372 French Kat'ional Institute. 



visible from each other when the weather is favourable. 

 The height of the Moreila is 1700 fret above the level of 

 the sea f that of Mola Cinia 1400; that of Silla Torellas, 

 in the island of Majorca, is about 4600. 



'•' Wc arc now employed on this great triangle and that for 

 Ivica, which will be as great. 



" The court of Spain has siiven the most positive orders 

 to the captain of the brig who is to convev us to the Ba- 

 learian islands, and to diticrcnt poitits of the coast of Ca- 

 talonia, as often as may be necessary. To defend the re- 

 verberators and lodge the observer with his instnnnent's on 

 mountains so elevated, and dining an inclement season, it 

 will be necessary to erect four huts of wood, or of stones, 

 as tents would not be suflicicnt. 



^' In regard to the success of the trianolcs, it is ver^' cer- 

 tain, at least in regavd tso that \\hich will join Majorca to 

 the coast ot Spain. That which is to join Ivica to the 

 coast of Majorca will not be certain, unless wc can firid in 

 Ivica a mountain 2400 feet in height : without this Ivica 

 cannot be observed. I have been assured that it may be 

 seen from Mola Cinia ; but dining the three weeks which 

 I spent oil that wretched peak, the weather was so dismal 

 that I could not ascertain the truth of this cir-cvrmstance, 

 which was told to iiie ele\cn years ago. I was favoured 

 onlv by one night to observe the reverberators of the moun- 

 tain of Leberia and the chapel of St. John. There were 

 two at Leberia, and three at the chapel of St. John. They 

 were more than sufficient, though the distance exceeds 58 

 miles, and though the visual ray passed over the sea. I, 

 liowever, employed only a circle of 18 inches with its old 

 sights. I can place twelve re\erberators, and even more, 

 on one of the summits, the most distant of those to be ob- 

 served, at the same time. It was proved about eleven years 

 ago, that one reverberator lighted on the Silla de Torellas, 

 Mas observed from Mount Jouy for two ho^urs, at the 

 heioht of b'25 feet above the levfel of the sea. This, in- 

 deed, was the case bv using a large achromatic telescope of 

 18 inches,' focus; but the telescopes which I applied to 

 the circle of two feet are as po\\crful as that of three 

 feet, and I shall have twice as nuich light, find even 

 more. There will also be a great advantage in regard Xo the 

 heiirht of the Morella and of Mount Sia, which is almost 

 triple that of Mount .louy. Nothing then can retard us in 

 regard to this first triangle, but waiting for a favourable mo- 

 ment to make our observations. As for the rest, I do not 

 know whether it will be possible till I traverse the ujoun- 

 taius of Ivica. But even if I find it impossible, the opera- 

 5 tion> 



