Washington, Juno 18. This afternoon the loug-proraised balloon ascensión for milnlry pnrposes took placo. The olevation attaioed was not very groat, tliougli it was pèrfectly satisfactovy as an experiment. The uronauts wero Prof. Lowo, Gen. Burní, of the Telegraph Coinpany, aTid II. C. Iíobinson, operator. The bailoon was comicctcd with the War Department by tolegraph. Tlio fir.'t mesrage ever telegraphed írom a bailoon was then sent to tha President of the United States by Prof. Lowe. It was as follows : Ualloon Enterprise, ) Washington, June 17. ) To the President of the United States: Sir : - This point of observation comniands an arca nearly iit'ty miles in diameter. The city, with its girdle of encaMpments, preBQnta a guperb scobc. I take graat ptuasuro in sendhig j-ou this first dispatch ever telegraphed from au rorial station, and in acknowledging my indobtedness to your encouragemeut for the opportunity of dcmousti ating the availabiiitj of the science of reronautics in tb o military service of the country. Very rcspeotfully, T. ö. C, LOWE. Mr. Lincoln waa very much ploásed with the experiment, and endorsed il ns certain ultiuiatcly to prove of grc;at value in military ïuevoracntii. Fpecial ilíspatoh to theX. Y. Tribune. Washington June 18, 1801. The highest ascensión was 450 feet. - Scveral mofe exporirücnts will bo requisito to cstablish the extent to whieh thu bailoon eau bo used on tho battle-fiold, to giro orders, and in recotmoisan.qcs to record observations in camp whilo workitig at a distarico, Aficr tlio experiment was concluded, the balloon was towcd up by ropos to the greuuds of the President, who reviowed it frora the window. The car was adornad with two American and O'io Britifih flag. ïhe tricolor was acci dontally -ibsont. ïho balloon sponds the night anchored iu rcar of tlie "ir]!tü House.