462 
USEFUL DISCOVERIES IN SCIENCE; 
ject, and not. persons, must be addi^essed. 
When the latter is the case, ' bitter and 
angry feelings are engendered in bosoms 
where nothing but amity, esteem, and true 
friendship should pervade, which ought 
invariably to be the case with all lovers and 
we -perceive an error on eubjecta con- 
nected with the public weal and with 
science, vve feel it to be our bounden duty to 
expose it, without having the least respect to 
persons, or to any other views than those 
of discharging the duty of an upright and 
promoters of science. Therefore, whenever independent journalist. 
.PROGRESS OF SCIENCE, 
AS APPLICABLE TO THE ARTS AND MANUFACTURES ; TO COMMERCE 
AND TO AGRICULTURE. 
IMPROVEMENTS UPON 'IME HY- 
DRO-OXYGEN MICROSCOPE. 
Sir,— In throwing tlie flame upon the lime 
in the liydi o-oxycen microscope, it is found 
that deep cavities ore formed in it by the 
violence of the flame, and that it is requisite 
to move it. to cause the fire to art upon another 
part, otiieruise the light becomes dull and the 
large lenses endanueied. I his at oresenl (or 
was lilt la>t year, when I directed the maker 
to cam-e it to revolve ami rise,) i.s moved by 
hand.whicli is incon ven’ent in saveia! res- 
pects; first, if a hole is made, the radiant 
point of tlie lens is abered, and peifi cl dis- 
tinctness is gone : tile object glasses are en- 
dangered, and in opening the door to adjust 
the lime, a light is thrown into the room. 
Moreover, one of tiie cylinders of lime will 
only last one exhibiiion, wlieieas, by being 
turned lemilaily, it would do for seveial. 
The improvement consists in causing the lime 
to revolve regularly and slowly, and, at the 
same time, lise gradually, wliereby the same 
part never comes under tlm action of the flame 
twice. (See plate, 3 fig. 5.) 
ABC is an uprigtit shaft, upon the upper 
end of which the cylinder ot Tune A is put ; 
DE a grooved wheel to be driven by an end- 
less screw, E, which endless screw lias a cog- 
ged wheel FGH, wliichis driven by a spring 
having a train of wheels, the whole being re- 
gulated by a fly. The screw Bis for the pur- 
pose of raising the shaft ABC when turning. 
By this screw the shaft A B C is raised ; one 
whole revolution raising it the distance of one 
thread on the scie'v ; the grooved wiieel D E 
slides freely upon the shaft by a sliding piece 
K, having a square hole in it filling the shaft, 
and which causes the wheel to turn along with 
it. That the wheel D E may not rise or fall, 
a groove or slit is marie in K. which runs in a 
piece of board L H. fastened to the lower 
b<i a i d . — Mech a n ic ’.v Maga zi rie. 
W. Ettrick. 
STRAINING DRAWING-PAPERS. 
Sir, — I'Perhaps the follovving methods of 
straining paper for drawingsCU’ithout ce- 
ments, may be u-reful to some of your read- 
ers:— (See plate 3, fig.s. 1, 2, 3, 4.) 
Fig. 1 is a plan of the drawing-board, with 
four grooves rt /) c d cut round it, in wliich 
four slips of wooil fit, as shown in fig. 2, which 
is a section llirounii f)ue of the grooves. The 
damp p.iper is to be laid on the board and 
tucked inio the grooves. 'I'he slips of wood 
are then to I e put into the position shovvn at 
fig. 2. along ine whole side at once, and then 
piessed dow'n into the groove.^, as in fig. 3. 
It will be seen that the more tlie paper strains, 
the moie firmly it will he held. 
1 have had a board made as above for an- 
tiquariaii paper, and find the plan to answer 
in firaclice. 'I'lieie is a lilile difficulty in put- 
ting the slips into their place.®, wliich may be 
very n-iiicli lessened liy the grooves and slips 
being made perfectly straight and parallel ; 
or it may be entirely removed by the contriv- 
ance seen in fig 4. .y; 
ti l> is one of tlie grooves ; ccthoslip of wood, 
much nariower than the groove, so that it can 
be laid in its place, and forced light up by tjie 
wedges w iv. 1 he enipty parts of the grooves 
may seive to prevent the instruments rolling 
oftThe board. 
Y^ours, &c., 
James Hennell. 
J une 4, 1836. Ibid^ 
NOTES AND NOTICES. 
OIL FROAI FLIES. — A society ha® feen 
formed in Geirnanyto e\tr,ic.i oiLfrom fiies, 
for trrpasing \v\\ee\> - Camhri m. 
A EROS r A fl ON.— A balloon is being 
consirucled, under ihe diiection of Mr. Green, 
of siicii dimensions as to be cauable of carfy- 
itig lO persons. Tlie gores of silk by which 
it will he I’ofmed are iieaily 100 feel in length, 
the centre being about 4 feet in width, and 
verging al the extremity to nearly a pouit. 
When finished, the balloon will be about 70 
feet high. It is made of the best manufac- 
tured silk, 'J’he net which will sunound it 
weighs 3 cwt., whije' the wliole apparatus, 
• .Ffj;-'\viieels, I suppose. <^Print6r's> De»U\ 
