, 1879-06-21
TIRE AUDIOAfETEE.

At the last meeting of the Roya1 Society, Dr.,
Richardson demonstrated the action OF q ne1v
instrument which be has named the audimeter,
or aud!ometer, and which has Just been in
vented hY Prof. Hughes, the diacoserer OF the
misrophouo. The audiometes Is used AZ pre-
etsa. measurer Of the sense of hearing. It IL
formed Of small battery Of ons or two
Leclanchs cells, nav mcrnphouic.key, two
fixed primary coils, q graduated insulated bar,
N which ut each end one Of the fxcd coils IL at
tached, 1 secondary induction coll, which moves
along tho gradunted bar, and telephone, tho
terminals Of which arc connected With the tcrnai-
nails Of the induction coll. Tho principle Of
tho audtometer s based on the physical
fact that when the battery is in action, and !
current Is passing through the two primary co!Ea,
the secondary coll on the bar becomes charged,
By induction, whenever It II brought near to
brought TO the prertso centra between the
primary coils thcre IL neutral point, or eicct-
rscal balance, where Tie electric phenomena
from Induction ccssa to bo manifested. BY
and ono OF the primary coils, aud BY attaching
the terminals Of tic Induction coil to llle tele-
phone, Prof. Hughes ~aa able TO mako the tclc-
phonc Produce sotlnda Whenever he brought the
induction coil near to ona Of the primary colla and
moved the Gslcrophonlc key 80 Us tU make It
play Oh I Ane uccdla suspended In the circuit.
When the induction coll Ia close to ono ut the
primary coils tie noise Is very loud, but % the
noise dtm!nladea until 1t ccnscs Al the ccntre a.
together. The scale on tho bar Is graduated
Into 3N degrees, rcnfesentlng units Of sounds
from 200 to or zero. At 200 aIl who can hear
telephone. At 0 no one can hear, whllo bet1con
tho two poluts there Aru 90 eradattous OF
sound, from l.a hiEhcst down to zero, ItusIng
The initrnment ule telephone Is put to tho car
nt &hn5S 6tnFJn A.
ctophoote key, and at the same stno shifts tho In
duct1on coll the graduated bar 10 u to noasUre
the hcarlng power Of the peraon under e1amtua-
uou UF. Richardson presented q preliminary
n.onts With tho audlometsr. md showed that
already, by !ts means, some useful aud practi-
cal, ~ Tel a. cuFious. facts had been obtained.
Among many Of these was one relating to an To-
giai tytnpanums and the best form Of artificial
tympanutpa for caaea Of defective hearing from
periorauon or destruction OF the naturni drum.
Hs has found gold made tnto tic form Of lttlc
cups or cupsules exceedingly effcctlvo for this
purpose. The audtonesor promises to become
ono OF those useful ad1uncts to practice Of which
we shall say. ultimately How did we ret on bo-
foro Il was known1
SPONTANEOUS COMBUSTION.
There was IN interesting discussion on this
subject At rocont meeting Of tho French
accident which had occurred In hls laboratory
few days bsiore, While tho narrator was work.
Ing In the laboratory. portion OF the boarding
Of the door apoutaueously took fire. The
boards were In the ytcintty Of N atr-hole, fed
with warm air from stova four metres
away On the floor bolov. A siu.-
liar accident took place two years
aRo, and. tn consequence. n. Coason had the
boards ID djoIn!nH the airhole replaced hy = slab
OF marble. Ti,G boanl which now igntted Ad-
Joiued the marple. The heat TO which tho boards
were subjected was, however, very moderate.
Nevertheless, II. Cosson said tie wood had uu-
doubtedly been slowly catbonlzed: being thus
ssnleted extremely porous, = rapid absorption
OF the osJEen OF tbs stnioephsre had
resulted, aud sufficient calorlc was
theFeupon produced TO originate COM
buIuon. The danger thus disc'osed.
aaid II. Cossou, u oue 10 which tho attention Of
builders ought 10 be directed. In tue lnstsnce
Ia question. II. Cossou waA able to sx.lugulsn
tic ars with little water. u he was present
and Witnessed !ts beElonIng; but had 1t %.
CURED Il night, during hts ahsance, It would
undoubtedly have completed isa york Of d.
stvucton. n, Faye ssated that 1t Paasy, = taw
days before, . similar casu Of spontaneous 6ro,
!. due To the action OF the warmth from tho air.
hols OF skuye upon the woodwork, had oc-
Cured at The houae Of one OF his frIeuds-