FLUIDS DEFYING GRAVITY. 



then it will be easier to fit the strip of paper 

 smoothly. The function of the paper, again, is 

 not to hold the glasses together by its strength, 

 but simply to distribute the air-pressure evenly, 

 and prevent bubbles from entering at some 

 points while water passes out at others. To 

 bring out the point of the experiment, there- 

 fore, it is well not to use strong, good paper, 

 or the result might be ascribed to the wrong 

 cause. Accordingly, it is a good plan to choose 

 some halfpenny evening paper whose texture 

 is as weak as its principles, and so filled with 

 rubbish that in its case, as in theirs, a little 

 washing almost reduces the whole to pulp. We 

 shall be sure, then, that we are not attributing 

 to atmospheric pressure what is due to the 

 strength of the paper. 



Beginners in experimentation may be 

 warned that it is not in the preliminary task 

 of working up an experiment to a successful 

 issue that the chief danger of failure lies. This 

 arises by preference after success has been 

 privately obtained, and when the experimenter 

 is showing the phenomenon to intended ad- 

 mirers. The wise experimenter, therefore, will 

 demonstrate, as well as practise, the last two 

 principles in and over the bath. Then, in case 

 of a tumbler or its contents circumventing 

 the atmospheric pressure, there will be no 

 damage of glass-ware, tablecloths, or carpets to 

 account for to those in authority. 



87 



