These windmills had long vertical driveshafts with rectangle shaped blades.[93] They may have been constructed as early as the time of the second Rashidun caliph Umar (634-644 AD), though some argue that this account may have been a 10th-century amendment.[94] Made of six to twelve sails covered in reed matting or cloth material, these windmills were used to grind grains and draw up water, and used in the gristmilling and sugarcane industries.[95] Horizontal axle windmills of the type generally used today, however, were developed in Northwestern Europe in the 1180s.[91][92] Wilson's theorem: This is first mentioned by ibn al-Haytham.[14]