Laun-oii of a Toiiprdo Boat. — Xew York. Sopt !). — Tho I first torpedo boat worthy of any notice which has bai>n planned sinuii (ho i'.'b>l!i.in, was liiuncho'.l yost-irday aftar- J noon, at half-p.ist :) o'clooli, at Fairhav.ju. Conn, i lor hull was built and modi'lletl by MrS. 11. Poj!;. son of tho naval constructor of that name. Sh »is a woodiiii voss>l, 7-j f ot i!i lenutli. 20 foct beam, and 7 r>)ot d.-ptli of hold. She is built in On most substantial manner, with heavy b.v.ma supported by luuu'ing kn^os soo.mvly boltod and fastened. The deck is crammed about two foot fore and aft. and about as much athwart ships, and this will bo covered with v thickness of iron armour suillciently stroiur to mako it shot and shell proof. Thj vcssjl will sit very low ill the water under tiny circumstances; but when not actively employ od she will float somo iwenlyinchesabovo tho surfaces; but when npproaohin,' a vessel to destroy her or engage in blowing up obstructions, only tho cram of her dock will \ta above w.itor. Tlkm-o arc but thivo objects visible above tho docks— viz pilot houso. s:noke stack, and ventilator. Those only show a few inches at the most. Thcso objections aro pjrfoctly shot proof, and their openings aro pi'otoetMl in tho most aeouro mannoi 1. The novelty of the affair is not sueu until a visit is ni \do below the dock. Away aft v pi icod tho enginj, with a cylindor of 18 inches in diimolorund IS inch '« strok.: of piston. This engine works a screw of a si/.', capable of forciujr the vossol through the wv.tor at tin rat.' of say twelve miles per hour. Next comes tho boil.T which fur nishes tin strum for tho main cngino as well as for tho auxiliary engines which work tiio submerging pui.ip-i. niul tho mocbauioisni by which tho torpxlo arm places tho torpedo bonoath tho ship. Under the pilot-hoiiHo is tin torpedo machine. T-et us suppose th:;'. an cnoniy's il-.'ct woro blockading our harbor, and wo wore in possession of o'.u? or more of thcso torpedo vessels. Twelve m:"i. including engimvr oificers, man the vessel. Tin a!.\i:n is miaod, and undor cover of night slu; steams out ujjijn h>-r mission. 