224 



THE NATIONAL GEOGRAPHIC MAGAZINE 



The system was effective at about ten 

 miles, and, though designed for torches, 

 it could be easily modified for mirror 

 signaling, as it contains the fundamental 

 principle of the best modern system of 

 signaling. 



If the Greeks could invent such a 

 theory of communication, it would seem 

 likely that the Romans, a century and 

 a half later, could have perfected its 

 practice by using mirrors. Even our 

 American Indians, having mirrors, sig- 

 naled with them extensively, both on the 

 plains and in the Rockies, the chief fre- 

 quently being enabled to direct his war- 

 riors with certainty from a distant point 

 overlooking the field. 



MIRROR SIGNALS SEEN AT A DISTANCE OF 

 1 60 MIEES 



Gallup's Hand Book of Military Sig- 

 naling states that "under favorable con- 

 ditions the distance to which messages 

 may be sent and received is only limited 

 "by the curvature of the earth ;" also, that 

 ''square mirrors are better than round 

 ones only because they contain about 

 •one-quarter more reflecting surface for 

 the same packing space." Round mir- 

 rors are used now. Mirror signals have 

 been seen with the unassisted eye at dis- 

 tances of 160 miles. While this is, per- 

 haps, a record, and although there is no 

 statement as to the size of the mirror, 

 it probably did not exceed twelve inches 

 square. 



The reasonableness of the Capri "wire- 

 less" station theory tempts one to specu- 

 late as to how much signaling was done 

 and how it was done. It will be remem- 

 bered that Tiberius, the unpopular suc- 

 cessor of Augustus, spent eleven years 

 of his reign on Capri, and without com- 

 ing to Rome directed most successfully 

 the affairs of the vast Empire. He even 

 foiled the conspiracy of his trusted min- 

 ister, Sejanus, who was supposed to have 

 general charge of affairs after Tiberius 

 retired to the island. 



Though Tiberius went to Capri an old 

 man, he was the actual ruler — emperor 

 in fact — and his heavy hand was felt all 

 over the Empire until the very end. 

 With regular news bulletins and reports, 

 received daily if need be, containing con- 

 fidential information, he would be able 



to issue instructions and manage affairs 

 as thoroughly as if he were in Rome. 



BEACON FIRES BY NIGHT, MIRRORS BY DAY 



Possibly the Publica acta (Senate 

 Journal) and the Diitrna acta (author- 

 ized news) were sent to Capri by signal 

 instead of by messenger. We can con- 

 ceive that such a system, organized most 

 likely under Augustus, must have oper- 

 ated very smoothly after some years of 

 experience and practice. I hazard the 

 theory of mirrors because of its simplic- 

 ity and convincing character. Signaling 

 by beacon seems too primitive for the 

 wonderful civilization of the Empire. 

 Of course, at night-time beacon fires 

 would have to be employed ; mirror sig- 

 naling was a fair-weather method. 



It is not entirely clear how the Roman 

 lighthouses were managed. If the early 

 representations on coins and reliefs do 

 not mislead us, we may imagine a squat 

 tower on a headland, perhaps 100 feet 

 high and perhaps twelve feet square on 

 top, w r ith fire blazing all over the top 

 platform. How long would the resinous 

 wood fire last ? During the long hours of 

 darkness? It would not burn that long. 



Obviously, the fires must have con- 

 sumed immense quantities of wood and 

 been replenished at intervals throughout 

 the night. In periods of storm and rain 

 the operation of the Pharos must have 

 been a trying task. Just how the fire 

 was replenished is not very clear. The 

 Capri Pharos appears to have been pro- 

 vided with an outside staircase by which 

 billets of coniferous wood could be car- 

 ried up and thrown on the fire. 



ROMAN EIGHTHOUSES OPERATED EIGHT 

 MONTHS OF THE YEAR 



It is most improbable that any Roman 

 lighthouse could have been operated 

 throughout the entire year. It was kept 

 alight during the passage of the grain 

 fleets and possibly then allowed to go 

 out. Navigation began in March and 

 came to an end in November. Accord- 

 ing to Merivale, the sea w r as not used for 

 one-third of the year. 



A little island like Capri would be de- 

 forested in a short time, a vear or two, 



