24-8 ZIGZAG MOTION OF THE ELECTRIC FLUID, 



Fresh-water plants.— -Rind, air vessels, wood in scattered 

 vessels all over the pith, being partly wood, partly albu. 

 men, but having no spiral vessels within, but the line of life 

 in the centre, in a tl.ick line: buds proceeding from the 

 root. 



Half-voater plants — Rind, bark, air vessels disposed in it 

 with inner bark vessels ; wood, either in rows or scattered 

 vessels with albumen, and spiral vessels within ; line of life 

 meandering \u the pith. 



Marine P/ants.— Rind, the rest vesicles of a glutinous 

 matter, with a pore to each, but no communication from 

 one to the other. Though an appearance of stalk, yet formed 

 exactly the same as the rest of the plant, and without any 

 vessels or lines except the line of life difficult to find, but 

 in the fructification most plainly appearing. 



The other parts of the cryptogamia will be given in my 

 next letter. 



II. 



On the Zigzag Motion of the electric Spark, In a Letter 

 from a Correspondent. 



To W. NICHOLSON, Esq, 

 SIR, 



Zigzag course i\LLOW me, through the medium of your valuable 

 of the electrie Journal, to communicate a supposition on a point, that 

 seems to have been withheld entirely from public discussion x 

 1 mean the zigzag appearance of the electric spark passing 

 from one body to another, as from a positive to a negative, 

 &c. Partial to the science, but limited in experiment, or you 

 might have had enough to prove a belief in the idea now 

 formed ; the only account I have ever heard at lectures was, 

 that its own rapidity of motion condensed the air to such a 

 degree, that it had to move from a solid, as it were, to a 

 less dense medium, which seems to me impossible. My 

 eupposition is, that the fluid passes in a more direct line, 

 according to the best or worst conducting substances pre- 

 Owingtothe sented to it. Our atmosphere, being a compound of oxi- 



gea 



