44 Kansas academy of Science. 



ulare are always brown; those of P. erectum bright green. I once saw the P. 

 erectum growing right up through a patch of P. aviculare. They are as easily dis- 

 tinguished as any other two species. 



PHXSALIS LANCEOLATA, PENNSYLVANIOA, AND HIETA. 



Gray makes all three of these varieties of the same. Wood makes the first two 

 varieties, and does not mention the third. I have seen many specimens of all three. 

 I have not noted a difference in the leaves or the flowers of the first two, but P. lan- 

 ceolata is pubescent or puberulent; branches near the ground, is soon prostrate or 

 leaning, only a foot high, blossoms in June, and its fruit calyx is cylindrical, more 

 than an inch long, and has at the base a hemispherical depression. 



P. Pennsylvanica is glabrous, has a clean stem half its height, always erect, height, 

 twenty to twenty-four inches, blossoms in August, and its fruit calyx is broad-oval, 

 three-fourths of an inch long, and has a convex base. 



P. hirta is very unlike to either of these. Stem and leaves pubescent, leaves 

 entire, somewhat rhomboidal, twice as large as those of the other two, and the blos- 

 soms are all yellow. Mr. Gray was in a hurry when he said this was a variety of P. 

 Pennsylvanica. 



QUERCUS TINOTUEIA AND COCOINCA. 



The older editions of both Gray and Wood make them distinct species; the later 

 make them only varieties. I cannot think of a reason for doing so. The leaves of 

 Q. tincturia are always obovate, those of Q. coccinca never. The full descriptions 

 are as distinct as those of any other two species. 



THE INSULATION RESISTANCE OF SOME ELECTRrC-LIGHT WIRES. 



BY PROF. LUCIEN BLAKE AND H. EADCLIFFE, LAWREXCE. 



The insulation resistance of electric-light wires is commercially of great impor- 

 tance. Leakage through defective or insufficient insulation represents not only 

 expensive waste, but great danger to the generating machines by grounding them, 

 and thus exposing their armatures to burning out. The element of risk to life and 

 property also depends somewhat upon the character of the insulating sheath of the 

 wires. 



Ten years ago the so-called underwriters' wire was extensively and almost exclu- 

 sively used for outside work, because recommended by the board of underwriters in 

 New York. To-day, however, no thoroughly-posted electrician will use it, for it 

 cannot resist moisture, and many fires in buildings and many burnings-out of 

 armatures traceable to it have justly led to its condemnation. 



At the present time there are some eight or ten well-known wires upon the mar- 

 ket. The reputation of these wires has been established largely by the firms hand- 

 ling them, and not often have any scientific tests upon them been made. 



The insulation sheath of an arc-light wire may be considered to have two func- 

 tions, one electrical and the other mechanical, though the former is largely dependent 

 upon the latter. Electrically, it must keep the electric current in the wire without 

 leakage; mechanically, it must resist abrasion, heat, and moisture. The experience 

 of any good and observant electric-light company will determine a wire's claims to 

 the mechanical part, though wires have not been under trial a sufficiently long time 

 yet to thoroughly prove them; a long-time exposure may develop faults not yet 

 suspected; in fact, what changes may occur in the mechanical qualities of wires 

 bearing for many years high-tension currents, we do not know. Particularly as re- 



