UNCLE IN ENGLAND. 



contiguous portions of air, of different densities. 

 One of these experiments he was so good as to 

 shew us ; and as it is so simple, that Marianne 

 can easily try it, I will endeavour to describe it 

 here. 



He put a little clear syrup into a square phial, 

 and then poured about an equal quantity of water 

 into it, over the syrup. The phial was set on 

 the table, and having placed a printed card about 

 an inch behind it, he made us observe that when 

 we looked through the syrup^ or through the 

 water, the letters on the card appeared erect; 

 but, that when they were seen through that part 

 where the two fluids were gradually mixing to- 

 gether, the letters were equally distinct, but 

 inverted. A similar effect, he said, may be pro- 

 duced with hot and cold water, or even by two 

 portions of cold and heated air - y and to shew us 

 this, he performed another very easy experi- 

 ment. He placed two of the library chairs back 

 to back, and about a foot apart ; he connected 

 the tops of the chairs with two bits of strong 

 wire, and on the wires he laid the kitchen poker, 

 the square end of which he had made red hot. 

 Exactly in the direction of the poker he pinned 

 a large printed A upon the wall, which was about 

 ten feet distant ; and then desired us to look at 

 it along the heated poker. We did so, and we 

 all distinctly saw three images of the A, the 



u 3 



