`You will tell him that you want to see the waste-paper of yesterday. You will say that an important telegram has miscarried and that you are looking for it. You understand?'

`Yes, sir.'

`But what you are really looking for is the centre page of the Times with some holes cut in it with scissors. Here is a copy of the Times. It is this page. You could easily recognize it, could you not?'

`Yes, sir.'

`In each case the outside porter will send for the hall porter, to whom also you will give a shilling. Here are twenty-three shillings. You will then learn in possibly twenty cases out of the twenty-three that the waste of the day before has been burned or removed. In the three other cases you will be shown a heap of paper and you will look for this page of the Times among it. The odds are enormously against your finding it. There are ten shillings over in case of emergencies. Let me have a report by wire at Baker Street before evening. And now, Watson, it only remains for us to find out by wire the identity of the cabman, No. 2704, and then we will drop into one of the Bond Street picture galleries and fill in the time until we are due at the hotel.'