170 ANNUAL OF SCIENTIFIC DISCOVERT. 



eratum of con'ectly ascertain in a;, in a minute or less, the exact 

 weight of vessels of ail descriptions, Avith their cargoes, at all 

 times when at rest in the water, whelher salt or fresh. It indi- 

 cates not only any diminution or addition to the cargo, thus pre- 

 venting frauds in transportation, but also reveals at a glance the 

 condition of the vessel as to leakage on the voyage, thus con- 

 tril)Uting, by an "alarm" easily ailapted, to the safety of passen- 

 gers, and the preservation of frcigiit. It is of great value in 

 cheajienino^ freight, increasing accuracy of measurement, and 

 avoiding damage to boats by the racking in the old-fashioned 

 weigh-locks, the last item being often, a quarter of the worth of 

 the cargo. 



KESISTANCE OF "WATER TO FLOATING AND IMMERSED BODIES. 



At the Nottingham meeting of the British Association, Prof. 

 Rankine read the report of the committee appointed to make 

 experiments on this su!)}ect, giving the results of two hundred 

 and twenty experiments. The committee have deferred for tlie 

 present deducing any general laws of resistance ; but he stated 

 that the results of the experiments led to the following general 

 conclusions: 1. That, agreeabl}- to what was previously known of 

 the behavior of small bodies at low speeds, the resistance in- 

 creased on the whole somewhat more slowly than as the square 

 of the velocity. 2. That, when the velocity went bej'ond the 

 maximum velocity suited to the length of the model, as ascer- 

 tained b}' Mr. Scott KussolTs w^ell-known rules, the resistance 

 showed a tendency to increase at a more rapid rate. 3. In all 

 cases the resistance seemed to be much more nearly proportion- 

 ate to the main girth than to the midship section. 



Mr. Bailey and Admiral Belcher having spoken with disap- 

 proval of hollow lines or wave-lines at tlie bows of sea-going 

 vessels. Prof. Rankine pointed out, that the wave-line theory con- 

 sisted of two branches, one relating to the form of the bows, the 

 other to the relation between the length of the vessel and the 

 speed at which she was to be propelled through the water. He 

 did not attach much weight to the hollow bow, but thought that 

 much was to be said in favor of the theoi'y that the length should 

 have a certain relation to the speed. 



NON-RECOIL GUN. 



Mr. G. P. Harding has recently experimented on a gun on a 

 principle so new, that, if his expectations are fulfilled, the manu- 

 facture of fire-arms will be I'evolutionized. His gun is a simjjle 

 cj'lindrical tube, without any breech. The shot is jilaced at the 

 ci'utre, the charge behind it confined by a wad, and a second wad 

 is introduced at such a distance as to leave an air-space behind 

 the charge. The extraordinary fact devoloped by Mr. Harding's 

 experiments is this : That, although the gun is equally open in 

 both directions, almost the whole force of the explosion takes 

 eft'ect on the shot, which attains the same velocity as Lf fired from 



