Scotty was prompted to use mouse

I agree about the transparent aluminum not being necessary except for movie special effects. But Scotty was PROMPTED to use the mouse. He first addresses the computer then Dr. Nichols says he should use the mouse, THEN Scotty picks up the mouse and addresses the computer. Finally Dr. Nichols says to use the keyboard and Scotty says _How quaint._ One of the funniest scenes in the movie.

not transparent aluminum

The guy from the plexiglas factory said it would take *years* to devolop the transparent aluminum. Scotty and Bones probably traded the formula for some of the plexiglas they had in stock, since they wouldn't have been able to pay for it otherwise.

McCoy pointed to it

When Scotty first sat down he did begin talking. When the computer did not respond, McCoy pointed to the mouse. Scott then picked up the mouse thinking it was a microphone. Whether McCoy made the same misinterpretation remains a mystery.

Transparent aluminum not used

The material used for the whale tank was not transparent aluminum. The manager of the plexiglass factory said is would take years to develop. The material was (drumroll please...), plexiglass, which is transparent. The formula for transparent aluminum was given to the manager in *exchange* for the plexiglass Scotty needed (since they had no money), thus giving rise to the whacked out Scotty/computer scene. As to why Scotty picked up the mouse...who knows. Maybe because it was there.

Does anyone watch movies anymore?

Do any of you nitpickers watch a scene before you nitpick it? Let's get the easy stuff out of the way: Scotty was prompted to use the mouse after he already started talking to the computer, and he was prompted because McCoy thought that since the computer didn't understand out-loud voice commands, the mouse might have been a microphone. Don't ever try to nitpick that point again. The material surrounding the whale tank was transparent so the whales would have light in their temporary tank; had they used an opaque material, the sudden change from the open, lighted ocean to the small, totally dark temporary tank would have been too much. The transparent aluminum was used as barter material to obtain the acrylic plastic sheeting to transport the whales.

Plain Aluminum Not The Point

Sure, plain aluminum would have worked, but it would've cost in the thousands of dollars for enough to build a tank 30' x 60' x 10' high (18000 cubic feet), and they had no money. So the technology of transparent aluminum was a bargaining tool to get clear materials to construct the tank, because transparent sheets of something was the desired choice, and not for the benefit of the audience either. Being able to see how the whales are doing was a design requirement, and the height of the tank was taking up most of that deck anyway. So they couldn't be viewed from above the tank. Viewing the whales, plus the whales seeing their own caretakers, was a requirement implied in the theme of being concerned for the whales welfare, and comforting them during the stress of the unusual journey.

What to Make a Tank Of

To the commentors stating that having the tank's sides being transparent was a design requirement, did it ever cross your mind that 23rd century humans (as well as the Klingons of that time) know of the magic secret of cameras and viewscreens, while whales usually prefer using their sonar over eyesight?

The one and only reason for the tank sides to be made transparent was that that's the material the plexiglass factory had at hand. If they had had time to have that factory buy appropriate material instead of grabbing whatever is in stock, the material of choice (cheap, sturdy, no need to withstand rust for more than a couple hours) would've been steel. That's why so many constructions visible in 20th century Bay Area used that material, too. Not to forget that that makes the required tools more readily available as well.

Why they concluded the bargain with a plexiglass factory in the first place, instead of one that would be more used to processing aluminium, or at least metals, is admittedly unclear. However, in order to avoid a time paradox, they would be required to give the advanced technology to the very same company that is reported to have "invented" it in their history databases, which would explain it rather neatly.