1886.] PROCEEDINGS OP UNITI^D STATES NATIONAL MUSEUM. <S9 



although observations on this point are lacking. In this connection 

 Fig. 4 is of interest, being nn accnrate representation, natural size, of 

 the holes, made by lightning in a hollow copper ball or globe that 

 formerly surmounted a tiag-staff on the Old Capitol Prison in this city, 

 but is now in the collection of the National Museum. Four holes were 

 made in all within a space of some 2 by G iuches. Two considerably 

 larger than the others and more nearly circular in outline, while the two 

 smaller had the form shown in the cut. Their resemblance to the out- 

 line of a cross-section of some of the fulgurites is quite striking.* 



On the whole, it appears to the writer that the irregularity in out- 

 line of the tnbes near the surface is due to the exceeding energetic ac- 

 tion of the current during the first part of its course and tbe lack of 

 homogeneity in the conducting material. At greater depths, wher^e the 

 force has been to some extent reduced and the sand is more compact 

 and homogeneous, the tube is therefore more nearly cylindrical. In 

 Fig. 1 it will be noticed the tube at the very toj) is about 12"''" in diam- 

 eter, but almost immediately enlarges to about 35"^"^, whence it again 

 gradually tapers off to a diameter (not including the wings) of about 

 10'""^. This eidargement is not merely superficial, but the tube walls 

 remain approximately of a thickness throughout. In Fig. 2 the bulb- 

 like enlargement, which Mr. Abbott says corresponds to the stratifica- 

 tion of the sand, I find to be filled with a firm nearly white quartz 

 sand, with but a small hole or rift on one side, through Mhicli a x>ortion 

 of the electric fluid seems to have passed without fusion, while the 

 whole inner wall of the bulb itself is glazed like the rest of the tube. 

 Another interesting fragment is 3"" long and about as broad, and only 

 about 1*^'" in thickness. In this there is a single orifice at the top and 

 two at each corner of the bottom, the one at the low^er left-hand corner 

 being the largest. Held to the light the fragment is found to be rid- 

 dled with small holes as though made by the point of a pin. 



Aside from the interest on account of the peculiar form of the fulgu- 

 rites and the composition of the glass, the case is remarkable on 

 account of the number of specimens occurring in so limited an area, 

 Mr. Abbott stating that he found " several pairs or couples (of tubes) 

 situated only a few inches apart." Concerning a simila-r occurrence at 

 Maldonado, Darwin expressed the opinion that the flash for some un- 

 known reason was divided into several branches prior to striking the 

 sand, rather than that the several bores were caused by distinct flashes. 

 Facts given concerning the Whitesides County tubes would seem to 

 show that while the closely adjoining ones may have been formed by a 

 single flasTi, yet throughout the region examined there were at least 

 three independent sets of tubes that must have required as many dis- 

 tinct discharges for their production. 

 • , 



* In each of these cases the fused copper has ma back upon the outer surface of the 

 globe, and the appearaucc of the hole itself is as though no other agency than that of 

 heat had been employed in their product! ou. 



