# Talk:Logarithmic Scale and the Slide Rule

### Active Comments

**Great things about this page**

- Great introduction. It not only sets up the context for what makes slide rules useful, but does it in a really amusing way. Nice work!
- Great historical context for logarithms.
- The section describing how slide rules are set up (beginning of the more mathematical explanation) has a really good blend of general principles, examples, and images.

*Abram, 6/16*

**Remove one step from the beginning of the more mathematical explanation**

Describing this process as replacing x with log base 2 of 2^x, and then dropping the log base 2, is unnecessarily confusing. Instead, just say that x is replaced with 2^x. It won't change the rest of your argument at all. (Abram, 6/16)

- I don't quite agree. People will ask why replace x with 2^x? It is a jump in process. Xingda 6/18
- Simply dropping the from expressions is equally mysterious. Either way, you end up just replacing one number with a different number (and in fact, either you end up replacing x with 2^x) without a particularly good reason . Is there a reason why you think this intermediate step is helpful? (Abram, 6/21)
- Issue addressed (Xingda 6/30)

- Simply dropping the from expressions is equally mysterious. Either way, you end up just replacing one number with a different number (and in fact, either you end up replacing x with 2^x) without a particularly good reason . Is there a reason why you think this intermediate step is helpful? (Abram, 6/21)

**Explain what slide rules are good for**

Even if it's clear why logarithmic scales are useful, that doesn't tell you what sorts of things a slide rule is useful for. For instance, if you describe an actual problem that is made easier by use of the properties of logarithms, explain how slide rules facilitate the solution. Maybe you are going to also address this question somewhat in the "operating principles" section? If so, awesome, but also give some idea of what you could do with a slide rule earlier in the page. (Abram, 6/16)

- Make sure that your operating principles not only describe how to use slide rules, but also give examples of the kinds of calculations engineers would use their slide rules for. (Abram, 6/21)
- Issue addressed (Xingda 6/30)

**Include mouse-over definitions**

You can assume readers know what logarithms are, but include a mouse-over when you refer to the change of base property and possibly also for the word "identity". Also, look for other places where a mouse-over might be helpful (I'm not sure if there are any). (Abram, 6/16)

- I referred the readers to the logarithms (Xingda 6/30)

**Make the history-section more image-heavy**

One easy way to do this is to replace some of your text with a timeline (see the Buffon's Needle page for an example). (Abram, 6/16) I put some pictures up. I will try timeline. Xingda 6/22

- There are timeline templates on mediawiki but we cannot put picture there and they look really ugly. Do you want it to look like that? We need to talk about it. (Xingda 6/30)

### Archived Comments

**Explain why logarithms and logarithmic scales are so useful**

When you have a quote like, "My Lord, I have undertaken this long journey purposely to see your person, and to know by what engine of wit or ingenuity you came first to think of this most excellent help unto astronomy", it's not clear what's so amazing about logarithms. It's *great* that you describe that logarithms let you solve equations of the form b^x = k. It would be really helpful to have an example of the kind of problem that is made much easier by use of *properties* of logarithms.

You do this abstractly when you talk about transforming multiplication problems into addition problems, but an actual specific computation that some astronomer would actually have found useful would be great.

It would also be helpful to explain why we sometimes use logarithmic *scales*. For instance, we use pH as an index of acidity, but why do we bother taking the negative log of the H+ concentration instead of just reporting H+ concentration directly? (Abram, 6/16)

- General Comments: I don't know how to talk about the history before I even present the John Napier and Henry Brigg's original works. No one is going to appreciate the ingenuity of its invention unless they know how it was done. Maybe I should truncate this history part and give details in The Logarithms, Its Discovery and Development?

- I think you made a really good decision by moving the extended to the history of the page, and this also allows you to avoid giving lengthy descriptions of what logarithms are good for. (Abram, 6/21)