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Account of a Luminous Animalcule, By Captain Home, R.N. 

 F.R.S., &c. in a Letter to the Editor. 



Ham, Dec. 6, 1828. 

 My dear Sir, 



According to your desire I send you the following account: 

 Being at Lancing on the coast of Sussex in October 1827, 

 I considered it a good opportunity to examine into the cause of 

 the light which I had often before observed so brilliant in the 

 sea-weed thrown upon the beach. 



It had blown hard from the south-west on the 8th and three 

 following days, and so great a quantity of weed had been 

 thrown up, that the beach was covered with it to more than 

 two feet deep in many places ; it appeared for the most part to 

 be of the same species. After it was dark, I collected a small 

 quantity of the most brilliant, and found it always to be that 

 which had been left at the first of the ebb, and was only moist, 

 rather than that just washed up. This portion was taken into 

 a dark room, where I picked out a single spark, the brightest 

 that could be found, and carried it to the next room where 

 there was a candle. After seeing the shape of the weed in my 

 hand, I returned and picked off every thing, leaving that only 

 on which the light appeared, keeping my eye on it through 

 a common lens, till I was so near the candle as to lose the 

 light upon the weed. In this manner I ascertained that it was 

 produced by a minute body adhering to the sea-weed, which I 

 am informed by Mr. Brown is Sertularia volubilis of Ellis 

 (Clytia volubilis of Lamouroux.) 



The light would remain steady sometimes for about five 

 seconds, often less, and when it ceased, was renewed by 

 touching it with the finger. I immediately made a sketch of it 

 as it appeared in a small microscope I had carried with me. 



I had still my doubts that what I had seen was the cause 

 of the light, but was convinced of it after repeating the same 

 observations for the five evenings I remained at Lancing. 



Being anxious to examine these bodies in daylight, I entirely 

 darkened a room, but was surprised to find they gave no light 

 whatever ; yet the same weed, kept till the evening, was as 

 brilliant as any I had seen. 



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