At the re-opening of the Royal United Service Institution last week by H.R.H. the Prince of WALES, in new premises at Whitehall, a novel and ingenious electrical instrument was exhibited. By means of this addition to the list of communicators a general in the field is able not only to send an autograph letter to a colleague or subordinate at a distance, but also to convey in _fac simile_ a drawing of his own composition. On the occasion to which reference is made, the Prince of WALES sent a message to his brother. To this despatch the Duke of CONNAUGHT was obliged to respond that he did not quite understand its full meaning. According to the reports some slight error was rectified, and then the machine worked to everyone's satisfaction. However, the fact remains that the initial attempt to convey intelligibly a message was not entirely successful. To impress upon those answerable for the perfect action of the instrument the importance of their task, we subjoin an imaginary scene of a nearly impossible situation. We will assume that a commander-in-chief is conversing with a general in the field some ten miles distant. _Commander-in-Chief_ (_wiring_). We hear here that a force of twenty-five thousand infantry are advancing by the Dover road with a view to turning your left front. _General in the Field._ Kindly repeat. (_Message repeated._) No, we do not want any more marmalade, as we have plenty of butter. _C.-in-C._ I said nothing about marmalade, I was talking of the enemy. Twenty-five thousand men are advancing on your left front. _Gen._ I think I now understand what you mean, but we can't get near Woolwich, because our gas has failed us. However, we will look out for the twenty-five thousand balloons you say are coming. _C.-in-C._ I said nothing about balloons. Infantry, I spoke of. They are approaching by the Dover Road. _Gen._ Thank you for your offer, but we have plenty of hammocks. We have just seen this. Can you identify her? I forward sketch. _C.-in-C._ You have sent me what appears to be a drawing of either a grand pianoforte or a hippopotamus. Which is it? _Gen._ It is very difficult to make out your messages. We think we understand your last. Yes, the mail to India did start without the elephants. We did not know that any had been ordered. _C.-in-C._ I said nothing about elephants. What is the meaning of your drawing? _Gen._ Very sorry; can't make out your message. Besides, have no more time for telegraphing. Twenty-five thousand infantry of the enemy have just been noticed on the Dover Road, threatening our left front. Why did you not tell us they were coming? But of course, as we have already said, when the hour arrives everything will be in perfect working order. It is to be hoped that there will be a supplementary signal to be used in cases of extreme emergency, to decide promptly a line of action where two courses are open for adoption. It might signify "Toss up." * * * * *