370 NOVUM ORGANUM. 



previously placed at the bottom a small globe, on which the bell was 

 to be set. By this means we discovered that if the globe was small 

 (in proportion to the cavity) the air retired into a smaller space, and 

 was pressed together without being thrust out : but if the globe was 

 too large for the air to yield readily, then the air, impatient of the 

 increased pressure, raised the bell on one side, and began to ascend 

 in bubbles. 



Again, to test the degree of extension (as well as of compression) 

 which the air would endure, we made use of the following means. We 

 took an egg of glass, with a small hole at one end ; we exhausted the 

 air by violent suction, and immediately closed the opening with our 

 finger ; we then plunged the egg into water, and lastly removed our 

 finger. The air being constrained by the suction, and being expanded 

 beyond its natural limits, and so struggling to recover and contract 

 itself (so that if the egg had not been immersed in water, it would 

 have drawn in the air with a hissing noise), now drew in water in 

 sufficient quantities to allow the air to recover its former volume or 

 dimensions. Now it is certain that rare bodies, like air, will undergo 

 a visible amount of contraction, as has been said ; but tangible bodies, 

 such as water, admit compression much more impatiently, and to a 

 less degree. How much they do admit we have investigated in the 

 following experiment. 



We caused to be made a hollow globe of lead, containing about two 

 wine pints, and sufficiently thick at the sides to support considerable 

 pressure. We poured water into it through a hole which we had 

 made in it ; and when the globe was filled, we stopped up the hole 

 with melted lead, so that the whole became quite solid. We then 

 flattened the globe on two opposite sides with a heavy hammer, thus 

 forcing the water into a smaller space, the sphere being the figure of 

 greatest capacity. And when the hammering ceased to take effect, 

 through the resistance offered by the water to further contraction, we 

 employed a mill or press ; untill at last the water, impatient of further 

 pressure, exuded through the solid lead in the shape of a fine dew. 

 We afterwards computed the space lost by the compression, and 

 understood that the water had undergone a corresponding degree of 

 compression, but not until subjected to a great amount of violence. 



But solid bodies, and those that are dry and more compact, such as 

 stone, and wood, and also metals, endure a still less degree of com 

 pression or extension ; such indeed as to be scarcely perceptible ; for 

 they free themselves by breaking, by progression, or by other efforts ; 

 as is apparent in the curvature of wood or metal, in clocks moved by 

 coiled springs, in missiles, hammerings, and countless other kinds of 

 motions. And all these, with their measures, are to be marked and 

 explored in the investigation of Nature ; either to a certainty, or by 

 estimation, or by comparison, as opportunity shall offer. 



xlvi. Among Prerogative Instances we shall put in the twenty- 

 second place, Instances of the Course^ which we also call Instances of 

 the Water ; borrowing the word from the clocks of the ancients, into 

 which water was poured in the place of sand. They measure Nature 



