NaiutaUPhihsophicdl dsliecUdns. 151 



fluenced each other, in ixitli a itfafittef, thaC wKetlier the sounds are' communicated 

 to the atmosphere from the column of air, or to a conductor froih the vibrating 

 tongue, the quantity of the sound undergoes no change. The transmission of the 

 sounds of reed wind instruments lie therefore found as perfect as those of instru- 

 ments dependent on the vibrations of sounding boards. In other classes of wind 

 instruments, the difficulties of transmission are greater ; for it is not possible to 

 transmit the vibratiorts of the air immediately through solid conductors with any 

 degree of intensity ; but if the intermediation of other bodies which enter readQy 

 into vibration, from the agitations" of the air, be employed, the transmission may 

 be effected. Thus, if the end of the conducting wire be placed in the most 

 strongly vibrating part of the column of air in a flute, there is but little percepti- 

 tile transmission of sound ; but if it touch the sides of the instrument, it will more 

 i^dily transmit tlie sounds in proportion as the sides are more susceptible of en- 

 tering into vibration. In a similar manner, the sounds of an entire orchestra, 

 or of the human voice, may be transmitted, viz. by connecting the end of the 

 Conductor with a sounding-board so placed as to resound to the various instru- 

 ments ; but in such cases the sounds are by no means so intense as when they 

 are communicated directly from the instruments. The effect of such intermediate 

 jttansmission was exemplified by some perforhiances on Mr. W.'s new instrument, 

 the symphonion. A few observations were then made on various proposed appli- 

 cations of this principle, and on the possibility of telephonic communication. It 

 was stated, that as sound has been proved to travel tlirough several conducting 

 ^bstances at the extraordinary velocity of 18,000 feet in a second, were it possi- 

 ble to transmit audible sound so far, a phonic communication might be made be- 

 tVeen London and Edinburgh — a distance of nearly 400 miles — in less than two 

 ihinutes. Theoretical considerations have shown, that when sound is communi- 

 nicated without any divergence through a perfectly elastic body of equal density 

 throughout, its energy suffers no diminution ; it follows, therefore, that the more 

 perfectly we can approximate to these conditions of a conducting body, the less 

 limitation there will be to the transmission of the sonorous undulations. But, 

 these points can be determined only by extended experiments — Lit, Gaz. „,, 



Kater^s Small Pocket Azimuth and Altitude Instrument— A& Captain Ka- 

 ter has not as yet given a detailed description of this exceedingly useful instru- 

 ment, the following brief account may not be unacceptable. 



The great advantages it possesses, are — extreme portability ; the ease and ac- 

 curacy with which it can be used ; and its cheapness. 



■ A circle, three inches in diameter, is fixed to a hollow cone, which moves upon 

 a solid axis, and the whole is supported by a tripod stand, into which this axis 

 Screws. At the back of the circle is fixed a spirit level. A telescope, magnify- 

 ing about eight times, to which are fixed too opposite verniers, moves upon the 

 circle ; there is, also, a tangent-screw for slow motion. A ball and socket it 

 screwed into the back of the instrument, which serves as a counterpoise when ver- 

 tical angles are taken. 



■ In the focus of the telescope are placed one vertical and three horizontal spiders' 

 ftireads, which are illuminated by a very ingeniously contrived reflector, forming. 

 a portion of a hollow cone, silvered inside, which fits upon the object end of the 

 telescope. 



The motion in azimuth is given by two projecting pieces attached to a tube, 

 Which fits rather tightly on the conical axis ; tliese pieces serve also, by being, 

 brought in a line with one of the radii of the tripod-stand, when the telescope i» 

 directed to a star, to turn the instrument 180° in azimuth, so as to bring the star 

 into the field of view when the face of the circle is changed from left to right. 



To use this instrument, it must be carefully levelled, and the telescope being 

 directed to a star, or other object, so that it appears upon the horizontal wire, 

 and upon or very near the vertical wire, the verniers read off the apparent eleva- 

 tion to minutes. The circle is then turned half-round in azimuth, and the angle 



