Tuesday, September 12, 2006


BRIAN WRITES... Hey Jim, I always thought that the closer you get to the equator, the hotter the temperature. However, Mexico tends to be much more mild than here in Texas, even though Texas is more northern. What in the world is going on?

First of all, let us define our terms properly. When we refer to Mexico, we will be using weather data from Mexico City in southern Mexico. When we refer to Texas, we will use weather data from Austin, a town in northern Mexico as seen in the map of Mexico from 1851.

Latitude is only one of many factors that influence weather. Mexico is cooler than Texas only in the summertime. In the winter, Mexico is warmer. Let’s take a look at some average high temperatures for Austin and Mexico City.

Austin’s hottest months are June, July, and August with average monthly highs of 91, 95, and 96, respectively. Mexico City, on the other hand, has it’s hottest weather in April and May with monthly average highs of 79.

In the winter, Austin’s coldest month is January, with an average monthly high of 60, while Mexico City’s average monthly high is 70.

So Mexico’s weather is milder in all seasons. The reason for this is, besides latitude, major factors that influence weather are oceans, prevailing winds, and terrain. As Mexico city is closer to the Pacific in a latitude that has prevailing westerly winds, its temperatures are modified by the cool Pacific Ocean. Austin, on the other hand, is many miles from the Pacific and has much land and many mountains between it and the Pacific. Even though Austin may be close to the Gulf of Mexico, with the wind coming out of the west, the Gulf has little influence on Texas’s weather.

The same moderating affects can be seen when you compare weather in Europe with weather in North America. Paris, which has relatively mild winters is on the same latitude as International Falls, Mn., which has incredibly harsh winters. That is because Paris’s weather is greatly influenced by the warm Gulf stream that flows from the Caribbean, up the eastern seaboard of the U.S. then across the Atlantic from Virginia to Ireland. That was one of many factors that left the Pilgrims so il-prepared for such harsh winters when they arrived at New England. They had no way of knowing the winters would be so much harsher even though they were actually south of their homeland.

Wednesday, September 06, 2006


JUSTIN (SAME NAME AS YOURS) WRITES... How does the cable TV company know how many TV sets I have hooked up to their service? I called them about a service question and they knew I had 3 without me telling them.

Well Justin (same name as mine), welcome to Ask Jim. I’m not sure I can tell you technically how they can tell you how many TVs you own, but I can give you a guess as to some of the methods they might use. These are going to be guesses based on electronic systems, such as fire alarm and security, that I have installed in the past.

One thing that is not clear in your question is what equipment you have. For instance, do you have a cable box? Do you have a cable box for every TV? Lets start with the assumption that you have one cable box for each TV. Each cable box will probably have some type of internal address like an electronic serial number. The cable company will send out electronic probes that will look for these electronic serial numbers. As each cable box is “pinged” it will answer back with it’s own address. Depending on how sophisticated the inquiry is and what information the box tracks and stores, it could be telling the cable company when the TV is on, what channels are watched and when. I’m not real sure how they would determine a specific address belongs to a TV in your house as opposed to the house next door unless they assign that address to you when they first install the cable and box in your home. Often there is a SKU number on the box somewhere that they can scan (or just write down the number). That way they have your box number in their system. This would be the simplest of scenarios.

Now let’s assume you have one cable box that feeds all three TVs. In that case, the cable box probably has the capability of monitoring it’s output. One brand of fire alarm system I have installed has the ability to not only poll all the devices installed and ask them what status they are in or command them to take a certain action, but the system can tell how much wire is between each device and where, in the circuit, there are splices. This is done by measuring minute differences in voltage and current.

There is also the possibility that there is something in each television that the cable company can “ping” that will tell them how many televisions are in your household.

Ever since there has been cable television, there have been people trying to steal it. I’m sure the cable company has gone through great lengths to detect unauthorized televisions on their system, not to mention the vast sums of money they could make my selling such information as number of TVs in a household and what they watched and when they watched it. (Not that they would ever actually do that, would they?)

Friday, September 01, 2006


NEIL WRITES... If you put a coin on the track of a small commuter train, what will happen to it? I ask this because when certain persons have done this very act nothing is left but a dark smear and a faint image (not indentation) of the coin in the polished steel of the track. It appears that it is effectively vanishes, but surely a small commuter train isn't sufficient to do that, is it?

Yes, it is!

I’m sorry, I just couldn’t resist. Actually putting a coin on the track, especially a commuter train, is a very dangerous practice. If the train hits the coin at the right angle and speed, the coin can actually de-rail the train. Such was the case in September of 1984 in Birmingham, England. The eastbound train to Liverpool had just reached it’s cruising speed of 63 miles per hour. It is suspected that young children from a nearby schoolyard had put a shilling on the track to see what would happen. When the train hit the coin, the second car jumped the track dragging the rest of the train with it. Thirteen people and three sheep were killed and no one ever found out who put that shilling on the track. The only trace of the coin was a dark smear and a faint image (not indentation) of the coin in the polished steel of the track.....

Okay, okay, I’m sorry. It must be the coffee talking. The real answer is the coin gets thrown off the track. You have to do some searching to find it, but it is there. I’ve never put a coin on the track of a commuter train before, but when my larvae were young, we would put coins on the track of regular trains and they would get flattened and thrown a few feet from where we put them on the track. Sometimes it would take a while to find them and occasionally we would lose one, but most of the time they showed up.