Oh, crikey, you mean I'm going to have to do math at this time of night? Remember that the f/stop ratios are just a convenient way of expressing what really counts: the area of the aperture through which light rays pass. The larger the area, the more light rays can get through, and their effect on exposure is based on simple proportions.
The f/stop ratio tells you the diameter of the aperture, based on the focal length, and from there you use good old pi x radius ^ 2 to compute the actual area.
Assuming that the 40mm's actual focal length is 40mm, and that its maximum aperture is really f/1.4 (both potentially risky assumptions, but as good a starting point as any) then its aperture area is 641.14 sq mm.
Now if we assume that the 35's maximum aperture is really f/1.8, as Huck says Pop reported, then its aperture area is 296.95 sq mm. That means the 40's area is 2.16x as large as the 35's -- confirming, as Huck notes, that the speed difference between the two is more than a full stop (which would be exactly 2x.)
On the other hand, if we assume that the 35's maximum aperture is its marked value of 1.7, then its area is 332.91 sq mm. That means the 40's area is only 1.93x larger, or slightly less than a full stop.
All that simply from tweaking our assumptions by 1/10th! And if you tweaked any of the other assumptions (such as marked vs. actual focal length) by the same amounts, you'd get similar variation in the results.
This is why I don't usually worry about tiny variations in aperture values.
[Yes, I know that the next full stop after f/1.4 is supposed to be f/2... and it is, if you carry everything out to enough decimal places -- the aperture numbers are actually based on powers of 2, but we round them off because it would take up a lot of space to engrave "f/1.414214" on a lens barrel.]
So it looks, based on areas, as if Huck's right in saying that the difference between the two lenses is closer to a full stop than it might look. On the other hand, we haven't accounted for transmittance yet... and at this time of night, we ain't GOING to!