May 24, 1888] 



NATURE 



93 



Jobes, both orders presenting a ganglion of large cells in the 

 dorsal part. 



With the Teleostei it agrees in the multi-axial fibre, which 

 anterior to its termination resembles the Mauthner's fibre, also 

 in the position aad fact of its decussation. 



With the Petromyzon it agrees in the structure of the tela 

 choroidea which covers the fourth ventricle. 



April 19. — "On the Heating Effects of Electric Currents, 

 No. III." By W. H. Preece, F.R.S. 



I have taken a great deal of pains to verify the dimensions of 

 the currents as detailed in my paper read on December 22, 

 1887, required to fuse different wires of such thicknesses that 

 the law 



C = ad 3 /* 



is strictly followed ; and I submit the following as the final values 

 of the constant "a" for the different metals : — 



Table showing the Current in Amperes required to Fuse Wires »f Various Sizes and Materials. 



C ■ cid*\ 



dW. 



0*022627 

 0*016191 

 0*OI05l6 

 0*006831 

 0*004685 

 0*003263 

 0*002415 



0*001801 

 0*001381 

 0001122 



Copper. 

 a = 10244. 



231*8 

 1658 

 IO77 



69-97 

 48 OO 



33-43 

 24*74 

 1 8*44 



I4-I5 

 11*50 



Aluminium. 

 a = 7585. 



I7I*6 

 1 22 '8 



7975 

 5I'8l 



35 '53 

 2475 

 1832 

 13-66 

 10*47 

 8512 



Tin. 



<t= 1642. 



37-15 

 26*58 

 17*27 

 11*22 

 7*692 



5357 

 3'965 

 2*956 

 2*267 

 1-843 



Tin-Lead 



Alloy. 

 a = 1318. 



29*82 

 2134 

 13 86 

 9*002 



6-175 

 4-300 

 3-l8 3 



2-373 

 1-820 



1-479 



Lead. 

 " = 1379- 



3I*20 

 22*32 

 I4'50 

 9*419 

 6*461 



4*499 

 3-330 

 2*483 

 1*904 

 1*548 



Table giving the Diameters of Wire; of Various Materials which will be Fused by a Current of Given Strength. 



