THE ROYAL ARTILLERY INSTITUTION. 
191 
the cost or weight of the .instrument. Possibly an instrument-maker would 
construct a chronograph for £100, and a clock for £25. The shed to hold 
the two might cost £50. Thus the cost would be about £175 ; but to cover 
all contingencies I would double the above sum and estimate the cost at 
£350. But, on the other hand, the saving in powder and shot must be 
considered in making a connected series of experiments. Por instance, the 
chronograph makes 10 records, or more, for a single shot. And further we 
must allow the value of each record to be at least 10 times the value of that 
made by an instrument which measures only one interval. So that it seems to 
me that the new chronograph, in economy of ammunition, compared with any 
chronograph in use, may be placed at 100 to 1. Extravagant as this estimate 
may appear, it is really understated. I maintain that any one of the eleven 
shots already described gives more exact information than all previous expe¬ 
riments made with the same gun fired with the same charge. But there 
need be no difficulty about cost, for the instrument is already constructed 
complete in all its parts, and ready to make all experiments required for a 
perfect system of gunnery in the course of a few weeks. To shew the 
capability of the instrument, we will suppose the chronograph placed in 
some central position at Shoeburyness, and provided with wires running to 
six different ranges, and that no less than six different parties wished to 
conduct experiments at the same time. Eive or ten minutes at least are required 
to repair a set of screens, but only a few seconds are required to complete 
the experiment when the gun is ready to be fired. Each party then, as it 
was prepared, would have to telegraph that it was ready. Communications 
would be made so as to send the galvanic current through the proper screens, the 
fly-wheel would be put in motion, the signal to fire would be given, and the 
experiment would be completed. By each party keeping an account of the 
exact time of the firing of their guns, they would be able to claim their own 
records at the end of the day without the slightest difficulty or confusion. 
I trust that the reader who has had the patience to follow me through this 
long account of the chronograph, and of the way of using it, will be aware 
that many questions have been put to me in the course of the last two years, 
to which I was not able to reply in a brief and satisfactory manner without 
opening the whole subject. I hope also that they who have urged objec¬ 
tions to my methods will be satisfied that I have provided against all 
real difficulties, and that where I could not overcome a difficulty I have found 
a way of avoiding it. The screens are perfectly satisfactory, and looking 
at the instrument as it stands, I cannot see any point in which greater sim¬ 
plicity is practicable or desirable. Certainly if the fly-wheel could be made 
to revolve with perfect uniformity and with a known velocity , the labour of 
forming a time-table for each experiment would be avoided, but no sensible 
increase of accuracy would be obtained in the result. Undoubtedly there is 
trouble attending the reduction of these as well as of all other observations 
where the greatest attainable precision is required. All this trouble I am 
ready to take upon myself, if in other respects every facility is given me for 
completing the proposed work. 
In conclusion, I must remind the reader that the questions raised in this 
tract are purely mathematical and mechanical. I have found it necessary to 
endeavour to clear the way by shewing the exact value of some formulae and 
instruments which have gradually come into use from the absence of some- 
