telephony 
illK'ill^ S'lUlnU. r>|icc'i;illy ;i rl ii'llla I c- >|K-l-i-ll, ill 
H distaiK'r from llicir Honrri-. 
Telephoiidae(t<-l-<'-for'i-di>), ./>/. [NU (Leach, 
1H17), < Tfefopftorm + -iil.T. ] A family of ser- 
rirorn bi-i'tlcs, InolndingthOM Forms commonly 
(ullrd mil/In r-ln; lira, now usiiiilly merged with 
the l.iinipiiriilii: See 7V If /ilinriini'. Mnlin-n/li ;- 
itnil;v is ji synonym. 
Telephorinae (t> 1 e r<i 1 ' 1/li< ' 1 . " /'' K '/'''/''"'- 
).< + -/'//'. J The 'l'i'l(/ilmriil;i' ;is :t subfamily 
of tilt' l.il in jiifritltr. They have tin- middle euxie con- 
tiguous and On- cpipliMlra distinct unil natron < 
arid mesotliorarie epiHterna. nut sinuate on the inner aide. 
They lire slender :iinl nitlitT si.fl bodied he, -tics of medium 
size, usually v L'I I aMe-feeilerH,iilthough carnivorous in the 
larv:il state. Ch<nUi"<lniitttitx,rtnl(ttirii*,itnt\ Til>'i'li"rttx an; 
the principal gcncrii represented in the I' nil ed States. See 
rut under xultlier-bfetlr. 
Telephorus (le-leTo-riiix), . [NL. (Schaeffer, 
17(ili), < (ir. Ti'i'/.f, afar, + -^opof, < *</>i' = K. 
/;'.] A jenus of serrii'orn beetles, typical 
of the family Tcli'plioridir. ItisofcoBiiiopolitandis- 
tribution, and comprises more than 300 species, the major- 
ity of them inhabiting cold or temperate regions. Thirty- 
six species occur In tin- 1 nitcd States. T. Irilineatiu, the 
two-lined soldier beetle, is In its larval state, according I" 
Biley, ii ciiiiimon enemy of the larva of the codling-moth 
(Carpocapun ptnrwufUa). See cut under toldier-beetle. 
telephote (tel'o-fot), . [< Or. r^t, afar, + 
0<jf (<J>UT-), Uxat.1 An instrument designed to 
reproduce at :i distance, by the aid of electri- 
city, pictures or images of visible objects. 
telephotograph (tel-e-fo'to-graf), . [< tete- 
plintc + Or. }/<//!', write. Cf. photograph.] A 
picM nre or linage produced by a telephote. 
telephotography (tel'e-fo-tog'ra-fi), . [< tele- 
/i/iiit<i//i-<t/i/i + -//.] The art (not yet attained) 
of producing a photograph of an object distant 
and invisible from the camera, by means of elec- 
trical connect ions with a suitable apparatus sit- 
uated near the object. Nature, XLIII. 335. 
teleplastic (tel-e-plas'tik), a. [< Gr. rij?.e, afar, 
+ TrUaaeiv, form, mold, shape.] Noting the 
alleged spiritualistic phenomena of materiali- 
zation, or the formation of phantasmal figures 
of persons and things. Also teleaomatic. See 
the quotation. [Hare.] 
M. (A. N.) Aksakof uses the term " telesomatic " for the 
phenomena of so called "materialisation," the formation 
of " spirit-hands " and the like. Elsewhere he calls these 
phenomena "plastic." Inasmuch as other material ob- 
jects are asserted to he thus supernormally formed, he- 
sides quasi-human hodles, it would be better, I think, to 
give the name teleptantic to all this class of alleged phe- 
nomena. F. W. II. Myers, Proc. Soc. Psych. Research, 
[Dec., 1890, p. 069. 
telepolariscope (tel"e-po-lar'i-skop), n. [< Gr. 
r>?Xr, afar, + E. polariscoj>e.] An optical instru- 
ment consisting of a combination of the polari- 
scope with the telescope. 
teleradiophone (tel-e-ra'di-o-fon), . [< Gr. 
riftje, afar, + E. radiophone.] An adaptation of 
telegraphy to the radiophone. 
Telerpetoh (te-ler'pe-ton), n. [NL., < Gr. r^Ae, 
afar, + IpirtrAv, a reptile, < ipirciv, creep, crawl.] 
1. A genus of fossil lizards of the Mesozoic pe- 
riod, belonging to the order Rliynehocephalia. 
2. [/. C.] A member of this genus. 
telescope (tel'e-slcop), n. [= F. telescope = Sp. 
Pg. It. telexvopio = D. teleskoop = G. Sw. Dan. 
teleskop, etc., < NL. tclescopium (NGr. rriteoif&- 
mav), < Gr. r)/U, afar, + aimirelv, view.] 1. An 
optical instrument by means of which distant 
objects are made to appear nearer and larger. 
It originated in the first decade of the seventeenth cen- 
tury, apparently earliest in Holland ; but Galileo In 1608 
independently invented the form which bears his name, 
published it to the world, and was the first to apply 
the instrument to astronomical observation. The tele- 
scope consists essentially of two members : one, the oi- 
jective, a large converging lens, or a concave mirror (tech- 
nically *ptculum\ which forms an optical image of the 
object; the other, the eyepiece, a small lens or combina- 
tion of lenses, win. h magnifies this image. The optical 
parts are usually set In a tube, and this Is so arranged that 
the distance between the objective and the eyepiece can be 
adjusted to give the most distinct vision. Telescopes are 
classed as rrj'ractinn or reflfctinff. according as the objec- 
tive is a lens or a speculum. The simple refracting telescope 
luis for an objective a large convex lens, A (fig. 1), of long 
Fig. i. The Simple Refracting Telescope. 
focus, while the eyepiece, R, is also a convex lens, but of 
short focus, the two being placed at a distance slightly 
less than the sum of their focal lengths. The "real" in- 
verted image of the object formed at m by theobject-glast* 
is viewed by the magnifying lens II. the magnifying jiower 
being equal to the ratio between the focal lengths if tin- 
lenses A and n. With this form of instrument the object 
is seen inverted. In tin i Galilean telescope the eye-lens 
is concave instead of convex, and intercepts the rays from 
the objective before they reach the focus, so that the ob- 
6817 
Ject IB seen erect. But the Held of vii:w Is very restricted, 
MliltliiHformiif instrument n.iw survives cud) in the opera- 
]ass. The si in | ilc 1 1 t!."-i int: telescope in any of its i-.nn- 
a very Impctfe, i Imtmnmt, owinf tothe fact that rys 
of different color are not alike refrangible, the focus be- 
ing nearer the lens fctr tin- lilue rays th:in for the red. l:y 
III liking Hie !c 1. -c "I" MIC, long in pri 'portion to its diame- 
ter, the injiii ion-- i tti-et c.f this i hioniatir atcerrati .m 
be great h n-'lii. -eel. and about lm Illlygens and i 
llseil inslrilinc nts re tlian HKI feet loni; in thcii 
vatlonR upon Saturn. About tlu middle of the atghtcentli 
century it was distncvrie:! in Klii/land that, liy c omlcininu' 
lenses <>f different kinds of glass, objeetinv, i.ciil. I In made 
nearly free from chromatic aberration, and all the refrac t- 
ing telescopes now constructed have achromatic olijc < t 
glasses of some form. The usual construction Ua double 
convex lens of crown- glass ccuuliiiuMl with ii(neiirly)plainc 
concave lens of flint-glass, the focal lengths ccf the- io 
lenses being proportional to their dispersive JMCWITS, and 
tin c urves so chosen that the spherical iiberratlon is cor- 
reet edat t In- same- timcv But other forms are postilile and 
even preferable. Klg. 2 shows some of those most used. For 
Clark 
Fig. a. Different Forms of the Achromali 
many years after the inventlott of the achromatic telescope 
It was impossible to obtain suitable glass for lenses of 
more than 5 Inches in diameter. The discoveries of (iiii 
nand about 1800 partially relieved the difficulty, and fr 
about 1870 to 1890 a considerable number of Instruments 
have been made with apertures exceeding 2 feet the larg- 
est so far being the great Lick telescope (fig. 3), of 86 Inches 
Fig. 3. The I.ick Telescope. Lick Observatory. California. 
diameter and 57 feet in length, the object-glass by Clark of 
Cambridge, Massachusetts. The next in size is the Pnlkowa 
telescope, 30 inches in diameter, the object-glass also by 
Clark. The achromatic objective constructed of flint- and 
crown-glass is, however, by no means perfect, and cannot 
be made so while these kinds of glass are used. When the 
correction for the rays of mean wave-length in the spec- 
trum is the best possible, the extreme rays the red and 
violet refuse to coincide with the others, so that the 
Image of a bright object is surrounded by a purple halo, 
which renders It somewhat indistinct. This "secondary 
spectrum," as it is called, Is not very obtrusive in small 
instruments, but is a serious defect in large ones, and un- 
fits the ordinary achromatic refractor for photography. 
For this purpose it is necessary to use an object-glass spe- 
cially corrected for the violet rays, and therefore practi- 
cally worthless for visual observations. But while It Is 
impossible to secure a perfect color-correction with any 
lens composed of ordinary crown- and flint-glass, there is 
no reason why kinds of glass may not be Invented which 
will render it possible ; and since 1880 experiments, under 
the auspices of the German government, by Professor Abbe 
at Jena, appear to have resulted in at least partial success. 
Lenses as large as 12 inches in diameter have been made of 
the new glass. If large disks of this glass can be obtained 
siitlieientl) homogeneous, and not corrosible under expo- 
sure to the air, the art of telescope-making will immediate- 
ly make enormous progress. The reflecting telescope was 
invented between lOflO and 1670. independently by Gregory 
and Newton, by the latter as the result of his discovery of 
the decomposition of light by refraction, which led him to 
conclude(erroneously)that the faultsof the refracting tele- 
scope were necessarily Incurable. There are four different 
forms of the In- 
strument, dif- 
fering only in 
II. e method by 
which the rays 
reflected 1>\ the 
concave specu- 
lum which 
forms the olv 
Jeetlve are 
brought to the Fig. 4.- The Gregorian Reflecting Teleicope. 
telescope 
eycplree. In the I;I.-L'"I ian tel. .-."] (tig. 4 ) the rays rr. 
Meeted from tin spe. -iilnm are a sec-und time M Meeted by 
a small eom-ave mi iii th.- e. -liter of the Mb*. sod just 
i!h. ('.ens. The lame minor Is |-i -foratttd, and the 
. \. pi. -e. -, plac ed behind the perjoiation, reeeives the rays 
thus twice reflected. In thcCassegrainlanthfconstruetlon 
Is precisely similar, except that the small min or i- .-.,n-. > 
and Is placed within the focus; this shortens the Instru- 
ment a little, but restricts tin- Held of view. In both these 
forms the observer looks toward the object just as with a 
refractor. In the Newtonian form, which is the most used, 
the small mirror is plane, and set at an angle of 46, so thai 
the rays arc reflected out at the side of the I nhc. Finally, in 
I h. hunt-view or II ei>i-helian foi m the -mall mil tor is tils- 
pen*'.! with, the speeuliini beinu' slii/htly tilted soas to 
throw the image to one side "t tin month of the tube. 
This saves the loss of light due to tin- M<nd I'Meetion, 
but involves some injury t" the dellnition Although tin 
reflecting telescope Is free from cliromatii- aherrati"n i' 
M -lilum gives as perfect definition as an achronmtic instru- 
ment, and iH mneli more subject to atniosphetii- di-turb 
ance; the Image also Is less brilliant than that given by 
a refractor of the same aperture; but tin -p.' uluni Is 
much easier and leu costly to construct than an aeln 
Ic object-glass of the same site, so that the hirgc-i 
scope* ever made have been reflectors. At the head of 
the list stands the six-foot " leviathan " of Lord Roue, 
erected In 1846, and still In use : it is of the Newtonian form. 
The five-foot sllver-on-glau Cassegralnlan reflector of Mr. 
Common, erected In 1889, stands next, and there are In ex- 
istence a number of instruments with apertures of 3 and 
4 feet. Herschel's great telescope, erected In 1789, but long 
since dismantled, was 48 Inches In diameter and 40 feet 
long. The magnifying power of a telescope depends upon 
the ratio between the focal length of the object-glass and 
that of the eyepiece. (See eyepiece.) It can therefore be 
altered at pleasure by merely exchanging one eyepiece for 
another. As a rule, the highest power practically availa- 
ble, with the best object-glasses and under the best clr- 
c iimstances. Is from 76 to 100 to every Inch of aperture. 
The Illuminating power Is proportional, other things equal, 
to the area of the object-glass or the speculum ; so that a 
telescope of 12 Inches aperture ought to give four time* as 
much light as one with a 6-Inch lens. Practically, how- 
ever, the larger lenses, on account of the Increase in the 
thickness of the glass, do not reach their theoretical per- 
formance. Reflecting telescopes vary greatly in their light- 
gathering power. A Newtonian reflector with a silver-on- 
glass speculum freshly polished Is not very greatly Inferior 
in light to an achromatic of the same aperture ; bat m* 
rule a reflector In it - ordinary working condition has only 
aliout half the light of the corresponding refractor. Small 
telescopes for terrestrial purposes are usually unmounted, 
but the tube Is ordinarily made In several sections which 
slide Into one another, reducing the length of the Instru- 
ment, and making It more portable, as in the common spy- 
glass. Larger telescopes are mounted upon stands of some 
kind, and the practical efficiency of the instrument de- 
pends greatly on the firmness and convenient arrangement 
of the stand. At present telescopes for astronomical use 
are almost always mounted equatorially that Is, the tel- 
escope-tube Is attached to an axis, which itself is carried 
by another axis with Its bearings so arranged that it points 
toward the pole. This principal axis is called the polar 
axis, and a clockwork is usually arranged to make it turn 
at the rate of one revolution in a sidereal day. When the 
telescope Is once pointed at a celestial object, the clock- 
work will keep it apparently stationary in the field of view 
for any length of time. By the help also of graduated circles 
attached to the two axes It is easy to " set " the telescope 
so as to find any object whose right ascension and decli- 
nation are known. Fig. 5 represents diagrammatic-ally 
the equatorial of the 
usual German form. 
It is quite certain 
that previous to 1600 
the telescope was un- 
known, except pos- 
sibly to Individuals 
who failed to see Its 
practical Impor- 
tance, and who con- 
fined its use to "cu- 
rious practices" or 
to demonstrations of 
natural magic." 
. Brit., 
fXXIII. 136. 
2. [cap.] Same 
as Tclcucojmtm . 
Axis of a tele- 
scope. See anil. 
Binocular tele- 
scope, an Instru- 
ment composed of 
two similar small 
telescopes fastened 
together side by side 
and parallel, so that 
both eyes can be used 
at once In looking through it The opera-glass Is its most 
common form. Brachy-telescope. or Imichyte, a form 
of silver- on-glass reflector in which the small mirror, con- 
vex in form, is placed out of the axis of the large speculum, 
which is slightly inclined, the distortion thus produced In 
the image being partly compensated by the corresponding 
Inclination of the small mirror. This construction avoids 
the perforation of the speculum, and leaves Its whole area 
unobstructed; it also considerably diminishes the length 
of the instrument. Broken telescope, a telescope which 
has a reflecting prism or mirror inserted about half-way 
bctw ecu the object-glass and its focus, the t nl H- being thus 
bent at right angles: much used in transit-Instruments 
and theodolites. Cane telescope, a telescope or spy 
glass fitted in a walking-stick. CaBsegrainian tele- 
scope, a form of reflector in which the small mirror is con- 
vex. See def . i . Catadloptrlc, catoptric telescope, H 
reflecting telescope. Dlalytlc telescope. Sec- tUtjfk. 
Equatorial telescope. See equatorial, n., and def. 1. 
Galilean telescope, the form of refracting telescope 
invented b\ ilalile. i, and still used as the opera-glass: it Is 
Pig. 5. The Equatorial 
