Identity of Calc-sinter and calcareous Spar. 227 
then tread the axle round at a force of 100 lbs. The superiority 
over the common method is this :—A man when he pulls sculls or 
oars, pulls them through the water twenty-four times in a minute, 
and the strength of his pulling is computed at about 30 Ibs. each 
time. By Mr. Van H.’s method the paddles pass through the 
water 136 times in a minute ; and as only two paddles are in the 
water at the same time, each paddle is passed through the water 
by a force of 50 lbs. ‘There is not sutficient space on a canal to 
allow of the use of oars, This newly invented machinery is very 
simple and can be taken off the vessel in a moment, and so light 
that a man can walk away with it with as much ease as he can 
with a pair of oars. Two men can propell a canal barge with this 
contrivance at the rate of five miles an hour. The expense of 
keeping track roads for horses to draw the barges, and the ex- 
pense of keeping the horses themselves, seem to make this a 
great desideratum to all canal property.” 
(<= We suspect that the patentee will meet with objections 
not easy to be overcome respecting the application of such ma- 
chinery to canal navigation. Even in the present method of 
moving the barges, when the horses go beyond a certain rate, the 
motion given to the water tends to wash down the banks ;—but 
what is this compared to the moving tide that would be pro- 
duced hy the working of paddles ? 
IDENTITY OF CALC-SINTER AND CALCAREOUS SPAR, 
The Rev. Dr. Fleming, of Flisk, transmitted to me lately two 
specimens of this substance, with the following remark: “ La- 
mellar cale-sinter from Macalister’s Cave in Sky. I procured 
these crystals in shallow pools in the cave filled with the calea- 
reous water. The indications of crystallization are distinct, but 
the crystals seem to be but in progress. The summits of the 
crystals of the smallest piece are smooth aud flat, and indicate 
’ the prisms below to be five-sided, and sometimes four-sided. I 
regard these specimens as exceedingly curious, as they are ge- 
nuine examples of Neptunian calcareous spar. 2. Acicalarly 
crystallized fibrous Calc-sinter.— This substance is from the 
Isle of Man; the specimen from which these fragments were se- 
parated was given me by Mr. Stevenson several years ago, and is 
interesting as being a recent aqueous formation.” Dr. Fleming 
adds, “ that all the caleareous matter in Macalister’s Cave, what- 
ever be its external form, stalactitic, stalagmitic, or encrusting, 
is all more or less in the state of calcareous spar, with the usually 
foliated structure ; that which lies in the pools or hollows of the 
caves has its crystalline forms like those in the specimens sent.” 
Upon examining these interesting specimens, I succeeded in ex- 
tracting from them regular rhombs of ‘calcareous spar, having 
Ff2 their 
