SCIENTIFIC SUMMARY. 
97 
Murchison’s or Sedgwick’s determination of the limits of the Silurian, made 
in an early stage of the science, have anything more than a historical 
interest ? To throw the Lingula Flags down into the Cambrian, as Lyell 
has done, is violating historic truth ” as much as to throw the Primordial 
Cambrian beds up. ^‘Historic truth,” in fact, has little weight in the ques- 
tion, though important as regards the labours of two eminent English 
geologists. Whichever course best exhibits the system of geological truth 
should be the one adopted by the science. If the term Cambrian has advan- 
tages over Primordial sufficient to make its substitution for the latter 
desirable, that will take place, whatever the past may say ; but otherwise, 
not. In a similar manner, if the distinction between a Paradoxides and an 
Olmus, and other differences less important between the living species of 
these groups, is not enough to demand that the Primordial (or Cambrian) 
should be separated from the Silurian, and be made a separate and equiva- 
lent grand division in the system, it should not be done, whatever the 
authority for it. 
A new Fossil Bird. — The Scientific American,” October 26, is responsible 
for the statement that the skeleton of a fossil bird, found during the past 
summer in the upper cretaceous shale of Kansas, indicates an aquatic bird 
as large as a pigeon and differing widely from all known birds in having 
biconcave vertebrae. The species is termed Ichthiornis dispar. 
The Edinburgh Geological Society. — We have received the first part of the 
second volume of this Society’s Transactions. It is full of admirable papers, 
though they are somewhat late in their publication. Several fine plates 
accompany the volume. 
MECHANICS. 
Steam Traction on Hoads. — Professor R. W. Thurston recently gave a 
very interesting address before the Polytechnic branch of the American 
Institute. He showed conclusively that for heavy truckage on common 
roads and streets, the steam traction engine may be used with an economy 
of seventy-five per cent, over the cost of employing horses. In other words 
steam-carts can be employed at only one fourth of the present expense of 
horse-carts. During the subsequent conversation, the subject of steam 
street cars and carts was talked over, and one of the members expressed the 
ridiculous and monstrous opinion that the reason why horses were 
frightened at the steamers was because the animals were superstitious. 
They saw the machines were without horses, and instantly assumed that the 
movement was the work of the devil. 
A Perpetual Motion Swindler. — A correspondent of the Scientific 
American,” Mr. H. R. Birdsall, of Green, New York, gives a description of 
“ a perpetual motion,” constructed by an adventurer, which worked so well 
that he succeeded in obtaining sums of money (2,500 and 1,800 dollars) 
from various simpletons, and then left “ to secure his European patents.” 
He has not returned, and a visit to his deserted apartment has revealed a 
hole in the wall and certain surreptitious mechanism by which the per- 
petual motion was driven. The beautiful device which elicited the sub- 
YOL. XII. — NO. XLYI. H 
