Excavated: 1914 (GdS 1914, 109 (April 16-18); NSc 1914, 148, 284; Pasqui, Calza).
Mosaic: SO IV, 73 nrs. 103-104, tavv. 172 (bottom) and 174 (top).
Inscription: ---.
Date: 190-200 AD (SO IV).
Meas. of tesserae: 0.015-0.02 (SO IV).
Mosaic
General descriptionMost of the floor of the back room has been preserved, only parts of the edges are missing. In the centre is a black frame, five tesserae wide, with a depiction (3.70 x 4.30). Around the frame are white tesserae with black speckles.
Much of the floor of the front room has been preserved. The west end, part of the south end and part of the passage to the back room are missing. In the room is a black frame (4.00 x 3.20), five tesserae wide, with the remains of a tabula ansata and a depiction. The interior of the north-east and east part of the frame is lost. The frame is not in the centre of the room, but moved slightly to the south. To the south and north of the frame are some black and white tesserae, partly forming a checkerboard pattern. The front room is separated from statio 23 by a line of white marble on the axis of the central column, followed by a black band.
TextNo text has been preserved.
DepictionsIn the lower part of the frame in the back room are two dolphins above a few horizontal lines indicating the sea. In the upper part is a depiction of the Claudian lighthouse in Portus. On the top floor, below the fire, is a white, vertical line with a bowl-shape on top (now lost; see the Lugli-Filibeck photo). Becatti suggests that it indicates the round or cylindrical shape of this floor. The fire burning on top is flanked by two black patches with 90 degree angles. The left one is considerably wider than the right one.
The mosaic in the front room has been restored with many errors, see the photo published in Scavi di Ostia IV. Apparently the restorations were carried out on the basis of memory only. In the upper part of the frame is the right half of a tabula ansata. The text is lost. It should be noted that the frame of the tabula is intact, as if only the text was removed in antiquity. In the lower part are two dolphins flanking a slightly curved branch. The tails of the dolphins are modern. The left one was already lost when the room was excavated, the right one was preserved, but was later restored with a completely different shape. The branch as seen today is completely modern. When excavated it had two times eight side branches, most not precisely opposite each other. A few black tesserae indicate that more was depicted in the north-east part of the frame.
Becatti
Lighthouse. Il faro ostiense a quattro piani a scala, con una porta bianca ad arco nel primo, e due finestre rettangolari ai lati del secondo e del terzo, il quarto cilindrico ha un segmento verticale bianco terminante in una mezzaluna, forse per accennare alla convessità della costruzione. Sopra è rappresentato il fuoco con lingue bianche su fondo nero. Ai lati del quarto piano sono due zone ad angolo nere che non credo che siano da interpretare come ingenuo tentativo del mosaicista di simboleggiare il fumo diffuso intorno, ma come semplice uso di tessere nere per riempire parte del fondo.
Dolphins (back room). Due delfini affrontati, con l'occhio rotondo, linea bianca che sottolinea il corpo, con coda falcata.
Dolphins (front room). Due delfini opposti ai lati di un ramoscello verticale schematico. I delfini hanno l'occhio rotondo, qualche linea bianca per la cresta e per il corpo, con coda trilobata.
Masonry
The back room has a rear wall of opus reticulatum. It has a south and north wall of opus vittatum simplex, both having a double width (nine layers preserved of the north wall, four of the south wall). The west part of the south wall is missing (the wall probably shows the core of the wall, but is restored). On a photo taken in 1931 (DAI, 1289_B05) can be seen that the southern outer column is resting on a wall. In the south part of the intercolumnium the wall continues, in the north part is a stone threshold that is still visible.
Interpretation
The branch in the lower part of the front room is presumably a grain ear, but there are no seeds (cf. stationes 17 and 56).
There is no reason to think that the two black patches flanking the fire of the lighthouse are restorations, they are part of the design. Becatti rightly rejects the idea that they depict smoke. Smoke could be a useful signal during the daytime, but this would be a strange way to depict it. We can also reject the idea that they depict the light emitted by the lighthouse. A burning fire does not create a beam of light, as modern lighthouses do.
Visually the black patches create a sequence: dark area (long) - white fire - dark area (short). I suggest that this means that the fire of the lighthouse was not seen as burning continuously, but with intervals. Pliny the Elder notes that beacons similar to the lighthouse of Alexandria "... now burn brightly in several places, for instance at Ostia and Ravenna. The danger lies in the uninterrupted burning of the beacon, in case it should be mistaken for a star, the appearance of the fire from a distance being similar" (... iam compluribus locis flagrant, sicut Ostiae ac Ravennae. Periculum in continuatione ignium, ne sidus existimeretur, quoniam e longinquo similis flammarum aspectus est) (Naturalis Historia XXXVI,xviii,83). He does not say whether a solution had been found.
It is important to realize that depicting a flashing light signal in a still image requires quite a bit of creativity, especially when only two colours are used. Modern depictions tend to look like this. It should be noted that the mosaicist has switched colours. All other mosaics from Ostia with a lighthouse have a black fire on a white background. Our mosaicist could have done the same, but chose for a white fire, and created a small black rectangle to make it visible, perhaps also indicating that the fire was enclosed. If the fire had been black, a contrast would have to be indicated by two white patches next to it. In that case the whole background would have to be black, and the building and the dolphins white, which would be highly unusual.
The flashing light could have been achieved by a rotating construction, or by a so-called occulting system: a cylindrical screen is then periodically raised and lowered around the light source. The bowl-shape depicted on the upper floor (of which we know that it was cylindrical [1]) suggests that the former solution was used, that an encasement of the fire was rotated to create the intervals.
On another lighthouse mosaic (bottom), in the Palazzo Imperiale, two curved lines flanking the fire can be seen.[2] This might be a reference to the mirrors of the lighthouse of Alexandria (mythical or not), perhaps used in Portus as well.[3]
It is rather surprising to find a complete depiction in a back room. Also the back part of the back room is not set apart, as seen so often. The visitors ran into a blind wall. This suggests first of all that on the back wall a fitting painting could be seen. It also suggests that this statio and a neighbouring statio worked together, sharing a single area in the back part. In view of a possible door in the south wall the best candidate is statio 21, used by Caralis (Sardinia). In that case statio 22 may have been used by another port on Sardinia, such as Tarrae (Tharros) or Olbia.[4]
(1) See our page about the Claudian lighthouse.
(2) SO IV, 166-167 nr. 307, Tav. XV (bottom).
(3) On lighthouses in general see the Pharology website of Ken Trethewey, which also hosts a comprehensive study of the lighthouse of Alexandria. It seems to me quite plausible that mirrors were used in Alexandria. According to legends they were also used to set ships on fire and as telescopes with which ships could be seen that departed from the harbour in Constantinople.
(4) In an inscription (CIL XIV, 423) mentioning a macellum and pondera we read "Tarrensibus".