BY N. DE M1KL0UH0-MACLAY. 463 



Captain de Amezaga was kind enough to take before me the 

 Lithodes shell out of its silver case with glass top, in which it has 

 been kept hanging on the wall in his cabin, and to sprinkle the 

 shell with a few small drops of water. In less than half a minute 

 the wetted spots became of a pink colour, which soon got darker. 

 It was a very decisive test of the hygroscopic property of the shell. 



I think, however, that very likely not only the Lithodes 

 Antarcticus shells have this property, but many of other genera and 

 species, the capacity of which in this respect have not been yet 

 discovered. 



The shells of the Lithodes antarcticus, which have this peculiar 

 change of colour, are only of a certain size (age). The shells of 

 large (old) specimens appear to lose completely the property of 

 alteration of colour. 



The shell which I saw on board the " Caracciolo " acting as the 

 " Barometro," was not more than 4 inches wide and 3 inches long. 

 The usefulness of the Lithodes shell as a Barometer is greater 

 in such localities where the moisture of the atmosphere corresponds 

 very intimately with the changes in the direction of the winds ; for 

 instance, as it is on the south-west coast of South America, where 

 the " Barometro Araucano " is not only an indicator of 

 approaching rain, but also of change in the direction of the wind, 

 because there the predominant winds are the north and the south 

 winds. The north wind from the end of April until September is 

 moist, and brings rain, the south wind is dry, so that there the 

 change of wind is constantly followed by a change of weather. 



I have not hesitated to take this opportunity to mention the 

 " Barometro," or more correctly, the " Hygrometro Araucano" 

 because having consulted different books about Chiloe, I have 

 found not one line about this strange instrument. 



NOTES AND EXHIBITS. 



Baron Maclay exhibited and made some remarks on a very 

 ingenious instrument invented by Dr. Gottschau of Wurzburg, to 

 enable accurate measurements to be taken of photographed 



figures. 



