Firing distance of the Heat Ray

[jeffwaynefan]

Im curious to know if there has been anything bought forward regarding the distance travelled by the Heat Ray. I now its a complete work of fiction, but since it publication in 1897, has anyone ever come to any conclusions to how far the 'beam' could travel - such as taking out a object at 2000 yards for example.

H_C

[Gerkinman]

I guess being a beam of pure heat it would keep going till it hit something or until it cooled down.

[lanceradvanced]

It has a minimum range of around 2 miles, as the martians are able to clip the narrator's house, from the pit on the common..

But the trouble was the blank incongruity of this serenity and the swift death flying yonder, not two miles away. - How I Reached Home

I and my wife stood amazed. Then I realised that the crest of Maybury Hill must be within range of the Martians' Heat-Ray now that the college was cleared out of the way. - The Fighing Begins

[Topaz]

Air will absorb radiated heat (infrared energy) a bit, so the air immediately in the beam would heat up. Once it does, the index of refraction changes and the beam starts to 'bloom' or spread out as if by a weak lens, dissipating the energy. Then as the air heats further, you get convection currents and turbulence that increase the blooming. This effect is minimized if you keep the beam moving around, as it keeps the air from heating up. The higher the power, the worse the effect, I'm afraid.

Mineral dust and haze in the air can scatter the beam, as well.

The M-THEL mobile tactical laser system is supposed to have a range of up to five miles, so I'd guess the 'range' of the heat-ray would probably fall in that ballpark as well.

Here's a link to THEL and M-THEL:

www.military.com/soldiertech/0,14632,Soldiertech_MTHEL,,00.html

[jeffwaynefan]

lanceradvanced said:

It has a minimum range of around 2 miles, as the martians are able to clip the narrator's house, from the pit on the common..

But the trouble was the blank incongruity of this serenity and the swift death flying yonder, not two miles away. - How I Reached Home

I and my wife stood amazed. Then I realised that the crest of Maybury Hill must be within range of the Martians' Heat-Ray now that the college was cleared out of the way. - The Fighing Begins

Thats what I had in my mind about the distance it covered, thinking if it could reach this far, how much farther could it have gone.

[lanceradvanced]

Horsell_Common said:

Thats what I had in my mind about the distance it covered, thinking if it could reach this far, how much farther could it have gone.

The only other clue I can think of in the text, is with regards to the battle on the 4th day, when they use the black smoke...

This they did with the vapour banks near us, as we saw in the starlight from the window of a deserted house at Upper Halliford, whither we had returned. From there we could see the searchlights on Richmond Hill and Kingston Hill going to and fro, and about eleven the windows rattled, and we heard the sound of the huge siege guns that had been put in position there. These continued intermittently for the space of a quarter of an hour, sending chance shots at the invisible Martians at Hampton and Ditton, and then the pale beams of the electric light vanished, and were replaced by a bright red glow.

If the martians targeted responded directly, and didn't move, the distance between the points refrenced would be a good guess, but it's chancey, as the martians could have moved, or other martians closer could have responded...

[Lensman]

Topaz said:

The M-THEL mobile tactical laser system is supposed to have a range of up to five miles, so I'd guess the 'range' of the heat-ray would probably fall in that ballpark as well.

Actually, it's not a laser. One heat ray waved around quickly sets fire to an entire section of woods. It's a narrow cone-shaped beam, not a line like a laser.

It peters out after about 2 miles because the effect lessens as the beam spreads out.

"and as the unseen shaft of heat passed over them, pine trees burst into fire, and every dry furze bush became with one dull thud a mass of flames. And far away towards Knaphill I saw the flashes of trees and hedges and wooden buildings suddenly set alight." --Book one, Chapter 5

"the beam swung close over their heads, lighting the tops of the beech trees that line the road, and splitting the bricks, smashing the windows, firing the window frames, and bringing down in crumbling ruin a portion of the gable of the house nearest the corner.

"In the sudden thud, hiss, and glare of the igniting trees..." --Book one, Chapter 6

~~~~~~~~~

BTW, a laser beam may ionize the air, but that does not make it spread out significantly. If you want a laser beam to spread sigificantly over a distance of a few miles or less, you have to shine it thru a lens or other object which will cause it to spread.