124 Mr C. G. Ehrenberg's Observatimis an the 



time, for the purpose of enlivening his poetical representations, 

 and considered it as a direct encroachment of the gods on the 

 established laws of nature. 



If the Red Sea really has its name from the colour, this 

 would be the third historical notice, and is to be placed after 

 that of Homer ; but the old Jewish records do not call the 

 Arabian Gulf the Red Sea ; and it is called so only by the later 

 translators of them from the Alexandrian. I have myself ob- 

 served and examined the periodical appearance of blood-red sea- 

 water in the Red Sea, and shall here briefly explain myself, but 

 in another place more circumstantially. 



This appearance is also frequently mentioned in the Greek and 

 Roman classics ; and, till those times, these phenomena were 

 generally considered as immediate operations of supernatural 

 power, and violations of the established laws of nature. Cicero 

 was perhaps historically the first who expressed his doubts re- 

 garding the preternaturality of the appearances of blood at that 

 time, and attempted to connect these appearances with physical 

 phenomena, by directing his attention to the error of confound- 

 ing the expresss traces of blood, and of the bloody colouring 

 of moisture ; and he found the latter to depend on a mixture of 

 coloured earthy ingredients. 



From this time till the commencement of the seventeenth 

 century, historians have recorded many such natural phenomena, 

 though we cannot discover that any one has taken the trouble of 

 comprehensively and accurately investigating cases of this kind. 

 The Hippocratic school gave an absurd explanation ; thus the 

 physician Garcaeus, in 1568, says, blood-rain is rain boiled by 

 the sun, and compared it with red urine in fever. 



To introduce into this article Chladni's important aim of ad- 

 vancing the knowledge of truly cosmical and atmospherical bo- 

 dies, it may be of advantage to bring together the notices he 

 collected of appearances of blood, previous to the commencement 

 of the seventeenth century, according to the following scheme, 

 in which I take advantage not only of the work of Chladni, 

 but also of the spirited labours of Necs von Esenbeck, to which 

 I make some additions of my own. 



