In a recent post on the Logos Bible Software newsgroups (the news://news.logos.com/greek newsgroup), someone asked about using Tischendorf's apparatus.

I'd be remiss if I didn't mention where you could purchase these tools. There are two primary tools discussed below. The first is the Stuttgart Electronic Study Bible (SESB), available from my employer, Logos Bible Software, in the US. The second is the Novum Testamentum Graece Apparatum Criticum, also available from my employer. A third helpful tool (not discussed below) is Bruce Metzger's Textual Commentary on the Greek New Testament.

I also need to state that I'm not a text critic, simply an interested amateur. I may very well misinterpret (particularly if it requires translating Latin); if you have corrections for the below please drop a comment or an email to let me know what to fix.

The first thing one needs to realize when beginning to consult an apparatus to determine textual evidence is that these things have their own language, and until you take the time to learn that language, you'll wonder how anyone ever uses the things. The LDLS edition helps out because the wacky symbols are all self-defining via popup or context, and of course the MS sigla (and abbreviations) are defined via popup as well.

Anyway, I thought it might be helpful to look at one entry in both Tischendorf (hereafter simply 'T' unless context demands otherwise) and NA27 and see how they both say the same thing (yet, in this case, draw different conclusions). The verse in question is 1Ti 3.14. The verse is:

Ταῦτά σοι γράφω ἐλπίζων ἐλθεῖν πρὸς σὲ ἐν τάχει·

In T's text, the verse is:

Ταῦτά σοι γράφω ἐλπίζων ἐλθεῖν πρὸς σὲ ἐν τάχιον·

The NA27, of course, displays the text with apparatus sigla in red in the graphic below. Note that we're only discussing the variant for ἐν τάχει, not any of the other sigla.

You can see the replacement containment indicators around ἐν τάχει. If you hovered your mouse cursor over these in the LDLS edition, the variant content (see below) would show in a popup. And here's the text in T:

Tischendorf's text does not have any indicators around the variant. In order to know if there is a variant, you must scan the apparatus to see if there are any readings that T lists variant readings for. But before we get to T's apparatus, let's check out the NA27 apparatus. In the LDLS, the below green text would hover the MS information (content, century, location of MS).

There's so much going on here it isn't even funny. The degree to which the apparatus packs data is something that one just needs to get used to. First is the replacement indicator itself, reminding the user that this variant replaces the text under discussion. After that is a dagger, which indicates that the following variant was actually the primary reading in the NA25 edition. So we also know that for some reason the editors changed their minds on this one in the past 40 years or so.

So, "ταχιον" replaces "ἐν τάχει" for uncials Aleph, D (hand of the second corrector), F, G. Minuscules 1739 and 1881 also support the variant reading, as does the "Majority text".

NA27 lists the variants first, and at the end (the 'txt' reading) lists the MSS that support the reading that the NA27 editors agree with. In this case, they go with uncials A, C, D (original hand), P and Psi. Minuscules 33 and 81 as well as a "paucity" (small number) of other MSS support the NA27 preferred reading.

Where this gets interesting is to go back and track the dates of the MSS, to research their provenance, and to get familiar with their content and their reliability. There is no easy guide to this (wait ... check both Metzger The Text of the New Testament and Early Versions of the New Testament as well as Aland & Aland's Text of the New Testament), it just takes time and interest. But I'm guessing that the NA27 editors went with ἐν τάχει because they would rather rely on A C and D (original hand) instead of Aleph and D's second corrector.

Tischendorf surveys largely the same information but comes to a different conclusion (of course, he is somewhat partial to Sinaiticus (Aleph), and who could blame him?) Here's T's apparatus entry.

The first difference to note is that T lists his preferred reading (and support) first, and lists the variants after that. This actually makes T a little easier to use outside of his NT (that is, as a scrolling resource in the LDLS next to a non-Tischendorf Greek NT, like the NA/UBS text). For uncial support, he lists Aleph, D (corrected, no corrector number noted), F, G, K and L. So he's listed two uncials that NA27 didn't list. He also notes that uncials F, G and K have an orthographic variant (difference in spelling, not in meaning). They have ταχειον instead of ταχιον. Tischendorf also cites some supporting evidence from citations of the Church Fathers (Chrysostom, Euthalius, Theodoret and John Damascene (sorry, don't quite know that English translation).

For evidence against his reading, T lists the uncials A, C and D (original hand) just like NA27 does. He also adds P. Then a few miniscules. Note that 17 is equivalent with NA27's 33 (this information is available in the descriptive popup in the LDLS edition). 71 and 73 are other MSS that NA27 does not cite.

More interesting, T also cites other Greek editions. You can get this information in the print NA27 in the Editonem Differentiae appendix, but that's not in the electronic edition offered by the SESB. And it's a pain to look up in the print. But T informs us that both Greisbach and Lachmann use ἐν τάχει, the same reading that NA27 prefers. Of course, these two editions were pre-Sinaiticus so they didn't have that evidence to consider. My guess is that T went with ταχιον because he weighed the Sinaiticus (Aleph) readings as more reliable/important than successive editors (NA27) did; perhaps also the citations from the Fathers carried some weight in his mind. 

So, there you have it. Two different critical editions, two different apparatuses. They weigh much the same information (for this particular variant, anyway) and come to different conclusions. But, importantly, they've listed their evidence and allowed the reader to consider the same basic information that they had to hand. We don't have easy access to facsimiles of the actual MS to consult (though some are available and Comfort & Barrett's The Text of the Earliest New Testament Greek Manuscripts is coming), but we can see at large what evidence the editor weighed and the decisions made.