Oct. 5, 1876] 



NATURE 



509 



THE PUY-DE-D6ME OBSERVATORY 



WE have already given some information concerning 

 this important meteorological observatory, and to- 

 day we present three illustrations showing its site and 

 construction. 



The site of this observatory is 1,465 metres above the 

 level of the sea and about 1,000 metres above the level of 

 Rabanesse, the meteorological station connected with it 

 and situated in the gardens of the Clermont Faculty of 

 Sciences. The Puy-de-D6me was in ancient times sup- 

 posed to have been the scene of so-called Druidical sacri- 

 fices, and was certainly the seat of a Roman temple, 

 probably of Mercury. In excavating the mountain for 

 the foundation of the observatory the extensive ruins of this 

 temple were again brought to light. A number of medals, 

 statues, and other objects have already been found and 

 collected in a special museum. But it is intended to 



replace them in a repository which is to be bui.t on the 

 very top of the mountain. 



It was on September 19, 1648, that Perrier, the then 

 president of the Cour des Aides, verified on the top of the 

 Puy-de-D6me the great law of the diminution of pressure 

 discovered by his brother-in-law, Pascal. Descartes 

 says somewhere that he had suggested the experiment to 

 Pascal. The illustrious philosopher was then an exile at 

 Stockholm, where he died a few years afterwards. He 

 vvas keeping up correspondence through Father Mersenne 

 with a number of French savants, and especially with 

 Perrier, Comparative observations for obtaining the 

 height of the mercury were carried on during the years 

 1649, 1650, and 1 65 1 at Clermont, at the Convent des 

 Minimes at Stockholm in the palace of the queen by 

 Descartes, and after his demise by one of his friends, 

 and at Paris by an observer whose name has not been 

 preserved. 



Fig. I. — View of the Ruins of the Soman Temple beside the Puy-de-D6me Observatory. 



The idea of building an observatory on the Puy-de 

 Dome was originated by M. Alluard, the present director, 

 about fifteen years ago. It was supported first by M. 

 Duruy, the Minister of Public Instruction, under the 

 Empire. M. Faye, then on a tour in the capacity of 

 general inspector, approved it, and reported favourably. 

 The astronomer paid more than one visit to the Puy- 

 de-D6me to ascertain the practicability of the proposal, 

 which was supported also by M. Leverrier. 



Up to the present moment the Government have paid 

 only the expenses for the instruments, the whole of the 

 costs of building having been supported by the Depart- 

 ment and city of Clermont. The expenses have amounted 

 to 10,000/. 



The distance from Clermont to the Puy-de-D6me is about 

 ten kilometres, six of which can be done in a cart. A 

 motintain road has been made at the expense of the 

 Department, and with very little difficulty ; the track of 

 the old via Romana had only to be followed.j 



Commandant Perrier, Director of the French Ord- 

 nance Survey, has established a barracks close to the 

 observatory for determining, by electricity, the latitude of 

 the Puy-de-D6me. He will continue his work as long as the 

 state of weather permits. For such observations the Puy- 

 de- Dome is connected telegraphically with Mount Souris. 



The observatory, as we have already intimated, was 

 inaugurated on August 22, during the meeting of the 

 French Association at Clermont. Eight hundred persons 

 made a pilgrimage to the top of the Puy-de- Dome, to be 

 present at the opening, and in spite of the unfavourable 

 state of the weather, the ceremony was successful. Under 

 an enormous tent a collation was provided for the visitors, 

 and after the repast, many pleasant congratulatory 

 speeches were made. M. Bardoux, president of the 

 General Council, in speaking eloquently of Pascal, whose 

 name is intimately associated with the Puy-de-D6me, 

 announced that the Government intended to erect a 

 bronze statue to the great philosopher, in Clermont. Dr. 



AA 2 



