Thoughts on
How to Build a Glider
By Carl Bates

Construction
The first thing that struck me is that there's so little about the shape of the airfoil of the wings. There's just the instruction to see that all the ribs have the same curve -- but what curve? Clearly the shape is controlled by the angles given to the ends of the crosspieces. In Fig. 2, it's clear that these are not square, but there is no mention of what the angles should be.
 
There's nothing to form or support the trailing edge of these wings. There's not even a wire for stiffening. But, perhaps that's the way it was done.
 
Also there's no mention of any finishing: no varnish on the wood, no shrinking the fabric, no paint. I reckon these were not intended or expected to last too long.

Flying
There's not much practical advice about flying here. For example, there's no mention that a wing will stall if your airspeed drops below some minimum. In fact there's no mention of airspeed at all, and of course nothing about the possibility of wind sheer. I would think that an aircraft whose airspeed is probably not going to exceed 20 mph would be very subject to the effects of wind sheer -- but hey, this is 1909, and wind sheer will not be invented for many years to come.

What's Wrong With This Picture?
The illustration of flight paths, Fig. 5, looks like something that Ron Machado would draw to show everything the pilot should not do. It shows a flight path right over an oncoming freight train! Then the path leads over a river, and finally it ends right at the row of houses on the opposite bank! Obstacles? Dangerous terrain? Populated areas? As Alfred E. Neuman would say, "What, me worry?"
 
Of course, the fact that the two illustrated flight paths both start with an initial climb is also quite interesting.

Lack of Technical Terms
I was surprised to read about construction of an aircraft and not see any of the technical terms I would have expected to describe it: missing, for instance, were Airfoil, Biplane, Spar, Strut, Airspeed, Stall, &c.

So, did he really build and fly this thing?
All the above made me wonder who was Carl Bates? Did he really build and fly aircraft? Just a little investigation on the web makes it clear that he certainly did.