Category 3: Two sets have additional dotted curves for each hour since sunset up to sunrise, with lighter markings for each 15m of each hour. These are for latitudes 32°30' (14h6m) and 34° (14h17m). The use of 32°30' is surely significant, but that significance is unclear. The standard Mughal value for Lahore was 31°50', sometimes rounded to 32°.

The upper back bears a quadrant of trigonometric markings and a solar quadrant with curves for the midday solar altitude throughout the year for latitudes 32° (Lahore) and 27° (Agra). A double shadow square (bases 7 on the left and 12 on the right) is superposed on these markings, which would normally be situated below the horizontal diameter. There we find half of a complete set of astrolabic markings for latitude 27° (Agra). There are altitude circles for each 6°, with those for each 18° dotted. Also the curves for hours before sunrise are dotted. Since the ecliptic is marked, the standard operations of spherical astronomy can be performed with the alidade (compare the Ottoman quadrant in LOT >). No other Mughal instrument with such markings is recorded. Around this ensemble are a list of the lunar mansions and shadow scales (now appropriately with base 12 on the left and base 7 on the right).