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and I am very thankful that I, at least, was not the cause of any such anxiety.
   In conclusion, my sincere thanks are due to the coroner for his kindness and consideration.  It is much to be desired, though perhaps not to be expected, that others would more frequently have the same thought.
        I am, sir, your obliged servant,
Royal Institution, July 31.         M.  FARADAY.

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                    From Mr. Ottley.
   Sir,--Being at all times unwilling to have my sentiments and opinions misrepresented, but more especially so in your paper, which deservedly commands so much more public confidence than any other, I am induced to trouble you with a few lines respecting the evidence I gave at the inquest on the body of Mr. Cocking.
   If the object of the remarks I then made had been merely the value of a few philosophical truths, or the interest they might have in a scientific point of view, I should not have troubled you with the present communication.
   My object, however, was of far greater public importance than this.  There appears to have been an opinion entertained by many of those present, and which was insisted upon by some with a degree of zeal scarcely to be accounted for, that had the parachute of Mr. Cocking been strong enough to resist fracture, the result of the experiment would have been successful.
   My calculations were made with a view to show that this could not have been the case, in consequenee of the little resistance afforded by the air to a convex parachute.  The results of these calculations I stated to the court, because I thought it of the greatest importance to deter the adventurous from attempting the formation and use of other parachutes on the principle of that of Mr. Cocking, and trusting to them in the idea that, having given them more strength, they might depend upon their safety.  In my evidence I stated that my attention had been drawn to the subject by thenovelty and notoriety of the intended experiment, and that I had made calculations comparing the relative powers of convex and concave parachutes previous to the experiment in question ; and I showed that from those calculations it followed that a fatal result might be considered as the natural consequence of the structure of the machine, independently of its accidental fracture in the descent.  
   The fact is, that from the inherent defects in the nature of the structure, any attempt to increase the strength and size of such a machine must increase its weight in a still greater proportion, and, consequently it must still remain inefficient.
   On the other hand, in the concave parachute, the surface, and consequently the resistance and efficiency, may he increased to any extent, without augmenting the weight in a greater degree, and therefore the power of such a parachute may be increased almost without limit, setting aside the inconvenience of managing one of extremely large dimensions.
   Although these calculations are not of a very abstruse character, and may be performed by all persons competent in mechanical and pneumatical science, the results are such as could never be arrived at without the aid of such calculations ; and consequently, as I have said above, I consider the pronulgation of them at the present moment to be important, inasmuch as it may prevent more lives being lost in experiments, which, from the necessity of failure attendant upon them, can scarcely merit the name.
     I am, Sir, your obedient servant,
    WILLIAM CAMPBELL OTTLEY, M.A.,
     Fellow of Caius College, Cambridge.    

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    Calculations from the Railway Magazine.
   The unfortunate experiment of Mr Cocking, in his descent on the 24th ult., with the parachute, has excited so painful a feeling in the public mind, that we shall be excused for saying a few words on the subject.  It appears that Mr. Cocking's apparatus was an inverted frustrum of a cone, 34 feet diameter at the top, and three or four at the bottom, which was open.  We are informed the upper ring was a tin tube, about two inches' diameter, and the lower a wooden hoop ; the superfices of the cone was strong linen or canvass, and the whole, with the basket in which he was, weighed about 150lb.  He took up, we are informed, 2cwt. of ballast, making, with himself, a total of about 5cwt.  We know not the proportion of the axis
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of the frustrum to either diameter of the cone ; but supposing the parachute a flat circle, which would have been a better form for resistance, of the 34 feet diameter, it would expose a resisting area of little better than 900 square feet.  With these dimensions the mass would have descended with a velocity of near 13 miles an hour--three times greater than safety would permit; but from the bad formation of the machine, and the great hole in the middle, the resistance must have been less, and the velocity greater.  Could he have rid himself of the 2cwt of ballast, he must have descended more than 10 miles an hour--that is, near three times as fast as he ought.  In every way it was an ill-contrived, ill-judged experiment ; the tube was too weak, and, we are informed, it came unsoldered the day before he went up.  To descend with a velocity of five miles an hour, rather too much for perfect safety, requires a resisting area of 1,000 square feet for every 100lb.; Cocking's had only 900 for more than five times the weight.  His distance was nearly 60 feet from Mr. Green, too much for easy communication.
   It has been stated, that several scientific men had approved of calculations of the safety of Mr. Cocking's parachute.  We can hardly believe it; we ourselves, at 4 o'clock, gave our opinion against it to friends who asked us.  From the height, 5,000 feet, stated by Mr. Green, and the time of descent, 70 seconds, or more, observed by Mr. Bishop, we perceive that our computation of the maximum velocity, 13 miles an hour, would have been very near the truth, had the parachute not have collapsed.
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