History of the Cannon

           Theresolutionspassedatthelastmeetingproducedagreateffectoutofdoors.Timidpeopletookfrightattheideaofashotweighing20,000poundsbeinglaunchedintospace;theyaskedwhatcannoncouldevertransmitasufficientvelocitytosuchamightymass.Theminutesofthesecondmeetingweredestinedtriumphantlytoanswersuchquestions.Thefollowingeveningthediscussionwasrenewed.

           "Mydearcolleagues,"saidBarbicane,withoutfurtherpreamble,"thesubjectnowbeforeusistheconstructionoftheengine,itslength,itscomposition,anditsweight.Itisprobablethatweshallendbygivingitgiganticdimensions;buthowevergreatmaybethedifficultiesintheway,ourmechanicalgeniuswillreadilysurmountthem.Begoodenough,then,togivemeyourattention,anddonothesitatetomakeobjectionsattheclose.Ihavenofearofthem.Theproblembeforeusishowtocommunicateaninitialforceof12,000yardspersecondtoashellof108inchesindiameter,weighing20,000pounds.Nowwhenaprojectileislaunchedintospace,whathappenstoit?Itisacteduponbythreeindependentforces:theresistanceoftheair,theattractionoftheearth,andtheforceofimpulsionwithwhichitisendowed.Letusexaminethesethreeforces.Theresistanceoftheairisoflittleimportance.Theatmosphereoftheearthdoesnotexceedfortymiles.Now,withthegivenrapidity,theprojectilewillhavetraversedthisinfiveseconds,andtheperiodistoobrieffortheresistanceofthemediumtoberegardedotherwisethanasinsignificant.