Re-reading the form of Chahar-taqy dome in Takht-i Solomon fire temple of Azerbaijan1- by the evolution of Sassanid dome

Naser Hadi Dehghani2

Abstract Chahar-taqy3 of Takht-i Suleiman4 fire temple is one of the important Sassanid constructions in Azerbaijan5 which deteriorated in later periods (especially after Ilkhanid period 1300 AD) because of desolateness and lack of attention and now The only remaining of this historic monument are dome bases and signs of the ruined Ribs between four dome piers. The main objective of this paper is to re-reading the main form of Chahar-taqy dome through field studies, analysis of historic documents, comparative studies and exploring evolutionary trend of the work regarding similar cases and also considering technology and philosophical and practical basis of construction period. It appears that the dome form of the Takht-i Suleiman Chahar-taqy, like other Sassanid domes, is oval.

Keyword Dome, Re-reading, Takht-i Suleiman (Throne of Solomon), Chahar-taqy (Square Dome), Sassanid dome

1. INTRODUCTION Historic construction form re-reading is conducted to create a clear visual and imagery perception of its basic form for the visitors. Although it can be done better because of scrutiny and new archeological research and findings, but an acceptable shape re-reading can be done through comparison and analysis of similar cases.

1 This paper is a part of a research which was done to design a protective coverage of Takht-I Solomone fire temple in 2010 by author. 2 Naser Hadi Dehghani, Master student’s of Urban and Architecture Conservation, Art University of Isfahan, Iafahan ,Iran, Email: naserhadi@gmail.com 3 . (Square dome) A form of Azerbaijan and Iran architecture which is formed of four piers (dome base) and a dome on top of it. It was used in the construction of palaces and fire temples of Sassanid era. 4 . Throne of Solomon. 5 . Takht-i Suleiman complex has been recorded in the UNESCO World Heritage List

The objective of this study is to re-reading the main form of Takht-i suleiman fire temple Chahar-taqy dome to use it in protective coverage design to prevent from the threat of corrosive factors and gradual destruction of the building and create a clear image of its basic form for the visitors. General lines and main volume of the Chahar-taqy (dome) are destructed by time passage and desolateness of the building. The only remaining of this historic monument, which dates back to the Sassanid era (224-651 AD),are dome piers and signs of the ruined ribs between four dome piers (four thick column). Research method of this paper is based on historic documents of the construction and comparative studies. Furthermore, other sources of reference are archeologist findings and their reviews conducted regarding historic discoveries and texts. Some of the studies are in form of historic reviews and some have resulted in presenting a two and three-dimensional image. The complement of historic documents and field observations includes comparative studies and exploring evolutionary trend of the building regarding similar cases and also considering technology and philosophical and practical basis of construction period. Many researchers have made attempts to reconstruct this building; most of their designs have deviated. Arthur Pop (2008) reference to Bronze tray design in Armitage museum, reconstruction design of Kurt Erdman (2008) according to the bronze tray engraving, Filiz Acerman reference to Takht-i Taqdis shape (painted on Sassanid silver plate) in re-reading of the Takht-i suleiman, visual reconstruction of Oscar Reuters based on the Takht-i Taqdis are among the designs (Pope 2008). Also, traversal profile design by Navman is imagery and lacks any types of exact sizes and appropriations (Navman1994). Historic documents existing about form and status of the fire temple before its destruction are also exaggerated descriptions not able to help with its form and construction technique. Other materials relate to foreign researchers’ visits through two later centuries just contribute to description of present status of piers and domes and do not contain any about its geometry and construction method. But the point of paper is to study residues, similar cases, geometric appropriateness and their construction method. So, in this paper, first Chahar-taqy elements and then construction form re-reading in two parts of dome pier re-reading and transmission area and dome are presented.

2. CHAHAR-TAQY ELEMENTS

Domed Chahar-taqy is an exceptional element of large buildings in Sassanid period in Azerbaijan and Iran architecture which displaying the buildings structures and forms. This form is used in palaces and fire temples. These basic forms comprise the following elements: piers, pendentives and dome on square field. Chahar-taqy in Sassanid buildings is a sacred place with a square plan and dome ceiling. A wide rib is located on each side of the room which makes “four ‘in total, Because it is called Chahar-taqy (Four-Rib). In this architecture evolutionary trend, peripheral corridors and porch arrest it (Holf, 1969) (Figure 1). The same evolutionary trend is also observed in Takht-i suleiman fire temple (Figure 2).

Figure 1-The evolution of Chahar-taqy form .

Step 1 Step 2

Step 3

Figure 2- The location of Chahar-taqy in Takht-i Solomon Complex and its evolution(Source: Author).

3. FORM RE-READING OF CHAHAR-TAQY

Takht-i Suleimon which is formed basic elements, known in Sassanid architecture; these elements include a dome on the thick piers and the surrounding roofed corridor (Figure3). The whole re-reading in this paper is set around the re-reading of piers of Chahar-taqy and its dome.

Figure 3- The plan of Takht-i Suleiman Chahar-taqy (Source: Author).

3.1 Form Re-reading of Chahar-taqy Piers

To access dome beginning level, we need Chahar-taqy piers form re-reading. All part of four piers of the dome is destructed and there only remains rib ruin. What is observed by the analysis of the remaining of the ruins ribs is their similar status, namely, they are cracked at a 43 degree horizontal angle and destructed (figure 4). Southern side rib is totally destructed and there is not any trace of it even at its beginning level (spring point). Western rib is relatively in good condition and it is possible to re-read its original form (Figure 5).

Figure 4 - Existing statues of Chahar-taqy ribs of Takht-i Suleiman fire temple (Photo: by Author).

Step 1

Ribs a-b Ribs a-d Ribs d-c Ribs c-b

Step 2

Step 3

Step 3

Figure 5- Form re-reading of Chahar-taqy rib between western piers (Source: Author).

3.2 Dome and Pendentives Form Re-reading

The pendentives (Transition of square field to circular base of the beginning point of dome) and the dome of Takht-i Suleiman have been completely destroyed with no trace. Accordingly, its re-reading is conducted in two parts: Pendentives Re-reading and Dome Re-reading.

3.2.1 Re-reading of pendentives In Sassanid period, pendentives was used in transforming from square filed to dome circle base(Dome in Iranian Architecture 1990), namely, after constructing piers and ribs between them, by making some brick or pillar course, a level surface was created for transforming from square filed to dome circle base.The pendentives building start by putting a small arch-shape course in the angles of the square field, then, put course on each other, to transfer domes load in square field diagonals(figure 6). The primary pendentives were wooden (Figure 7) (Iran's Cultural Heritage 1990). Next, these pendentives were built by the use of the structure’s own materials. These pendentives were very tiny and could bore no load (figure 8). In the following step, these pendentives got bigger in order to convert the square field to an octagonal shape (figure 9)(Godar 1990). However, this process did not succeed in Sassanid era. Now, the matter is how big these pendentives were in Sassanid era (Figure 10). It was supposed to be equation (1):

AB = BD (1) But to construct a regular dome, it is crucial to be eqution 2:

AB = √2/2BD = BG (2) And because AB is larger than the AH in the Sassanid era, the head of the pendentives does not fix, symmetrically with the circular base of the initial dome. This is due to the small size of the pendentives. The true solution was to make the head of the pendentive bigger to be matched symmetrically with the circular base of the dome. In other words: BG matches on HJ (figure 10) And the circular base of initial dome is fixed with the internal octagon of the square. Though, this easy geometrical solution had never crossed its Sassanid architects. The evolution process of Sassanid pendentive making was toward the conversion of square field to an octagon but this matter because of Sassanid architectures unfamiliarity with geometry of octagon did not happen. The domes, which are made as the above-mentioned way, are not completely circular at the starting point of domes construction and are majorly similar to a part of an ellipse rather than a circlei. After making the pendentives to reach the circular shape, in every course (layer), the brick was pulled forward to get the size of the intended dome, in this method, the brick or stone courses are pulls outward to decrease the sharpness of the corners and make the shape circular. Niasr Chahar-taqy (with a fire temple function), Firuz Abad palace, and Sarvestan Palace are of the kind. Inside the Chahar-taqy dome, course of dome square filed convert to circular with a quachichment. This design can be imagined as hemispheres which have been pressed on square fields. They are shown in illustration (figure 11)(Godar 1990).

Figure 6 - The beginning points of penedentives in square field angles (Source: Pope 2008,645)

Figure 7- Baze hur Chahar-taqy , an ancient sample of wooden pendentives (Source: Iran's Cultural Heritage Administration1990,17)

Figure 8- Primary penedentives : showing the primary and irregular shape of pendentives which bore no load (Source: Iran's Cultural Heritage Administration 1990,31).

Figure 9- The evolution of pendentives size of Chahar-taqy in Sassanid era (Source: Author).

The Vaboo Citadel in Afghanistan The Firuz abad palace

Natanz fire temple Sarvestan palace Takht-I Solomon fire temple

Figure10 - Andre Godar’s suggested analysis about the structure and evolution of the Sassanid’s domes (Source: Godar 1990, 17).

Figure 11 - The sections of Sassanid dome in square field axis (Source: Godar 1990,17).

In the process of conversion square field to a circular shape of dome base, where transition area reach the beginning point of dome, architect of Sarvestan Place has been developed. He limited the transition area by two decorative bounds, one on top, the other under it, which divides the Chahar-taqy into three parts: the square shape, the middle part and the dome on the decorative line which is completely regular. Also, he has been able to put the dome on encrobellment and the section of dome is completely flat on the axis of square filed, which changes to a well-designed structure (figure12).Also, in most structure of this era, the pendentives have been concave from inside of the dome and their outer shape which is on a square field were put inside a wall .AN example would be Niasar fire temple where a wall was built around the pendentives under the beginning point of dome. This method has been used in other Chahar-taqy like Baze Hur fire temple and Robat Sefid (belonged to Ashkanid era – before Sassanid era). In this structure, first floor which is performed on the transition area has four sides, too. Describing of this method, Andre Godar believes that after building of the pendentives and the wall between them, before making the domes, to create a base for putting the plaster mold as a guide for making the dome and controlling buoyancy forces, at it is customary nowadays too, walls are made are them(figure13).

\

Figure 12 - Sarvestan Palace – The transition area from square field to circular base of the the dome (Source: Godar 1990,18).

Figure13-Transition area in Sassanid domes –Niasar Chahar-taqy(Source Godar,1990,22).

3.2.2 Dome Re-reading After construction of pendentives and wall between them, it is the time for construction of dome. Takht-i suleiman dome has also destructed and no traces have remained. Historic text existing about form and status of the fire temple before its destruction are also exaggerated descriptions not able to help with its form and construction method and contain no information about its geometry. Other materials relate to foreign researchers’ visits through two later centuries just contribute to description of present status of piers and domes and do not help with its construction plan and technique. Many researchers have made attempts to reconstruct this building; most of their designs have deviated. Arthur Pop (2008) reference to a plate design belonging to the period and kept in Berlin museum (Figures 14-a), reconstruction design of Kert Erdman according to bronze tray engraving kept in Berlin museum (Figures 14-b) (Nawman 1995), and Filber Acerman and Oscar Reuters designs based on tray design kept in Armitage museum of Saint Petersburg are among the designs (Figure 15)(Abbaszadeh 2001). Furthermore, German researchers working in Takht-i suleiman for twenty years presented schematic designs which were imaginary and erroneous (Figure 16). But in this paper, the point is to study the residues, similar instance, geometric appropriateness and their construction plan to present an optimal design of Sassanid domes evolutionary trend and their existing proportions (Nawma 1995). Firuz Abad palace dome is an example of the first dome construction at late Ashkani and early Sassanid period, then Kashan Niasar Chahar-taqy dome, and Qa’l-e Dokhtar (Doghter Citadell) dome related to early Sassanid period, reconstructed form of Qasr-e Shirin Chahar-taqy fire temple, and Sarvestan palace dome are evolutionary instance of domes of the late Sassanid which have been studied. Arthur Pope relates architectural style of constructing dome on four piers of a Chahar-taqy to Ashkani period- before Sassanid era (Pope 2008). Early domes, had an oval or elliptical shape which were majorly built by brick or stone and were used as the place and fire temple (Hosseini 1999). The Sassanid domes are always constructed on square fields (Pope, 2008).ii In early domes like Firuz Abad palace (Figure 17), cause of the lack of early pendentives evolution, the ratio of dome rise to dome opening is more than one namely they are in oval form. Gradually and by development of pendentives technique and their size increase, dome height decreased and the ration approached one(Tbale 1). The dome which has been built same time with Chahar-taqy of Takht-i Suleiman is Sarvestan palace and Chahar-Qapi of Qasr-i Shirin fire temple(figure 18)(Godar 1990).The Sarvestan palace has been show the evolution of Sassanid dome structure, but Qasr-i Shirin, technically, has

been made clumsily which is related to late Sassanid. Probably the reason of this clumsiness, has been the use of some non standard stones which have been the only choice (Pope 2008). Because of the lack of evidence, the issue of Sassanid dome light is not clear. It must be noted that because of rites - and since Zoroastrians believed that fire is sacred and they kept it in closed space - it was not possible to build an opening or hole at the top of domes (Abbaszadeh 2001).

Figure 14- (a) A sketch in a Sassanid bowl that shows Tkht-i suleiman fire temple(kept in Armitage museum of

Saint Petersburg), (b) reconstructed form of Takht-i suleiman fire temple designed by Oscar Reuters (Pope 2008,673).

Figure 15- (a)A sketch in a Sassanid bowl that shows Tkht-i suleiman fire temple (kept in Berlin museum) (b) reconstructed form of Tkht-i suleiman fire temple, designed by Kurt Erdman(Source: Pope 2008,694).

Figure 16- Re-reading the form of Takht-i Solomon fire temple by Nawaman (Source: Nawman1995,102).

a b

a b

Figure 17 - Paln and dome section of Firuz abad palace as a primary Sassanid dome (Source: Author).

Figure 18 - The Sassanid domes –From left to right: 1. Chahar-Qapi fire temple 2. Qal'e dokhtar (Daughter

Citadell), 3. Sarvestan palace, 4. Niasar fire temple (Source: Author).

Table 1- The evolution size of pendentive and dome in Sassanid era (Source: Author).

4. CONCLUSION

No evidence has remained from dome and the way to transmit from square field to dome circular base (pendentives) of Takht-i suleiman Chahar-taqy, So similar instance dimensions and construction method have been essentially used in form re-reading. Studying structural evolutionary trend of Sassanid domes (Table 1) shows that - because of the lack of the period architect knowledge of the polygons and lack of pendentives evolution - transmission from squared field to circular dome base was done through raising rows. Because of the lack of early pendentives evolution, the ratio of dome rise to dome opening is more than one namely they are in oval form. Gradually and by development of pendentives technique and their size increase, dome height decreased and the ration approached one. The study demonstrates that Takht-i Suleiman Chahar-taqy form was like all Sassanid and Ashkanid period Chahar-taqy, and its dome form was just like other Sassanid domes constructed by primary pendentives and is in oval shape (figure 19-22).

Era surrounded -corridor

AC/FC BD/AB

(BD=√2AB)

Dome-rich(Dome height/dome crater)

Dome and pendentive materials

Case study

Late Ashkanid

* AC<<FC 2.60/4.6=.056

AB>>BD 15.80/13.3= .١ 8 Stone Firuz Abad palace

Late Sassanid

۶٢٨- ۵٩٠ * AC<<FC

4/3.81=1.05

AB=BD ١۶.١/١٨ =0.89 Stone

Char-qapy fire temple

Sassanid

- AC<FC

3.8/3=1.2

AB<BD 13.4/13.6=.98 Stone

Daughter Citadel

Late Sassanid

* AC<FC

3.4/3.1=

1.09

AB=BD

12.٨/12.8=١

Stone pendentive with brick dome

Sarvestan Palace

Late Ashkanid

- AC<FC 1.4/1.4=1

AB=BD 4.30/5.5=٠.٧٨ Stone

Niasar fire temple

Middle Sassanid

*

AB=BD Dome height/dome crater=١

Brick Takht-i Solomon fire temple

Figure 19 – Dome form re-reading of Takht-i Suleiman fire temple (Source: Author).

Figure 20 – Dome form re-reading of Takht-i Suleiman fire temple in Azerbaijan (Source: Author).

Figure 21- Inside view of Chahar-taqy dome of Takht-i Suleiman fire temple (Source: Author).

Figure 22 - Geometry in plan and section – Chahar-taqy of Takht-i Suleiman fire temple (Source: Author).

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publication,,Tehran. Iran. Hosseini,S.B.,(1999). Understanding of the sacred space of fire temples within the form and meaning,Fine art

Journal of Tehran University, Tehran. Iran's Cultural Heritage Administration,(1990). Iranian dome, Journal of asar, Teharn,Iran Nawman,R. and Fan darstone,H.,(1995). Takht-i Solomon and Solomon prison, Cultural heritage of I.R. of

Iran,Tehran.Iran Nawman,R.,(1994). Ruins of Takht-i Solomon and Solomon prison. Cultural heritage of I.R.of Iran,Tehran. Pope,A.U.,( 2008).A Survey of Persian(Iranian) Art, vol.2,3 , Oxford. Rawlinson,H., (1840).Journal of the Royal Society 10, ,51. Reuter,O., (2008).Sassanian Architecture. In: survey of Persian art,hsrg.V.A.U. Pope. Vol. 1,554 f.

Notes i . In the evolutionary process of the construction of the dome on square field, a regular dome by the conversion of square field to octagon, regular 16gon, regular 32gon were built in the Islamic period (636-2000 AD - After the Sassanid era) and the pendentives played the role of carriers(Godar 1990). ii . There is no clear information about domes construction technique. Arthur Pope believes that Sassanid oval domes can be constructed without any frame (Erdman 1969). However, Andre Godar argues another way to emphasize on using frame in constructing Sassanid domes. He points to chalk molds gained from Niasar quadric arch. And in how-to-do of it, he points to making chalk molds on the ground and based on dome profile design. After mold completion, it was placed on transmission area and dome construction got started (Figure 19) (Godar 1990).

Figure 19 – Sassanid domes construction method using molds. (a) drawing mold lines on the ground and making it (b) plan of how to place molds in transmission area, and (c) a model of how molds are placed in

transmission area(Godar 1990).