I now think that the perceived depth is is not as important as I first imagined... I suspect the hole still has a large quantity of tailings inside it. This because I believe that the drill test has actually reached very close to its maximum depth of around 50 mm (2"). My reasoning behind this assumption is that it appears that the 'Forward Sample Chamber' of the drill sleeve has left a smooth 'disk like' impression on the mound of tailings surrounding the hole, this smoothing effect stops abruptly a short distance from the hole in approximately the position I would expect considering the short chamfered lead and inward tapered profile of the F.S. Chamber. However, as always such interpretations are open for debate

Some Sol 182 MAHLI focussing (size 180%):


I don't know how to accurately infer the quantity of tailings inside the hole by vision.

I love those! That is such a good idea!

Thanks! Nice, when others like the same things.

Here a preliminary before/after blink for the second drill hole. It is based on a slightly rotated sol 180 and a sol 182 MAHLI image.

The high resolution version of the final blink seems to be not yet downlinked.

Thanks again, Joe, those are just what we need. A displacement of 6.5 mm and a distance from MH to hole of 14.9 cm (from hole angular diameter and MH fov), together with a directly measured parallax angle of 0.15 degrees between rim and bottom, then gives 0.93 cm for depth from rim to top of tailings in hole.

An alternative method uses just the sol 180 MR image. The distance (using angular diameter and fov) was about 229 cm. The angle corresponding to the projected hole depth can be measured straight from the image as 0.15 degrees (that's just the angular depth of the far side of the hole). Using Joe's elevation angle of -49.19 degrees, that can be de-projected into an actual depth, assuming a vertical drill hole, of 0.89 cm.

Both of these are well below the stated drilling depth of 2 cm, so we can estimate that the tailings are around 1 cm deep.

Like Gerald says, the new MH image lets us directly compare this to the depth of the new hole.

Tough work, Fred!
So by assuming a cylindrical hole with radius 8mm we get a volume of about 2 cubic centimeter of tailings in the first hole (V = r² x pi x h).
The depth of the second hole from rim to top of tailings should be near 2.0 cm; if the hole turns out to be actually 5cm deep, as Paul suggested, we get a tailing depth of 3cm and a tailing volume in the hole of about 6 cm³.
This was the easier part.

Now, a before/after blink based on two Sol 182 MAHLI images, taken from almost the same position, is available:

A size adjustment of about 0.5% was necessary.

More info about the drilling in this press release.
The hole is 1.6 cm wide and 6.4 cm deep.

Given that this drill will have undergone test and trials to the nth degree, can we safely assume that the drilling resistance (based on the relationships of penetration depth for revolutions, force, torque etc) can provide an accurate assessment of the cohesion or 'hardness' of this rock?

from sol 182
the hand cam has some Z-axis depth maps
-- mind you they are jpg's so...
http://mars.jpl.nasa.gov/msl/multimedia/ra...mp;camera=MAHLI
---
http://mars.jpl.nasa.gov/msl/multimedia/ra..._DXXX&s=182
http://mars.jpl.nasa.gov/msl-raw-images/ms...0007S0_DXXX.jpg
and
http://mars.jpl.nasa.gov/msl-raw-images/ms...0003S0_DXXX.jpg

An image not quite trivially composed of the two sol 182 MAHLI images "overexposed" and this one:

So the floor of the second hole becomes visible.

Perhaps grossly, but given all the things the drill has to do, I suspect that making this sort of measurement was secondary at best.
See http://www.esmats.eu/amspapers/pastpapers/pdfs/2010/okon.pdf for a very interesting and detailed account of the drill mechanism design.

It's amazing what the designers had to think of to cover as many bad situations as possible and for the general day to day use.

MAHLI Sol 182 stereo:

Shadows may need some practice.

Sol 182 ChemCam blink: