580 THE INTELLECTUAL RISE IN ELECTRICITY. 



down categorically. Here is the list noted in his diary 

 under date of November 7th, 1749 : 



" Electrical fluid agrees with lightning in these particu- 

 lars: i. Giving light. 2. Color of the light. 3. Crooked 

 direction. 4. Swift motion. 5. Being conducted by 

 metals. 6. Crack or noise in exploding. 7. Subsisting 

 in water or ice. 8. Rending bodies it passes through. 9. 

 Destroying animals. 10. Melting metals, n. Firing in- 

 flammable substances. 12. Sulphurous smell." 



In all these things the agreement of lightning and elec- 

 tricity is perceptible by the senses. Yet it does not nec- 

 essarily follow that they are identical. That can only be 

 resolved by determining whether they obey the same laws 

 under the same conditions. 



There is one fact which he has recognized to his com- 

 plete satisfaction, and that is, that the so-called electrical 

 fluid of his jars and globes is attracted and drawn off by 

 points. Here there is a direct apparent control of the 

 fluid. He has no evidence that lightning possesses what 

 he calls a similar property of being attracted. But if it 

 has, if it will come out of a cloud to go to a point, as the 

 electric fluid seemingly comes out of his glass globe, that 

 shows that the same fluid is in the cloud and in the glass. 

 The necessary test for the identity of lightning and elec- 

 tricity is now plain. He ends his minute thus: "Since 

 they agree in all the particulars wherein we can already 

 compare them, is it not probable that they agree likewise 

 in this? L,et the experiment be made!" 



In July 1750, Franklin sends to Collinson the most elab- 

 orate and longest of all his communications. It is one 

 which he regarded as of especial importance, and for that 

 reason asks Collinson to convey it to "our honorable Pro- 

 prietary," to show to him that his "generous present of a 

 compleat electrical apparatus" had been put to good use. 

 In it, he describes the making of the proposed experiment, 

 though only in miniature. But the results so completely 

 confirm his anticipations, that he is willing to base upon 



