- Museum number
Table timepiece; verge escapement with balance; dial showing age and phase of moon, equal hours (engraved on outer ring I-XII), and unequal or planetary hours (indicated by curved lines on dial-plate); hand indicates equal hours at tip; middle is marked with twelve zodiac signs; unequal hour read off at any date from the intersection of the corresponding zodiac position with the curved unequal hour lines; base of case engraved (on inside) with altitude dials for setting of the clock in summer or winter; outside: zodiacal calendar and index for the planetary influences.
- Production date
- Curator's comments
- The following text is the entry for this object from the unpublished catalogue of pre-pendulum clocks by John Leopold, former Assistant Keeper of Horology at the Museum. This information is unedited and should be used accordingly.
ROUND TIMEPIECE BY PHILIPP IMSSER, TüBINGEN, 1554.
With associated alarum-attachment.
Presented by Augustus W. Franks Esq.
Baillie 1 (1929) 192.
Baillie 2 (1947) 166.
Coole/Neumann (1972) 48-49.
Maurice (1976) fig.492.
Brusa (1978) figs.72-74.
Vincent/Chandler (1980) 104.
Tait/Coole (1987) 10.
Vincent/Chandler (1989/90) 164-5, 168.
Engraved on the inside of the base: "ANNO DNI 1554 TVBINGAE EX OFFICINA PHIL. IMSS" (Anno Domini 1554, from the workshop of Phil.Imss[er], Tubingen).
The case is made of brass, gilded on the outside and on the area on the inside of the band which remains visible when the movement is in place.
The band was bent out of sheet and brazed at the join. Along its top edge a profile ring has been brazed; this ring was bent out of a cast strip and brazed at the join. The inside of this ring has a groove, which holds the chapterring in a snap-fit.
The chapterring is divided I - XII with quarter-hour divisions; along its outer edge twelve touch-knobs are riveted, that at XII being more prominent than the others. The main dial-plate is riveted to the underside of the chapterring; this dial is engraved with the lines for the planetary (temporal) hours. The line for the start of the day is marked ORTVS (sunrise), the 12th hour OCCASVS (sunset). The engraving of the lines makes the longest day 16 hours and the shortest 8 hours; this corresponds to a latitude of ca.49. There are several unused holes in the edge of the central disc, showing that some difficulty was expirienced in fixing it.
The dial is read by the leading edge of the large gilded-brass hand: the equal hours at the tip, the planetary ones at the point where the apropriate zodiacal sign is engraved on it. The centre of the hand is engraved with a scale 1 - 29½ centred by a small moon and a volvelle. On top of this revolves the lunar disc with a pointer to show the age of the moon and a hole to show the phases; this disc is engraved with an aspectarium.
Hand and disc are now held by a pin with a washer, but the end of the centre abor is threaded and so originally there will have been a nut (compare no. Morgan 105)
The band of the case is engraved with three roundels with the heads of a woman and two men, the woman and one of the men being crowned. The roundels are separated by panels of leafy tendrils.
The inside of the band has two guiding-ridges to locate the movement; these are riveted. There are three rectangular holes to take the latches of the movement; a fourth, round hole is probably later and may have held a pin to lock the movement into place. The lower edge of the band has been hammered out in five places (see Conversions).
The base consists of the circular plate to which a profiles ring has been brazed; the ring was bent out of strip, brazed at the join. Three small xbun-feet are riveted to the plate. The base, which is friction-tight on the band of the case, is engraved on both sides.
The inside has the signature and date, two sundials, and a shadow-square marked SCALA ALTIMETRA. Two holes and a slot in the ring of the base are associated with these instruments: the holes are for suspending the base vertically, the slot is for admitting the sun-beam.
Each sundial is engraved for half of the year: the larger one for Summer (from Aries over Cancer to Virgo) and the smaller one for Winter (from Libra over Capricorn to Pisces). When the sundials are to be used the base is suspended from one of the holes (in Summer the hole at SCALA; in Winter the one at DNI) in such a way that a beam of sunlight enters the slot and skims the surface; the hour is indicated by the place where the beam intersects the line for the appropriate Zodiacal sign. The Summer-hole is also used with the shadow-square; this measures the maximum elevation of the sun at noon on a scale of 24 parts.
All three instruments are engraved for a latitude of approx. 48.
The outside of the base is engraved with six rings and has a adjustable volvelle at the centre. The outer four rings show signs of the Zodiac and its degrees (every second degree marked), the date (every second day marked) and the months; 1 Aries = 12 March. The inner two rings of the fixed portion of the base are divided in seven parts, marked with the weekdays and their ruling planets, in the order: Sun, Venus, Mercury, Moon, Saturn, Jupiter and Mars. These rings are to be used in combination with the moveable volvelle at the centre. This is engraved with a spiral divided in seven segments, and numbered twice 1-12 for the day- and night-hours (when the first hour is lined up with the apropriate weekday-planet the volvelle indicates the ruling planet for each of the other hours).
When acquired this clock was associated with an alarum-attachment, which has lost its case and feet (the latter replaced by large curving springs).
The movement slides into the case from the bottom; it is secured in the case by means of three hook-shaped latches that fit into holes in the case-band. One of the latches and the click for the set-up of the mainspring are riveted over the same post and were originally loaded by a single spring (now missing). Both plates have three slots to take the guiding-ridges of the case, the slots near the barrel being apparently a mistake of the maker.
The movement is constructed of iron, with the exception of later parts (cock, slideplate, balancewheel and scapewheel). Plated movement with skeletonized backplate; three rectangular pillars with curved champhering, rivited under the dial and pinned on the back. Going train only. All wheels and the barrel pivoted in the front plate but only the barrel and the great-wheel pivoted in the backplate. Two arms that hold the bottom end of the verge and the top pivot of the 2nd wheel are pinned over the pillar near the barrel; a double arm holding the scape-wheel is pinned over the pillar between fusee and contrate. There is no potance or counter-potance. Great- and second wheel have four crossings, the contrate three; all have champhered insides to their rims. All arbors pivoted in steel except the greatwheel and the dial-side of the second wheel, which now have brass bushes.
5 6 15 | 60 50 40
────── ─ ── | ── ── ── 33 (x2)
 60 5 6 | 6 5 6
Great-wheel: split fusee of 8½ turns, re-cut for chain (at the top the groove has been repaired in brass). 23 ratchet teeth for winding. Barrel: wall is solid with one cap, the other cap dovetailed; the spring hooked into a hole in the wall, but the caps have slots for the original cross-bar. Inner end of the spring hooked into a slanted slot. Spring later; not blued, 10.5 x .4 mm. Set-up wheel of 14, with two holes to fit a male key. Stopwork secured by a loose rivet.
Scape-wheel and its arbor later (wheel of brass) as is the rest of the escapement with the cock and the slideplate. The original scape-pinion will have been 5, and the cock was pinned under the plate.
The pinion-of-report (15) and the brass idler (6) it meshes with are secured by a riveted brass clip; both pinions may originall have been pinned. The square hole in the pinion-of-report has been made smaller to fit the present suare end of the great-wheel: this is probably a simple repair. The idler pinion drives a tall pinion of 5 held by a brass cock (the movement-side of this pinion has a smaller diameter, making it effectively into a double pinion); it drives the dial-wheel assembly. The moon-wheel has been cropped to a small disc (wheel-count calculated). The brass parts in the under-dial work replace the original steel ones, but have the correct wheel-count. The hour-hand wheel of 60 and the remains of the moon-wheel are friction-tight on their arbors; the construction is now repaired with brass but the hand and the disc were probably always adjustable.
The clock is associated with an alarum-atachment, which has lost its case and feet, the latter being replaced by a strange three-part steel spring. The movement has circular plates and three pillars, one waisted and the others plain; the pillars are riveted on the dial-side and pinned under the bell.
── 9 (x 2)
Great-wheel: three crossings. Split arbor; clickwheel of 14. Open spring secured to the inside of one of the pillars and to the arbor by screws. Spring possibly original, not blued and slightly irregular in width: 16.4-17.3 x .3 mm.
Second wheel: mounted in a clip pinned over one of the pillars.
Bellstand secured to the upper plate by a nut. Bell with recessed rings, held by a gilded brass screw and a gilded brass ornamental washer.
The release is cocked, but only the locking-piece between the plates is original; the remainder of the parts was lost when the case was discarded, to be replaced by the present construction mounted on the three-part spring.
The clock has undergone one major conversion, which probably took place in the late 18th or early 19th century, when the clock was converted to balance-spring. The original escapement was discarded and replaced by the present one, which involved replacing the scape-wheel and fitting a new balance, cock and slideplate. This conversion raised the height of the cock, and the band of the case was hammered out in five places to ensure that the base could not be pressed on too deeply.
Presumably at the same time the gut was replaced with chain, the fusee re-cut, and perhaps also the repairs made to the under-dial work.
When the under-dial work was repaired is not clear; presumably at an early stage and certainly before the moon-wheel was cropped, for after that there would have no point in repairing its friction-fit.
Movement: greatwheel - one rev. in 3 hours.
Duration - 25½ hours.
Escapement - 14666 2/3 beats per hour (with scape-pinion of 5: 17600).
Dial: Lunation - 29½ days.
Clock (without alarum): diameter - 86 mm
height - 49 mm
(with alarum): height - 127 mm
Movement: diameter - 73 mm
distance between the plates - 21 mm
Alarum-movement: diameter - 52 mm
distance between the plates - 23 mm
HISTORY AND PROVENANCE.
None known. Presented by Augustus W.Franks; reg. 1874,7-27,1.
The clock (i.e. the case, dial and hand only) was loaned to the exhibition "Die Renaissance im deutschen Südwesten", Heidelberg Castle, Heidelberg, 21 June 1986 - 19 October 1986 (not included in the catalogue).
The busts of the band of the case are after Virgil Solis, from a series of six busts dated 1541 (O'Dell-Franke  no. h 56). No exact counterpart for the leafy tendrils was found.
24-hour dials with convertors for planetary hours are not uncommon (see e.g. ). In combination with a 12-hour dial, however, such convertors are extremely rare; only a single other example is known to exist. This is a small cylindrical timepiece with a steel movement with solid plates and screwed pillars, marked DI in a shield (unidentified maker). The band of the case is engraved as a pillar-dial, and the base, with a convertor for Italian hours, is signed THOBI: KLIEB: FA: AN: DO: 1578 (Kulturhistorisches Museum, Stralsund; unpubl.). For the sundial-maker Tobias Klieber of Augsburg (born ca.1545, worked 1572, died 1619) see Bobinger (1966) 79, 87-95, 248-250.
There can be little doubt that Philip Imser (born Strasbourg, mentioned Tubingen 1526, professor of mathematics there 1537/8, resigned 1557, died 1562?) designed and made the unusual sundials in the base. He did not, however, adapt an existing conventional clock, for the movement is unusually shallow to accomodate the deep dial and the under-dial work. Who the clockmaker was is unknown; Gerhard Emmoser, who collaborated with Imser on the latter's magnificent but ill-starred planetary clock made for the Elector Ott-Heinrich of the Palatinate (now Technisches Museum, Vienna), seems to have first met the mathematician in 1556, two years after the date of the present clock (Vincent/Chandler 1980 and 1989/90). In fact the adaption of the movement to the lunar dial, with its rather akward arrangement of pinions, may have been Imsser's own work.
Check: brass bushes in the train. Are there steel bushes ?
Is there a steel washer at the top of the dial-assembly?
The spring is very strong and quite regular in width.
No individual teeth marked.
Brass bushes for great wheel (both sides), 2nd (front plate) and double pinion in the underdial work (front plate).
- On display (G38/dc4)
- Exhibition history
1989 14 Feb-31 Aug, France, Paris, Cité des Sciences et de l’Industrie, L’Invention du Temps
1986 21 Jun-19 Oct, Germany, Heidelberg, Heidelberg Castle, Die Renaissance im Deutschland Südwesten (movement not sent)
- Acquisition date
- Britain, Europe and Prehistory
- Registration number