in the central dial. The outermost states Circulus 

 horartus Soli, Luna,-, Fixis, Nodis, Aestuiqut marino 

 communis (the hour circle, common to the mid, the 

 moon, the fixed stars, the nodes and to the sea tide). 

 This inscription is divided into lour parts b) the in- 

 sertion of four divisions for the day into canonical 

 hours [Horae] Vocturnat (night hours); Matutinae 

 (morning hours): Diurnae (daytime hours) and 

 Vesper tinat (evening hours). 



The next section of the central dial is inscribed 

 Intumescite Detun ris< md fall of the tides) 



repeated at intervals of approximately e\ er) six Ik mis. 

 Within the next section is the following inscription, 

 inscribed continuously around the ring: 



Lege fluunt, refluunt, dormitant hac maris undae: Ad 

 Phoebi et Phoebes concordia iussa moventur Aequora; 

 i lis i[ i li tussu suspensa quiesi unt. 



Translated, this is: 



By this law the sea waves ebb and flow and lie dormant : 



When Phoebus and Diana agree in their commands, 

 the waters .ur moved; when they disagree, the waters 

 lie sili n 



Within the central boss of the dial plate, thename 

 of the maker is inscribed: 



Bvrghesio Doctore, et Bertolla Limatore Annaniensibvs* 

 ied. this is: 



[By] Doctor Borghesi and Bertolla. mechanii ian 

 i itizens of Anauni. 



INDICATORS IN THE FRONTISPIECE 



There are 12 windows in the frontispiece, through 

 each of which appears an indication relating to time. 

 Beginning at the top of the frontispiece of the dial. 

 tbe Inst opening occurs on the breast of the imperial 

 eagle. This indicates the dominating planet, repre- 

 sented by its symbol, and its house. 



The openinc; in the eagle's left claw, labeled 

 "Lit. Horn."' is the dominical letter. The first seven 

 days in the month of January are each assigned one 



>' "Phoebi" or Phoebus, called Apollo, the Mm god; Phoebes 

 or Diana, the moon goddess. M*t' t of \pollo. 



of the letters <' through g in order ul appearance. 

 I lie lettei w hich Coincides with the In -t Sim. la \ within 



this period is called the dominical letter, .md it serves 

 lor tin- following \ear. In leap year, two letters arc 



required, one In lebru.uv 29th and the lettei next 

 ling lor the rem under ul the year. I Ins letter 



is used in connection with establishing the ii 



I'.aster Sunday. The date "I I. aster regulates the 

 dates of the other movable leasts. 



I he eagle's right (law is labeled '( ., | p] i 



.m<\ represents the epact, or the age oi the moon mi 

 January 1st. It serves to find the moon's age b) 

 indicating the number of days to be added to each 

 lunar year in order to complete a solar year. Twelve 

 lunar months arc nearly 11 days short of the solar 

 year, - 1 thai the new moons in one year fall 11 days 



earlier thin tlie\ did the preceding \ear. However. 



30 days are deducted as an intercalary month since 

 the moon lias 111 ide a revolution in that time, and the 

 rem linder, ■*>. would be the epact. 



Below the imperial eagle two winged cherubs 

 support a riband with three indictions of the Julian 

 period. This period of 7980 years is the product 

 derived from multiplying together the sums ol :"•'■. 

 which represents the cycle of the sun; 19. representing 

 the cycle of the moon; and 15, which represents 

 the Roman indiction. The Julian period is reckoned 

 to have begun from 1-713 B.C. so that the | 

 will be completed in \l> I 67. Hie first of the three 

 openings is mnked "11111. Rom." or "Roman indic- 

 tion," which was an edict by thi I i i ( lonstantine 

 ii VI >. 312, providing for the assessment of a property 

 tax at the beginning of each 15-year cycle. It con- 

 tinues to be used in ecclesiastical contracts. The 

 second opening, which occurs immediately, below 

 the eagle, is marked "Cyc. Sol." (cycle of the 

 sun). This cycle takes a period of 28 years, after 

 which the days ol the week once again fall upon the 

 same days of the month as they did during the first 

 \en of the former cycle. There is no relationship 

 with the course of the sun itself, but was invented for 

 the purpose ol determining the dominical letter which 

 designates the days of the month on which the Sundays 

 occur during each year of the cycle. Since cvcles of 

 tin- sun dan- from 9 years before the Christian era. 

 it is necessary to add the digit 9 to the digits of the 

 current year and then divide the result by 28. The 

 quotient is the number of cycles which has passed, 

 and the remainder will be the year of the cycle answei - 

 ing to the current year. The third opening on the 

 riband is labeled "Num. Aur." (golden number). 



PAPER 35: THE BORGHESI ASTRONOMICAl CLOCK 



47 



