Inspector Johnson will give you any assistance you may require." "And see that I don't pocket the original," added Thorndyke, with a smile at the inspector who had shown us in.
"Oh, I'll see to that," said the latter, grinning; and, as Mr.Singleton returned to his table, Thorndyke unlocked the microscope case and drew forth the instrument.
"What, are you going to put it under the microscope ?" exclaimed Mr.
Singleton, looking round with a broad smile.
"Must do something for my fee, you know," replied Thorndyke, as he set up the microscope and screwed on two extra objectives to the triple nose-piece.

"You observe that there is no deception," he added to the inspector, as he took the paper from Mr.Singleton's table and placed it between two slips of glass.
"I'm watching you, sir," replied the officer, with a chuckle; and he did watch, with close attention and great interest, while Thorndyke laid the glass slips on the microscope stage and proceeded to focus.
I also watched, and was a good deal exercised in my mind by my colleague's proceedings.

After a preliminary glance with the six-inch glass, he swung round the nose-piece to the half-inch objective and slipped in a more powerful eye-piece, and with this power he examined the blood-stains carefully, and then moved the thumb-print into the field of vision.

After looking at this for some time with deep attention, he drew from the case a tiny spirit lamp which was evidently filled with an alcoholic solution of some sodium salt, for when he lit it I recognised the characteristic yellow sodium flame.

Then he replaced one of the objectives by a spectroscopic attachment, and having placed the little lamp close to the microscope mirror, adjusted the spectroscope.