First installment of a serial article on testing textile fibres, yarns and fabrics, published in Posselt's Textile Journal, October 1907. It explains why manufacturers and buyers need to test materials, then covers yarn testing (count, twist, strength, evenness, grease and moisture) and microscopic identification of fibres. The sampled pages describe the compound microscope and how to prepare fibres for it, then wool, cashmere, mohair, alpaca, camel, goat, cow and horse hair, and the reclaimed wools shoddy, mungo, extract and flocks. One engraving shows wool fibres under the microscope.