第17章 Off at Last(2)

"A splendid fellow,"said my uncle;"only he little suspects the marvelous part he is about to play in the history of the world.""You mean,then,"I cried in amazement,"that he should accompany us?""To the interior of the earth,yes,"replied my uncle."Why not?"There were yet forty-eight hours to elapse before we made our final start.To my great regret,our whole time was taken up in making preparations for our journey.All our industry and ability were devoted to packing every object in the most advantageous manner-the instruments on one side,the arms on the other,the tools here and the provisions there.There were,in fact,four distinct groups.

The instruments were of course of the best manufacture:

1.A centigrade thermometer of Eigel,counting up to 150degrees,which to me did not appear half enough-or too much.Too hot by half,if the degree of heat was to ascend so high-in which case we should certainly be cooked-not enough,if we wanted to ascertain the exact temperature of springs or metal in a state of fusion.

2.A manometer worked by compressed air,an instrument used to ascertain the upper atmospheric pressure on the level of the ocean.

Perhaps a common barometer would not have done as well,the atmospheric pressure being likely to increase in proportion as we descended below the surface of the earth.

3.A first-class chronometer made by Boissonnas,of Geneva,set at the meridian of Hamburg,from which Germans calculate,as the English do from Greenwich,and the French from Paris.

4.Two compasses,one for horizontal guidance,the other to ascertain the dip.

5.A night glass.

6.Two Ruhmkorff coils,which,by means of a current of electricity,would ensure us a very excellent,easily carried,and certain means of obtaining light.**The Ruhmkorff coil is used to obtain currents of induced electricity of great intensity.It consists of a coil of copper wire,insulated by being covered with silk,surrounded by another coil of fine wire,also insulated,in which a momentary current is induced when a current is passed through the inner coil from a voltaic battery.When the apparatus is in action,the gas becomes luminous,and produces a white and continued light.The battery and wire are carried in a leather bag,which the traveler fastens by a strap to his shoulders.The lantern is in front,and enables the benighted wanderer to see in the most profound obscurity.He may venture without fear of explosion into the midst of the most inflammable gases,and the lantern will burn beneath the deepest waters.H.D.Ruhmkorff,an able and learned chemist,discovered the induction coil.In 1864he won the quinquennial French prize of L2,000for this ingenious application of electricity.A voltaic battery,so called from Volta,its designed,is an apparatus consisting of a series of metal plates arranged in pairs and subjected to the action of saline solutions for producing currents of electricity.

7.A voltaic battery on the newest principle.

Our arms consisted of two rifles,with two revolving six-shooters.

Why these arms were provided it was impossible for me to say.I had every reason to believe that we had neither wild beasts nor savage natives to fear.My uncle,on the other hand,was quite as devoted to his arsenal as to his collection of instruments,and above all was very careful with his provision of fulminating or gun cotton,warranted to keep in any climate,and of which the expansive force was known to be greater than that of ordinary gunpowder.

Our tools consisted of two pickaxes,two crowbars,a silken ladder,three iron-shod Alpine poles,a hatchet,a hammer,a dozen wedges,some pointed pieces of iron,and a quantity of strong rope.